Content Differences Content Differences for Abstract and Concrete Concepts Katja Wiemer-Hastings & Xu Xu Northern Illinois University, DeKalb Running head: Abstract and Concrete Concepts Please address correspondence to: Katja Wiemer-Hastings Department of Psychology Northern Illinois University DeKalb, IL 60115 Phone: 815.753.5227 Fax: 815.753.8088 Email: katja@niu.edu 1 Content Differences Abstract The content of 36 abstract and concrete noun concepts was explored and compared in a feature generation task with 31 participants. Abstract concepts had significantly fewer entity properties, more properties expressing subjective experiences, and overall less specific features. Situation properties generated for abstract and concrete concepts differed in kind, but not in number. Abstract concepts were predominantly related to social aspects of situations, including agents. Abstractness emerges as a function of types and specificity of conceptual components. Systematic relations of conceptual content were revealed with context availability and imageability. The implications of the findings are discussed with respect to cognitive processes involving abstract concepts. Content Differences for Abstract and Concrete Concepts Abstract words, like indecision, difference, or consideration, are abundant in daily conversation. We use such words to describe, interpret, and explain events or circumstances in our social and physical environment. Abstract concepts contain a variety of categories each of which has sparked its own domain of research, including personality traits, behaviors and social cognition, emotions, cognitive processes, and events. As such, there is considerable interest in abstract concepts across disciplines within and beyond psychology. In spite of this, very little is known about their representation. Abstract entities are not experienced directly: they are not spatially constrained entities that we can see, or touch, or interact with. Instead, abstract concepts represent complex entities such as behaviors, scenes, or subjective experiences. Thus, they are more aptly described as constructs of the mind which represent and structure experiences. The instances represented by an abstract concept vary considerably. This is reflected in ratings of contextual variety which tend to be higher for abstract concepts (Galbraith & Underwood, 1973). For example, difference can refer to sensory units, such as the result of adding a bit of salt to a soup or a height difference, or to mental units such as two opinions. At first glance, abstract (e.g., difference) and concrete entities (e.g., bucket) are easily distinguished. However, researchers have struggled to outline exactly in what respect they differ. The obvious difference is that only the concrete things are physical entities with defined by spatial boundaries. This ontological difference has important implications. We 2 experience abstract and concrete things as qualitatively different – they seem to belong to different realms. As salient as this distinction may be, however, it mostly reveals what abstract concepts lack (i.e., physical substance, spatial boundaries). This leaves open the interesting question what abstract concepts do represent. The distinction of physical and nonphysical concepts is unsatisfying in a second regard: there are graded differences in concreteness. For example, people perceive scientist to be more abstract than milkbottle, and notion as more abstract than climate. Physicality, being a dichotomous variable, cannot easily explain the more subtle differences. What makes concrete concepts vary in concreteness? These questions motivate the research presented here. We explored the content of abstract versus concrete concepts by systematically analyzing participantgenerated features, to identify differences at a componential level. The analysis focused on the kinds of features that characterize people’s knowledge of concrete versus abstract concepts, the quantity of these features, and their relations to perceived concreteness and associated variables, such as imagery. Since a majority of concept processing models are based on the notion of conceptual components, this analysis is an important step in advancing our understanding of abstract concepts. Variables Associated with Concreteness Differences between abstract and concrete concepts have been studied in detail in form of concreteness effects on different kinds of processes. Generally, abstract concept processing is more challenging than concrete concept processing. Concreteness effects have been reported in a variety of tasks, including studies of learning, memory retrieval, comprehension, lexical decision, translation and semantic deficits. Imageability and context availability. The most influential theories that have been put forward to explain concreteness effects are the dual-coding theory and context availability theory. Both make distinct assumptions about storage of and access to abstract and concrete concepts in memory. Put in very simple terms, the dual-code theory assumes that concreteness effects are due to abstract concepts lacking a perceptual representation (Paivio, 1971; 1986), whereas the context-availability theory attributes concreteness effects to more relevant information stored in memory for concrete concepts, which facilitates their processing (Bransford & Johnson, 1972; Kieras, 1978). Ratings of Content Differences imageability and context availability tend to be highly correlated with concreteness (Paivio, 1986; Rubin, 1980; Schwanenflugel, Harnishfeger, & Stowe, 1988). However, the foundations for imagery and the nature of context effects in memory are not well understood. The basis for both is likely linked to conceptual content. The present analysis may thus shed light on why abstract concepts evoke less or no imagery, and why less information may be stored in memory for abstract concepts. A conceptual content analysis may also be able to resolve the interesting recent finding that concreteness and imageability, and concreteness and context availability are not consistently correlated for the entire range of concreteness (Altarriba, Bauer, & Benvenuto, 1999; Wiemer-Hastings, Krug, & Xu, 2001). While high correlations were found for word samples that span the entire concreteness range, the correlation patterns differed when calculated separately for concrete versus abstract words. In particular, imageability ratings were correlated with concreteness ratings only for abstract words (N=155; r=0.57, p<0.05), but not for concrete words (N=100; r=0.02) (Altarriba, Bauer, & Benvenuto, 1999). In contrast, the association between rated context availability and concreteness was much stronger for concrete words (r=0.68, p<0.05) than for abstract ones (r=0.25, p<0.05). Thus, context availability increases strongly with concreteness of physical items, but only little with concreteness of nonmaterial items. In a similar study with 18 abstract and 18 concrete items, we replicated this pattern for context availability (Wiemer-Hastings, Krug, & Xu, 2001). However, in this sample, neither ratings for imageability (r=0.33) nor ratings for context availability (r=0.17) were significantly associated with concreteness of abstract concepts. Both were significantly correlated with concreteness of physical items (imageability: r=0.48, p<0.05; context availability: r=0.58, p<0.05). The findings suggest a qualitative difference between abstract and concrete concepts, which coincides with the dichotomous physicality dimension. This difference may be the main contributor to the strong correlations that are observed for samples spanning both concrete and abstract items. Further, it seems that the main factor underlying ratings of imageability and context availability is predominately varying among concrete concepts, and that imageability ratings may further be influenced by a separate factor that predominately varies for abstract concepts. These hypotheses can be tested through correlations between these measures 3 and measures based on the features generated for abstract and concrete concepts. Ease of predication. Jones (1985) suggested in the context of dyslexia that imageability effects may be mediated by a semantic factor which he calls ease of predication, which is the ease with which individuals can access predicates of a concept. He found that rated imageability and ease of predication were highly correlated (r=0.88). However, this account is also unsatisfactory as an explanation for concreteness effects, because it is unclear how people rate ease of predication. It is possible that people base their ratings of ease of predication on the ease with which they can access an image (a related argument is made by de Mornay Davies & Funnell, 2000). Jones instructed his participants to ignore other factors than ease of predication in their ratings, but imagery may be an automatic process that mediates the participant ratings without their knowledge. Thus, ease of predication measures, too, require explanation at a fundamental conceptual level. Overview Knowledge of differences in the conceptual content due to varying concreteness could better explain concreteness effects, as well as provide a better understanding of imageability, context availability, ease of predication, and other variables related to concreteness. Further, a componential analysis of abstract concepts may allow for more sophisticated predictions in research involving such concepts, including encoding and recall, semantic relations, semantic access in priming studies, and categorical organization. What types of information may be involved in the representation of abstract entities like a thought or a goal? While our research is largely exploratory, we are building on a few earlier studies from which we have derived a few hypotheses regarding the content of abstract concepts. Psychological situations and action schemata. A large majority of abstract concepts are agent-centered; that is, they are strongly related to a person or group. This is true of large categories of abstract concepts, including emotions, cognition, actions and interaction, communication, character traits and attitudes, and others. Such abstract concepts would likely be associated with aspects of the internal and external context of the agent, such as behaviors, mental processes, another person, and states of affairs. The extent to which agents and agents’ contextual properties are part of the content of abstract concepts has not yet been subject of Content Differences systematic investigation. However, related analyses suggest that they likely are. For example, Hampton (1981) investigated the prototypicality structure of abstract concepts using a property generation task. Many of the generated properties describe a social situation involving an agent and agent-related aspects of the situation. Hampton suggests that abstract concepts would commonly involve behaviors, agent characteristics such as goals, and other aspects of a situation, consistent with our reasoning. Similarly, researchers on personality traits have proposed agents, agent characteristics, and agent experiences as abstract concept components (Chaplin, John, & Goldberg, 1988). Research on psychological situations has revealed quite similar components as the properties of situation prototypes, such as agents, their behaviors, and dispositions, as well as physical attributes such as states, and objects (Cantor, Mischel, & Schwartz, 1982). On the basis of these studies, we predicted that descriptions of abstract concepts would show a strong focus on an agent and agent-related properties, including cognitive and emotional states and behaviors. Subjective experiences. There is evidence that abstract concepts are linked closely to subjective experiences that are only accessible through introspection. Introspective features have recently been proposed as a necessary component of abstract item representation (Barsalou, 1999). For example, a concept like decision cannot be understood without having experienced the mental process of weighing two or more choices against each other in terms of their good and bad sides. A large number of abstract concepts involve such elements of subjective experience, which may be mental, emotional, or even physiological in nature. Recent data also show that such components directly affect the perceived concreteness of an item. The larger the proportion of an item’s introspective elements is (i.e., goals, interpretations, evaluations, or emotions), the higher people judge its concreteness (Wiemer-Hastings, Krug, & Xu, 2001). Based on this finding, we predict that people will list significantly more properties for abstract concepts that express subjective experiences of an event or a situation. Such a finding would further support the finding that concreteness is in part a function of introspective components, and it would indeed be stronger because the measure for the proportion of introspective content would be based on properties generated by the participants, whereas in the above study, it was based on the experimenters’ coding schema for abstract concepts. 