Publications

2008

Schnall, S., Harber, K., Stefanucci, J., & Proffitt, D. (2008). Social support and the perception of geographical slant. Journal of Experimental Social Psychology, 44(5), 1246–1255.
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.
Bakdash, J., Linkenauger, S., & Proffitt, D. (2008). Comparing decision-making and control for learning a virtual environment: Backseat drivers learn where they are going. Proceedings of the Human Factors and Ergonomics Society 2008 Annual Meeting, 52(27), 2117–2121.
A considerable amount of research has been conducted on the role interactivity, active versus passive navigation, for learning the spatial layout of a virtual environment (VE). However, active navigation is not unitary. It has two distinct components: decision-making and control. In the present work we investigated which main component of active navigation was critical for acquiring spatial knowledge of a virtual city. We found that spatial knowledge was comparable when the VE was learned with active navigation or decision-making in the absence of control, but was much worse when only control was present. These results suggest decision-making, not control, is the critical component for learning a VE.
Witt, J., & Proffitt, D. (2008). Action-specific influences on distance perception: a role for motor simulation.. Journal of Experimental Psychology: Human Perception and Performance, 34(6), 1479.
Perception is influenced by the perceiver’s ability to perform intended actions. For example, when people intend to reach with a tool to targets that are just beyond arm’s reach, the targets look closer than when they intend to reach without the tool (J. K. Witt, D. R. Proffitt, & W. Epstein, 2005). This is one of several examples demonstrating that behavioral potential affects perception. However, the action-specific processes that are involved in relating the person’s abilities to perception have yet to be explored. Four experiments are presented that implicate motor simulation as a mediator of these effects. When a perceiver intends to perform an action, the perceiver runs a motor simulation of that action. The perceiver’s ability to perform the action, as determined by the outcome of the simulation, influences perceived distance.

2007

Witt, J., & Proffitt, D. (2007). Perceived slant: A dissociation between perception and action. Perception, 36(2), 249–257.
Perceived slant is grossly overestimated, such that 5° hills look to be about 20°. However, overestimation is found only in visual and verbal measures of apparent slant; action measures are accurate. This dissociation is consistent with several lines of research that suggest that there exist two perceptual processes, one for visually guided actions and another for explicit awareness. However, studies in other contexts have shown that analogous effects can be the result of differences in the task demands associated with the responses themselves as opposed to the processes underlying the responses. Two experiments are reported in which these alternatives were tested. Our results are consistent with the hypothesis that two perceptual processes underlie the dissociation between explicit awareness and visuomotor assessments of perceived slant.
Witt, J., Stefanucci, J., Riener, C., & Proffitt, D. (2007). Seeing beyond the target: Environmental context affects distance perception. Perception, 36(12), 1752–1768.
It is commonly assumed that perceived distance in full-cue, ecologically valid environments is redundantly specified and approximately veridical. However, recent research has called this assumption into question by demonstrating that distance perception varies in different types of environments even under full-cue viewing conditions. We report five experiments that demonstrate an effect of environmental context on perceived distance. We measured perceived distance in two types of environments (indoors and outdoors) with two types of measures (perceptual matching and blindwalking). We found effects of environmental context for both egocentric and exocentric distances. Across conditions, within individual experiments, all viewer-to-target depth-related variables were kept constant. The differences in perceived distance must therefore be explained by variations in the space beyond the target.
Stefanucci, J., O’Hargan, S., & Proffitt, D. (2007). Augmenting context-dependent memory. Journal of Cognitive Engineering and Decision Making, 1(4), 391–404.
The goal of this study was to design a human-computer interface that would increase the memorability of information presented by providing context as compared with memory with no context. Our focus was in augmenting context-dependent memory because it is a powerful and often unexploited characteristic of human cognition. To amplify this cognitive strength, we built the InfoCockpit, which included a large screen containing projected images of places, a three-dimensional surround-sound system that played ambient noises congruent with the projected images, and a flat-panel monitor that served as the focal display for the presentation of the to-be-remembered information. Participants in our study learned and recalled information in either the InfoCockpit or a standard desktop environment. The InfoCockpit group demonstrated a 131% memory advantage. Contextual factors that were previously found to be effective in isolation created a large effect when presented in combination.