Size Perception of Enclosures

Transcription

1 1 Size Perception of Enclosures Sarah-Jane Abate, Toshiro Kubota Susquehanna University, Selinsgrove, Pennsylvania It is anecdotally noticed that a room looks different when inside than when looking at its foundation from the outside. We examined the effects of environment on perception of enclosures and objects, using the Gibsonian view of affordance to examine the reaction of perception to environment. Subjects perceived a room and two tables, and then examined sample rooms in an outside field and an indoor track. They chose a constructed room and table that most matched their perception of the actual. In examining the relationships between subjects choices in environment, a significant difference was found. There was no significance between perception of enclosure and object; however, there was a pronounced degree of reduction, suggesting a trend, and evidence that when an enclosure is outside, we stop viewing it as an enclosure. Our findings clearly show that there is a significant difference between the way we view enclosures outside and inside, with an increased tendency to underestimate size when outside. INTRODUCTION We often hear people saying things such as a living room looks tiny when it is only at its foundation, a window looks small when seen from the outside, or a house looks puny from above. These anecdotal observations attribute to enclosure. One possible explanation for these perceptual discrepancies is the same explanation we give to the Ebbinghaus illusion: when an object is surrounded by larger objects, it looks smaller than when it is surrounded by smaller ones. However, is this explanation sufficient for these anecdotal effects? Does the degree of discrepancy compare to that of the Ebbinghaus illusion? We can relate the above observations to studies on size perception of objects, but it does not explain everything. Li et al. (2011) have shown that we underestimate the frontal extent of an object in relation to egocentric distance to it. But this finding is not applicable to the size discrepancy of enclosure, as the average egocentric distance to four walls does not change as we move around the enclosure. We believe that perception of enclosure is an interesting and important problem. According to Gibson s ecological view, a living space provides a special type of affordance: because it supplies foods, sleep, security, and comfort, our perception treats it differently from

2 2 other objects inside it (Gibson 1986). When the space is viewed from outside, we no longer enjoy the same affordance. Thus, if Gibson s view is correct, our perception of the enclosure will be drastically different whether we are inside or outside. However, there is also evidence of enclosures having a negative effect on our perception: when the room affords confinement or fear, we can become vulnerable to a psychological disorder known as Security Housing Unit Syndrome. This occurs in solitary confinement in prisons, bringing anxiety, paranoia, memory loss, depression, hallucinations, and other perceptual distortions (Guenther 2012). This, therefore, indicates that the loss of affordance has the potential to significantly alter our perception, and enclosure has an intricate influence on our perception in general. In this study, we are interested in our size perception of the enclosure itself. This is different from effects of enclosure on size perception of regular objects as demonstrated in the Ebbinghaus and Muller-Lyer illusions. We are interested in how our perception of an enclosure changes when it no longer functions as enclosure. More specifically, we are interested in how the perception of a small enclosure (a room) changes when it is placed under a larger environment (for example, an open space). To this end, we expect significant changes in our perception when the room is perceived as only a part of a larger enclosure as it no longer provides the same affordance. Are there any evidence suggesting the view? As mentioned above, there is some anecdotal evidence that we perceive a room as being much larger when we are enclosed in it compared to when we are outside looking at its foundation alone. However, to our knowledge, no quantitative experiment has been done to support the evidence. Further looking at the literature yields some information on previous studies of size perception, as well as the factors that may influence us in different environments. Size perception has long been known to be inaccurate and dependent on many factors, such as distance, depth cues, environment, and lighting (Edwards and Boring 1951; Stamps 2011; Witt et al. 2007). This perception inaccuracy is fairly consistent, with distance usually being underestimated (Foley et al. 2003). Wagner (1985) discovered that objects seen in depth are judged as half the size of objects in the frontal plane, demonstrating that visual space is compressed compared to physical space. This error in size perception is well documented by this point; not as well theorized are the possible causes behind the underestimation of size. A few have also studied the perceived spaciousness of area, which relies on size perception on a large scale. In regards to three-dimensional size and space perception; Norman et