4 Context variability. Abstract words occur in a larger variety of contexts, just as abstract entities can occur in a large variety of situations (Galbraith & Underwood, 1973). Contextual variability may be a factor underlying context availability differences for abstract and concrete concepts. Context may be less accessible in memory because the large number contexts stored with an abstract concept are competing for activation, or because contexts need to be actively generated during concept processing. Since abstract concepts represent instances from a larger variety of contexts, their features may place low constraint on context generation. A likely consequence of contextual variability is that abstract concepts involve components that are relatively unspecified, i.e., features that act like slots in a script or schema (Minsky, 1975; Schank & Abelson, 1977) that allow for a variety of specific attributes. For example, the restaurant script contains a slot for an agent bringing the menu to the table, for the type of food served in the restaurant, etc. Abstract concepts resemble scripts in that they refer to actions, goals, and agents at a general level. Thus, we expected that abstract concepts would be characterized by unspecific features. For example, an intuitive analysis suggests that difference occurs in contexts that contain any two or more items that can be compared on some dimension. At the extreme, perhaps some abstract concepts can be described as content-free schemata (Fiske & Taylor, 1991) in that they only specify abstract components and relations between them. Distinct versus graded differences. Abstract versus concrete items are typically defined dichotomously, as physical and non-physical items. Concreteness ratings are consistent with this view only to some extent. The consistent finding is that concreteness ratings tend to form a clearly bimodal distribution (Nelson & Schreiber, 1992; WiemerHastings, Krug, & Xu, 2001) with each mode centered in one of the two halves of the concreteness scale. This suggests a qualitative difference in representation which may be associated with distinct content elements that form part exclusively of either concrete or abstract concepts. This is in line with the finding that imageability and context availability correlate to different extents with concreteness ratings for abstract versus concrete concepts (Altarriba, Bauer, & Benvenuto, 1999). On the other hand, there are many degrees of concreteness, which suggests that there are additional concept characteristics that vary gradually across sections of the concreteness range. Thus, we expected to find semantic components which were exclusively named Content Differences for abstract or concrete items, as well as components which varied gradually with concreteness. Participants in our experiments received a property generation task for 36 nouns spanning the entire scale of concreteness. Property generation tasks have proved useful in concept research. Perhaps the best known example of this is the prototype research by Rosch and colleagues (e.g., Rosch & Mervis, 1975). Our focus of interest was on proportions of different knowledge domains in the content of abstract and concrete concepts, and whether these varied in a graded fashion, or whether there were realms of experience exclusively applicable to just either concrete or abstract concepts. While participant-generated features unlikely represent exact conceptual content, they should accurately reflect these types of knowledge and systematic differences in knowledge domains across the concreteness dimension. Features provide insight into only one aspect of representation. We acknowledge that by focusing on features, we are ignoring more complex aspects such as relations among features, or organizations of features according to individuals’ assumptions about entities, which play an important role for concept processing. However, our hope is that providing this groundwork will facilitate more complex research of this kind. Method Participants Thirty-one undergraduate students at Northern Illinois University participated in this experiment for course credit. All participants were native speakers of English. Materials We constructed a random set of thirty-six nouns, varying in concreteness across the concreteness scale. Words were sampled from an initial sample of 1993 nouns retrieved from the MRC2 database (Coltheart, 1981; Wilson, 1988). The database provided for all of these nouns familiarity ratings and concreteness ratings from a variety of norms. The concreteness scale was divided into six equidistant subsections to include words of all levels of concreteness. From each section, six nouns were sampled randomly but matched in familiarity across the concreteness levels. The complete list is shown in Appendix A. Our sample consists of items representing a variety of categories, including plants (tree), animals (mackerel), nonliving things (beehive), substances (venom), actions (removal), emotions (happiness), social processes 5 (emancipation), states (inaction), temporal concepts (day), communication concepts (story), and so on. The word sample was deliberately chosen at random across the concreteness range because our concern was with general trends of feature components as a function of concreteness, rather than types of concepts. A systematic comparison of instances of each of these categories would likely reveal further differences. Design Three sets of 12 items were constructed of the 36 words. Each set contained two words from each concreteness level, matched in familiarity. Each set was presented to a participant with one of three tasks. One task asked participants to generate features for each item. Another task asked participants to generate context elements that always occur with the given item. This second task was included to address the argument that abstract concepts are more strongly anchored in context information, whereas concrete concepts have a component that is independent of context. The two instructions allowed us to compare, between subjects, the number and kinds of features generated for these two conditions. To the extent that context is a natural part of a concept’s content, the instructions should not have a significant effect on the resulting properties. A third task was a response time measure for a related variable which we will not report here. Each word set was presented as first, second or third word set equally often, and was presented equally often with each of the tasks. Finally, task order was also counterbalanced. Within each set, words were presented in different random orders. The design thus included, as independent variables, word type (with six concreteness levels) and instruction (item versus context feature), both varied within participants. Analyses averaged effects across the word sets. The smaller sets of twelve items each were formed so that the task was doable in a reasonable amount of time. Ten participants generated features for each item in each condition. Procedure Data were collected in individual sessions. The experimenter read the instructions aloud. Instructions included examples ranging in concreteness that were not used in the study. Participants were given a practice trial with three words: one abstract, one concrete, and one intermediate word. After clarifying questions, participants started on the 12 words for this block. A standard list of near-synonyms for unknown target Content Differences words was provided to participants to not bias their answers by describing the items. All descriptions were tape-recorded with the participants’ consent. The experiment took between 20 and 40 minutes to complete. Participants worked on the two tasks in succession, with twelve of the items presented in each. One task asked participants to list properties for each item. Part of the instructions was repeated before every new item to remind participants of the main task. The intent was to reduce carry-over of processing strategies such as exhaustive scene descriptions to subsequent items. The instructions for the item feature generation task read as follows: “Please describe as exhaustively as you can what aspects characterize this object: (item)”. The instructions for contextual features were: “Please describe as exhaustively as you can aspects of a situation that MUST be true for this object to occur in it: (item)”. Results Analysis of Transcripts The recorded data were transcribed manually and then coded for types of knowledge. Only twenty-six of the transcripts were used in the analyses. The data from five participants were unusable for a variety of reasons, including misunderstanding of the instructions, experimenter error in the presented items, and most commonly, too many item omissions to include a transcript without biasing the results. Omissions were not necessarily due to unfamiliarity with words; a few participants struggled with descriptions of the more abstract items (e.g., aspect and exception). Coding of transcripts. The transcripts were parsed into feature units, which consisted for the most part of individual words. For a systematic evaluation and comparison of conceptual content, all features were coded using a coding schema that was developed based on feature occurrences in previous data analyses (Wu & Barsalou, 2004). The Wu and Barsalou coding schema was developed for coding features of concrete objects. This coding schema was chosen for two reasons. First, it allows coding of features for both concept types because it covers several domains of concept knowledge: item properties, situation properties, and introspective properties, which are aspects of a person’s subjective experience related to an item. As such, the schema covers all knowledge domains which were hypothesized to be of relevance for abstract concepts. Second, this coding schema has been successfully 6 applied in previous studies involving feature representations and has been shown to cover relevant aspects of conceptual knowledge (e.g., McRae & Cree, 2002; Cree & McRae, 2003). Entity properties describe the item’s characteristics such as parts, appearance, material, and characteristic behaviors. These properties cover the internal structure of a concept, as opposed to knowledge of associated items, actions and the like. For example, a tree’s item properties include roots, branches and leaves, green and brown colors, wood, growing, producing oxygen, etc. Situation properties cover knowledge of the context in which an item is used. This includes animate beings, actions, physical and social states, functions, locations, and other aspects. Situation properties generated for tree typically include animals such as birds and squirrels; water and soil; actions such as climbing or felling a tree; and functions such as producing furniture, making fire, or offering shade. Finally, introspective properties are produced when participants access personal experiences with an object. This can include emotional or evaluative responses, negation, representational states and more complex features such as contingencies and causal relations. Some of these properties are procedural in that they organize the feature descriptions (e.g., “if then”, or “not”). Others are more informative by themselves, especially emotions and representations. For tree, example experiential features may include evaluations such as valuable or beautiful. Strictly speaking, only entity properties are actual features of a concrete item. The other domains express knowledge surrounding the use and typical occurrence of an item. For example, when an agent is mentioned in describing a basketball (e.g., kids throw them through a basket), then kids are not a feature of the basketball. However, features such as situational and introspective ones indicate that a participant accesses knowledge about how the item is typically used, rather than just information confined to the item itself. This coding schema also accommodates taxonomic properties, such as exemplars, category membership, coordinates, synonyms, and the like. By listing features falling into this domain, participants describe an item’s characteristics by positioning it in relation to other items. Such statements reflect predicative knowledge about items, but they do not specifically reflect an item’s content, but rather how it is organized in semantic memory. For example, listing joy, a synonym, for happiness does not reveal any of its content, but only shows that the participant correctly understands the target. Content Differences Another indication for taxonomic properties not strictly expressing conceptual content is that many of the properties that could be classified as taxonomic could be double-classified in one of the other domains. For example, when generating fork for the target knife, fork is both a coordinate in the same category, and it is also an object that is found in the same context (thus, a situation