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We examined whether the apparent size of an object is scaled to the morphology of the relevant body part with which one intends to act on it. To be specific, we tested if the visually perceived size of graspable objects is scaled to the extent of apparent grasping ability for the individual. Previous research has shown that right-handed individuals perceive their right hand as larger and capable of grasping larger objects than their left. In the first 2 experiments, we found that objects looked smaller when placed in or judged relative to their right hand compared to their left. In the third experiment, we directly manipulated apparent hand size by magnifying the participants' hands. Participants perceived objects to be smaller when their hand was magnified than when their hand was unmagnified. We interpret these results as demonstrating that perceivers use the extent of their hands' grasping abilities as "perceptual rulers" to scale the apparent size of graspable objects. Furthermore, hand size manipulations did not affect the perceived size of objects too big to be grasped, which suggests that hand size is only used as a scaling mechanism when the object affords the relevant action, in this case, grasping. (Contains 7 figures.)

This research was designed to test the predictions of 2 approaches to perception. By most traditional accounts, people are thought to derive general-purpose spatial perceptions that are scaled in arbitrary, unspecified units. In contrast, action-specific approaches propose that the angular information inherent in optic flow and ocular-motor adjustments is rescaled and transformed into units related to intended actions. A number of studies have shown, for example, that the apparent distance to targets is scaled by the effort required to walk the extent. Such studies can be accommodated by the traditional account by asserting that the experimental manipulations of walking effort influenced not perception itself, but rather postperceptual response processes. The current studies were designed to assess when and how action-specific influences on distance perception have their effects. The results supported the action-specific account. (Contains 6 figures.)

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. (Contains 1 footnote, 1 table and 11 figures.)

Previous research has suggested that perceived distances are scaled by the action capabilities of the body. The present studies showed that when "reachability" is constrained due to a difficult grasp required to pick up an object, perceived distance to the object increases. Participants estimated the distances to tools with handle orientations that made them either easy or difficult to grasp with their dominant and nondominant hands. Right-handed participants perceived tools that were more difficult to grasp to be farther away than tools that were easier to grasp. However, perceived distance did not differ in left-handed participants. These studies suggest that, when reaching toward a target, the distance to that target is scaled in terms of how far one can effectively reach, given the type of reaching posture that is executed. Furthermore, this effect is modulated by handedness. (Contains 1 footnote and 8 figures.)

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.

Recent research demonstrates neurologic and behavioral differences in people's responses to the space that is within and beyond reach. The present studies demonstrated a perceptual difference as well. Reachability was manipulated by having participants reach with and without a tool. Across 2 conditions, in which participants either held a tool or not, targets were presented at the same distances. Perceived distances to targets within reach holding the tool were compressed compared with targets that were beyond reach without it. These results suggest that reachability serves as a metric for perception. The 3rd experiment found that reachability only influenced perceived distance when the perceiver intended to reach. These experiments suggest that the authors perceive the environment in terms of our intentions and abilities to act within it.

Experiments with 251 male and 280 female college students demonstrated that subjects' representations of the water levels in a tilted container could be influenced by problem presentation. Subjects who did not appear to know that water remains horizontal were attempting to solve an object-relative, rather than environment-relative, problem. (SLD)

In 5 experiments, assessments were made of subjects' understandings of the dynamics of wheels. The subjects--111 undergraduates and 19 high school physics teachers--made highly erroneous dynamical judgments about this commonplace event, both in explicit problem-solving contexts and when viewing ongoing events. Findings are related to accounts of dynamical event complexity. (TJH)

This research was designed to test the predictions of 2 approaches to perception. By most traditional accounts, people are thought to derive general-purpose spatial perceptions that are scaled in arbitrary, unspecified units. In contrast, action-specific approaches propose that the angular information inherent in optic flow and ocular-motor adjustments is rescaled and transformed into units related to intended actions. A number of studies have shown, for example, that the apparent distance to targets is scaled by the effort required to walk the extent. Such studies can be accommodated by the traditional account by asserting that the experimental manipulations of walking effort influenced not perception itself, but rather postperceptual response processes. The current studies were designed to assess when and how action-specific influences on distance perception have their effects. The results supported the action-specific account. Keywords: distance perception, effort, perceptual scaling, intention DOI: 10.1037/a0019947

Previous research has suggested that perceived distances are scaled by the action capabilities of the body. The present studies showed that when 'reachability' is constrained due to a difficult grasp required to pick up an object, perceived distance to the object increases. Participants estimated the distances to tools with handle orientations that made them either easy or difficult to grasp with their dominant and nondominant hands. Right-handed participants perceived tools that were more difficult to grasp to be farther away than tools that were easier to grasp. However, perceived distance did not differ in left-handed participants. These studies suggest that, when reaching toward a target, the distance to that target is scaled in terms of how far one can effectively reach, given the type of reaching posture that is executed. Furthermore, this effect is modulated by handedness. Keywords: handedness, distance scaling, near space, spatial perception, affordances DOI: 10.1037/a0016875

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. Keywords: height perception, distance perception, perception and emotion, fear of heights, acrophobia

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. Keywords: distance perception, motor simulation, affordances, perception-action coupling, intention