3 3 al. (1996) found that although subjects could notice small differences in two-dimensional lengths, their ability to discern differences in line segments in three-dimensional space was compromised. In one of the earliest modern studies, Anatasi (1936) examined the estimated area of shapes such as squares, stars, and triangles, when compared to others in a series. Anatasi found that not only was the estimation of area much more difficult than the estimation of onedimensional lines, but that almost every figure in the study was overestimated when compared with squares, and all figures were overestimated when compared with triangles. This tendency towards overestimating area when in a series is interesting, as we tend to underestimate distance. This degree of overestimation was greater the larger the figure; however, larger standards of shapes were underestimated and smaller were overestimated. Ultimately, it was theorized that areas were estimated in terms of their linear magnitudes, which causes these results. Stamps (2011) used virtual reality Japanese streets to examine the effects of horizontal area, height, color, and elongation on perceived spaciousness; he found that horizontal area had the strongest effect, with height having the second strongest effect on perceived spaciousness. Stamps also created virtual rooms to test these same variables, and discovered that rooms with lower ceilings are perceived to be more spacious than rooms with higher ceilings. This indicates that height influences size perception, possibly through an enclosing feature of height. Perceived spaciousness is a particularly popular topic in architectural studies. For example, while looking at virtual Tokyo streets, Ishikawa et al. (1998) found that areas with wider frontages looked larger than those with deep setbacks; Stamps (2011) found that not only were larger areas viewed as being more spacious, but that streets with shallow and longer setbacks were seen as more spacious than those that were deeper and shorter. Sadalla and Oxley (1984) found that more rectangular rooms are perceived as being larger than less rectangular rooms when they are identically sized. Therefore, even though a space may take up the same amount of area, the way it is arranged greatly affects size perception and perceived spaciousness. Most of interest here is the effect of environment on size perception, although most work has been done on size perception while outside. It has mostly been found that being outside does affect size perception, although the ways in which the outside environment influences perception are varied. Bertamini et al. (1998) argue that observers use the horizon to measure relative size, as these judgments are best around the horizon. Witt et al. (2007) have argued that non-depth cues in vista space (both inside and outside) affect the perception of distance despite ample depth

4 4 cues; Bingham (1993) found that observers used trees while attempting to perceive the size of a similarly shaped object, a cylinder. Andre and Rogers (2006) examined verbal and blind-walking distance estimates both inside and outside, and found that subjects underestimated outside distances in verbal estimates. However, little has been done regarding the effects of enclosure on size perception, or on the effects of enclosure on perceived spaciousness. The effects of enclosure can be demonstrated in several famous illusions. One of these illusions is the Ebbinghaus illusion, where two physically equal circles are perceived to be two different sizes, due to one s enclosure in a ring of larger circles, as seen in Figure 1. Another illusion that demonstrates the effects of enclosure on size perception is the Muller-Lyer illusion, as seen in Figure 2. This illusion consists of two identical lines with arrows: one line with arrows facing inward, one line with arrows facing outward. The line with the arrows facing outward appears to be smaller than the other, and it has been proposed that this is due to the enclosing effect the arrows have on the line (Fellows 1968). Through illusions such as these, the effects of enclosure can be clearly seen. Fig. 1 Fig. 2 In this study, we investigate how the size of a room appears different when it is enclosed in different environments. Upon being placed in a larger environment, the room becomes a regular object in the environment and no longer serves as an enclosure. If the apparent size of the room decreases more dramatically than regular objects such as tables, we have supporting evidence that our perception treats an enclosure differently from non-enclosure objects. METHOD Participants. Twenty-six subjects, (13 females, mean age = 22.1, median age = 20, range = 18-47) participated in this study. All of the participants had normal or corrected-to-normal vision, and received food and snacks, but no monetary compensation, for participating.

