Form as a Visual Encounter: Using Eye Movement Studies for Design Reasoning Ameya Athavankar CEPT University, India In spite of the architect’s interest in controlling viewer’s attention, design research has not identified attributes that control attention as measurable and controllable variables. Cognitive scientists, on the other hand have studied attention and shown how variables like complexity and order can be controlled to gain and maintain attention. This paper reports an experiment using patterns created based on information theoretic principles and eye tracking to reveal various interrelated insights that explain attention, visual focus and interest. It extrapolates these findings to understand architectural forms and concludes by offering a set of design strategies or a visual rationale for creating form. Introduction Of the many concerns that decisively drive the making of an architectural form is its quality as a visual and perceptual experience. While architects and designers are quite conscious of the quality of their visual expression, the fact remains that this is not often acknowledged as a design problem with a rationale of its own. Architectural criticism too has lacked objectivity in dealing with the matter and so has been of little value in this respect. As a consequence, most of them turn to their intuition or experience for decisions involving judgments of visual and perceptual quality. The situation calls for investigation of the rationale influencing visual decisions about architectural form that enables architects to go beyond the intuitive approach. J.S. Gero and A.K. Goel (eds.), Design Computing and Cognition ’08, © Springer Science + Business Media B.V. 2008 123 124 A. Athavankar In Search of a visual rationale Design-related visual research has dealt with the ‘look of the environment’ or issues relating its visual form in some detail. Lynch’s study was one of first to point out the visual importance of the environment and produced several generic insights such as ‘imageability’ and ‘legibility’ as attributes dealing with city form [1]. Martin Krampen reported a study conducted by Bortz, establishing the parameters that influence ‘subjective impressions’ describing the experience of viewing building facades [2]. Another particularly interesting study by Sanoff aimed at establishing the relation between viewers’ judgment of ‘visual satisfaction’ with an environment and the visual attributes influencing it [3]. Sanoff’s study emphasizes the importance of attributes such as complexity, novelty and ambiguity in positively influencing the judgment of visual satisfaction. The findings, Sanoff felt, supported Berlyne’s experiments in complexity [4]. To Berlyne, these attributes were ‘conditions leading to arousal and attention’. His study goes a step further in establishing order and organization as attributes that keep arousal within limits. However, the studies treat visual attributes ‘complexity’ or ‘order’ as discrete and undefined adjectives. Though they are insightful, the relevance of the above studies to architectural design seems limited as they do not point out what makes a form perceivably ‘complex’ or ‘ordered’. In other words, these studies do not suggest a method for controlling the attributes like ‘complexity’ or ‘order’. This limitation is rooted in the inability to deal with these attributes as measurable properties of form. It underscores the need for a different framework where attributes ‘complexity’ or ‘order’ may be treated as measurable properties of form instead of discrete and undefined adjectives. Complexity and order as measurable attributes The information theoretic framework successfully overcomes some of the above limitations. It treats visual attributes such as complexity and order (as information content and redundancy) independent of the perceiver as measurable properties of form. This is perhaps one of the main reasons for its appeal to pattern perception. The framework also allows creating visual patterns with attributes that may be precisely described in informational terms. Such patterns have been used to measure the effect of complexity as well as order in different perceptual tasks. Eye Movement Studies for Visual Reasoning 125 Controlling complexity in visual patterns Studies involving the use of patterns with measured complexity were pioneered by Fred Attneave [5]. He created two dimensional `patterns using matrices of three definite sizes (each twice the size of the previous). In a given pattern, each cell of the matrix represented an event with two possible outcomes: it could either contain a dot or could remain empty. Using this technique, Attneave created two sets of patterns. In the first set of patterns, the states of all cells of the matrix were determined independently using a table of random numbers while the second set contained symmetrical patterns of the same matrix sizes created simply by reflecting one half of the patterns belonging to the first set. The complexity of a pattern equaled the total number of cells in the matrix. Complexity, order and memory for patterns The patterns were then used to study viewers’ performance in three different perceptual tasks: immediate reproduction, delayed reproduction and identification. The results led Attneave to conclude that constraints affect the spatial relationships between elements and create ‘dependency’ between. This seems to build a certain amount of predictability due to which remembering a part of the pattern is enough to reconstruct the rest. So, in constructing a pattern, he concluded, any visual decision (location of a dot) that is dependent on the outcome of a previous choice or decision has an element of ‘order’ in it. Perceivable order thus seems to manifest as dependency among decisions while perceived visual complexity could be seen as a relation between the two variables, the number and independence of decisions (in locating dots) required to (re)construct a form. Attneave’s study offers an effective method to capture ‘complexity’ and ‘order’ as measurable and controllable attributes based on the number and independence of decisions required to (re)construct a form. Viewing ‘order’ as dependency among decisions is gives the concept greater universality. (see Figure 1) It is possible to account for various types of constraints (location, shape, color) as dependencies among visual events. However, it partially helps overcome the limitations of Sanoff’s study. It does provide a method to measure attributes of form but not reveal their effect on attention or arousal. This understanding is of significance to architects and designers involved in the process of architectural form making. 126 A. Athavankar Fig. 1. Shows examples of dependent and independent decisions. In the example on the left elements 1,2,3,4,5 share a spatial dependency while 6, 7 are spatially independent. In the example on the right 1,2,3 are dependent shape decisions while 4, 5 are independent shape decisions. Research focus There can be little doubt about the fact that there are aspects of attention that are of importance to architects and designers. For instance, what viewers are likely to notice or find interesting, what makes a likely foreground and what recedes to the background significantly influence visual expression and are questions of interest to architects. The aim of this study is thus to measure the effect of form on attention and explore the significance of the insights to the process of architectural form making. This study will thus try to establish: What in a form is likely, unlikely, or more likely to (a) evoke interest or invite attention (b) sustain interest or retain attention. Further, what properties of a form are likely to arouse or capture viewers’ focus and on the other hand when do viewers show a tendency to wander? This paper, due to reasons discussed later, uses controlled experimental settings and stimuli. It then attempts to extend some of the insights to present a new understanding of architectural forms and visual strategies employed by architects to achieve some of the objectives discussed above. Experimental approach: Attention and eye-behavior The studies cited earlier use instruments such as semantic differential for recording descriptive responses to visual environments. This study takes a similar experimental route to seek the answers to the above questions. However, as opposed to the above studies, it ensures greater objectivity by: Eye Movement Studies for Visual Reasoning 127 • Studying eye movements instead of relying on verbal judgments • Using forms with controlled and measurable attributes as stimuli. Eye movements have been considered by researchers to be an ‘overt behavioral manifestation’ of visual attention [6]. Besides, technological developments in eye tracking have made it possible to record and precisely measure and study various characteristics of eye movements. Although its early use was restricted to fields such as psychology and human factors, in recent times eye tracking has found several other applications in many areas of visual research. These include reading, human computer interaction, advertising, visual art and films [7]. The experimental approach involves isolating visual characteristics of form and capturing them in a set of non-representational forms as controlled and measurable attributes. It proceeds to seek differences in eye movement responses to these forms so as to reveal the effect of measured changes in attributes. The insights or principles derived from the experiment are then extrapolated to understand architectural forms that are difficult to measure. Although more direct insights could have been obtained by recording viewers’ eye movements in actual settings, available eye tracking instruments did not allow for this. Also, as research has shown that eyebehavior in the real world is influenced not only by visual but also semantic characteristics and familiarity or prior knowledge of a scene [8].The interaction of visual and semantic characteristics also poses other difficulties. This became apparent in initial experiments that used photographic representations of building facades and seemed to reduce objectivity in interpreting eye movement data. As would be of interest to architects and designers in particular, it was decided to focus on studying visual (or structural) characteristics of form or its pre-meaning perception. It is true that semantics is likely to significantly influence not only eyebehavior but also the ‘look’ of an architectural form. However, it may be argued that its role is restricted to providing an overall governing visual framework. It is unlikely to greatly influence architects’ local visual decisions about form and the effect of this on visual attention cannot be denied. This study focuses only on establishing visual attributes and their role in influencing attention. In spite of the effect of semantics or prior knowledge, such understanding continues to hold valuable insights for architects. This, in no way implies that it underrates the influence of these factors. It merely attempts to serve as a pilot enquiry and must be seen as a starting point for studying various aspects of attention and its implications to design. 