property). Because of this, we coded features as item, situation or experience properties wherever possible. The items that were coded as taxonomic were analyzed separately. Slightly more taxonomic properties were mentioned for abstract items than for concrete items, but this difference was only marginally significant in a subject analysis (F1(1, 25)=4.21, MSE=0.19, p=0.051). Individual analyses of the taxonomic properties reveal that this is mostly due to more coordinate terms and synonyms being listed for abstract items. The feature lists for all words were coded by one of the authors. Only one person used the coding schema so that the codes would be used consistently. Beforehand, a subset of features were coded by both authors to discuss the use of the schema categories and to establish clear coding guidelines. Many features were coded by assigning a code to individual words; in other cases, a code was applied to a proposition. Items belonging to a proposition were marked with a “\”, and only the last word belonging to that feature was coded using the feature code. Examples for one coded concrete and one coded abstract item are shown in Appendices B and C, respectively. Feature summary scores. We evaluated differences between abstract and concrete conceptual content based on type and token measures for the broader knowledge domains (i.e., object vs. situation vs. experience features) and for the subcategories within the situation domain. Types refer to the different feature categories mentioned for a word; tokens refer to the number of instances that a particular feature category is mentioned for a word. Thus, the type scores show how many kinds of features were used for a word, but not how often. This score is useful in evaluating the complexity with which participants flesh out the features related to an item in each of the domains. For example, a situation type score of “1” would indicate that people on average only refer to one type of situation property (e.g., an action), whereas scores of “3” and higher suggest that a scenario is described (e.g., a person, an action, and an object). The token score reflects more accurately the proportion of features generated for a word that fall 7 into the different categories. Variation in these scores can be quite informative. For example, people might list fewer parts for a less concrete object, or a situation for pity is likely to involve two persons, so that the person code would justly apply twice. Tokens did not count an item more than once when it was evident that it referred to an identical element; e.g., “an object”, “it”, “it” may all refer to the same object and were not counted as three occurrences of a situation object, but as one. The type scores depict more schematic, ontological characteristics of the items. Category scores summed up the number of its subcategories used to code the feature list for a word. Category type scores counted just the number of different subcategories mentioned, whereas category token scores also counted individual instances for each. Likewise, the subcategory token score counted how often each subcategory was used for a given word and participant, whereas the subcategory type only counted whether or not a subcategory was used, resulting in scores of either 1 or 0. Category Type Analysis The mean number of situation, entity and introspective features are listed in Table 1. These scores are absolute scores, meaning that they do not present the proportions of features mentioned overall that fall into each category. Proportion scores do not make much sense here because the tokens were not counted, and thus the type measures do not accurately reflect the actual proportion of features generated for each domain. A weighed type score was calculated additionally which divided all scores by the number of subcategories in their respective knowledge domain. As can be seen from Table 1, the scores in the situation domain are much larger (if not weighed) than those in the other two domains. In fact, participants used altogether 16 types of situation properties, 11 types of entity properties, and only 6 types of experience-related properties. The weighed scores presented in Table 1 indicate the proportion of the kinds of features in a domain that were, on average, presented by the features generated by a participant in the different instruction conditions. Analyses were performed on the original type scores. How did abstract and concrete concepts differ with respect to the kinds of features generated? Domain differences were confined to entity and experience-related properties. There were no concreteness effects on situation properties. Instructions to generate relevant context features (as Content Differences opposed to item features) increased the number of different kinds of situation properties only marginally (subject analysis only: F1(1,25)=3.51, MSE=1.66, p=0.07). Thus, only few participants used additional situation properties to the ones used to describe item features when their direction was focused on the context. This suggests that participants access roughly the same number of different types of situation knowledge for abstract and concrete concepts. Whether these types are the same for concrete and abstract concepts is not evident from this analysis; we will address this question below. Further, the data suggest that shifting participants’ focus from items and their features to features of the context does not appear to increase the number of different kinds of situation knowledge. Again, this does not show whether participants use the same types of situation properties in each case, or whether they switch them. It does show, though, that the complexity of situation properties that are generated does not increase. As expected, significant differences were observed between abstract and concrete concepts both in the number of types of entity and experiential features. First, participants generated significantly more kinds of entity properties for concrete than for abstract concepts (F1(1,25)=27.67, MSE=0.36, p<0.001; F2(1,34)=21.31, MSE=1.16, p<0.001). Instructions to generate item features increased the number of kinds of entity properties, but only significantly for concrete items: a significant interaction was found for item concreteness and instruction, F1(1,25)=22.90, MSE=0.33, p<0.001; F2(1,34)=8.97, MSE=0.51, p<0.005. Thus, in general, when participants focus on an object’s context instead of on the object itself, they appropriately list fewer item properties. At the same time, they still make significantly more mention of entity properties when asked to describe the context, suggesting that the concrete target object may dominate in the process of activating situation knowledge. This difference is critical for our understanding of abstract items, since entity properties are the only internal features of items. The data show that for abstract items, predominantly situational features are mentioned, suggesting that these concepts are firmly entrenched and not separable from events and states in a situation and subjective experiences associated with these. This is of course consistent with the typical definition of abstract items as nonmaterial entities. In fact, it is surprising that any entity properties are listed for abstract concepts at all. A closer look at the kinds of 8 entity properties shows that such properties were only listed for items of the “somewhat abstract” group. For many of these, it may be argued that the features coded as entity properties may be coded as situation properties more appropriately. These include “parts” listed for story and saga such as beginning, climax and ending, plot, etc., all of which could alternatively be considered social artifacts. Clearly, these are as little material as the targets themselves. Possession, too, yielded some entity properties such as “my initials on the bottom”, where possession was treated as a specific object. A reverse pattern of differences was obtained for experience-related features. Participants listed significantly more different introspective features for abstract than for concrete items (F1(1,25)=76.99, MSE=0.24, p<0.001; F2(1,34)=20.09, MSE=0.64, p<0.001). This difference, too, was robust across instructions. Interestingly, the proportion of experience-related features was increased significantly when participants were instructed to generate context features (F1(1,25)=4.72, MSE=0.48, p<0.05; F2(1,34)=10.58, MSE=0.17, p<0.005). Thus, as participants focus on an item’s context, they appear to access more differentiated information about mental processes and states, such as goals, emotions and so on. An average of one experience-related property was generated for each abstract target. This suggests that subjective experience is a regular aspect of such concepts, rather than knowledge that is occasionally activated when processing the concept. We also looked through the codes to examine more closely what kinds of experience-related properties were generated by participants for concrete items. Such properties were listed predominantly for a few specific targets, most notably, for labyrinth and prize. A mental state like confusion was listed quite regularly for labyrinth; likewise, emotions were frequently mentioned for prize. About half of the features coded as introspective were more procedural in nature, indicating feature contingencies and negated features. Entity and experiential properties across the concreteness scale. Do different knowledge domains apply dichotomously either to abstract or to concrete concepts, as suggested by simplified definitions along the physical / not physical dimension, or are there gradual differences that may account for the large variation in perceived concreteness? In previous work, it was found that particularly the proportion of introspective (or experiential) properties is significantly correlated with rated concreteness of abstract items, suggesting that abstract items vary Content Differences gradually on this dimension. Similarly, an object with many internal features may be perceived as more concrete. Thus, we may expect to see an increase in the proportion of experience features within the abstract target sample as items get more abstract, and an increase in the proportion of entity features for concrete items as these get more concrete. We observed before that there are items that seem to be somewhat concrete and somewhat abstract. It may be that there is a grey range in the middle of the scale where items would be described by a mix of features that are typically part of abstract or concrete items. We plotted the proportions of entity and introspective features across the six concreteness levels for easier comparison. They are displayed in Figure 1. The Figure does not suggest a dichotomous break in the types of features predominantly activated for abstract versus concrete concepts. Rather, it seems that only concepts at the two most concrete and the two most abstract levels have clearly distinctive conceptual content. Very concrete concepts contain a large amount of item properties and evoke few if any experiential properties. In contrast, experiential features are regularly part of very abstract concepts, for which few if any concrete item properties are produced. The relation between the number of properties (tokens) expressing knowledge about entities (r=0.74) and experience (r=-0.69) to concreteness ratings was significant in a correlation analysis (p<0.01 for both). That is, the more concrete a concept is, the more entity properties and the fewer experience properties are generated. The concepts rated as somewhat concrete and somewhat abstract have a lower proportion of both entity and experiential features. By exclusion, this means that their conceptual content may be largely dominated by situation properties. Further, the amount of experiential and entity features is almost balanced for these concepts: they contain a few concrete properties, but also knowledge that is experiential in nature. Subcategory type analysis for situation properties. The analyses at the category level did not reveal a difference in the number of different situation properties generated for abstract versus concrete concepts. This could indicate that situation properties do not distinguish between abstract and concrete concepts. On the other hand, differences may be hidden at the finer level of subcategories. To test for this possibility, we examined whether there were specific subcategories within the situation knowledge domain that would be mentioned 9 significantly more often for one of the two concept types. For abstract concepts, we expected to see frequent mention of a person, actions and events, and social categories. In contrast, we expected that more concrete situation elements such as objects, buildings, locations, physical states and the like would be more central to concrete concepts. Table 2 shows the type scores obtained for concrete and abstract concepts for the situation subcategories. All these scores vary