Berkeley proposed that space is perceived in terms of effort. Consistent with his proposal, the present studies show that perceived egocentric distance increases when people are encumbered by wearing a heavy backpack or have completed a visual-motor adaptation that reduces the anticipated optic flow coinciding with walking effort. In accord with Berkeley's proposal and Gibson's theory of affordances, these studies show that the perception of spatial layout is influenced by locomotor effort.

The visual perception of geographical slant is influenced by physiological resources, such as physical fitness, age, and being physically refreshed. In two studies we tested whether a psychosocial resource, social support, can also affect the visual perception of slants. Participants accompanied by a friend estimated a hill to be less steep when compared to participants who were alone (Study 1). Similarly, participants who thought of a supportive friend during an imagery task saw a hill as less steep than participants who either thought of a neutral person or a disliked person (Study 2). In both studies, the effects of social relationships on visual perception appear to be mediated by relationship quality (i.e., relationship duration, interpersonal closeness, warmth). Artifacts such as mood, social desirability, and social facilitation did not account for these effects. This research demonstrates that an interpersonal phenomenon, social support, can influence visual perception.

Visualizations—visual representations of information, depicted in graphics—are studied by researchers in numerous ways, ranging from the study of the basic principles of creating visualizations, to the cognitive processes underlying their use, as well as how visualizations communicate complex information (such as in medical risk or spatial patterns). However, findings from different domains are rarely shared across domains though there may be domain-general principles underlying visualizations and their use. The limited cross-domain communication may be due to a lack of a unifying cognitive framework. This review aims to address this gap by proposing an integrative model that is grounded in models of visualization comprehension and a dual-process account of decision making. We review empirical studies of decision making with static two-dimensional visualizations motivated by a wide range of research goals and find significant direct and indirect support for a dual-process account of decision making with visualizations. Consistent with a dual-process model, the first type of visualization decision mechanism produces fast, easy, and computationally light decisions with visualizations. The second facilitates slower, more contemplative, and effortful decisions with visualizations. We illustrate the utility of a dual-process account of decision making with visualizations using four cross-domain findings that may constitute universal visualization principles. Further, we offer guidance for future research, including novel areas of exploration and practical recommendations for visualization designers based on cognitive theory and empirical findings.

Emotion and psychopathology researchers have described the fear response as consisting of four main components -subjective affect, physiology, cognition, and behavior. The current study provides evidence for an additional component in the domain of height fear -perception -and shows that it is distinct from measures of cognitive processing. Individuals High (N = 35) and Low (N = 36) in acrophobic symptoms looked over a two-story balcony ledge and estimated its vertical extent using a direct height estimation task (visual matching), and an indirect task (size estimation); the latter task seems to exhibit little influence from cognitive factors. In addition, implicit and explicit measures of cognitive processing were obtained. Results indicated that, as expected, the High Fear group showed greater relative, implicit height fear associations and explicit threat cognitions. Of primary interest, the High (compared to Low) Fear group estimated the vertical extent to be higher, and judged target sizes to be greater, even when controlling for the cognitive bias measures. These results suggest that emotional factors such as fear are related to perception. Keywords visual perception; implicit associations; height fear; acrophobiaIndividuals typically think about emotion in terms of the subjective affect they experience. Yet, emotion researchers have long recognized that there are other modes for expressing emotion. For example, Lang's (1979) seminal bio-informational theory proposed three components to the fear response -physiology, cognition, and behavior. More recently, Barlow (2002) and others (Davis & Ollendick, 2005) have noted the importance of the affective state in feeling fearful as well. While these four modalities encompass a large part

