Running Head: PROCESSING-CENTERED REDUCTION A Processing-Centered Look at the Contribution of Givenness to Durational Reduction Jason M. Kahn and Jennifer E. Arnold University of North Carolina at Chapel Hill Author Note Jason M. Kahn, University of North Carolina at Chapel Hill; Jennifer E. Arnold, University of North Carolina at Chapel Hill. This research was supported by: NSF grant BCS-0745627 to J. Arnold. We gratefully acknowledge the assistance of Kellen Carpenter, Isaac Hellemn, Jennifer Little, Michael Parrish, Giulia Pancani, Jennifer Tate, and Alyssa Ventimiglia, in both running the experiments and transcribing the data. Address correspondence to: Jason Kahn, CB#3270 Davie Hall, Chapel Hill, NC 275993270. Email:jmkahn@email.unc.edu PROCESSING-CENTERED REDUCTION 2 Abstract Givenness tends to lead to acoustic reduction in speech, but little is known about whether linguistic and non-linguistic givenness affect reduction similarly, and there is little consensus about the underlying psychological mechanisms. We examined speakers’ pronunciations of target object nouns in an instruction-giving task, where speakers saw objects move and described this to a listener. The target objects were linguistically or non-linguistically given (i.e. spoken aloud or flashed). With predictability held constant, linguistic givenness resulted in more reduction than non-linguistic givenness, while both elicited more reduction than control conditions. We use these findings to consider two possible mechanisms of givenness effects: an explicit information status-based trigger account and a facilitation-based account. We propose that our findings are most naturally accounted for by a mechanism in which givenness leads to facilitation of representations and processes in the production system, which leads to reduction. Key words: reduction, predictability, givenness, acoustic prominence PROCESSING-CENTERED REDUCTION 3 A Processing-Centered Look at the Contribution of Givenness to Durational Reduction When a professor introduces the concept of neural network to her psychology class, she pronounces the words clearly and distinctly: “nur-ral net-work,” perhaps pointing to a diagram on the board. For the rest of the lecture, her pronunciation may more closely resemble “n’ral netw’rk,” with the same words, although less clearly and with shorter duration. This variation in pronunciation is ubiquitous, and is systematically related to properties of the word, its referent, and the discourse context. Perhaps the most influential account of this phenomenon observes that the professor’s use of “neural network” changes the information status of both the words and their associated concept. The phrase enters the conversation with new status, but thereafter the phrase and the concept are both given as a part of the shared discourse. In this paper, we examine the role of linguistic and nonlinguistic givenness on acoustic reduction, with the goal of outlining possible mechanistic accounts for why speakers reduce the duration of given words. Speakers produce words along a continuum, ranging from acoustically prominent and emphatic to reduced. Reduced tokens have relatively shorter duration, lower pitch and voweltarget articulation, less pitch variation, and/or incomplete segmentation (Aylett & Turk 2004, 2006; Bell, Jurafsky, Fosler-Lussier, Girand, Gregory & Gildea, 2003; Bell, Brenier, Gregory, Girand, & Jurafsky, 2009; Jurafsky, Bell, Gregory & Raymond, 2001, Pluymaekers, Ernestus & Baayen, 2005a, 2005b; inter alia). The reduction of pitch height and pitch movement may be related to choices about whether to accent a word or not, but it has been demonstrated that variations on acoustic clarity do not depend entirely on accenting (Aylett & Turk, 2004; Bard & Aylett, 2004; Watson, Arnold, & Tanenhaus, 2007). All of these prosodic features contribute to an utterance’s overall intelligibility (Arnold, Kahn & Pancani, in press; Bard, Anderson, Sotillo, PROCESSING-CENTERED REDUCTION 4 Aylett, Doherty-Sneddon & Newlands, 2000; Galati & Brennan, 2010), i.e. how easily a listener can identify the word out of context. There is abundant evidence that speakers reduce words that are repeated or that refer to given (previously evoked) information. However, there is little agreement about exactly how speakers represent information status, or how these effects emerge from or within the mechanisms of language production. Moreover, there are no psycholinguistic models of these processes. In this paper we experimentally test how acoustic reduction is affected by different kinds of “given” information status, focusing on the contrast between information that has been mentioned linguistically and that which has been evoked non-linguistically. This provides one of the first systematic explorations of how linguistically and non-linguistically presented information affect production differently. The comparison between two types of givenness is theoretically relevant to our broader goal of investigating possible mechanisms that explain speakers’ tendency to reduce given information. We specifically consider two types of mechanism. Under the traditional account, speakers explicitly represent information status, and this representation triggers their use of particular acoustic forms. This view predicts that the representation of the discourse must contain any information relevant to acoustic form, such as its degree of availability, or its source (e.g. linguistic vs. non-linguistic). In contrast, we propose a facilitation account, whereby the facilitation of language production representations and processes determines acoustic form, without necessarily referring to an explicit representation of information status. We begin with a summary of the effects of givenness on prosody, and then outline each account before describing the experiments. PROCESSING-CENTERED REDUCTION 5 Information Status Effects On Acoustic Prominence It is well established that linguistic form varies as a function of the information status that it encodes. Most simply, many theorists mark a distinction between given and new information status (Chafe, 1976; Clark and Haviland, 1977; Halliday, 1967; Prince 1989, 1992). Given information has already been mentioned, or otherwise evoked, by the participants in a conversation, whereas new information has not. More fine-grained categorizations of information status provide better accounts than a simple given/new contrast (see Arnold, 2008), but here we focus primarily on the given/new dichotomy for simplicity. Given information status correlates with numerous aspects of linguistic form, including accenting and acoustic prominence (Breen, Fedorenko, Wagner & Gibson, 2010; Halliday, 1967; Venditti & Hirschberg, 2003), lexical choices (e.g. pronouns vs. more specified expressions; Ariel 1990; Arnold, 2008, 2010; Chafe, 1976; Gundel, Hirschberg & Zacharski, 1993; Prince, 1992), word order (Birner & Ward, 1993), and constituent order (Arnold, Wasow, Ginstrom, & Losongco, 2004; Bock & Irwin, 1980). Here we focus on acoustic variation, particularly word duration. Analyses of word pronunciations in running speech have demonstrated that references to previously-mentioned information tend to be shorter and less intelligible than references to new information (Brown 1983; Fowler 1988; Fowler & Housum 1987). For example, in a map description task, speakers who have already produced a reference to a landmark on the map tend to reduce its form on the second production (Bard & Aylett 2004, with data from Anderson, Bader, Bard & Boyle, 1991). This phenomenon appears to have more to do with the act of referring than the linguistic form itself, as non-co-referential repeated mentions do not get reduced (Bard, Lowe & Altmann 1989; Fowler 1988). Comprehension experiments have also PROCESSING-CENTERED REDUCTION 6 demonstrated that listeners tend to prefer reduced forms for given information (e.g., Arnold 2008; Baumann & Grice 2006; Bauman & Hadelich 2003; Dahan, Tanenhaus & Chambers 2002). An open question in this domain is whether only the linguistic context can grant given information status, or whether other contexts can as well, such as the environment or the speaker’s goals. Some accounts of givenness suggest that information can be evoked nonlinguistically. Clark and Marshall (1981) propose that given status can result from either linguistic or visual co-presence (see also Prince, 1981; 1992). I could say “neural network”, or I could point to the words written on the board, and either way make the information salient. Yet the canonical “given” status results from explicit linguistic mention, and this is the most frequent experimental manipulation of given status (although cf. Brown-Schmidt, 2012; Horton & Keysar, 1996). No current theory of givenness suggests that linguistic mention confers a different status than non-linguistic evocation of the same information. Few studies have explicitly examined the difference between linguistic and non-linguistic sources of givenness. Baumann and Hadelich (2006) found that visual primes did not constrain listeners’ accenting preferences as strongly as linguistic primes. They suggested that visual primes may be less “given” than linguistic primes. By contrast, Brown (1983) found deaccenting for both textually and situationally given information, and Bard and Anderson (1994) found that visual givenness led to lowered intelligibility. However, neither experiment systematically