128 A. Athavankar Experimental design In order to focus on visual attributes (and eliminate semantics) nine nonrepresentational patterns were created based on the information theoretic principles used by Attneave [1], [9]. As in Attneave’s study, differential complexity and order were created through measured changes in variables matrix size (number of elements) and spatial independence of elements. Constructing sample patterns The visual field or display of 4:3 (1024x768) was assumed to consist of matrices of the same proportions. The sizes of matrices were fixed at three different levels: 48 (8x6), 192 (16x12) or 768 (32x24) cells. Each cell of the matrix represented an event with two possible outcomes. It could either be blank or could contain a dot. The overall probability or the total number of dots in a pattern was fixed at 1/4 (12 dots), 1/8 (24 dots) and 1/16 (48 dots) for the three levels. To begin with positions of dots were fixed in a regular or homogeneous arrangement to create three patterns (S11, S21, S31). These patterns were then reproduced with 25 percent, (S12, S22, S32) and 50 percent (S13, S23, S33) displacements in the dot-positions using a random number generator. The result was a set of nine sample patterns with three different levels of matrix size and three degrees of spatial independence of elements. (see Figure 2) Procedure The nine patterns were mixed with five similar patterns and shown to 8 viewers while their eye movements were recorded. All the viewers belonged to the age group 20-30 years and were found to be naïve to the purpose of the experiment. The sequence and timing of slides containing patterns was controlled by ‘Presentation v11’ software. Viewers were instructed to themselves control the viewing duration through a response key. Setup The experimental setup consisted of two computers: the subject system (a Pentium V with a 72 dpi 13” LCD monitor set to 1024x768) used for displaying the patterns and the operator system (SMI’s REDIII and iViewX system) for recording eye movements. The subject’s monitor was placed at 900mm from the chin support. The REDIII is a contact-free and non-intrusive device which views the subject from a distance. Eye Movement Studies for Visual Reasoning 129 Fig. 2. Shows the analytical scheme for comparing trends in values for all five measures to reveal the independent and interactive effect of the variables. Scheme for analytical treatment of eye movement data Eye movement data was processed and analyzed using SMI’s BeGaze v1.2.76. The software was used to visualize eye movements as scanpaths and attention maps as well as to identify and log fixation and saccadic data. To systematically study the independent and interactive effect of each variable, an analytical scheme was created. The set of nine sample patterns can be arranged in a 3x3 arrangement (see Figure 2) where: 1. The rows contain patterns with the same degree of spatial independence, but show an increase in the matrix size and number of elements from left to right while the columns contain patterns with same matrix size and number of elements, but show an increase in the 130 A. Athavankar degree of spatial independence from top to bottom. So, row-wise and column-wise comparisons of data reveal the independent effects of increase in matrix size or number of elements and spatial independence. For eg. S11, S21, S31 and S11, S12, S13. 2. Patterns located along: a.The right diagonal (connecting the top-left to the bottom-right corner) shows an increase in number as well as spatial independence of elements. For eg. S11, S22, S33. b. The left diagonal (connecting the bottom-left to the top-right corner) shows an increase in number but a decrease in spatial independence of elements. For eg. S13, 22, 33. Comparison of data along the right and the left diagonal with the data along the rows and columns reveals interactive effects of variables. Scope and limitations of the analysis A search revealed no previous instances of the use of eye tracking for purposes similar to this study. As a pilot, the study had the added task of establishing measures capable of capturing relevant changes in characteristics of eye movements in response to changes in attributes. This was an effort intensive task involving a breadth-first survey of many more measures than presented here. Importantly it created two limitations: • Eye movements of a limited sample of 8 viewers could be considered. • Small sample of 9 patterns could be used. A set of 9 patterns are unlikely to yield totally consistent patterns across 8 viewers. The analysis was directed to making broad categorical inferences such as relative increase or decrease rather than making detailed enquires into actual quantities or degrees of change. It was restricted to comparing and observing trends in mean values calculated from data obtained over 8 viewers consistent with the analytical scheme