Mila Sugovic’s research while affiliated with Purdue University West Lafayette and other places

Owing to errors made by the authors, Jessica K. Witt, J. Eric T. Taylor, Mila Sugovic, and John T. Wixted, the main conclusion of the article was reached using the wrong formula. A reevaluation with the correct formula confirmed the main conclusion. Jessica K. Witt, J. Eric T. Taylor, Mila Sugovic, and John T. Wixted (2015)

Action abilities are constrained by physical body size and characteristics, which, according to the action-specific account of perception, should influence perceived space. We examined whether physical body size or beliefs about body size affect distance perception by taking advantage of naturally-occurring dissociations typical in people who are obese but believe themselves to weigh less. Normal weight, overweight, and obese individuals made verbal distance estimates. We also collected measures of beliefs about body size and measures of physical body size. Individuals who weighed more than others estimated distances to be farther. Furthermore, physical body weight influenced perceived distance but beliefs about body size did not. The results illustrate that whereas perception is influenced by physical characteristics, it is not influenced by beliefs. The results also have implications for perception as a contributing factor for lifestyle choices: people who weigh more than others may choose to perform less physically demanding actions not as a result of how they perceive their bodies, but as a result of how they perceive the environment.

According to the action-specific account of perception, a perceiver's ability to act influences how the environment is perceived. For example, in a computer-based task, participants perceive fish as moving faster when they use a smaller net, and are thus less effective at catching the fish (Witt & Sugovic, 2013a). Here, we examined the degree to which attention may influence perceptual judgments by requiring participants to engage in a secondary task that directed their attention either toward (Exp. 1) or away from (Exp. 2) the to-be-caught fish. Though perceived fish speed was influenced by participants' catching performance-replicating previous results-attentional allocation did not impact this relationship between catching performance and perceived fish speed. The present results suggest that action directly influences spatial perception, rather than exerting indirect effects via attentional processes.

The visual system is influenced by action. Objects that are easier to reach or catch look closer and slower, respectively. Here, we describe evidence for one action-specific effect, and show that none of the six pitfalls can account for the results. Vision is not an isolate module, as shown by this top-down effect of action on perception.

A common conceptualization of signal detection theory (SDT) holds that if the effect of an experimental manipulation is truly perceptual, then it will necessarily be reflected in a change in d′ rather than a change in the measure of response bias. Thus, if an experimental manipulation affects the measure of bias, but not d′, then it is safe to conclude that the manipulation in question did not affect perception but instead affected the placement of the internal decision criterion. However, the opposite may be true: an effect on perception may affect measured bias while having no effect on d′. To illustrate this point, we expound how signal detection measures are calculated and show how all biases—including perceptual biases—can exert their effects on the criterion measure rather than on d′. While d′ can provide evidence for a perceptual effect, an effect solely on the criterion measure can also arise from a perceptual effect. We further support this conclusion using simulations to demonstrate that the Müller-Lyer illusion, which is a classic visual illusion that creates a powerful perceptual effect on the apparent length of a line, influences the criterion measure without influencing d′. For discrimination experiments, SDT is effective at discriminating between sensitivity and bias but cannot by itself determine the underlying source of the bias, be it perceptual or response based.

Perceptual judgments of objects, such as judgments of their size, distance, and speed, are influenced by the perceiver's ability to act on these objects. For example, objects that are easier to block appear to be moving slower than objects that are more difficult to block. These effects are known as action-specific effects. Recent research has found similar patterns when a person observes someone else act: When the other person's task is more difficult, objects look farther away and faster to the observer, whereas when the other person's task is easier, the objects look closer and slower to the observer. These previous findings that another person's ability penetrates into perceptual judgments challenge the idea that action-specific effects are specific to the perceiver's own abilities. However, in the present study, we show that the apparent effects of another person's ability on the observer's judgments are actually due to the observer's own abilities as if he or she was in the other person's situation. This implicates a type of self-projection motor simulation mechanism. The results also preserve the critical idea that action-specific effects are perceiver specific and, consequently, that they could be adaptive for planning future actions.

Action abilities are constrained by physical body size and characteristics, which, according to the action-specific account of perception, should influence perceived space. We examined whether physical body size or beliefs about body size affect distance perception by taking advantage of naturally-occurring dissociations typical in people who are obese but believe themselves to weigh less. Normal weight, overweight, and obese individuals made verbal distance estimates. We also collected measures of beliefs about body size and measures of physical body size. Individuals who weighed more than others estimated distances to be farther. Furthermore, physical body weight influenced perceived distance but beliefs about body size did not. The results illustrate that whereas perception is influenced by physical characteristics, it is not influenced by beliefs. The results also have implications for perception as a contributing factor for lifestyle choices: people who weigh more than others may choose to perform less physically demanding actions not as a result of how they perceive their bodies, but as a result of how they perceive the environment.

According to the action-specific account of perception, the perceiver's ability to act influences perception of the target. For example, targets that are easier to acquire are reported to look closer, bigger, and slower. However, an alternative explanation for these effects is that they are due to response bias, rather than to changes in perception. To test the role of response bias, we employed two separate manipulations. We manipulated people's abilities to block a ball and measured the corresponding effects on estimated ball speed. We also created an explicit task demand by giving participants instructions that emphasized responding either slow or fast. Participants were grouped, based on whether they were compliant or non-compliant with the instructions. Regardless of their compliance, we found an action-specific effect of blocking ability on estimated speed. Given that non-compliant participants still showed the effect, the results provide strong evidence against a response-bias explanation of this action-specific effect. Paired with earlier research, we conclude that blocking ability influences perceived speed. Perception expresses the relationship between the environment and the perceiver, and this view is consistent with emerging neural and behavioral evidence for an interconnected perceptual-motor system.