Spatial perception is sensitive to the energetic costs required to perform intended actions. For example, hills look steeper to people who are fatigued or burdened by a heavy load. Similarly, perceived distance is also influenced by the energy required to walk or throw to a target. Such experiments demonstrate that perception is a function, not just of optical information, but also of the perceiver’s potential to act and the energetic costs associated with the intended action. In the current paper, we expand on the notion of “cost” by examining perceived distance in patients diagnosed with chronic pain, a multifactorial disease, which is experienced while walking. We found that chronic pain patients perceive target distances to be farther away compared with a control group. These results indicate the physical, and perhaps emotional, costs of chronic pain affect spatial perceptions.

Previous research has demonstrated that changing perceivers' action capabilities can affect their perception of the extent over which an action is performed. In the current study, we manipulated jumping ability by having participants wear ankle weights and examined the influence of this manipulation on the perception of jumpable and un-jumpable extents. When wearing ankle weights, jumpable gaps appeared longer than when not wearing ankle weights; however, for un-jumpable gaps, there was no difference in the apparent gap extent, regardless of whether the participant was wearing ankle weights. This suggests that the perception of a jumpable extent is affected by one's action boundary for jumping, but only if jumping is an action that can be performed over the extent.

Perception of one's body is related not only to the physical appearance of the body, but also to the neural representation of the body. The brain contains many body maps that systematically differ between right- and left-handed people. In general, the cortical representations of the right arm and right hand tend to be of greater area in the left hemisphere than in the right hemisphere for right-handed people, whereas these cortical representations tend to be symmetrical across hemispheres for left-handers. We took advantage of these naturally occurring differences and examined perceived arm length in right- and left-handed people. When looking at each arm and hand individually, right-handed participants perceived their right arms and right hands to be longer than their left arms and left hands, whereas left-handed participants perceived both arms accurately. These experiments reveal a possible relationship between implicit body maps in the brain and conscious perception of the body.

Previous studies have shown that 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 than the bottom, possibly because they are dangerous to descend. In the present study, participants stood at the top of a hill either on a skateboard or a wooden box of the same height. They gave three estimates of the slant: a verbal report, a visually matched estimate, and a visually guided action. Fear of descending the hill was also assessed. Those participants who were scared (by the skateboard) consciously judged the hill to be steeper than unafraid participants. However, the visually guided action measure was accurate across conditions. These results suggest that explicit awareness of slant is influenced by the fear associated with a potentially dangerous action that could be performed on the hill.

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.

When people are engaged in a skilled behavior, such as occurs in sports, their perceptions relate optical information to their performance. In the present research, we demonstrate the effects of performance on size perception in golfers. We found that golfers who played better judged the hole to be bigger than did golfers who did not play as well. In follow-up laboratory experiments, participants putted on a golf mat from a location near or far from the hole and then judged the size of the hole. Participants who putted from the near location perceived the hole to be bigger than did participants who putted from the far location. Our results demonstrate that perception is influenced by the perceiver’s current ability to act effectively in the environment.

There is an increasing need for methods for secure dissemination of interactive 3D graphics content, providing protection for valuable 3D models while still allowing them to be widely shared. Existing systems for protected sharing of 3D models may introduce perturbations into the rendered images of the content, in order to defend against potential malicious reconstruction attacks that could otherwise recover the 3D model shape. However, the particular nature and magnitude of these perturbation defenses has not been based upon any rigorous analysis or measurement of their perceptual effect on non-malicious users of the protected graphics system. In this paper, we take the first steps toward such an analysis, conducting a series of user studies that evaluate the impact (as measured by user reaction time) of varying amounts of noise applied to user interactions in a real-time 3D rendering system. We are thus able to experimentally determine the most appropriate tradeoffs between noise perturbation defenses and the security of the 3D content against typical reconstruction attacks.