for a variety of measures. The small sample size of viewers ruled out the possibility of testing the results for their statistical significance or conducting an ANOVA. The limited number of sample patterns also had its implications. It may be recalled that the patterns were created using a random number generator. This method can sometimes result in unexpected, yet strong local grouping or Gestalts. Such grouping produced some inconsistencies, visible in the data. Ideally, as in case of Attneave’s study the effect of such grouping should have been eliminated by considering a large number of samples of a pattern [1]. However, increasing the number of patterns would not only have stressed viewers but also produced an enormous amount of eye Eye Movement Studies for Visual Reasoning 131 movement data. Processing data for a large number of measures would be much beyond the scope of the study. The conclusions of the study will thus be speculative and at times tentative in tone. They must be seen as initial findings that are in need of further study. However, the results seem promising and yield interesting insights into form and visual attention. Therefore are considered worth sharing. Interpreting eye-behavior A discussion on concepts of eye movements has been avoided here, for reasons of economy. Those interested in deeper understanding may want to refer to Yarbus’s or Duchowski’s book for a fascinating account of theory as well as applications of eye tracking [10], [7]. The results have been discussed in relation to the aims of the study so as to enable an assessment of whether the study has succeeded in answering the questions that were raised earlier. Evoking visual interest One of the questions the study aimed to answer dealt with the ‘foregroundness’ of the entire group of dots or elements as a whole and their ability to evoke visual interest. It was framed as: What in a form is likely, unlikely, or more likely to evoke interest or invite attention? This section deals with the question in detail. Fixations: Number and locations Ratio of on-target fixations (Preferred fixation sites): The ratio of on-target fixations compares the number of fixations received by the entire group of elements (cells with dots) to the total number of fixations received by the pattern. It captures viewers’ preference for fixation sites. Significance: In a pattern, elements (as a whole) receiving more fixations relative to the background must have greater collective ability to evoke visual interest and therefore a greater foreground-ness as compared to those receiving fewer fixations. This collective ability among elements can be captured by the ratio of on-target fixations. In usability research, ratio of on-target fixations has been used to determine the efficiency of scanning behavior [11]. Considering the 132 A. Athavankar differences in experimental task, its use and interpretation have been suitably modified in this study. Ratio of elements-hit or hit-rate (Chance of an element being fixated): The hit-rate compares the number of elements-fixated to the total number of elements in the pattern. It captures the overall chance of an element being fixated. Significance: An element with a higher chance of receiving a fixation must belong to a group that evokes more visual interest as compared one where fewer elements receive fixations. This individual ability among elements can be captured by the ratio of elements-hit (fixated) or the hitrate. Independent and interactive effects The effects of the variables on the measures (see Figure 3) are as follows: Independent Effects: The (a) ratio of on-target fixations (b) hit-rate seems to increase as the spatial independence of elements increases and decreases when the number of elements increases. Insight: Increased spatial independence among elements seems to improve their collective and individual ability to evoke visual interest while addition of elements seems to marginally diminish it. Interactive Effects: The (a) ratio of on-target fixations (b) hit-rate seems to marginally decrease along the right diagonal. The decrease is less than the independent effect of increase in number of elements.The (a) ratio of on-target fixations (b) hit-rate seems to sharply decrease along the left diagonal. The decrease is more than the independent effect of either variable. Insight: Reduction in the collective and individual ability of elements to evoke visual interest due to a four fold increase in the number of elements may partially be balanced by a 50 percent increase in spatial independence. Insight: Increasing the degree of spatial independence and reducing the number of elements seems to severely diminish their collective and individual ability to evoke visual interest. Consolidated insights Due to commonalities in content as well as to enable a better comparison, the insights presented above will be discussed in 3.3.3. Eye Movement Studies for Visual Reasoning 133 Sustaining visual interest The ‘foreground-ness’ of a group of elements cannot be fully studied without establishing what influences the ability of elements to sustain visual interest. One of the questions the study aims to answer was framed as: What in a form is likely, unlikely, or more likely to sustain interest or retain attention? This section will discuss the question is detail. Fixations: Duration and location Relative fixation time (Share