between 0 and 1. They indicate whether, on average, a feature of each given subcategory was generated. Seven out of the 14 categories listed (two categories were not included in this analysis: quantity, because it is not readily interpretable, and manner because of no occurrences) revealed significant differences in the extent to which the feature was mentioned for abstract versus concrete concepts, across items and participants. For the most part, the patterns are consistent with our expectations. In particular, abstract concepts are clearly centered around a person most of the time, whereas concrete concepts only mention an agent a third of the time (F1(1,25)=37.03, MSE=0.11, p<0.001; F2(1,34)=14.13, MSE=0.29, p<0.01). In terms of the scores, actions and a person are the most frequently mentioned situation properties for abstract concepts (M=0.84, averaged across instructions). This means that on average, participants mentioned an agent and an action for 8 out of 10 abstract items. Actions were also mentioned considerably more often for abstract than for concrete concepts, but this difference only approached significance in the subject analysis (p=0.11 or p=0.07 for item and subject analysis, respectively). Less frequently used properties mentioned more often for abstract concepts were social states (M=0.23) and social artifacts (M=0.16). Social states are mentioned close to never for concrete concepts (M=0.02; F1(1,25)=46.23, MSE=0.03, p<0.001; F2(1,34)=11.63, MSE=0.07, p<0.005), neither were social artifacts (M=0.02; F1(1,25)=25.24, MSE=0.02, p<0.001; F2(1,34)=6.52, MSE=0.05, p<0.05). Thus, social concepts can be considered quite distinctly associated with the contents of abstract concepts. All these situation elements are consistent with suggestions made in previous research (e.g., Hampton, 1981) on the content of abstract concepts, such as agents, behaviors, and social aspects. For concrete concepts, the most frequently mentioned situation properties that were mentioned significantly more often than for abstract concepts were objects (F1(1,25)=29.56, MSE=0.09, p<0.001; F2(1,34)=5.09, MSE=0.33, p<0.05), location (F1(1,25)=16.19, MSE=0.05, p<0.001; F2(1,34)=4.92, Content Differences MSE=0.14, p<0.05), living things (F1(1,25)=56.81, MSE=0.08, p<0.001; F2(1,34)=10.27, MSE=0.24, p<0.005), and a function (F1(1,25)=12.10, MSE=0.02, p<0.005; F2(1,34)=4.05, MSE=0.05, p=0.05). Thus, out of the 14 situation properties, seven are mentioned significantly more often for either abstract or concrete items. Three of the remaining items, actions, social organizations, and spatial relations approached significance. Buildings were mentioned so rarely that no differences emerged. The analysis at the level of individual properties shows that while both abstract and concrete concepts are described in terms of situations, they seem to activate aspects of context that are to some extent distinct. If we were to summarize these, the best description for abstract item specific situation properties would be socially relevant aspects (agents, behavior, social states, social artifacts), whereas those for concrete items would be item predicates (e.g., function and location) and co-occurring concrete items (living things, objects). These separate aspects reflect the ontologically different domains of things material and nonmaterial. The data suggest that abstract and concrete conceptual content does not converge on the level of situation knowledge, but that each are associated with (or contain) different aspects of situations. Category Token Analysis The patterns for types were repeated for tokens. As a reminder, tokens measure the overall number of features generated for an item in a domain, regardless of the number of different kinds of properties. Different features for a type of property are counted separately in this analysis; so, for example, if a participant lists eight different parts for an object, then the token for parts will be 8. The average number of tokens generated within each knowledge domain, entity, situation, and experience, are summarized in Table 3. Consistent with the results for types, there was no effect of the concreteness level on the number of situation properties. Instructions to describe the context increased this count. This difference was significant only in the subject analysis (F1 (1.25)=4.32, MSE=2.30, p<0.05). As before, there were main effects for concreteness on the number of entity and experiential features generated. Participants listed significantly more entity properties for concrete items regardless of instruction (F1(1,25)=72.13, MSE=0.64, p<0.001; F2(1,34)=24.08, MSE=1.28, p<0.001). A main effect 10 was also observed for instruction, but as the data clearly show, this was due to a large change only for the concrete items. The interaction was significant, with more entity properties listed for concrete than abstract items, and more for concrete items that were listed under feature instructions (F1(1,25)=20.90, MSE+0.34, p<0.001; F2(1,34)=7.82, MSE=0.56, p<0.01). So, when asked to list features that are true of an abstract concept, participants list on average one entity property for every fifth item, whereas they list an average of two per concrete item. For experiential features, we once again observed the reverse pattern. Abstract concepts evoked significantly more knowledge involving subjective experiences than concrete concepts across both conditions (F1(1.25)=69.72, MSE=0.34, p<0.001; F2(1,34)=22.15, MSE=0.77, p<0.001). Furthermore, instructions to focus on context increased the number of experiential properties for both abstract and concrete concepts. This effect was significant only in the item analysis (F2(1,34)=9.09, MSE=0.19, p<0.01), the subject analysis revealed a marginal effect, p=0.08. Subcategory token analysis for situation properties. The token scores showed stronger differentiation for situation properties of abstract versus concrete concepts, particularly in the subject analyses. Items were analyzed in a mixed ANOVA with item type (abstract vs. concrete) as betweenitem and instruction (features vs. context) as withinitem factor. The subject analyses were a withinsubject analysis with item type (abstract vs. concrete) and instruction (features vs. context) as repeated measures. Table 4 shows the mean number of tokens obtained for each situation property, separate by item type and instruction. The first five situation properties listed in the table were all mentioned significantly more frequently for abstract than for concrete targets, including person (F11,23)=29.12, MSE=0.37, p<0.001; F2(1,34)=14.82, MSE=0.64, p<0.001), action (F1(1,23)=5.36, MSE=0.22, p<0.05; F2 marginal effect, p=0.08), social state (F1(1,23)=38.56, MSE=0.03, p<0.001; F2(1,34)=9.79, MSE=0.09, p<0.01), and social artifacts (F1(1,23)=19.95, MSE=0.02, p<0.001; F2(1,34)=6.39, MSE=0.06, p<0.05). These results are consistent with the type analysis except for actions. These were mentioned more repeatedly for abstract concepts, whereas its type score had not differed as a function of concreteness. Concreteness effects were observed for six further situation properties, which were mentioned significantly more often for concrete concepts. These were object (F1(1,23)=12.54, MSE=0.12, p<0.005; F2 Content Differences only marginal, p=0.11), location (F1(1,23)=15.34, MSE=0.07, p<0.005; F2(1,34)=4.42, MSE=0.16, p<0.05), living things (F1(1,23)=35.86, MSE=0.10, p<0.001; F2(1,34)=9.88, MSE=0.29, p<0.01), time (F1(1,23)=26.09, MSE=0.02, p<0.001; F2 not significant), function (F1(1,23)=10.08, MSE=0.03, p<0.01; F2 marginal, p<0.06, and physical state (F1(1,23)=6.24, MSE=0.04, p<0.05; F2 not significant). There was also a marginal effect for spatial relations in the subject analysis (p=0.06). Time and physical state scores were only significantly higher in the token analysis. Given that abstract concepts are more temporal in nature, since they include processes and events, it is somewhat surprising that time was mentioned more often for concrete concepts. We explain this effect by the effects of random sampling of our word materials, which put two time concepts (day, daybreak) into the low-concrete sample. Especially day triggered a lot of time features such as week, 24 hours, etc. Meanwhile, temporal aspects could also be expressed differently, such as in the mention of actions, events, or emotions. Overall, the differences in the use of situation properties in the description of abstract versus concrete concepts were more pronounced in the token analysis, involving more kinds of situation properties. Again, the data show that situation knowledge features strongly in both types of concepts, but that there are aspects of situations that are predominantly relevant for either abstract or concrete concepts. In fact, the situation properties for which no significant differences were observed had token scores close to zero (with the exception of events). It is quite possible that in a larger sample, some of these would also be used differently. A small number of instructional effects were observed. When participants were instructed to list features of the relevant context rather than of the target itself, they mentioned a person significantly more often (F1(1,23)=29.12, MSE=0.37, p<0.001; F2(1,34)=4.80, MSE=0.19, p<0.05), and social organizations less often (F1(1,23)=9.78, MSE=0.05, p<0.01; F2(1,34)=6.03, MSE=0.01, p<0.05). For social organizations, the interaction approached significance in an item analysis (p=0.10); tokens were mostly high for abstract concepts when asked to generate item features. Living things, events, objects and physical state were marginally affected by instructions (with p values between 0.06 and 0.10); all of them tended to be generated more often when describing context. Closer analysis shows that for all but events, the increase in token scores happens predominantly for concrete concepts. 11 The analyses so far have shown that abstract and concrete concepts both contain knowledge about the situations in which they occur, and that entity properties are predominantly part of concrete concepts, whereas experiential properties are mostly found in abstract concepts. Situational and experiential features are rarely considered parts of a concept’s internal structure. Our analysis suggests that abstract concepts (at least those rated as highly abstract) have a weak internal structure (cf. Gentner, 1981). That is, in place of the internal structure that is common to concrete concepts, abstract concepts are combinations of specific situation properties combined with subjective experiences. As such, they are more akin to abstract schemata for scenes and events than to concrete concepts. Features versus Associative Knowledge One possible confound in our data is that participants may have generated features that are not really part of the target’s conceptual representation. In particular, participants may first list some features, and then start to give examples, which could result in the high number of situation properties. The first features mentioned may be used as cues by participants to mention related knowledge, which may be more related to the first features rather than to the target itself (comparable issues have been discussed for associative sets, cf. Nelson & Schreiber, 1992). Since our participants could end their feature lists anytime, we were not strongly concerned about this, however, quite a few participants generated very lengthy lists for some targets. To estimate whether such processes affected our data, we therefore repeated the token analysis just for the first five coded properties listed for each target. We expected that if situational knowledge is mostly activated as an afterthought through associations, then their counts may be lowered in this analysis, and entity (and perhaps experiential) features may emerge as more central sources of conceptual knowledge. The analysis was performed only on features generated under feature instructions since these are supposed to yield the actual conceptual knowledge. Table 5 shows the resulting average numbers of features. Overall, the numbers resemble the results from the full analysis. However, the differences between abstract and concrete items appear somewhat stronger in these first features. There are close to no entity properties listed for abstract concepts, and close to no experiential features listed for concrete concepts. Both of these were highly significant in both item and subject analyses (Entity: Content Differences F1(1,24)=141.25, MSE=0.01, p<0.001, t(34)=4.97, p<0.001; Experience: F1(1,24)=45.45, MSE=0.01, p<0.001, t(34)=4.69, p<0.001). Interestingly, the difference in situation properties was significant in a subject analysis, with abstract concepts evoking significantly more situation properties early on than concrete concepts (F1(1,24)=34.86, MSE=0.02, p<0.001, t approaching significance, p<0.1). That is, situation properties seem to be accessed earlier on for abstract concepts, whereas for concrete concepts, about an even number