Conscious awareness of hill slant is overestimated, but visually guided actions directed at hills are relatively accurate. Also, steep hills are consciously estimated to be steeper from the top as opposed to the bottom, possibly because they are dangerous to walk down. In the present study, participants stood at the top of a hill on either a skateboard or a wooden box of the same height. They gave three estimates of the slant of the hill: a verbal report, a visually matched estimate, and a visually guided action. Fear of descending the hill was also assessed. Those participants that were scared (by standing on the skateboard) consciously judged the hill to be steeper relative to participants who were unafraid. However, the visually guided action measure was accurate across conditions. These results suggest that our explicit awareness of slant is influenced by the fear associated with a potentially dangerous action."[The phobic] reported that as he drove towards bridges, they appeared to be sloping at a dangerous angle." (Rachman and Cuk 1992 p. 583).Does fear really make us see a hill differently? Previous research has shown that steep hills are consciously estimated to be steeper from the top as opposed to the bottom, possibly because these hills were too steep to walk down and were viewed as dangerous (Proffitt et al 1995). Typically in these studies, the conscious awareness of the slant of a hill was overestimated, but visually guided actions directed at the hill were relatively accurate (Bhalla and Proffitt 1999;Proffitt et al 1995;Proffitt et al 1999;Witt and Proffitt 2007). Furthermore, when an observer's physiological potential was manipulated by having him go on a long run or wear a heavy backpack, hills appeared even steeper with the conscious measures of slant, but the visually guided action remained unaffected (Bhalla and Proffitt 1999). In the present studies, we extend this research to show that viewing the hill in a fearful way also increases conscious estimates of slant, but not visually guided actions. The results suggest that anecdotal reports of perceptual distortions from highly fearful individuals may be accurate.The experimenter stood at the top of the 7° paved hill with a sign advertising the experiment and participants stopped if they were interested. Participants stood at the top of the hill either on a skateboard (that was secured in place with wooden blocks) or on a wooden box of the same height. The box served as a control for the skateboard because it equated eye-height without being dangerous. All participants were then asked to imagine themselves going down the hill. Then, they gave three estimates of the slant of the hill (in randomized order): verbal report of the angle of the hill in degrees, a visually matched estimate of the slant using a visual disk to match the angle of the hill with a representation of the cross-section of the hill, and a visually guided action using a haptic palmboard (for further description of methodologies, see

Previous research has shown that changes to the body can influence the perception of distances in near space (Witt et al 2005). In this paper, we question whether changes to the body can also influence the perception of extents in extrapersonal space, namely the perception of aperture widths. In experiment 1, broad-shouldered participants visually estimated the size of apertures to be smaller than narrow-shouldered participants. In experiment 2, we questioned whether changes to the body, which included holding a large object, wearing a large object, or simply holding out the arms would influence perceived width. Surprisingly, we found that only when participants' hands were widened was extrapersonal space rescaled. Experiment 3 explored the boundaries of the effect observed in experiment 2 by asking participants to hold their arms at different positions to locate the arm width at which apertures appeared smaller. We found that arm positions that were larger than the shoulder width made apertures appear smaller. The results suggest that dimensions of the body play a role in the scaling of environmental parameters in extrapersonal space.

Previous research on perceiving spatial layout has found that people often exhibit normative biases in their perception of the environment. For instance, slant is typically overestimated and distance is usually underestimated. Surprisingly, however, the perception of height has rarely been studied. The present experiments examined the perception of height when viewed from the top (e.g., looking down), or from the bottom (e.g., looking up). Multiple measures were adapted from previous studies of horizontal extents to assess the perception of height. Across all of the measures, a large, consistent bias was found: vertical distances were greatly overestimated, especially from the top. Secondary findings suggest that the overestimation of distance and size that occurs when looking down from a high place correlates with reports of trait- and state-level fear of heights, suggesting that height overestimation may be due, in part, to fear.

Studies of locomotion in virtual environments assume that correct geometric principles define the relationship between walking speed and environmental flow. However, we have observed that geometrically correct optic flow appears to be too slow during simulated locomotion on a treadmill. Experiment 1 documents the effect in a head-mounted display. Experiment 2 shows that the effect is eliminated when the gaze is directed downward or to the side, or when the walking speed is slow. Experiment 3 shows that the effect is unchanged by stride length. Experiment 4 verifies that the effect is not attributable to image jitter. The change in perceived speed from straight ahead to side or down gaze coincides with a shift from expanding optic flow to lamellar flow. Therefore, we hypothesize that lamellar flow is necessary for accurate speed perception, and that a limited field of view eliminates this cue during straight-ahead gaze.