compared types of givenness. In sum, there is substantial evidence that information status predicts referential forms, but it remains unclear how the source of givenness contributes to this effect. In addition, there is little consensus about the psychological mechanisms that underlie this correlation. PROCESSING-CENTERED REDUCTION 7 Processing Mechanisms We consider two possible mechanisms to explain the effects of information status on acoustic prominence. Because it is beyond the scope of the current project to present a full model of acoustic reduction, instead we provide a sketch of two general approaches. First we consider the kind of psychological mechanism that would be most consistent with the traditional view, that information status selects for acoustic forms. Although these theoretical positions are typically not framed in a mechanistic way, we suggest that they are most consistent with a Trigger account, in which information status is explicitly represented. We then propose an alternative, a Facilitation account, in which acoustic forms result directly from facilitation of production processes. These approaches are not mutually exclusive, but do make different predictions with respect to elucidating different possible psychological mechanisms of reduction. Our discussion draws heavily on recent work on the processes of language production. There is widespread agreement among current models that language production includes several planning and processing stages (e.g. Bock, 1982; Dell, 1986; Garrett 1980; Levelt, 1989; Levelt, Meyer & Roelofs (1999)). A characteristic outline of one such model (Levelt, 1989) is presented in Figure 1. In this model, as in most of the models mentioned here, speakers represent the concepts and relations they wish to express at the conceptualization stage, non-linguistically. At the formulation stage, the lexical, syntactic, and phonological forms are encoded, and at the articulation stage, the system generates a phonetic plan for articulation. The Information Status Trigger Approach. The standard linguistic view suggests that acoustic prominence results from pragmatic specialization, e.g. rules such as “select a H* pitch accent for discourse-new information” (see, e.g. Pierrehumbert & Hirschberg, 1990). On this PROCESSING-CENTERED REDUCTION 8 view, some information statuses trigger reduced pronunciations, whereas some trigger fuller pronunciations. Although psychological mechanisms for such models have not been explicitly proposed, such theories seem to require that the speaker have a representation of the conditions of selection, for example a distinction between given and new status. This kind of information status-based selection of acoustic form has parallels in choices between different referential forms, such as pronouns vs. more explicit expressions (e.g., Arnold, 1998; 2008; 2010; Gundel et al., 1993; Bard et al., 2000). For example, Schmitt, Meyer, and Levelt (1999) propose a model of German pronoun production (see also van der Meulen, Meyer, & Levelt, 2001). Their model is based on Levelt’s (1989), which, like other current models of language production, assumes that speakers represent information status at the message or conceptualization stage of language production. Schmitt et al. posit a single “focus” representational unit at the conceptual level, described as a “discourse-dependent switch in the processing model”. This focus unit serves as a gate that determines whether a pronoun or name is selected (pp. 316-317). In fairly direct analog, this type of model could apply to choices about reduction. It might select a reduced form if the focus node has sufficient activation, and an unreduced form otherwise. Alternatively, the focus node might trigger an acoustic reduction rule (e.g. ‘deaccent here,’ or ‘shorten this vowel’), as opposed to a categorical choice between forms. Selection in this latter case would occur in addition to any other constraints on prosodic form (e.g. coarticulation, prosodic or syntactic position, etc.). Crucially, the trigger approach posits a categorical representation of information status, and that the model selects a form or rule based on the information status category. Although the Schmitt et al. (1999) model includes only a binary contrast between “focus” and “not focus,” it could in principle include finer-grained information status differences. For example, Levelt PROCESSING-CENTERED REDUCTION 9 (1989) proposes that speakers model the information status of referents with four categories: a) inaccessible, b) accessible, c) in discourse model, and d) in focus. This view coheres with literature on information status, and in particular with proposals that allow given information to vary in accessibility or focus status (e.g. Ariel, 1990, Chafe, 1994, Gundel et al., 1993). Likewise, if linguistic and non-linguistic givenness affect reduction differently, this approach would need to include different nodes for each status type. The Facilitation-Based Reduction Hypothesis (FRH). A second possible explanation for acoustic reduction, which we propose here, is that it emerges from facilitation of the mechanisms of production. We hypothesize that reduction results from some combination of 1) activation of the conceptual and linguistic representations associated with a word, and 2) facilitation of the processes associated with generating an articulatory plan from a concept. The strong version of this view is that any stimulus that differentially facilitates processing associated with a to-be-produced word or its environment should lead to some measurable amount of reduction. Moreover, the degree of reduction should correspond to the degree of facilitation, either within or across levels of processing, although not necessarily in a linear fashion. Facilitation of the concept associated with an entity, for example, might lead to more reduction when paired with facilitation of the appropriate word’s lexical or phonological representations. Although this strong version may not hold, we can use it to generate testable predictions about gradient effects of reduction due to language processing facilitation. The FRH builds on other suggestions that processing facilitation may lead to reduction (e.g., Balota, Boland and Shields, 1989; Bard et al., 2000; Bell et al., 2009; Lam & Watson, 2010). For example, Balota, et al. explain the priming of one word (e.g., cat) from an associated word (e.g., dog) as the result of greater activation of the target lemma representation. This PROCESSING-CENTERED REDUCTION 10 activation influences the rate at which phonemes are selected and motor codes are sequenced. Their account builds in turn upon interactive models of production (e.g., Dell, 1986), which allow the activation of representations at one level to influence the activation of representations at another level in the production system. Bell et al. propose that speakers modulate word length as a result of a coordination mechanism between planning and articulation. We extend these ideas in two ways: 1) not just activation of representations, but facilitation of processing more generally, should lead to reduction, and 2) facilitation at any level of representation should lead to reduction. Our proposal is critically based on a view of givenness as a category with multiple features, each of which may facilitate processing independently. Givenness minimally includes processing of the conceptual features of an entity, which in and of itself may facilitate later reference to it. Often givenness also involves actual mention of the entity, and in situations where it may be predictable or not. The phonological processes associated with the name may be activated in other ways as well, potentially leading to independent facilitation. This view is broadly similar with Bock and Irwin’s (1980) analysis of how givenness affects syntactic choices. They propose that referential availability and lexical availability affect the speed of lemma activation independently, thus each contributing to the speaker’s syntactic choices. Facilitation may lead to durational reduction in a number of ways. One possibility is that greater activation results in faster selection of the conceptual representation, which results in faster selection of lexical representations. Likewise, activation of the lemma, phonemes, or articulatory routine could speed their selection (Balota et al., 1989; Bell et al., 2009; Gahl, 2008), although this view is not universal (for opposing views see Levelt, 1989; Jurafsky et al., 2001). In running speech, this means that the subsequent word could be planned and produced earlier as PROCESSING-CENTERED REDUCTION 11 well. Perhaps more importantly, speakers may experience priming of the processes associated with producing a particular word or phrase. For example, phonological encoding includes not only activating phonemes, but sequencing them as well (Levelt et al., 1999). Uttering a word or phrase, or hearing it uttered, may facilitate this ordering process, as well as activate the constituent representations (for further discussion see Arnold & Watson, under review). One benefit of a facilitation-based approach is its consistency with known correlates of acoustic reduction. In particular, it offers a natural account of the well-known tendency to acoustically reduce information that is predictable or probable within context (Bell et al., 2009; Gregory, Raymond, Bell, Fosler-Lussier & Jurafsky, 1999; Jurafsky et al., 2001; Lam & Watson, 2010; Lieberman 1963; Watson, Arnold, & Tanenhaus, 2008, inter alia; see also Levy & Jaeger, 2007). Although each of these studies finds slightly different results, and posits a slightly different mechanism of action, the pattern of findings points to an effect of language production processes on word duration. Predictions about Linguistic and Non-linguistic Givenness The Trigger hypothesis, as sketched above, critically differs from the FRH in that it explicitly models information status, whereas the FRH suggests that reduction emerges as a result of processing facilitation, without necessarily making use of a representation of information status. To explore this difference, we examine how acoustic reduction is affected by different kinds of givenness: linguistic and non-linguistic. The trigger account represents a mechanistic instantiation of current theories of givenness, which do not predict any different effects for linguistic and non-linguistic givenness. Many accounts of givenness implicitly focus on linguistic givenness, which might suggest that non-linguistic givenness does not lead to reduction at all. To the extent that non-linguistic PROCESSING-CENTERED REDUCTION 12 sources of givenness are acknowledged, the source of givenness (linguistic vs. non-linguistic) is generally considered irrelevant to the status of “given.” This account would thus predict an equivalent degree of acoustic reduction for both linguistically and non-linguistically given information, assuming both types of information make the entity given to the same extent (e.g. familiar, or activated). By contrast, the FRH predicts that the degree of facilitation throughout the production system will determine the degree of reduction. If linguistically primed, for example by being spoken aloud, reference to an object (e.g., “airplane”) should facilitate both the conceptual level and lower-level linguistic representations, such as lexical and phonological information. Nonlinguistic priming of the same referent should activate the conceptual representation, but not lower-level linguistic information to nearly the same extent. Although both sources of givenness activate the entity, and make it a possible conversational referent, they act on different levels of representation in the production system. Thus, the FRH contrasts with the trigger account, in that it predicts that non-linguistic priming should lead to acoustic reduction, but less so than linguistic priming. Experimental Overview and Logic In both experiments reported here, participants performed a variant of a referential communication task developed by Watson and Arnold (2005; see also Lam & Watson, 2010). Speakers issued instructions to listeners about the movements of three different pictured objects from an array, as in Figure 2. For example, after seeing a picture of an airplane shrinking, the speaker would tell the listener “the airplane shrinks.” The listener would then make the airplane shrink on his or her screen. A second and then a third object movement and an instruction would follow, with the same movement-utterance-execution sequence performed for a different object. PROCESSING-CENTERED REDUCTION 13 The critical manipulation was whether the objects were a) linguistically primed (by having their name previously mentioned), b) non-linguistically (i.e. visually) primed. Each of these conditions was compared with a control condition, in which the objects were merely displayed, with no special attention called to them. One potential problem with examining givenness effects is that they are frequently confounded with predictability at the referential level, which is also associated with the frequency of lexical items. A referent’s becoming given increases its likelihood of reuse in a conversation (Arnold, 1998, 2010; Givón, 1983). Indeed, some scholars define givenness in terms of predictability (see Prince, 1981, p. 226). Observing reduction on a particular word rarely allows one to reliably attribute the effect to givenness or predictability, even with considerable knowledge about the spoken context. Instead of doing away with it entirely, our experiments control for predictability, and assess the independent contribution of different types of givenness. In Experiment 1, given referents are all completely predictable; in Experiment 2 they are all relatively unpredictable. The type of predictability we control differs substantially from the type normally addressed in the literature (e.g. Bell et al., 2009). N-gram probability and frequency refer to properties of words in a text, whereas our experiments control referential predictability, the probability of referring to a particular entity. In Experiment 1, we test two major predictions of the FRH, which stem from the questions raised earlier: 1) Does non-linguistic givenness ‘count’ for the purposes of reduction? 2) Do linguistic and non-linguistic givenness elicit different degrees of reduction? In Experiment 2, we ask two questions that further clarify the effect of givenness: 3) Does givenness operate independently of predictability for the purpose of producing reduction? 4) Does the same PROCESSING-CENTERED REDUCTION 14 relationship between givenness and predictability hold for linguistic and non-linguistic information? There is an issue that is not addressed in the current study, namely the question of whether acoustic reduction is triggered by the needs of the addressee (c.f. Arnold, Kahn, & Pancani, in press; Bard et al., 2000; Bard & Aylett, 2004; Galati & Brennan, 2010; Halliday, 1967; Kahn & Arnold, under review; Lindblom, 1990; Rosa, Finch, Bergeson, & Arnold, under review). Addressees can identify given and predictable referents more easily than new or unpredictable ones, with the consequence that the speaker can produce a less explicit linguistic form and still expect the addressee to identify the correct referent. The production system might, as a consequence, include representations of the addressee’s knowledge, perhaps in parallel with each of the levels of processing outlined above. Speakers and addressees often share a considerable amount of information during a conversation, such that speaker-centric and addressee-oriented processes make similar predictions in many situations. In both of our experiments, the speaker gave instructions to a live addressee, who then performed the action on their screen. All our manipulations of information status were identical for both speaker and addressee. We discuss issues of audience design elsewhere (Arnold et al., in press; Kahn & Arnold, under review, Rosa et al., under review; Rosa & Arnold, 2011) These experiments provide the first (to our knowledge) systematic test of how linguistic and non-linguistic givenness affect speakers’ durational reduction, while controlling for predictability. Experiment 1 PROCESSING-CENTERED REDUCTION 15 Method Participants. A total of 15 female undergraduates participated in an instruction-giving experiment as speakers for course credit. Females were not specifically recruited; however, for homogeneity, females were asked to serve as speakers whenever possible. 3 were excluded due to equipment failure, for a total of 12 speakers. 9 additional undergraduates (2 female) participated in the experiment as listeners for course credit. The remaining 6 speakers were paired with a lab assistant (3 with one of two female assistants, 3 with a male assistant). Materials and Design. 221 colorized versions of the Snodgrass and Vanderwart (1980) line drawings served as the stimuli (Rossion & Pourtois, 2001). These drawings were normed by native French speakers for imageability, visual complexity, familiarity, as well as name agreement in French, although this latter measure was not used here. The appendix lists the names of the 221 experimental items. The English name of each picture, as reported in Rossion and Pourtois (2001), was recorded by the first author for use in the linguistic priming condition. All of these recordings were made on a Marantz professional solid-state recorder over an Audio Technica professional microphone headset, using citation format (i.e. no distinguishing inflection, and clear pronunciation). On each trial, participants saw an array of 8 objects. Three of these objects were the target objects, i.e. those that were to be mentioned by the speaker in spoken instructions (e.g., The windmill shrinks, the tomato rotates left, the candle fades). The third (last) object to be mentioned was termed the experimental target (here: the candle). The other two instructions referred to the non-experimental targets. Each target performed one of five actions (expand, rotate left, rotate right, shrink, and fade), which were assigned randomly, with the condition that each action could occur no more than once per trial. PROCESSING-CENTERED REDUCTION 16 The critical manipulation in the experiment was whether within the trial the target objects were linguistically given, non-linguistically given, or not made given explicitly. On linguistic trials, the target objects’ names were spoken aloud (over computer speakers from the recordings mentioned above) in random order, at a volume both participants could hear, before the instruction-giving portion of the trial. On non-linguistic trials, all three target objects flashed twice, simultaneously, on both participants’ screens, before the instruction-giving portion of the trial. On