of features accessed first are entity and situation properties. This makes sense given that abstract conceptual content appears to be largely constituted of situational knowledge. Thus, this analysis shows that situation knowledge is part of even the first knowledge people access about a concept; at the same time, differences between abstract and concrete concepts are more pronounced for these features, suggesting that later activated knowledge, part of which may be associative in nature, may be more similar for both. Feature Specificity We compared the specificity of features generated for abstract versus concrete concepts. For this analysis, we coded the specificity of features for properties generated under the feature instructions only. The analysis was constrained on properties of situations, entities, and experiences. A total of 3120 features were analyzed in this manner. Features were sorted by feature type and coded blindly by one of the authors, i.e., without information about the target item and its concreteness. Specific features were those that identified a particular object, action, person, location, emotion, etc., whereas unspecific features were those that identified a property but did not mention a specific one. This distinction is akin to the difference between a slot and a filler within a frame (Minsky, 1975). An unspecific feature is a slot, in that it can be filled in a situation by a variety of specific manifestations. Specific features are fillers for the respective feature type. Example pairs of specific versus unspecific properties of the same kind are listed in Table 6. For example, a person is a slot; Lincoln is a filler for this slot. An average of 70% of the features were specific overall. As expected, more specific features were found for concrete (84.4%) than for abstract concepts (57.2%), t(34)=7.11, p<0.001. The proportion of specific features was highly correlated with rated concreteness, r=0.73, p<0.001. Thus, not surprisingly, feature specificity plays an important role in the perception of concreteness. One 12 possibility is that this difference is due to experiential features being more unspecific and entity features being specific. To examine this possibility, we calculated t-tests and correlations for the specificity of the properties in all domains separately. Because many abstract concepts did not contain any entity properties and many concrete concepts no experiential properties, the variance of their specificity proportions was not equivalent. Sign tests show significant differences in the proportion of both (Experience: 91% for abstract, 100% for concrete concepts; Entities: 67% for abstract, 94% for concrete concepts). Again, abstract concepts have more unspecific features for both. Furthermore, the data suggest that experience-related properties are not less specific than entity properties (in fact, overall, they were specific more often). The correlations between concreteness and the specificity of entity properties (r=0.30) and experience properties (r=0.26) were not significant, thus, variation in specificity in these domains did not seem to be systematically related to concreteness. Situation properties were significantly more specific for concrete (81%) than for abstract concepts (48%), t(34)=6.85, p<0.001. The specificity score for these properties was also highly correlated with concreteness, r=0.77, p<0.001: the higher the proportion of specific features, the more concrete the concept was rated (see Table 7). Thus, specificity of situation properties was the only significant predictor of concreteness among these three knowledge domains. Since situation properties constitute the largest percentage of features generated for concrete and abstract concept types, this is an important finding. The finding is consistent with the contextual variety hypothesis: the situation components of abstract concepts are more abstract (or unspecific), enabling the concept to apply to a wider range of different situations. This suggests that a concept is more abstract, the more different situations it applies to. The results also confirm parallels between abstract concepts and scripts or very abstract schemata, as they share a significant proportion of features that represent a flexible variety of different instances. Abstract concepts emerge in this analysis as social abstract schemata, most of whose features are represented as feature slots rather than in terms of specific fillers. This shows that a sizeable component of abstract concepts is represented at a more abstract level (in terms of schema or frame levels, Minsky, 1975) than concrete concepts, which suggests that their characteristics may in some ways be parallel to Content Differences superordinate object categories, such as furniture or animals. Concreteness-Related Variables and Conceptual Content In the following, the results of the content analysis will be related to different variables that have been associated with concreteness in previous research. The goal is to identify links between these variables and conceptual content as reflected by type and token scores for knowledge domains, as well as specificity of conceptual content. Context availability. Ratings of context availability were significantly correlated with the number of entity tokens generated for a concept (r=0.55, p<0.01). They were not significantly correlated with any other feature scores. Thus, context availability was most strongly associated with an item feature that does not occur frequently for abstract concepts. This finding may explain why we did not observe a correlation of concreteness and context availability ratings for the range of abstract concepts previously (Wiemer-Hastings et al., 2001). On the other hand, context availability is slightly negatively correlated with the number of experience properties (r=-0.25). That is, the more introspective properties are part of a concept, the lower are its ratings of context availability. However, this correlation was not significant and much weaker than the one observed for entity properties. Our findings raise the interesting question why context may be more easily available for concepts with many entity properties. One possibility is that relevant contexts for concrete objects are closely related to their features, and that larger numbers of features put more constraints on typical contexts. Context availability ratings were also weakly correlated with the specificity of features (r=0.34, p<0.05). This correlation is easier to interpret – if many properties, especially situation properties, are unspecific, then it should be more difficult to generate a context for the item. Unspecific properties pose much less constraint on the kind of context that could be activated, thus, individuals may need to put more effort in accessing or generating a specific instance. It is actually somewhat surprising that the correlation of these measures was not stronger. The correlation coefficients for context availability and the specificity scores separate by knowledge domain show that entity properties and situation properties weighed into the relation most strongly. Neither individual correlation was significant, however. Imageability. Rated imageability of the target concepts was significantly correlated with the 13 number of entity tokens (r=0.62, p<0.01) and, somewhat weaker, the number of experience properties (r=-0.42, p<0.05). Thus, higher imageability of more concrete concepts may be related to the concreteness of their feature components: entity properties tend to be perceptual, so they may evoke imagery; experiential features may not evoke any imagery and may in fact impede the formation of imagery. Imageability was also significantly associated with specificity of properties overall, and in particular with the specificity of entity properties (r=0.36, p<0.05) and situation properties (r=0.49, p<0.01). This makes sense, since an image needs to be constrained by specific features of the object. One can imagine, for example, the parts and external surface features of a truck, but one can’t imagine equally well “the pieces of some object”. Thus, the entity properties, which are close to unique to object concepts, seem closely linked to the likelihood that imagery is generated, and the presence of experience-related properties appears to inhibit imagery generation. Predication. An approximate measure for ease of predication may be the total number of properties that are generated for an item. A more accurate measure would also include some measure of the time frame within which these properties are produced. The correlation of the number of features overall and concreteness was small, r=0.24. This suggests that in general, individuals list more properties for more concrete concepts, which is consistent with the ease of predication hypothesis. However, the association was quite weak. Perhaps, then, ease of predication is not so closely related to characteristics of abstract versus concrete concepts, but more closely related to variables like imagery and context availability. Complexity. Barsalou has suggested that abstract concepts are essentially not abstract, but simply more complex concepts than concrete concepts (Barsalou, 1999). One way to operationalize complexity is the number of different types of properties involved in a concept. For example, a concept that contains parts, surface features, emotions, a living thing, a location and a function would likely be perceived as more complex than a concept that simply contains an agent and an action, or a shape and a function. Cree and McRae (2003) calculated a score for visual complexity based on entity properties, which they conceptualized as the sum of all external properties of an item (including its parts and surface features) and found it to systematically vary across different item categories (e.g., nonliving items overall tended to be less Content Differences complex than creatures). For the current analysis, complexity needs to be conceptualized more broadly to apply to both abstract and concrete concepts. The type score presents a ready estimate of complexity: it indicates the number of different concept features that individuals list, on average, for a given concept. We expected that more complex concepts would contain a larger variety of features. If complexity is a characteristic of abstract concepts, then this simple measure of complexity should be correlated with perceived concreteness. We found marginal support for this hypothesis, r=-0.32, p<0.06. Thus, more abstract concepts tend to have larger numbers of different types of features. Separate analyses by feature domains show that this tendency was unique to situation properties: only the number of different types of situation properties was marginally correlated with concreteness, r=-0.32, p<0.06. Our data suggest that more abstract items tend to be related to more different aspects of situations; however, this relation does not seem to be strong as estimated by our measure. There may be a variety of other measures for complexity, such as the extent to which features from situation, experience, and entity properties are involved in a concept. It should further be noted that some features by themselves are more complex than others. For example, a person is relatively little complex in comparison to a social state, which implies at least one person (and typically a group of people), and various conditions such as freedom, specific relationships such as competition, and so on. A more accurate measure of complexity may use features weighted for rated complexity of each individual feature, and may result in a stronger correlation with concreteness. Discussion Although much is known about differences in the way abstract and concrete concepts are processed, accounts for such differences have rarely addressed the building blocks of such concepts. In particular, there has been no systematic investigation of factors that underlie variation of concreteness within the concrete vs. the abstract range of concreteness. We think that the key to concreteness can only be found by exploring systematic differences in the components of concepts. While participant-generated features are certainly not equivalent to a concept’s content, one can nevertheless argue that they reflect important aspects of its nature (cf. Cree & McRae, 2003). For example, in our study, distinctions could be made between knowledge related to an item, a situation, and 14 subjective experiences. The kinds of knowledge reflected in individuals’ descriptions of concepts can further serve as a basis for systematic comparisons across concepts of different concreteness. How do abstract and concrete concepts differ, qualitatively and quantitatively, in their content as described by participant-generated features? The most important findings from our study were that abstract concepts do not have any (or very few) item properties in the traditional sense – such as parts, functions, etc. Instead, they describe on an abstract level