5 5 Materials. Sample rooms were built of six-foot tall bamboo poles anchored in the ground when outside, and planted in two-liter bottles when inside, with red ribbon marking the boundaries of each room. Sample tables were constructed out of small flags and ribbon; rectangular tables consisted of orange flags and ribbon; square tables consisted of pink flags and ribbon. Rooms and tables were constructed in two areas; the first, an outdoor field; roughly 330 ft x 190 ft; the second, an indoor track. Procedure. The experiments took place in two trials over two days, with both days consisting of the same procedure. Subjects were taken to a break room inside, measuring x They spent about 30 minutes there without being told to notice the size of the room. Two tables were also set up in the room next to each other, one rectangular and one square. Subjects were told to remember the appearance of the tables. After the 30 minute period in the room, subjects were then split up into two groups. One group was led to an outside field, where sample rooms and tables had been set up (see figures 1.1, 1.2, and 1.3). There were four sample rooms, marked and measured as follows: A = 20% larger than the actual room (28 9 x ); B = same size as the actual room (23 11 x 30 9 ); C = 30% larger than the actual room (31 1 x ); D = 10% larger than the actual room (26 4 x ). Next to these rooms, there were four sample rectangular tables, marked and measured as follows: A = 20% larger than the actual table (5 5 x 2 6 ); B = same size as the actual table (4 6 x 2 1 ); C = 30% larger than the actual table (5 10 x 2 9 ); D = 10% larger than the actual table (4 11 x 2 4 ). Next to these tables, there were four sample square tables, marked and measured as follows: A = 20% larger than the actual table (3 7 x 3 8 ); B = same size as the actual table (3 x 3 1 ); C = 30% larger than the actual table (3 11 x 4 ); D = 10% larger than the actual table (3 4 x 3 5 ). Subjects were asked to choose, from a questionnaire, one of six choices for the room and each table: Smaller than any options shown, A, B, C, D, and Larger than any options shown. Subjects were encouraged to walk around and inside the sample areas, although they were not allowed to communicate with each other. When finished, subjects were taken to the indoor track, where the procedure was repeated with a new questionnaire. The second group of subjects was brought to the indoor track first, which had almost the exact same setup as the first (see figures 3, 4, 5, and 6 in Appendix). All measurements were the same in both arenas. Subjects were asked to perform the same task as outside. When the second

6 6 group of subjects was done with their task in the indoor gym, they then proceeded to the outdoor field and performed the task again. Each subjects performed the task both inside and outside, although roughly half performed the task outside first, whereas the other half performed the task inside first. When done with all tasks, both inside and outside, subjects handed their questionnaires to experimenters. After the experiment was completed, subjects were debriefed and thanked. RESULTS Subjects were separated by group when performing the experiment: one set of subjects visited the indoor site first, and then the outdoor site, while the other group visited the outdoor site first, then the indoor site. Their responses were separated by group and examined to determine if order, or repetition of the task, resulted in different responses. Fig. 3: Frequency histograms demonstrating the choice between groups, separated by graph into environment and then further into room, rectangular table, and square table. Figure 3 shows histograms of six categories, separated by groups: inside first and outside first. The six categories are products of two environments (inside and outside) and three objects (room, rectangular table, and square table). The horizontal axis is ranked in terms of apparent area size. The histograms for the outside room are relatively similar in shape between the two groups. In regards to the square table, there is very little similarity within either the inside by group or the outside by group histograms.

7 7 Fisher s Exact Test was run on the data between groups, to determine if there was a significant statistical difference between groups. The test was run on each category, and the results are shown in Table 1. As can be seen, there is no significant difference between the two groups in any category. Therefore, we will not treat them separately. Instead, we will combine them in our subsequent analysis. Table 1. P-values of Fisher s exact test between experiment order (inside first vs. outside first), further broken down by object. Object P-Value Inside Room Inside Rectangular Table Inside Square Table Outside Room Outside Rectangular Table Outside Square Table Figure 4 shows the frequency histograms of responses made in both inside and outside environments, separated by room, rectangular table, and square table. Figure 4 shows the frequency histograms of choices, comparing environments, for each object. As can be seen from the histograms, no subjects chose the correct size of the room while outside; however, 4 subjects did so when inside. When outside, subjects more frequently chose the 30% larger room; when inside, they tended towards the 10% larger or 20% larger room. Overall, histograms of the outside are skewed to the right more severely than histograms of the inside, indicating that subjects tended to underestimate marked areas more strongly in outside than inside. As can be seen from the histograms, there are only 4 counts in the Smaller than any option bins out of 162. We feel from the trend of the curves that these 4 counts would have been placed in 10% smaller if such area had been made available. Similarly, there are only 3 counts in