of Fixation time): Relative fixation time compares time spent by viewers fixating elements to the time spent fixating on the entire pattern. It captures the share of fixation time received by elements. Significance: A group of elements (as a whole) receiving a larger share of fixation time must have a greater ability to sustain visual interest compared to those receiving a relatively smaller share. This collective ability among elements may be captured by relative fixation time. Cumulative or total fixation time spent within a certain area of the image in usability studies is interpreted as the amount of interest shown by viewers [12]. However, considering the experimental design here, it was necessary to neutralize the effect of differential viewing time. The cumulative fixation time (on elements) was measured relative to the total fixation time for the pattern. Fixation time per element-hit (Dwell time over a fixated element): The fixation time per element-hit compares the total fixation time spent over elements to the number of elements fixated. It captures how much viewers dwelt over an element. Significance: An individual element on which fixations dwell more, arguably, sustains more visual interest compared to one on which they dwell less. This ability among individual elements may be captured by the fixation time per element-hit. Independent and interactive effects The effect of the variables on the measures (see Figure 4) is as follows: Independent Effects: The (a) relative fixation time seems to increase (b) fixation time per element-hit seems to increase when the spatial independence of elements is increased. The (a) relative fixation time seems to increase (b) fixation time per element-hit seems to increase when the number of elements is increased. 134 A. Athavankar Fig. 3. Shows values of ratio of on-target fixations (ot) and hit-rate (hr) for all nine patterns and typical eye-scanpaths for selected patterns. Note how elements (dots) in patterns S13 and S33 pull attention towards themselves with large saccadic movements while elements in patterns S11 or S31 cease to do so. Also note that the scanpaths shown above are typical examples and may not be consistent with actual mean data. Insight: Increased spatial independence seems to improve the collective and individual ability of elements to sustain visual interest. Insight: Addition of elements seems to improve the collective ability but diminishes the individual ability of elements to sustain interest. Interactive Effects: The (a) relative fixation time seems to sharply increase (b) fixation time per element-hit seems to marginally decrease along the right diagonal. The increase in relative fixation time is greater than the independent effect of either variable. The decrease in fixation time per element-hit is less than independent effect of increase in number of elements. The (a) relative fixation time seems to marginally decrease (b) fixation time per element-hit seems to sharply decrease along the left diagonal. The decrease in relative fixation time is lesser than the independent effect of Eye Movement Studies for Visual Reasoning 135 spatial independence. The decrease in fixation time per element-hit is greater than independent effect of either variable. Insight: Increasing the number and the degree of spatial independence of elements seems to improve their collective ability to sustain visual interest. Insight: Reduction in the ability of individual elements to evoke visual interest due to a four fold increase in the number of elements may partially be balanced by a 50 percent increase in spatial independence. Insight: Reduction in the collective ability of elements to sustain visual interest due to a 50 percent increase in spatial independence may partially be balanced by four fold increase in number. Insight: Increasing the degree of spatial independence and reducing the number of elements seems to improve their individual ability to sustain visual interest. Consolidated insights The ability to evoke (invite attention) and sustain visual interest (retain attention) seems to be strongly related to the spatial independence of elements. Spatial independence creates uniqueness in inter-element relationships and unpredictability the relative positions of elements. This is what possibly improves their collective as well as individual ability to evoke and sustain interest. Addition of elements, on the other hand seems to have an interesting effect. As one would expect more elements in a pattern competing for attention diminishes the ability of an individual element to evoke or sustain visual interest. Surprisingly, addition of elements does not seem to improve the collective ability of a group of elements to evoke visual interest or invite attention but it does help them sustain interest or retain attention. Capturing visual focus One of the questions that the study aims to answer concerns the ability capture visual focus. It was framed as: What properties of a form are likely to arouse or capture viewers’ focus and on the other hand when do viewers show a tendency to wander? This section deals with the question in detail. 