control trials, nothing distinguished the target objects from the other objects, all of which stayed on the screen for 2.5 seconds (the approximate mean time required to say three objects’ names, or make the objects flash) before the instruction-giving portion of the trial. A critical property of our design was that the experimental targets (i.e., the last objects to be mentioned on a trial) were perfectly predictable in the priming conditions. In the control condition they were not especially predictable, beyond the expectation that one of the 8 pictured objects would be mentioned. Thus, the linguistic and non-linguistic givenness conditions were identical in terms of referential predictability, and both differed from the control condition. Following Arnold and Griffin (2007) and Watson, Arnold and Tanenhaus (2008), we used a modified Latin Square design, in which each participant saw each item in all three conditions. This allowed us to directly compare the production of a word across conditions for each participant. The 24 experimental target items were organized into lists of 8 items, and each list occurred three times, once in each condition. Each list had approximately equivalent mean values of log frequency, syllables, imageability, familiarity, and visual complexity. One object from the appropriate list was randomly selected on each trial to serve as the target object. The other 7 objects in the array were selected at random. Two of these served as the nonexperimental targets. PROCESSING-CENTERED REDUCTION 17 Thus, there was a total of 9 blocks, including three of each condition type (i.e. three linguistic, three non-linguistic, three control). Conditions were organized into triads, such that each condition had to appear once before another could appear again, and no condition could appear twice in a row. Thus, the first three blocks represented a standard Latin Square design, where each item was only viewed once. Six sequences in this format were created from Latin Square combinations of the target item sets and the conditions. See Figure 3 for a schematic example of a sequence. A separate analysis (not reported here) of the first blocks was performed to test that our effects were not the result of repeated experience with an item over the experiment. Each of the 6 sequences was seen by two speakers. Each speaker participated in 72 trials, for a total of 216 uttered instructions. Procedure. The speaker and the listener each sat in front of a separate computer, at a distance that permitted them to communicate but not see the other’s screen. Both participants saw task instructions on their own screen. Participants were instructed that they would see arrays of objects, and were given an example of such an array (Figure 2). The speaker was told that she would simply issue instructions about the objects’ actions to her partner, who would mimic those actions on his or her computer. Examples of the possible actions were then shown with random stimuli, and a sentence frame was provided. For example, the speaker’s instructions might have said “You might see [an airplane rotating left], and you might say ‘The airplane rotates left.’” The listener would have simultaneously seen “You might hear ‘The airplane rotates left,’ and you would click the airplane and then the ‘Rotates Left’ button.” The task goal of the participants was simply to issue and follow instructions appropriately. The participants were told that the experiment would be divided into sets of trials, and that before each set they would know whether they would receive linguistic, non-linguistic, or no PROCESSING-CENTERED REDUCTION 18 priming information about the target items. Six practice trials followed these instructions, two from each condition. The objects on these practice trials were randomly selected, and did not include any experimental items. A customized Python script written by the first author controlled the experiment. The speaker’s stimuli were presented on a laptop PC, and the listener’s were presented on a desktop PC. Participants were offered an opportunity to take a break between blocks. The entire experiment took approximately 45 minutes. Analysis. Utterances were analyzed individually using Praat software (Boersma & Weenink 2009). The first author examined the visual waveform and listened to the sound file to identify the onset of each trial (indicated by a beep that co-occurred with each action onset), as well as the onset and offset of the determiner the, the noun, and the action phrase. We report analyses for the duration of each segment, across all three blocks. The latency to speak for each instruction should reflect planning time, where shorter latencies indicate less complex and/or demanding plans. The duration of the noun should most strongly reflect our manipulation, i.e. whether the primed object had in fact become a good candidate for reduction. Utterances were excluded if they were disfluent in any way (i.e. pauses longer than 250ms, coughs, false starts, disfluent ‘the’) or if the speaker used the wrong object or action word. The error rates (pooled across all error types) for the third instructions were 8%, 12%, and 13%, in the linguistic, non-linguistic, and control conditions respectively. For each segment, we built a multi-level model to assess the contribution of givenness. The logarithm of each duration was taken to increase its linear relationship with the predictors. Outlier exclusion was not necessary after this transformation. Models were constructed with the lmer function from R’s lme4 package, which uses maximum likelihood estimation to obtain PROCESSING-CENTERED REDUCTION 19 parameter estimates. We first constructed a baseline model to specify the random effects structure and to identify the significant control variables. Each baseline model included random intercepts for subject and item, as well as random slopes for the contrasts. If the slope for the contrast correlated with the intercept, or the individual contrasts correlated with each other, greater than .9, the redundant slope was removed to avoid overparametrizing the model. After adding the random effects, each model was built stepwise to include the following control variables: log frequency (based on the original Snodgrass & Vanderwart (1980) English names), imageability, visual complexity, and familiarity of the experiment target (taken from Rossion & Purtois (2001)), the number of syllables of the experimental target and of the action word, and the trial number (to control for practice effects). Because of high correlations among these control variables, the following two residualizations were performed by regressing one predictor on one or more others, and using the residuals as the control variable: log frequency had imageability, familiarity, and visual complexity residualized out; object syllables had log frequency and imageability residualized out. We also included the durations of the other segments of the utterance. The model for object noun duration, for example, included the onset, article, and action word duration. Any predictor that did not approach significance in this baseline analysis (a t value of approximately 1.5) was removed. The predictor of interest, condition, had three values, and all pairwise contrasts were relevant. To facilitate these comparisons, we constructed two sets of Helmert contrasts. These compare the mean of one level against the means of all the previous levels of a categorical independent variable. For the first set, we compared the control condition to the non-linguistic condition, as well as the linguistic condition to a combination of the control and non-linguistic conditions. The focus for this set was the comparison between the control and non-linguistic PROCESSING-CENTERED REDUCTION 20 condition. For the second set, we reversed the levels and compared the linguistic condition to the non-linguistic condition, and the control condition to a combination of the linguistic and nonlinguistic conditions. The focus for this set was the comparison between the two experimental conditions. Because both sets of contrasts could not coexist in a single model, we fit one model for each set, and doubled our significance criterion (from .05 to .025). Significance was assessed under the assumption that a sufficiently large dataset (n = 770 for the critical analysis here) could generate parameter estimates and standard errors whose sampling distribution approximates a zdistribution (Baayen, 2008). Results As shown in Table 1, both linguistic and non-linguistic givenness led to shorter target nouns than the control condition, with more reduction in the linguistic than non-linguistic conditions. Both given conditions also exhibited shorter onset latencies than the control condition. There were no effects in the action word region, and determiners were only marginally shorter in the linguistic condition. Tables 2 and 3 show the parameter estimates and overall model designs for each segment of the utterance, separated by the two different contrast sets. Onset to Speak We tested the significance of these patterns in two models, as described above. For the first set of contrasts, the durations of the onset to speak in the linguistic condition differed from a combination of the non-linguistic and control conditions (β = -.021, SE = .0028, t = -7.48, p < .0001), and the non-linguistic condition differed from the control condition (β = .071, SE = .0049, t = 