8 8 the Larger than any option bins. We feel that these would have been placed in 40% larger if such area had been made available. Thus, we approximate the above truncated distribution into a full distribution by interpreting Smaller than any option to 10% smaller and Larger than any option to 40% larger. We then assign numerical ranks to these bins: -1 to Smaller than any option, 0 to A, 1 to B, 2 to C, 3 to D, and 4 to Larger than any option. This arrangement allows us to treat the data as numerical for further analysis. Table 2 shows the means and standard deviations of responses for each category. There is a definite trend in the means of the objects: the mean is larger for the room, and then decreases for the tables. This trend is more pronounced for the outside environment than for the inside environment. The means are also larger overall for the outside environment as compared to the same objects in the inside environment. Table 2 shows the mean, standard deviation, max and min for each enclosure and object. Category Mean Std. Min Max Outside Room (O.R.) Inside Room (I.R.) Outside Rectangular Table (O.R.T.) Inside Rectangular Table (I.R.T.) Outside Square Table (O.S.T.) Inside Square Table (I.S.T.) A two-way repeated ANOVA was performed with environment (inside and outside) and objects (room, rectangular table, and square table) as two independent variables. The result showed that the environment affected the degree of area underestimation, F(1,25)=20.63, p< Thus, the outside environment made marked areas look smaller than the inside environment. The objects did not affect the degree of area underestimation, F(2,50)=0.565, p=0.57. The environment and object interaction was not significant, either, F(2,50)=1.28, p=0.29. Bonferroni post hoc tests showed that two pairs of comparisons gave significant difference. They were between O.R. and I.R. (p=0.02), and O.R.T. and I.R.T. (p=0.02). Thus, room areas outside looked significantly smaller than corresponding areas inside. Also rectangle table areas outside looked significantly smaller than corresponding areas inside.

9 9 We compared the response values for room, rectangle table, and square table with their actual areas. We did the comparison for the indoor set (I.R., I.R.T, and I.S.T) and outdoor set (O.R., O.R.T., and O.S.T.), separately. The areas were 735 square feet, 9.38 square feet, and 9.25 square feet for the room, rectangle table, and square table, respectively. Pearson correlation coefficients were 8.1E-3(p=0.94, df=76) between the areas and the indoor responses, and 0.16 (p=0.17, df=76) for the areas and the outdoor responses. Thus, there was moderate correlation between the size of an area and its apparent reduction in size in the outdoor environment. Table 3. P-values of pooled t-tests between genders, further broken down by object. Category p-value I.R O.R I.R.T O.R.T I.S.T O.S.T We compared results between genders. Table 6 shows p-values of pooled t-tests applied to each category separately. None shows significant difference. Thus, we conclude that there was no significant difference between gender responses in this experiment. DISCUSSION AND CONCLUSION The p-values between environments were statistically significant, indicating that there is a substantial difference in the way we perceive things while we are inside versus the way we perceive things while we are outside. There is a marked tendency to underestimate the size of the object in either environment, with the effect increased in an outdoor environment. Subjects underestimated to a lesser degree when inside, in an enclosed area, and more frequently chose the correct option. We hypothesize that this is due to the difference in allocation of cognitive resources in different environments, based on Gibsonian affordance. Inside environments offer us relative safety and predictability; therefore, we can allocate more of our cognitive resources towards observing and perceiving things. There are a limited number of threats in an inside environment; therefore, more cognitive space can be given to the task at hand, increasing our perception accuracy. However, when we are outside, we lose this safety and affordance. Things