scenes, events, and experiences in situations, which are quite frequently social situations. In contrast to concrete concepts, they can be characterized by a high proportion of features that reflect introspective processes and states, both mental and emotional, that are associated with our interpretations of situations. Further, distinctive situation properties for abstract concepts are agents and social aspects. In contrast, concrete concepts elicited a high number of item properties, as well as a few distinct situation properties such as functions and locations. While our word sample was quite limited for practical reasons, the results for concrete entities resonate well with the recent study by Cree and McRae (2003) which explored distinctive features of categories of 541 concrete items. This study used the same coding schema by Wu and Barsalou, allowing for a direct comparison of their results to the present study. Distinctive features were established by a cluster analysis and included functions, entity behaviors, external components, material, internal surface properties, external surface properties, locations, and internal components. This list contains 6 item properties as well as two situation properties (function, location), all of which also featured centrally in our participants’ feature lists for concrete concepts. This suggests that in spite of some variation in features that is probably due to idiosyncratic word effects, the pattern of data obtained in our study is fairly reliable. Our sample was too small to establish distinctive features for abstract concepts. In the introduction we mentioned the large variety of abstract concepts, such as emotions, personality traits, behaviors, attributes, attitudes, cognitive processes, relations, and so on. We think that the feature generation task may be a promising approach to try to identify systematic differences in the conceptual make-up of these different kinds of concepts. However, we suspect that overall abstract categories will be less distinct because of their relative unspecific features (more on this below). Content Differences Perceptual Representations of Abstract Concepts It seems that the results of our study replace the puzzling dichotomy of abstract versus concrete by a puzzling dichotomy of experience versus entity properties. Considering that concrete concepts are mostly described in terms of concrete features (i.e., parts, appearance, material), it is not surprising that abstract concepts have a sizeable proportion of abstract components. This is consistent with a previous finding in which we showed that concreteness of abstract concepts is best predicted by the proportion of its components that are related to introspective experiences, as established by a coded database (Wiemer-Hastings et al., 2001). Based on these findings, we think that any attempt to ultimately decompose abstract concepts into a neat set of concrete components is doomed to fail. Many situation components are ultimately concrete, and so, perhaps abstract concepts can be visualized in the mind to a good extent. However, subjective experiences are as abstract as abstract concepts get, and perhaps as challenging to cognitive scientists as the mind itself. Subjective experiences appear so central to abstract concepts that we are quite confident that any complete account of abstract concepts will have to integrate this component. It is a challenge that some of the unique components of abstract concepts tend to be just as abstract as the concepts, especially in regards to theories that argue that abstract concepts may be represented perceptually (e.g., Barsalou, 1999). However, assumptions about the nature of perceptual representations have been made that can handle the abstract features. One of Barsalou’s critical assumptions with respect to abstract concepts is that their representation would involve perceptual simulations of introspective features, such as representational states of the mind, emotions, and evaluations. Thus, properties reflecting mental experiences originating in the mind itself can be simulated, i.e., activated neurologically and integrated into an active representation of an abstract concept just like sensory-motor experiences that originate in sensory organs. Thus, in principle, the approach seems feasible. Of course, details remain to be fleshed out both theoretically and empirically. Second, we have identified several situation properties that appear to be central to abstract concepts when compared to concrete ones. They include agents, actions, and a variety of social aspects. Situation properties are more central to abstract concepts than they are to concrete concepts because they have more proportionate weight (given 15 that entity properties are mostly absent). Accordingly, abstract concepts may be based to a large extent on quite observable situations, actions and agents therein, fleshed out with introspective experiences and evaluations. Situating Abstract and Concrete Concepts: Difference in Focus In related work, Barsalou and WiemerHastings (in press) have suggested that while both abstract and concrete concepts are embedded in situational knowledge, the focus may be on specific items for concrete concepts, and on specific situation aspects for abstract concepts. Our findings are consistent with such a view. Figures 2 and 3 illustrate this focus difference. The outer frame symbolizes the boundaries of a situation. Both abstract and concrete concepts are situated in the same kinds of contexts, thus the general components within the frame are identical for all examples. We have largely simplified situations by only including two individuals, two objects, a person and an object attribute, and one action. The lines between these indicate relations. Circles in the frames are examples of a specific focus. In Figure 2, the focus is on an object along with its attributes, actions performed on or with the object, and relations to other objects. Objects and individuals may further be associated with specific locations, which would be included in the focus frame. This focus essentially resembles a semantic or propositional network model that represents information associated with an entity. Our data suggest that the focus frame for objects does not vary much – it will include the object and its attributes, and to some extent actions and functions that are immediately related to the object in a context. The main factor that varies is the amount of information stored with the object, as measured, for example, by the number of entity properties that participants generated. To the extent that typical actions are closely linked to a specific person, that person may also be part of the focus. For example, if the object is a syringe, then the situation may include a nurse or a doctor. Figure 3 shows a variety of foci for abstract concepts. These are different from object foci in several ways. First, the focus is not on objects and their properties (although an object may be part of the focus, such as shown in the lower right). Instead, the focus typically involves a person, along with some attribute, action, or other person. Different types of abstract concepts are probably associated with typical context foci; for example, emotions and attitudes will typically involve a person and an introspective Content Differences attribute; attributes will involve a characteristic and perhaps entities it is associated with. Second, many abstract concepts will not have a center entity within the frame of focus as concrete objects (Figure 2). Typically, network models symbolize concepts by nodes, and relations to attributes, actions, and related entities are shown as links or arcs. For abstract concepts, this is not always correct, as a variety of nodes and links are part of the entire concept. Exceptions are abstract concepts that are concurrent with a specific situation component, such as an attribute or an action. However, for many abstract concepts the focus is not on an entity and its relations, but on various entities and relations, all of which are related to the concept. For example, indifference would imply a person, a mental state, a relation to some state of affairs, and a state of affairs. Thus, while the majority of object properties are contained in the object and its attributes, the properties of abstract entities are part of the situation. If features were rated for importance for different kinds of concepts, we would probably see that within the frame of focus, most emphasis would be given to particular parts. For example, personality traits, attitudes, beliefs, and other mental states and processes would probably highlight the person and related characteristics, whereas events and processes would probably emphasize actions. A third difference in the context focus for abstract and concrete concepts concerns the size of the focus frame, which varies among abstract concepts. The focus may include as little as an attribute (e.g., size), or it may include a complex network of individuals, goals, and actions (e.g., strategy, discussion). Finally, abstract concepts often critically involve a temporal dimension. For simplicity, we did not include a dimension for time in the Figure. One thing that is quite obvious from these Figures is that they represent conceptual frames at a very abstract level (cf. Minsky, 1977). It is clear that individuals know a lot more about concepts than what situation components they are linked to. Figures 2 and 3 compare abstract and concrete concepts with respect to their relations to situation knowledge, rather than providing exhaustive schemata for their conceptual content. The Figures show that situation knowledge is more intricately related to abstract concepts, since it constitutes a central part of them, whereas it is involved in object concepts only to the extent that typical actions, functions and locations are involved. The effects of instructions in our study are interesting in the context of this discussion. When participants are instructed to describe features that are 16 true of the target item, the focus should be on the conceptual content; when asked to describe relevant context, the focus should shift away from the concept “core” to situational knowledge. We found that instructions to focus on context increased the number of tokens for experience-related properties, as well as for a number of situation properties: person, and marginally, events, and (for concrete concepts) living things and objects. At the same time, a decrease was observed in the number of entity properties (for concrete concepts only) and social organizations (for abstract concepts only). Thus, for concrete concepts, participants appropriately (but not completely) reduce the focus on the properties of the items themselves, and shift the focus to associated situation elements, predominantly concrete entities (person, object, living things). For abstract concepts, the shift affects the tokens of situation and experience properties only, with a focus (for situation properties) on person and event properties. Overall, the make-up of abstract concepts did not qualitatively differ by instruction, consistent with the finding that abstract concepts essentially represent elements, relations and processes that are typically referred to as context. This is also in line with the finding that a shift from a context focus to a target focus did not increase the number of entity properties generated for abstract concepts. Variables Associated with Concreteness We have found systematic relations of imageability and context availability to concept features, in particular, to the number of entity versus experiential properties. One question in this context is what determines a concept’s context availability. Correlation studies show that this variable is mostly associated with concreteness ratings for concrete items, as well as with items across the entire concreteness range. Within the concrete items, we also observed significant correlations between the rated context availability and the number of entity properties. This can be interpreted in two ways. Perceptual features may be accessing conceptrelevant information in memory. The other possibility is that the knowledge reflected by entity properties is the knowledge that needs to be accessed in memory during concept processing. If there are more entity properties, then a richer representation would be accessed, resulting in facilitation of concept processing. Interestingly, our data suggest that it may not be the mere amount of relevant knowledge in memory that matters, but that this effect seems to be related only to perceptual features. Content Differences Abstract concepts do not tend to have fewer properties in our analysis; likewise, no systematic differences have been found in the number of associates that are produced for abstract and concrete nouns (Altarriba et al., 1999; Nelson & Schreiber, 1992). This further supports the view that perceptual features are the driving force behind context availability