14.49, p < .0001). The second set of contrasts reversed the comparison, and showed that the linguistic condition and non-linguistic condition did not differ (β = -.004, SE = .0048, t = PROCESSING-CENTERED REDUCTION 21 0.78, p > .44), and that the control condition differed from a combination of the linguistic and non-linguistic condition (β = .046, SE = .0028, t = 16.13, p < .0001). The two models together showed that the onset was shorter for both linguistic and nonlinguistic given conditions, relative to the control condition, but there was no difference between types of givenness. Determiner The linguistic condition was somewhat shorter than the other two conditions, but there were no other significant differences. In the first set of contrasts, the linguistic condition marginally differed from the other conditions (β = -.007, SE = .003, t = -2.09, p < .037), but the non-linguistic condition did not differ from the control condition (β = .0047, SE = .0092, t = 0.51, p > .69). In the second set of contrasts, the control condition did not differ from the experimental conditions (β = .0058, SE = .0047, t = 1.23, p > .22), and the linguistic condition did not differ from the non-linguistic condition (β = -.0081, SE = .0072, t = -1.12, p > .26). Target Word The target noun duration, in contrast to the onset to speak, displayed a three way contrast: the non-linguistic condition was shorter than the control, and linguistic condition was even shorter. For the first set of contrasts, the linguistic condition differed from the other two conditions (β = -.0075, SE = .0016, t = -4.7, p < .0001), while the non-linguistic condition differed from the control condition (β = .0106, SE = .0028, t = 3.82, p < .0002). For the second set of contrasts, the control condition differed from the experimental conditions (β = .009, SE = .0016, t = 5.63, p < .0001), and the linguistic condition differed from the non-linguistic condition (β = .0059, SE = .0025, t = 2.42, p < .016). Action Word PROCESSING-CENTERED REDUCTION 22 The manipulation did not have any significant effect on the action word durations. For the first set of contrasts, the linguistic condition did not differ from the other two conditions (β = -.001, SE = .0016, t = -0.59, p > .56), nor did the non-linguistic condition differ from the control condition (β = -.0054, SE = .0028, t = -1.9, p > .06). For the second set of contrasts, the control condition did not differ from the experimental conditions (β = .0022, SE = .0016, t = -1.34, p > .18), and the linguistic condition did not differ from the non-linguistic condition (β = -.0041, SE = .0028, t = -1.48, p > .14). Discussion Our results demonstrated reduction for both given conditions compared with the control condition, and more for the linguistic than the non-linguistic condition. These effects occurred in three of the regions reported here: 1) latency to speak, which was equally reduced for both given conditions, 2) the determiner duration, where the linguistic condition was marginally shorter than control, but not the non-linguistic condition, and 3) the noun duration, which showed a three-way distinction between linguistic, non-linguistic, and control conditions. Because the carrier phrase was essentially identical across conditions, and the action words were not at all affected by the manipulation, the differences observed here can be attributed to the planning and/or execution of the noun. The result of greatest theoretical interest is the increased reduction in the linguistic condition relative to the non-linguistic condition. This difference appeared on the object noun duration, but not the onset duration. The second result of interest was the effect of non-linguistic givenness on reduction. Both the onset to speak latency and the object noun duration were shorter in the non-linguistic condition, compared with the control condition. This provides PROCESSING-CENTERED REDUCTION 23 empirical evidence that given status does not have to be linguistically established to elicit reduction, at least in a situation with a predictable referent. Critically, our givenness manipulation had an effect over and above any effect of speech rate. The models included the durations of the other segments of each utterance, and still revealed a significant effect of condition. Notably, not all segments significantly predicted the durations of the other segments, and neither were the durations of the segments very highly correlated with each other (fixed effect correlations approximately .2 or less). Similarly, an effect based entirely on speaking rate could reasonably be expected to have emerged on all regions of the utterance, with the possible exception of the onset latency. Each segment displayed a slightly different pattern of results, suggesting that speakers were not uniformly modifying their utterance length by modulating their speaking rate. A remaining question is whether the observed reduction was the result of the linguistic and conceptual givenness per se, or whether it depended on the fact that both types of givenness signaled strong referential predictability in the current task. This would be consistent with the fact that given information status correlates with predictability (Arnold, 1998). We examine this question in Experiment 2. Experiment 2 We tested the contribution of predictability to the results observed in Experiment 1, where all linguistically and non-linguistically given targets were 100% predictable in the task. Using a similar paradigm, we reduced the predictability of the targets, and tested the linguistic and non-linguistic givenness on acoustic reduction. In this experiment, participants saw primes on all trials, but only some of the primes were congruent, making the target given on only 1/8th PROCESSING-CENTERED REDUCTION 24 of the trials. The rest were incongruent, such that the target was “new” for that trial. The task was designed to mitigate the effects of predictability as much as possible by creating a situation where using the priming information to predict the target on a particular trial would “pay off” infrequently. Participants who rehearsed the names of the primed objects covertly would only benefit from doing so on 1/8th of the trials. Experiment 2 investigated two questions: 1) Does givenness lead to reduction even when the referent is not highly predictable? 2) When the referent is not highly predictable, do nonlinguistic and linguistic information still differ in their propensity to produce reduction, as they did in Experiment 1? Methods Participants. A total of 43 undergraduates participated in exchange for course credit. We excluded 1 speaker due to technical difficulties, and 2 for not following instructions, for a total of 22 speakers (11 female). 7 participants were paired with a lab assistant. 3 different lab assistants (2 female) played this role. All other participants were paired with another undergraduate. Materials. The same materials, including the colorized line drawings, recordings, and hardware were used as in Experiment 1. We chose the 16 two-syllable target words from Experiment 1 that elicited the greatest amount of reduction in the linguistic condition, relative to the control condition. We used this method partly to control for the number of syllables in the nouns and partly to give speakers the greatest opportunity to reduce. Design and Procedure. The design was similar to Experiment 1, except that each trial consisted of only one instruction, and all trials were preceded by a prime. After the prime, and the object’s action, the speaker issued an instruction, which the listener executed, just as in PROCESSING-CENTERED REDUCTION 25 Experiment 1. Half the trials had a linguistic prime, where subjects heard the name of one of the objects on the screen; the other half had a non-linguistic prime, where subjects saw the primed object flash. We manipulated the given/new status of the target by controlling whether the prime was congruent or not. Of all the trials, only 1/8th had congruent primes, such that the chance of a congruent prime was identical to the chance of selecting one of the eight objects on screen. Thus, the design was 2 (congruent vs. incongruent prime) x 2 (linguistic vs. non-linguistic prime). The entire experiment consisted of 128 trials, with a break at the halfway mark. Four lists were created that crossed which conditions a participant saw particular items in, 8 experimental items appeared in the first half of the experiment, with half of these appearing as linguistically primed. Half of the experimental items that appeared in the first half of the experiment were congruently primed, while the other half were incongruently primed, for a total of 16 congruent primes. Across all participants, each experimental item appeared an equal number of times in each of the cells formed by the 2x2 condition pairings. Each participant saw all items twice, once in each half of the experiment. If an item appeared in one condition pairing in the first half (e.g. linguistically and congruently primed), it appeared in the exact opposite pairing in the second half (i.e. non-linguistically and incongruently primed). The only congruent primes participants saw were for experimental items. Participants completed 12 incongruent practice trials prior to the experimental trials. These were designed to familiarize them to a greater extent with the action words, which several subjects in Experiment 1 struggled