10 10 are unpredictable: there may be predators or other environmental threats; therefore, we need to stay alert to the larger environment. The rooms and objects the subjects were asked to perceive were non-threatening; not much cognitive space needed to be spared for them in comparison with the outside environment. There is a different allocation of cognitive and neural resources when we are outside, decreasing our accuracy in perception. Another factor behind the differences in perception may be due to the unfamiliarity of the objects to the outside environment. Rooms and tables are not typically constructed outside, so this unfamiliarity in a familiar environment may contribute to the effect. We are more used to seeing rooms and tables inside, so we can more accurately perceive them. This could be further examined by testing the reverse: putting unfamiliar outside objects both inside and outside and seeing if the inside perception is less accurate. Although this may be a contributing factor, it is unlikely to be the only or the largest factor behind the error of outside perception. The p-values within an environment were not statistically significant. However, there is a moderate correlation between the areas and the degree of apparent size reduction in the outdoor environment, indicating that there is a difference in the perception of rooms and tables in outdoor but not indoor. The trend indicates that there is something happening with the effect of the distortion between room and objects, even if the data is not statistically significant. This lack of significance may have been caused by several things: the experiment s sample size was relatively small (26) and so there was not enough data to conclusively test this degree of effect between enclosures and objects. It is also possible that subjects did not spend enough time in the room, or enough time walking around the objects. It is also possible that there was a poor delineation of the tests areas, as the borders between the rooms may have been difficult for subjects to see, or they may not have been distinct enough. The height of the rooms and tables may also have been a problem, as it was not accurate: although the rooms were marked with sixfoot bamboo poles, the actual room was much taller. In addition, the tables were marked off a few inches off the ground, which was not the actual height of the tables. Therefore, the height difference between the samples and the actual may have attributed to the lack of significant data we saw between objects. Gender had no difference in the perception of the rooms and objects. Both genders experienced the statistically similar distortion of this effect, indicating that gender does not influence this error in size perception.

11 11 There are several interesting places this study could expand into. Interesting to note would be the effect of age on this effect. Gibson, in discussing affordance, notes that affordance is relative to size, as an environment would afford something entirely different to a smaller being than a larger one (Gibson 1986). Children are smaller than adults; therefore, they would perceive the environment differently. 24/26 subjects were between the ages of 19-22, with two outliers. Therefore, it is possible that different ages would perceive the illusion differently, with smaller and younger children being more susceptible to the effect in both environments. The effect of the presence of other people is also a factor that should be examined in the future. When performing this experiment, subjects were not separated. Instead, groups of subjects, typically between people, walked around and inside the rooms. Although they were not permitted to talk to each other, they examined the spaces in close proximity to each other. Gibson theorizes that other people are treated as being a part of our environment, as they also afford us things (1986). Therefore, the presence of other people most likely affected the perception of the subjects, as more cognitive space was spent paying attention to the other people. Therefore, a version of this experiment comparing the size perception of subjects alone with the size perception of subjects with other subjects would be useful to examine this theory of affordance. Also interesting to examine would be how the effect reduces when inside a smaller enclosure. It is hypothesized that we would see a decrease in the trend, and we may gain significant results between the rooms and objects. Subjects would more frequently chose the correct room, and underestimate less. This would further serve to back up our results and provide further evidence towards the connections between the affordance theory and size perception in environment. Another promising aspect would be to further examine the accuracy of size perception on square tables and square rooms, and possibly in constructed square indoor/outdoor environments. By comparing size perception of sample rooms and tables in inside and outside environments, we can strongly theorize that perception of enclosure markedly differs between environments. When outside, we greatly underestimate size; when inside, we underestimate less. In addition, from the correlation result, the apparent size of the room reduced more strongly than the apparent size of the tables, when in the outdoor environment. However, when viewed inside, this does not happen as strongly. We hypothesize this as being a result of the effect of

12 12 environment on size perception, due to the Gibsonian theory of affordance of environments. Because indoor environments offer more affordance, safety, and predictability, less cognitive space is taken up scanning the environment and being alert for threats. Therefore, size perception is more accurate inside, as more neurons can be spent perceiving size of non-threatening rooms and tables. However, when outside, the environment is less familiar and predictable and offers more potential threats, so there are fewer available neurons to correctly perceive a nonthreatening enclosure and object.

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14 14 Stamps, A. (2011). Effects of area, height, elongation, and color on perceived spaciousness. Environment and Behavior, 43, Wagner, M. (1985). The metric of visual space. Perception & Psychophysics, 38, Witt, J., Stefanucci, J., and Rien, C Seeing beyond the target: environmental context effects distance perception. Perception, 36,

15 APPENDIX 1 15