effects. Imageability is also predominantly related to entity properties, and to a lesser extent also to experience properties. Since imagery (particularly visual imagery) seems to be strongly limited to perceptual entity properties, this makes sense. The results from the content analysis suggest that imageability and context availability predominantly account for processing and concreteness differences that are due to the amount of perceptual features that concepts possess; they do not explain the variance in concreteness for abstract concepts. Other variables, such as specificity or complexity, may be more important variables in this lower range of concreteness. Feature-Based Concept Research To what extent do the data we presented advance our knowledge of abstract concepts? We will argue that the results can be used to inform and advance abstract concept research in several domains, just like feature lists have given rise to one of the most influential representational models in the concept literature, the prototype model (Rosch & Mervis, 1975). A review of the concept literature reveals that features (or semantic components) have been used widely as building blocks of models for concept representation, organization, and other processes. For example, Rosch and colleagues used feature lists to reveal the organization of concepts around prototypes, and levels of categorization, both of which have been very influential and productive approaches in the study of concepts. Most similarity models are based on a computation of feature overlap (Tversky, 1977). Categories are assumed to form, among other factors, based on feature similarities amongst their members. In short, the notion of feature components of concepts is firmly entrenched in many areas of research. Specific models vary in methodology, background assumptions and proposed format, but many if not most have the assumption of conceptual features in common (Barsalou & Hale, 1993). We think that one likely reason that our knowledge of abstract concepts is scarce is that there has not been a systematic account of abstract concept features. The features we identified in our study may be considered as a first important step towards 17 establishing a basis of knowledge that allows us to test conceptual models for abstract concepts. In what follows, we will outline hypotheses regarding cognitive processes involving abstract concepts, based on our findings. We will focus on similarity, a central process closely linked to a variety of cognitive processes, such as category formation and reasoning. Abstract Concept Similarity Comparison of objects entails the comparison of features. Thus, knowledge of an item’s features allows us to predict similarity and to identify how similarity of is determined. A feature shared by two objects increases their similarity in some respect, e.g., perceptually (both round), functionally (both used to eat), or ontologically (both alive). Similarity for a pair of items tends to increase with the number of features that they share (Tversky, 1977). Abstract concepts refer to situations varying in scope and complexity. In this context, "situation" refers to a small subset of components and relations in a context which are relevant to the concept, rather than the context in its entirety. For example, an abstract concept may refer to a person-action situation, or a person-person-relation situation, etc. (compare Figure 3). Thus, we use the term situation here to refer to abstract situations that are a subset of all the features found in a complex environment. Comparing situations is qualitatively different from comparing objects, which should have important implications. Less distinctiveness. Abstract concepts should be more similar to one another than concrete concepts, regardless of category, because overall they have more common and fewer distinctive features. This is mostly due to their most important features being situational properties which tend to be unspecific. We have shown that situation properties associated with abstract concepts are roughly half of the time (52%) unspecified features like some person, some object, do something, or something happens. The most commonly mentioned feature, person, was left unspecified in 92% of its mention, suggesting that a majority of abstract concepts have an unspecified agent in common. The level of vagueness about abstract concept features is very systematic. The immediate effect is that concepts will not be further differentiated at the level of specific features. For example, concepts like pity, hope, jeopardy, happiness, inaction all have a frequent property (person) in common. In contrast, a frequently used feature for concrete concepts, external component, will vary for every individual item: branches and leaves for tree, walls and corners Content Differences for labyrinth, and so on. Thus, for concrete concepts, individual feature types offer a high level of differentiation. Of course, this will also affect the distinctiveness of categories of abstract items. Many concrete item categories are distinguished based on specific features for feature types such as function (e.g., tools versus vegetables), systemic properties (e.g., living things versus non-living things) or material (e.g., plants versus furniture). Since abstract concepts share a limited set of properties, categories can be expected to overlap more. For example, communication concepts will share verbal components with some mental concepts such as worry or thought. In a first exploration of categorical similarity for abstract versus concrete concepts, higher similarity was found for typical abstract category exemplars of different categories than for typical concrete exemplars of categories (WiemerHastings, Barnard, & Felnar, under review). For both general categories, such as action and event, as well as narrower categories such as social offenses and character trait, the most typical exemplars for the categories were rated as more similar across categories than for concrete categories. There are some indications that social categories are not organized around an average prototype, but around ideal exemplars (Barsalou, 1985). In particular, structures consistent with such organization have been reported for traits (Borkenau, 1990) and traits versus states (Chaplin, John, & Goldberg, 1988). Chaplin et al. further suggest that the types of attributes that distinguish such categories are qualitatively different for social categories. As one such attribute, they suggest dimensional intensity, where exemplars vary in the intensity of some feature (e.g., somewhat angry). Ideal-based categories are typically related to goals (Barsalou, 1985), so these findings further emphasize the social character of abstract concepts. Higher variability. Abstract concepts that refer to unspecific situation elements, such as someone, doing something, are constituted of a limited set of features, resulting generally in higher likelihood of feature overlap. However, unspecific features offer no reliable basis for comparison because they include a large variety of instances. Accordingly, individuals may access specific instances to estimate the similarity of the concepts, which would result in high variance in their judgments depending on the overlap of the specific instances. Also, the similarity instructions may lead people to adopt specific processing strategies for abstract concepts with unspecific features. For 18 example, they may estimate similarity by activating instances that are maximally similar to each other, or by activating instances that are maximally dissimilar. One way to empirically assess this would be by varying instructions to either rate similarity or differences, and to test if the focus on similar aspects versus different aspects would result in higher asymmetries in ratings as for concrete concepts. More influence of context. Features do not influence into a similarity computation with a fixed weight. Instead, the item that it is compared to, as well as the context of previous items, have a strong influence. For example, a mouse and a lion seem more similar in a context of tools and vegetables than in the context of other animal pairs. Similarly, when comparing a knife and scissors, the function of cutting may be emphasized; when comparing a knife and a pan, the material and the location may be foregrounded. The context makes specific features more salient than others. In the case of abstract concepts, this may have more far-reaching consequences than simply shifts in focus. As we mentioned, abstract concepts quite often involve unspecific features. Because they vary so much across contexts, it is possible that the activation for a given concept will be more strongly influenced by the context of the other abstract concept in the pair. Given the low constraint exercised by the unspecific features on access to specific instances, people may use the context as an additional constraint to guide and facilitate access to the concept. Higher rates of thematic integration. Recently, much attention has been given to the observation that participants at times base high similarity ratings on thematic relations. Two items have a thematic relation when they play complementary roles in a scenario or event (e.g., knife, meat: the knife cuts meat). The thematic relation itself can vary. Concrete concepts are often integrated around locations, functions, and uses. For abstract concepts, the most common thematic relations are temporal (happens after, happen at the same time) and causal (leads to). The curious effect of integrations in similarity judgment tasks is that items that have very little in common (e.g., cow, milk) are rated as being very similar (Wisniewski & Bassok, 1999). For concrete concepts, this happens only if the item pair shares a salient thematic relation and no taxonomic similarity. For example, for a pair like bear, fish individuals are able to reject the “X eat Y” thematic relation in favor of the taxonomic “both are animals” as grounds for their similarity ratings. However, for abstract concepts individuals can be observed to predominantly use thematic relations and Content Differences frequently to ignore taxonomic relations. For example, jealousy and anger are rarely judged based on their categorical similarity (emotions) but instead are regularly integrated through a causal thematic relation “X leads to Y” (Wiemer-Hastings & Xu, 2003). Similarity ratings based on thematic integrations violate instructions because thematic relations do not cause similarity in the usual sense of the word – instead they reflect associative relations between two items. For example, soup is not really similar to spoon, neither is an explosion similar to a shock. Thus, the question is what explains the high frequency with which participants refer to thematic relations when judging abstract item similarity. It is possible to link the results of this paper to these findings. Concrete concepts are mostly described by perceptual and functional properties which also have been shown to be distinctive features that differentiate category membership (Cree & McRae, 2003). In contrast, when processing similarity of abstract concepts, participants would identify commonalities such as an agent, a social situation, and subjective experiences. These properties may be little distinctive (see above). Furthermore, social components (e.g., person, behavior, social state, etc.) likely activate individuals' schemata about people and behaviors. Our analysis shows that social situations are frequently and quite distinctly part of abstract concepts; so social schemata likely influence many similarity judgments. Research in the area of social cognition has shown that individuals interpret and evaluate behaviors, interpersonal relations, and people in order to make predictions. Many abstract concepts may thus automatically activate associated goals, outcomes, and causes (support for this hypothesis may be the goal-derived structure of some social categories described previously). This may put the abstract concepts to be compared in a specific, uniting context in which they are related. For example, mischief typically activates knowledge about typical agents (children) and likely outcomes (getting in trouble). Inaction is typically described in terms of a person, a situation that requires some action, and absence of action. Mere comparison of features may result in a judgment of dissimilar because one entails an action, while the other explicitly entails no action. However, when people judge the similarity of these concepts, the terms may conjointly activate a relevant social schema which would put mischief in the slot of the situation that requires an action, and inaction would be interpreted as the failed response to someone's mischief. This processing may be automatic, which 19 would make sense considering how important the appropriate interpretation of social behaviors and events is in our lives. If a good fit is obtained for the concepts within a schema, this