136 A. Athavankar Fixation time: Spatial distribution Ratio of Fixation/ Saccadic time (Distribution of fixation time): The ratio of fixation to saccadic time compares the time spent by viewers (in fixation) acquiring information from the pattern to the time spent searching for it (through saccades). A higher fixation/saccadic time indicates that fixation time was concentrated and fixations were retained in fewer locations about the pattern, while a lower value implies that fixations were short and scattered over many locations separated by saccadic search for these locations. Fig. 4. Shows values of ratio of relative fixation time (rf) and fixation time per element-hit (fe) for all nine patterns and typical eye-scanpaths for selected patterns. Note how elements (dots) in patterns S13 and S33 receive more as well as longer fixations (larger circles) while elements in patterns S11 or S31 receive fewer and shorter fixations (smaller circles) Also note that the scanpaths shown above are typical examples and may not be consistent with mean data presented. Significance: It may be argued that a pattern likely to capture visual focus must produce focused or directed scanning. On the other hand, a pattern unlikely to capture focus or one that divides or distributes focus may produce a wandering tendency in scanning. This should be reflected Eye Movement Studies for Visual Reasoning 137 in the spatial distribution of fixation time (sparse or concentrated) and may best be captured by the ratio of fixation/ saccadic time. In usability research this measure has been used to determine the search efficiency, since it compares time spent by viewers acquiring and processing information to the time spent locating it [11]. Its use and interpretation here have been modified to suit the requirements of this study. Independent and interactive effects The effects of variables on the measures (see Figure 5) are as follows: Independent Effects: The ratio of fixation/ saccadic time seems to increase when spatial independence among elements is increased and decreases when their number is increased. Insight: Increased spatial independence seems to capture visual focus while addition of elements seems to divide and distribute it resulting in a wandering tendency. Interactive Effects: The ratio of fixation/ saccadic time seems to marginally increase along the right diagonal. The increase is less than the independent effect of spatial independence. The ratio of fixation/ saccadic time seems to sharply decrease along the left diagonal. The decrease is less than the independent effect of either variable. Insight: Reduction in the ability to capture visual focus due to a four fold increase in number of elements may be partially balanced by a 50 percent increase in spatial independence. Insight: Increasing the number of elements and reducing the degree of spatial independence seems to least capture focus resulting in the highest tendency to wander. Consolidated insights The ability (or inability) in a pattern to capture viewers’ focus seems to be strongly influenced by the spatial independence of elements. Increasing the degree of spatial independence seems to break homogeneity of a pattern. It creates unique and unpredictable grouping among elements and a hierarchy among regions. This characteristic seems to be decisively influence for the ability to capture focus. Addition of elements, on the other hand seems to have quite the opposite effect. More elements seem to create more groups. This seems to taper the hierarchy, dividing and distributing it among more regions. It is however possible to counter the reduction in the ability to capture focus by proportionately increasing the degree of spatial independence of elements. 138 A. Athavankar Attention vs. memory for patterns The insights listed above are particularly interesting when seen in relation to Attneave’s findings on viewers’ performances in memory tasks. His study attributes learning difficulty to the independence of decisions (locating elements) required to (re)construct a pattern. The findings discussed in the previous sections also continually emphasize the decisive influence of independence of elements (or decisions), on the ability to evoke and sustain visual interest or capture visual focus. (see Figure 6) It seems that some of the characteristics of a pattern that help elicit a strong visual response, also seem to make it more difficult to memorize. Fig. 5. Shows the values of ratio of fixation/ saccadic time (f/s) for all nine patterns and typical attention maps for selected patterns. Attention maps indicate the distribution of fixation time about a pattern. It is represented as a color gradient from violet (relatively less fixation time) to red (relatively more fixation time). Note how pattern S13 shows a dense distribution while S31 shows a scattered distribution. Also note that the attention maps shown are typical examples and do not represent mean data. Eye Movement Studies for Visual Reasoning 139 Relevance to architects and designers This paper attempts to understand the relationship between form-attributes and visual attention through the analysis of eye-behavior. Using abstract patterns (with controlled attributes) it establishes principles that influence attention and arousal. In the sections that follow, an attempt is made to extend some of the ideas to create a different understanding of architectural form. With further research some of these ideas could also be developed as a design tool. In the near future eye trackers are likely to become increasing portable and possibly ubiquitous. This should enable direct use of