with. No experimental items appeared as moving objects in the practice trials. Participants were offered an opportunity to take a break halfway through the experiment, which took approximately 45 minutes. PROCESSING-CENTERED REDUCTION 26 Analysis. The analysis took the same general form as in Experiment 1, with two exceptions: the linguistic and non-linguistic conditions were first examined together to determine the overall effect, and then separately to test simple effects. In the full models, binary contrasts for congruence (congruent vs. incongruent) and prime type (linguistic vs. non-linguistic) were used. These parameters were centered to reduce collinearity with the interaction parameter. Effects were considered significant at a t value > 1.96, in accordance with Baayen (2008). This differs from the first experiment because we were not making multiple simultaneous comparisons. Approximately 11% of the data in the linguistic condition and 13% of the data in the nonlinguistic condition were excluded due to disfluency, with the same criteria as in Experiment 1. Results We report on the duration of each segment of the utterances. An examination of the means (Table 4) suggests that both linguistic and non-linguistic givenness led to shorter onsets and nouns. However, the model suggests that only linguistic givenness had a significant effect in this experiment, in contrast with Experiment 1. The parameter estimates for each segment’s model are shown in Table 5. Onset to Speak There was a significant effect of congruence (β = -0.049, SE = 0.011, t = -4.37, p < .0001), a marginal difference between the conditions (β = -0.02, SE = 0.011, t = -1.75, p > .08), and a marginal interaction (β = -0.04, SE = 0.022, t = -1.83, p > .07). In planned comparison analyses, there was a significant effect of congruence in the linguistic condition (β = -0.07, SE = 0.016, t = -4.38, p < .0001), but only a marginal effect in the non-linguistic condition (β = -0.027, SE = 0.016, t = -1.74, p < .08). PROCESSING-CENTERED REDUCTION 27 Determiner There was a significant effect of condition (β = -0.033, SE = 0.012, t = -2.8, p < .005), with shorter durations in the linguistic than non-linguistic condition. None of the other effects approached significance, either in the full model or planned comparisons. Target Word There was a significant effect of congruence (β = -0.013, SE = 0.0052, t = -2.48, p < .01), as well as a significant interaction between congruence and condition (β = -0.024, SE = 0.01, t = -2.55, p < .01). The difference between conditions was not significant (β = -0.0084, SE = 0.0052, t = -1.62, p > .11). Planned comparisons in each condition revealed significant differences due to congruence in the linguistic condition (β = -0.026, SE = 0.0072, t = -3.57, p < .0004), but not in the non-linguistic condition (β = -0.00044, SE = 0.0075, t = -0.06, p > .95). Action Word There was a significant effect of congruence (β = -0.013, SE = 0.056, t = -2.29, p < .02), such that congruent primes elicited shorter durations. While the effect of condition was not significant (β = -0.042, SE = 0.052, t = -0.82, p > .41), the interaction of condition and congruence (β = -0.018, SE = 0.010, t = -1.72, p < .09) was marginal. In planned comparisons, the non-linguistic condition revealed no effect of congruence (β = -0.0029, SE = 0.0076, t = 0.38, p > .7), whereas the linguistic condition was significantly affected by congruence (β = 0.018, SE = 0.0073, t = -2.52, p < .01). Discussion The results revealed shorter noun durations for linguistically primed words, just as in Experiment 1. The non-linguistic prime condition also led to numerically shorter words than the control condition, but in contrast with Experiment 1, this difference was not significant. Planned PROCESSING-CENTERED REDUCTION 28 comparisons suggested that these effects also extended to the onset latencies and action words, although these effects were weaker. As in Experiment 1, our models indicated that the priming manipulation had an effect over and above any effect of speech rate. Surprisingly, we also found that the determiner was shorter following linguistic primes than following non-linguistic primes, regardless of congruence. This effect was not predicted by either account, nor is it inconsistent with either account, so it will not be discussed further here (but see Kahn & Arnold, under review). Critically, this experiment demonstrated that the effect of linguistic givenness on acoustic reduction does not depend on the referent being entirely predictable, as it was in Experiment 1. The results also reiterated the contrast between linguistic and non-linguistic givenness. While linguistic givenness led to reduction, non-linguistic givenness did not. General Discussion The clearest result to emerge from these experiments was the difference between the effects of linguistic and non-linguistic givenness on reduction. In Experiment 1, although both conditions reduced planning time to the same extent, the linguistic condition elicited more reduction on the object word than the non-linguistic condition. And in Experiment 2, the linguistic condition led to reduction, both in the latency to begin speaking and the object word itself, whereas non-linguistic givenness did not. Together, these results suggest a separate role for each type of givenness in the determination of durational reduction. Experiment 2 further showed that after reducing the potential influence of predictability, the effect of givenness on the noun persisted. However, this pattern held only for the linguistic condition. There as a numerical trend toward reduction in the non-linguistic condition, but this effect was not significant for either the onset or word regions. This may have simply resulted PROCESSING-CENTERED REDUCTION 29 from a lack of power; we know that the effect size is small (given the results of Experiment 1), and thus should be difficult to detect. Unfortunately, methods of power estimation are not currently available for multi-level models. We can safely conclude that non-linguistic givenness leads to reduction when coupled with predictability, but more work is needed to confirm whether predictability is necessary, and why. These results contribute to our understanding of the information status of salient, visually available information, which has heretofore received relatively little attention. While some models suggest that visually-available information carries given status (Clark & Marshall, 1981; Prince, 1981), few studies have examined visual givenness independent from linguistic givenness. Bard and Anderson (1994; Experiment 2) report that pronunciations were less intelligible when the referent was present than when it was not, suggesting that visual givenness does lead to reduction. However, their tokens were extracted from a corpus of adult-child interactions, and their linguistic context was not reported. Thus, some referents may have been linguistically mentioned as well, or otherwise supported by the linguistic context. Bard et al. (2000; Experiment 4) report the converse, that visual givenness does not lead to any additional reduction over and above linguistic givenness. Our study adds to these findings, and shows that a) a direct manipulation of non-linguistic givenness produces reduction relative to a less-given control, and b) speakers reduce less for non-linguistic than linguistic givenness, with predictability held constant. It is worth noting that there are many ways in which information can be visually given. The simplest and most common circumstance is mere visual co-presence (Clark & Marshall, 1981), which suggests that anything that is visible to all interlocutors should count as given. In this sense, one could argue that all of our conditions made the objects visually given, even the PROCESSING-CENTERED REDUCTION 30 control condition. Yet intuitively it seems that some objects are more visually salient than others. We found support for this idea, in that speakers used shorter pronunciations for the nonlinguistically given condition in Experiment 1, in which the target was visually co-present but also salient. Our findings also demonstrate that the effect of linguistic givenness does not depend entirely from the referential predictability. Our experiments manipulate the likelihood that a prime would be the target across experiments, and find that linguistic givenness led to reduction in both. This evidence converges with the results of Lam and Watson (2010), who reported durational reduction for repeated words, regardless of predictability. By contrast, in their experiment predictability affects only intensity. The use of referential predictability differs from most studies, which focus on probabilistic relationships at the word or structural level (e.g. Bell et al., 2009; Levy & Jaeger, 2007; Gahl, 2008; Gahl & Garnsey, 2004). Our manipulation thus underscores (along with Lam & Watson, 2010; Watson et al., 2008) the importance of an additional, “real-world” variable that affects reduction, especially inasmuch as most corpora do not contain all the situational information necessary for drawing inferences about given and/or predictable references to entities (such as the entities present in the environment, where the participants are directing their attention, etc.). Our design controls for the n-gram and frequency information internal to the utterances, with our use of identical sentence frames (The [object] [verbs]), and