information may override schema-independent feature comparisons, resulting in some degree of perceived similarity. The integration frequency may also be increased by the large number of unspecific features for abstract concepts. Individuals have much flexibility in interpreting unspecific properties. Processing may be simpler by assuming feature identity across concepts. For example, hope and happiness both involve a person. Instead of creating a different activation for each concept, it may be more economical to assume that both refer to the same individual. Since humans are quite proficient at relating a person’s actions, dispositions and emotions to each other, it is likely that there is then a strong bias to relate the concepts to each other causally. In fact, it has even been shown that individuals can make connections between dispositions that seem contradictory (Asch & Zukier, 1984). Thus, there may be a strong bias to relate abstract concepts to each other causally, and to integrate them. Thus, abstract concepts may accordingly be integrated as readily as concrete concepts are compared taxonomically. Recursive Structures Abstract concepts do not occur independently of other concepts. Hampton (1981) suggests that “effects” of some behaviors are likely involved in abstract concepts. In any social situation, we make inferences about the people around us based on their behaviors, including their goals, their character, their attitudes, and their relations to other people. Behaviors and events are analyzed with respect to possible causes, consequences, and possible responses. Based on our inferences, we make predictions about future events, behaviors, and the development of relationships. Acting and responding intelligently in fact depends on our ability to make such inferences. In our data, such processing may be revealed in a variety of ways. First, many features coded as situation and experience properties may in fact be causes, associates, and effects of a concept. This includes emotions, representative states, evaluations, social states, actions, and events. Second, coordinates and synonyms of a concept were coded separately and not included in the analysis, because they are unlikely part of the conceptual content. Abstract concepts are relational concepts, which have been argued to have a weak internal Content Differences structure, paired with many external links to related concepts (Gentner, 1981). Accordingly, the rich connections between these concepts are likely to be reflected in descriptions of the individual concepts’ characteristics. As we have seen, abstract concepts are largely described in terms of feature types that are themselves abstract concepts, including three experience properties (emotion, representation, evaluation) and frequent situation properties (social state, social artifact, action, event). Such features may reflect external links of the target concepts to related concepts. For example, the target concept emancipation may be described as a transition from one social state to another. The first social state may be described as a state of social oppression, the second as a state of freedom or autonomy. The process leading from the first to the second may be described as a process of liberation. Notice that all these components of the concept of emancipation are themselves abstract concepts. It is impossible at present to decide whether such related concepts are merely associates or actual components of abstract concepts. At first glance, having an integrated network of abstract concepts constituting the content of an abstract concept is disturbing. If such concepts build the content of one abstract concept, what builds their concept, respectively? If the components of abstract concepts themselves consist of integrated networks of abstract concepts, then it becomes difficult to see where the meaning comes in. However, it is possible that a number of abstract concepts have components that are not themselves abstract, such as agents and specific behaviors. Perhaps the description of an abstract concept in terms of other abstract concepts reflects a cognitive economy where we use abstract concepts to reflect our knowledge of more complex abstract concepts. For example, oppression in the above example may be represented by a specific relation between two people, one of who constrains the liberty of the other person. Emancipation may then be represented by a simulation (Barsalou, 1999) of the transition from this state to one in which these constraints are removed. This process would be quite similar to the transition between frames for object rotation or movement as conceptualized by Minsky (1975). Another reason that we are not too concerned about recursive use of abstract concepts in each others’ descriptions is that a similar process can be observed in concrete concepts. When an individual describes their object knowledge in terms of parts and materials, they essentially describe their knowledge of an object through other objects. For 20 example, tree is often described with the features leaves, bark, trunk, roots, and wood. All of these are concrete objects themselves. Just like we may describe leaf as a part of a tree, we may describe freedom or autonomy as a result of emancipation, as a state where no oppression is present. Networks of abstract concepts may thus be quite similar in structure and function as those of concrete ones. Thus, to the extent that recursive structures present a problem, we argue that it is not a problem that is unique to abstract concepts. 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Stenning (Eds.), Proceedings of the twenty-third annual conference of the cognitive science society (pp. 1106-1111). Mahwah, NJ: Lawrence Erlbaum Associates. Wilson, M. D. (1988). The MRC Psycholinguistic Database: Machine readable dictionary, Version 2. Behavioral Research Methods, Instruments and Computers, 20, 6-11. Wisniewski, E.J., & Bassok, M. (1999). What makes a man similar to a tie? Stimulus compatibility with comparison and integration. Cognitive Psychology, 39, 208-238. Wu, L., & Barsalou, L.W. (2004). Perceptual simulation in property generation. Manuscript under review. Content Differences Appendix A. Word materials by concreteness level (concreteness measures are on a 7-point scale, with 1=most abstract, 7 = most concrete). Items Rated Concreteness (MRC) Highly Abstract Aspect 2.2 Desperation 2.6 Exception 2.6 Hope 2.6 Ingratitude 2.5 Jeopardy 2.7 Medium Abstract Emancipation 3.0 Happiness 3.0 Inaction 3.0 Mischief 3.3 Pity 3.0 Removal 3.5 Little Abstract Formation 3.8 Morass 4.2 Possession 3.8 Saga 3.7 Story 4.3 Zone 3.9 Little Concrete Day 4.8 Daybreak 5.1 Pest 4.8 Prize 4.7 Sedative 4.6 Venom 4.8 Medium Concrete Bass 5.5 Blossom 5.6 Hairpin 5.8 Labyrinth 5.2 Lace 5.5 Nectar 5.6 Highly Concrete Beehive 6.1 Insect 5.9 Mackerel 6.4 Owl 6.1 Tree 6.0 Vine 6.0 22 Content Differences Appendix B. Excerpt from Coded Transcripts for Concrete Concept. (Item: Tree; Instructions: Item Feature Generation.) Features Domain Domain Property Wood, Entity Material has \ branches, Entity External Component has \ different Entity Quantity colored Entity External Surface Feature leaves, Entity External Component animals Situation Living Thing to_live Entity Systemic in_them, Situation Spatial like Meta Meta squirrels, Situation Living Thing owls Situation Living Thing kids Situation Person climb Situation Action them, Meta Cue Repetition build Situation Action tree Meta Cue Repetition houses Situation Build 23 Content Differences Appendix C. Excerpt from Coded Transcripts for Abstract Concept. (Item: Hope; Instructions: Item Feature Generation.) Features Domain Domain Property mmm Meta Hesitation um Meta Hesitation maybe hope Meta Cue Repetition could have the_hope_that Meta Cue Repetition something \ will \ happen Situation Event good, Experience Evaluation you Situation Person really Situation Quantity want Experience Representation something \ to_happen, Situation Event 24 Content Differences 25 Author Note Katja Wiemer-Hastings, Department of Psychology, Northern Illinois University; Xu Xu, Department of Psychology, Northern Illinois University. The authors gratefully acknowledge Jan D. Krug and Patricia Fernandez for participation in the data analysis. We are also grateful to Larry Barsalou for insightful questions and comments which have contributed to our interpretations of this research, and for much help in the proper use of the coding schema used in the evaluation of our data. Correspondence regarding this article may be addressed to Katja Wiemer-Hastings, the Department of Psychology, Northern Illinois University, DeKalb, IL 60115 (email: katja@niu.edu). Content Differences Table 1 Average Number of Types of each Knowledge Domain Situations Entities Instruction Item Types Weighed Types Weighed Features Abstract 3.44 0.22 0.33 0.03 Concrete 3.62 0.23 2.09 0.19 Context Abstract 3.81 0.24 0.25 0.02 Concrete 4.19 0.26 0.93 0.08 Types 1.09 0.33 1.47 0.54 Experience Weighed 0.18 0.06 0.25 0.09 26 Content Differences Table 2 Type Scores of Situation Properties for Abstract and Concrete Concepts Item Features Context Features Situation Property Concrete Abstract Concrete Abstract More for Abstract Person** 0.34 0.71 0.38 0.96 Social State** 0.01 0.19 0.02 0.26 Social Artifact* 0.01 0.18 0.02 0.13 More for Concrete Object* 0.61 0.48 0.92 0.43 Location* 0.41 0.19 0.39 0.22 Living Thing** 0.35 0.01 0.44 0.03 Function* 0.18 0.04 0.08 0.01 No significant differences Action 0.65 0.83 0.65 0.84 Event 0.26 0.24 0.32 0.39 Time 0.24 0.13 0.23 0.11 Physical State 0.21 0.14 0.32 0.19 Building 0.01 0.00 0.04 0.02 Social Organization 0.03 0.10 0.02 0.02 Spatial Relation 0.1 0.06 0.10 0.03 Note. Situation properties for which a significant main effect of concreteness was obtained are marked with * (p<0.05) or ** (p<0.01). 27 Content Differences Table 3 Average Number of Features (Tokens) Generated for Each Knowledge Domain Instruction Item Situations Entities Experience Features Abstract 3.95 0.22 1.28 Concrete 3.88 2.02 0.36 Context Abstract 4.49 0.19 1.65 Concrete 4.29 1.01 0.62 28 Content Differences 29 Table 4 Token Scores of Situation Properties for Abstract and Concrete Concepts Item Features Context Features Situation Property Concrete Abstract Concrete Abstract More for Abstract Person** 0.38 0.99 0.49 1.34 Action* 0.66 0.87 0.69 0.93 Social State** 0.01 0.19 0.02 0.29 Social Artifact** 0.01 0.18 0.02 0.13 More for Concrete Object** 0.64 0.56 0.95 0.51 Location** 0.41 0.20 0.40 0.22 Living Thing** 0.36 0.01 0.48 0.03 Time** 0.27 0.13 0.24 0.11 Function** 0.19 0.04 0.08 0.01 Physical State* 0.22 0.14 0.32 0.14 No Difference Event 0.26 0.25 0.32 0.42 Building 0.01 0.00 0.04 0.01 Social Organization 0.03 0.10 0.02 0.02 Spatial Relation 0.10 0.06 0.10 0.04 Note. Situation properties for which a significant main effect of concreteness was obtained in the subject analysis are marked with * (p<0.05) or ** (p<0.01). Content Differences Table 5 Knowledge Domain Tokens Among first Five Features Situation Abstract 0.66 Concrete 0.42 Entity 0.02 0.40 Experience 0.19 0.04 30 Content Differences Table 6 Examples for Specific and Unspecific Features for Different Types of Concept Knowledge Property Specific Feature Unspecific Feature Entity – component Branch, Leg Part, Aspect, Pieces Entity – appearance Large, dark Characteristic Entity – material Wood, Metal Some Material Situation – person Doctor, Kid, A. Lincoln Someone, You, A Person Situation – object Road, Sign, Water Something, Things Situation – action Make, Collect, Grow, Run Activity, Doing Something Situation – event Gain, Game, Celebration Something Happens, Change Situation – living thing Bees, Birds Animals, A Creature Situation – location Jail, Forest Place, Area, Background, Anywhere Experience – emotion Anger, Sadness Emotion, Feeling 31 Content Differences 32 Table 7. Correlations of Token Scores, Type Scores, and Proportions of Specific Features with Concreteness and Related Variables. Concreteness Context Availability Imageability Token Scores Entity Tokens 0.74** 0.55** 0.62** Experience Tokens -0.69** -0.25 -0.42* Situation Tokens -0.03 0.14 0.10 Type Scores Entity Types 0.13 0.05 0.00 Experience Types -0.2 -0.16 -0.14 Situation Types -0.32 -0.06 -0.25 Proportion of Specific Features Specificity 0.73** 0.34* 0.51** Entity Specificity 0.26 0.29 0.36* Experience Specificity 0.30 -0.09 0.13 Situation Specificity 0.77** 0.31 0.49** Note. Significant correlations are marked with an asterisk; * signifies p<0.05, ** signifies p<0.01. Content Differences 33 Figure 1: Proportions of entity and experiential properties generated for items of six concreteness levels (numbers increase with higher concreteness). Figure 2: Situation with focus on an object. The focus is illustrated by the circle. Figure 3: Situations illustrating different foci for abstract concepts. Frequency of Mention Content Differences 0.6 0.5 0.4 0.3 0.2 0.1 0 Experience Entity 1 2 3 4 5 Concreteness 6 34 Content Differences 35 Content Differences 36