eye tracking to deal with some of the issues addressed here. However, at this point of time laboratory route seems the best available option in terms of the ability to isolate and control attributes as well as objectively analyze eye movement data. Insights as principles for architectural form-making There is no doubt about the fact that controlling viewers’ attention is one of the unstated objectives of an architect. It is not uncommon, for instance to find an architect or a designer taking special efforts to ensure that his form or its features capture the interest of viewers or so that their attention may linger on it more than what is functionally adequate. In other cases, he may wish that viewers do not notice a form or some of its features at all. He also hopes that they retain a certain memory of his form. The insights and findings presented here can be developed as visual strategies that could be employed by a designer to achieve some of these objectives. Interestingly, the variables (number and spatial independence of elements) to some extent represent real visual situations that architects often encounter. For instance, an architect or designer may be confronted with the problem of creating entrances, displays or signage that must capture viewers’ focus in settings such as commercial streets, airports, train terminals or shopping malls, where a large number of visual elements compete for viewers’ attention. In other cases, he may be expected to design a showroom that not only evokes but also sustains interest. On the other hand, highway signage, advertisements or displays as instances where viewers do not have the luxury of too much viewing time. After all, influencing attention is his first essential step in establishing communication with viewers. It must be noted that the perceived effect of form cannot be judged merely based on its ability to capture focus or invite and sustain interest. As Berlyne stated, an ‘aesthetic product’ is one that not only gains and 140 A. Athavankar maintains the attention of the audience but also keeps arousal within limits [13]. Balancing of complexity and order in a message has always been critical in any communication. After all features which do not capture focus or interest that make time and attention available to those which do. The insights presented earlier allow a designer to carefully plan the perceived hierarchy within the features of his form influencing what is likely to capture focus and what is not. Fig. 6. Shows changes in scanpath characteristics due to the effect of measured changes in number of elements and spatial independence. The concept of ‘visual space’ The true significance of the work is in the creative use of the insights presented in the earlier sections to develop a deeper understanding of Eye Movement Studies for Visual Reasoning 141 process of creating forms going beyond the current intuitive approach. The relationships between insights can be exploited to convert them into overall visual strategies that architects can use to predictably influence visual response. To facilitate this relationships between insights, the spatial arrangement of (nine) patterns can be visualized as a continuous and limitless ‘visual space’ where attributes can be treated as controllable variables. (see Figure 7) The perceived effect of a form can be establishing through its position in visual space. Fig. 7. Shows a representation of the ‘visual space’ and how built forms may take up different positions on it. The examples presented are (clockwise) German Pavillion at Barcelona, Lake Shore Drive Apartments at Chicago, Guggenheim Museum at Bilbao, Notre-Dame-du-Haut at Ronchamp. The visual space can serve as an effective analytical tool for understanding architectural forms. Positioning carefully chosen forms in the space can reveal interesting visual strategies employed by a particular 142 A. Athavankar architect or designer or during a particular time period or region etc. A preliminary attempt in this direction has been made here, by relatively placing renowned architectural forms in selected positions of the space. (see Figure 7) It seems to yield promising insights. With further research the visual space may be developed as a design tool with that can account for many more variables and reflect the actual complexity of architectural forms. This should allow an architect to position his form (or its different features) and predict the relative effect on visual interest, focus and learning difficulty. Architects can use the space for reasoning and taking visual decisions. The contention of the paper is that among its other roles, architectural form is something to be seen. It must be designed as a deliberate and designed encounter leading to an active and engaging visual dialogue. The ability to influence viewers’ attention is an important first step in doing so. References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. Lynch K (1960) Image of the city. MIT Press Krampen M (1979) Meaning in the urban environment. Pion, London Sanoff H (1974, 1991) Visual research methods in design. Van Nostrand Reinhold, New York Berlyne DE, Peckham S (1966) The semantic differential and other measures of reaction to visual complexity. Canadian Journal of Psychology Attneave F (1955) Symmetry, information and memory for patterns. 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