still demonstrates an effect of both linguistic and non-linguistic givenness. Our empirical results also serve as a basis for discussion of the psychological mechanisms that are likely to underlie reduction. Here we consider how the FRH and traditional PROCESSING-CENTERED REDUCTION 31 information-status accounts might explain them. Facilitation-Based Reduction The results of both experiments support the FRH, which predicts that facilitation of language production processes should lead to a corresponding degree of reduction. Specifically, we predict that both linguistic and non-linguistic givenness should facilitate the conceptual processing of a referent, whereas only linguistic mention would directly facilitate processes related to the linguistic representations of the word, such as lexical and phonological activation. Thus, linguistic givenness should lead to greater facilitation than non-linguistic givenness, and thereby to greater acoustic reduction. In addition, non-linguistic givenness should create some degree of facilitation, and thus some degree of reduction. Our findings support both of these predictions. The FRH also predicts that predictability should lead to facilitation of production processing, insofar as it facilitates utterance planning. This is consistent with the finding that predictability modulated the effect of non-linguistic givenness, but the precise mechanisms by which predictability affects facilitation await subsequent work. One possibility is that it leads to partial activation of the predictable information, which speeds the planning of the utterance, after the speaker recognizes the trial’s action. Another possibility is that strong referential predictability leads speakers to initiate planning of the target reference before the movement is even detected. Our results cannot distinguish between these two explanations. The above interpretation suggests that non-linguistic givenness leads to reduction only through facilitation of conceptual-level processes. However, we must consider an alternative: a “lexical activation” version of the FRH, consistent with other proposals that lexical factors lead PROCESSING-CENTERED REDUCTION 32 to reduction (Bell et al., 2009; Gahl, 2008). It may be that the only type of facilitation that matters is lexical/phonological processing. In the linguistic condition, participants hear the word form, which facilitates the processing of the word and its phonological representation. When the non-linguistic condition makes the primed objects predictable (in Exp. 1), speakers might name the primes sub-vocally, similarly activating the words’ representations. If non-linguistic priming facilitates lexical processes less reliably than linguistic mention, it might account for our results. Even if this interpretation finds support in future research, it is nevertheless important to note its consistency with the FRH, in that it explains reduction as the result of processing facilitation, rather than an explicit representation of information status. Implications for Traditional Information Status Accounts Although the distinction between linguistic and non-linguistic givenness is consistent with the predictions of the FRH, traditional information status models could account for this finding as well, with some slight modifications. However, these modifications rest on some potentially problematic assumptions. We have suggested that a model with a trigger mechanism best approximates the effect of information status on reduction, and this requires, at the very least, an explicit representation of information status. There are two variants of such a model that could explain our findings. One possibility is that speakers represent different kinds of givenness. Numerous theories of givenness identify different categories (e.g., Chafe, 1994; Levelt, 1989; Prince, 1981; 1992). Prince (1981) distinguishes between textually evoked and situationally evoked information, which might correspond to our linguistic and non-linguistic conditions. If so, each category may represent different triggering conditions for acoustic reduction. This approach faces the challenge of identifying the givenness categories that people actually represent. Does this require explicit PROCESSING-CENTERED REDUCTION 33 representation of all of Prince’s (1981) distinctions (e.g., brand new, unused, non-containing inferable, containing inferable, textually evoked, situationally evoked)? The precise taxonomy of kinds of givenness is an empirical question. Yet if too many distinctions prove necessary, such a system is likely to pose intractable memory or processing constraints. Moreover, an account like this would not include a number of linguistic variables that also affect durational variation, including frequency measures, lexical co-occurrence probability, and referential predictability. The model could represent these factors in some fashion, but they are not traditionally considered part of givenness per se. A second possibility is that speakers instead represent givenness along a single dimension (Ariel, 1990; Gundel et al., 1993). If so, different degrees of accessibility could trigger different degrees of reduction. Under this view, linguistic and non-linguistic givenness create different degrees of accessibility. This is consistent with Baumann and Hadelich’s (2006) conclusion that visual primes are “less given” than linguistic primes. An alternate version of this view is that speakers represent givenness as a binary category, but categorize non-linguistic primes as given less frequently or reliably, possibly because they are less memorable.1 However, both variants would predict that the linguistic and non-linguistic conditions should differ on all measures of accessibility. Evidence against this comes from two sources: 1) the onset times in Experiment 1 did not differ across the two given conditions, suggesting that speakers did not require more planning time in either condition, and 2) the error rates across conditions in Experiment 1 were about the same, which suggests that they had the same amount of difficulty with targets in both conditions. 1 We thank an anonymous reviewer for this idea. PROCESSING-CENTERED REDUCTION 34 A third possibility is that our results are not relevant to information-status models. One might argue that our experimental contexts establish an impoverished discourse context. The relationship between the prime and target is not particularly meaningful, especially in Experiment 2. There, givenness is also stripped of referential predictability, a fundamental characteristic of givenness in natural discourse (Arnold, 1998; Givón, 1983). This might suggest that there are two independent effects – acoustic reduction that is triggered by information status, which occurs in contexts with a rich discourse structure, and facilitation effects, which occur in tasks like the one used here. Yet such an account would entail positing two parallel production mechanisms to explain the reduction of given information. Moreover, if givenness in our task results in facilitation, it is likely to also result in facilitation in natural discourse, even with a richer discourse context. Conclusions Our empirical results show that 1) linguistic and nonlinguistic givenness both lead to reduction, 2) linguistic givenness has a stronger effect, and 3) referential predictability supports the effect of nonlinguistic givenness on reduction. These findings fit naturally with our proposal that facilitation leads to durational reduction. On this basis, we argue that it is not necessary to assume that reduction makes reference to an explicit representation of information status in order to account for our results. The primary appeal of the FRH is that it explains the results reported here, as well as results from the studies reviewed above, without having to posit any additional connections among representations or processes used for language production. The strongest version of the FRH, however, was not supported. The lack of an effect of non-linguistic information in Experiment 2 stood in contrast to the claim that any facilitation should lead to measurable reduction. This could merely suggest that there are floor effects, where PROCESSING-CENTERED REDUCTION 35 weak facilitation does not result in measurable reduction, as would be predicted by a formulation of the FRH that included non-linearities. Nevertheless, more work is needed to identify the precise conditions under which facilitation leads to reduction. The FRH supplies specific questions for future work, by specifying predictions about the ways in which different types of stimuli should influence word duration. The idea that givenness can facilitate levels of processing independently allows for a variety of distinctions. For example, it predicts that any stimulus that facilitates both the lexical and phonological levels should produce measurably more reduction than a stimulus that activates either only the lexical level or only the phonological level (see also Gahl, Yao, & Johnson, 2012; Yao, 2011). It might also predict that linguistic givenness could vary in the degree to which it facilitates conceptual processes.2 A further prediction is that speakers do not always reduce for their listener (Arnold, et al., in press; Bard & Aylett, 2004). This is consistent with Bard and Aylett’s (2004) claim that the production system cycles too quickly to incorporate information about the listener into prosodic choices. Arnold et al. (in press) go further, and suggest that audience behavior may itself lead to production facilitation. Moreover, we have found that speaking a word aloud leads to more reduction than naming it to oneself, suggesting that the articulatory level plays a role in reduction (Kahn & Arnold, under review). This result, however, is confounded with the speaker having heard the word at all, and requires additional testing. A further question is whether all levels of production contribute to reduction equally. Fowler (1988) finds that simple word repetition while reading from a list does not produce reduction. Perhaps facilitation at lower levels of the production system does not create reduction by itself, and in fact requires referential or conceptual anchoring. However, Lam and Watson 2 We thank an anonymous reviewer for this suggestion. PROCESSING-CENTERED REDUCTION 36 (2012) find that referential repetition is not necessary for reduction. Alternatively, the conceptual/referential level of processing may interact superadditively with lexical- or sublexical representations and processes to create even more reduction in our tasks like ours. Nevertheless, our work should not be taken to indicate that information status does not exist, or that speakers do not represent it. Information status distinctions are correlated with variation in linguistic form in multiple domains, and speakers are likely to represent this information in a way that influences production processes. In addition, an explicit representation of information status may prove necessary to explain some prosodic variation, such as pitch, intensity, vowel-space modification, segment deletion, and so on. The FRH does not make specific predictions about prosodic variables other than duration. Recent research suggests that pitch, intensity, and duration may vary independently, and not in service of a single pragmatic choice like “acoustic prominence” (Lam & Watson, 2010; Watson, 2010; Watson, Arnold, & Tanenhaus, 2008; for discussion see Arnold & Watson, under review). This speaks against duration as a categorical phenomenon, but also suggests speakers may perform the processes that lead to other forms of acoustic variation separately. At the broadest level, our findings contribute to the characterization of the conditions under which durational reduction occurs. We have considered two approaches to describing the psychological mechanisms underlying reduction. 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The effects of phonological neighborhood on pronunciation in conversational speech. UC Berkeley Dissertation. Zipf, G. (1929). Relative frequency as a determinant of phonetic change. Harvard Studies in Classical Philology, 40, 1-95. 47 PROCESSING-CENTERED REDUCTION 48 Table 1. Means and SD’s of the durations of each segment from Experiment 1, in milliseconds. Onset to Speak Determiner (the) Target Word Action Word Linguistic 921 (295) 94 (28) 377 (96) 758 (179) Nonlinguistic 895 (280) 100 (38) 397 (107) 799 (185) Control 1278 (469) 102 (35) 414 (108) 783 (172) PROCESSING-CENTERED REDUCTION 49 Table 2 T-values of the parameter estimates associated with particular variables in the analyses reported for Experiment 1 for the target (third) instruction. The columns refer to models of individual segments, and the rows to variables in the analyses. “--“ indicates that the variable was not included in the final model for that segment. The set of contrasts here compares the linguistic condition to the other two conditions, and the non-linguistic condition to the control condition. Trial Onset to Speak t = -2.04 Determiner (the) t = -4.73 Target word -- Action word t = -2.0 Imageability Familiarity t = 1.83 -- --- -t = 2.04 --- Visual Complexity Log Frequency t = -2.39 -- --- -t = -1.75 --- # Object Word Syllables -- -- t = 4.5 -- # Action Word Syllables Log Onset Duration t = -7.19 -- t = 3.24 t = 20.59 -- -- -- -- Log the Duration t = 1.42 -- t = 2.92 -- Log Object Duration Log Action Duration -t = -4.68 t = 2.59 t = 1.34 -t = 8.24 t = 7.45 -- Linguistic vs. (Nonlinguistic + Control) Non-linguistic vs. Control t = -7.48 t = 1.23 t = -4.7 t = -1.9 t = 14.49 t = -1.12 t = 3.82 t = -0.59 PROCESSING-CENTERED REDUCTION 50 Table 3 T-values of the parameter estimates associated with particular variables in the analyses reported for Experiment 1 for the target (third) instruction. The columns refer to models of individual segments, and the rows to variables in the analyses. “--“ indicates that the variable was not included in the final model for that segment. The set of contrasts here compares the control condition to the experimental conditions, and the linguistic condition to the non-linguistic condition. Trial Onset to Speak t = -2.04 Determiner (the) t = -4.73 Target word -- Action word t = -2.0 Imageability Familiarity t = 1.83 -- --- -t = 2.04 --- Visual Complexity Log Frequency t = -2.39 -- --- -t = -1.75 --- # Object Word Syllables -- -- t = 4.5 -- # Action Word Syllables Log Onset Duration Log the Duration t = -7.19 -- t = 3.24 t = 20.59 -t = 1.42 --- -t = 2.92 --- Log Object Duration Log Action Duration -t = -4.68 t = 2.59 t = 1.34 -t = 8.24 t = 7.45 -- Control vs. (Linguistic + Nonlinguistic) Non-linguistic vs. Control t = 16.13 t = -2.09 t = 5.63 t = -1.34 t = 0.78 t = 0.51 t = -2.41 t = -1.48 PROCESSING-CENTERED REDUCTION 51 Table 4 Means and standard deviations of the durations of each segment in Experiment 2 Onset to Speak Determiner (the) Target word Action word Congruent Incongruent Congruent Incongruent Congruent Incongruent Congruent Incongruent Linguistic 1548 (750) 1735 (776) 77 (31) 83 (35) 421 (90) 440 (88) 674 (118) 682 (128) Nonlinguistic 1669 (718) 1764 (767) 84 (55) 88 (43) 442 (89) 445 (92) 691 (138) 686 (151) 52 GIVENNESS AND DURATIONAL REDUCTION Table 5 T-values of the parameter estimates associated with particular variables in the analyses reported for Experiment 2. The columns refer to models of individual segments, and the rows to variables in the analyses. “--“ indicates that the variable was not included in the final model for that segment. Onset to speak Trial -- Determiner (the) t = -2.39 Imageability -- -- -- -- Familiarity -- -- t = 3.1 -- Visual Complexity -- -- t = 2.72 -- Log Frequency -- -- t = -2.89 t = 2.21 Log Onset Duration Log the Duration -- t = 1.87 -- t = -9.76 t = 2.9 -- t = -1.47 t = 1.39 -- t = 1.49 -- t = 1.32 t = -9.21 t = 1.61 -- -- t = -1.75 t = -0.95 t = -1.62 t = -0.82 Congruent vs. Incongruent t = -4.37 t = -2.8 t = -2.48 t = -2.29 Condition * Congruence t = -1.83 t = -0.52 t = -2.37 t = -1.72 Log Object Duration Log Action Duration Linguistic vs. Non-linguistic 52 Target word Action word -- -- 53 GIVENNESS AND DURATIONAL REDUCTION Figure 1. The stages of speech planning (adapted from Levelt 1989). 53 54 GIVENNESS AND DURATIONAL REDUCTION Figure 2. An example object array. 54 55 GIVENNESS AND DURATIONAL REDUCTION Ling Set 1 Ctrl Set 2 Nonling Set 3 Set 1 train ring toothbrush nail lamp basket snake finger Set 2 bee knife horse harp bell broom fly clock Set 3 shoe couch sheep bow needle bus whistle deer Ctrl Set 1 Nonling Set 2 Ling Set 3 Nonling Set 1 Ling Set 2 Ctrl Set 3 Figure 3. An example of the list design in Experiment 1. The three sets of words were randomized within each condition-set pairing. No condition could appear twice in a row, and a condition could repeat only after all three conditions had been seen the same number of times. (Ctrl = control condition, Ling = linguistic condition, Non-ling = nonlinguistic condition) 55 Givenness and Durational Reduction 56 Appendix accordion, airplane, alligator, anchor, ant, arm, arrow, artichoke, ashtray, asparagus, axe, ball, balloon, banana, barn, barrel, basket, bat, bear, bed, bee, beetle, bell, belt, bike, bird, blouse, book, boot, bottle, bowl, box, bow, bread, broom, brush, bus, butterfly, button, cake, camel, candle, cannon, cap, car, carrot, cat, caterpillar, celery, chain, chair, cherry, chicken, chisel, church, cigar, cigarette, clock, clothespin, cloud, clown, coat, comb, corn, couch, cow, crown, cup, deer, desk, dog, doll, donkey, door, doorknob, dress, dresser, drum, duck, eagle, ear, elephant, envelope, eye, fence, finger, fish, flag, flower, flute, fly, foot, football, fork, fox, frog, giraffe, glass, glasses, glove, goat, gorilla, grapes, grasshopper, guitar, gun, hair, hammer, hand, hangar, harp, hat, heart, helicopter, horse, house, iron, jacket, kangaroo, kettle, key, kite, knife, ladder, lamp, leaf, leg, lemon, leopard, lettuce, lightbulb, lightswitch, lion, lips, lobster, lock, mitten, monkey, moon, motorcycle, mountain, mouse, mushroom, nail, nailfile, necklace, needle, nose, nut, onion, orange, ostrich, owl, paintbrush, pan, pants, peach, peacock, peanut, pear, pen, pencil, penguin, pepper, piano, pig, pineapple, pipe, pitcher, pliers, plug, potato, pumpkin, purse, rabbit, raccoon, rhinoceros, ring, rollerskate, rooster, ruler, sailboat, salt, sandwich, saw, scissors, screw, screwdriver, seal, sheep, shirt, shoe, skirt, skunk, sled, snail, snake, snowman, sock, spider, spool, spoon, squirrel, star, stool, stove, strawberry, suitcase, sun, swan, sweater, swing, table, telephone, television, thimble, thumb, thumbnail, tie, tiger, toaster, tomato, toothbrush, top, train, trashcan, tree, truck, trumpet, turtle, umbrella, urn, vest, violin, wagon, watch, watermelon, well, wheel, whistle, windmill, window, wrench, zebra 56