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Various “embodied perception” phenomena suggest that what people sense of their body shapes what they perceive of the environment and that what they perceive of the environment shapes what they perceive of their bodies. For example, an observer’s own hand can be felt where a fake hand is seen, events produced by own body movements seem to occur earlier than they did, and feeling a heavy weight at an observer’s back may prompt hills to look steeper. Here we argue that such and various other phenomena are instances of multisensory integration of interoceptive signals from the body and exteroceptive signals from the environment. This overarching view provides a mechanistic description of what embodiment in perception means and how it works. It suggests new research questions while questioning a special role of the body itself and various phenomenon-specific explanations in terms of ownership, agency, or action-related scaling of visual information. Various “embodied perception” phenomena suggest that what people sense of their body shapes what they perceive of the environment and that what they perceive of the environment shapes what they perceive of their bodies. For example, an observer’s own hand can be felt where a fake hand is seen, events produced by own body movements seem to occur earlier than they did, and feeling a heavy weight at an observer’s back may prompt hills to look steeper. Here we argue that such and various other phenomena are instances of multisensory integration of interoceptive signals from the body and exteroceptive signals from the environment. This overarching view provides a mechanistic description of what embodiment in perception means and how it works. It suggests new research questions while questioning a special role of the body itself and various phenomenon-specific explanations in terms of ownership, agency, or action-related scaling of visual information. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effect of spectators' presence on actionspecific Perception and performance in the distal and proximal external focus condition. The current research was a semi-experimental study with a practical purpose. Among the female undergraduate students of the physical education faculty of Urmia University who had no professional and competitive sports experience in darts, forty people were selected randomly and divided into two groups based on the type of instruction: the distal external focusgroup and the proximal external focus group. In this research, the task of throwing darts was used and the participants made 20 attempts based on the type of instruction of their group, including proximal external focus (focus on the flight of the dart) and distal external focus (focus on the target), in two different conditions (with the presence of spectators and absence of spectators). The perceived target size test was performed at the end of the efforts, and before performing the dart-throwing task, participants filled out the Immediate Anxiety Measurement Scale (IAMS) to measure their anxiety in both conditions. To analyze the data, independent and paired samples t-tests were used to examine the differences between the two groups. The results indicated that the performance and perceived target size of both groups decreased in the presence of spectators compared to the absence of spectators, but this decrease was less in the distal external focus group. The findings recommend that athletes should benefit from effective and appropriate strategies to control anxiety, and also to reduce the destructive effect of anxiety caused by the presence of spectators on action-specific perception and performance, instructions of distal external focus should be used. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the relationship between performance and the perception of size of target under internal and external attention focus conditions as well as the relationship between the initial perception of the size of target and performance. 70 male students (mean age of 21±1.6 years) voluntarily participated in this study. They were randomly assigned to internal and external attention focus based on the type of attentional instruction. Subjects performed dart throwing task in 20 trials. The target size estimation test was performed before the trials, after the last trial and after the first successful trail. Pearson correlation coefficient was used for data analysis. The results showed a significant and positive relationship between the performance and perception of target size in external focus group. But in internal focus group, a significant relationship between performance and perception of the size of the target was not observed. Also, there was no significant relationship between the initial perception and performance in both groups. It is suggested that the focus of attention can be a mediating factor for action-specific perception phenomenon.

The present study examined mutual influences of visual and body-related signals during planning of an object-oriented action. Participants were to enclose a visual target object using two cursors controlled by the movements of their fingers. During movement preparation, they were asked to judge either the size of the object or a certain finger distance. Both types of judgments were systematically affected by the transformation of finger movements into the movements of visual cursors. We suggest that these biases are perceptual consequences of sensory integration of visual and body-related signals relating to the same external object. [ABSTRACT FROM AUTHOR]

In this experimental study, we tested whether athletes' judgments of affordances and of environmental features vary with psychological momentum (PM). We recruited golf, hockey, and tennis players, who were assigned to a positive or negative momentum condition. We designed a golf course on which participants made practice putts, after which they were asked to place the ball at their maximum "puttable" distance and to judge the hole size. Next, participants played a golf match against an opponent, in which the first to take a lead of 5 points would win the match. Participants were told that they could win a point by making the putt or by being closest to the hole. They wore visual occlusion goggles to prevent them from seeing the actual result, and the experimenter manipulated the scoring pattern to induce positive or negative PM. Participants in the positive momentum condition came back from a four-point lag to a four-point lead, whereas those in the negative momentum condition underwent the opposite scenario. We then asked the participants again to indicate their maximum puttable distance from the hole and to judge the hole size. After the manipulation, participants judged the maximum puttable distance to be longer in the positive momentum condition and shorter in the negative momentum condition. For the hole-size judgments, there were no significant effects. These results provide first indications for the idea that athletes' affordances change when they experience positive PM compared to negative PM. This sheds a new light on the dynamics of perception-action processes and PM in sports. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The ease with which a virtual fish can be caught influences perceived fish speed. • Perception was measured using explicit judgments and action measures. • Both measures showed similar effects of action on perception. • The action measure was uninfluenced by presence of the judgment measure. Abstract Action-specific effects, such as a fish appearing faster when it is harder to catch, have been primarily demonstrated using explicit perceptual judgments. These sorts of judgments rely on the cognitive or “what” visual pathway. An open question is whether action-specific effects also influence the action pathway. If fish look faster when the net is small, the net should be released earlier than when the net is big. Previously, this action measure was always paired with an explicit measure of fish speed, which is known to evoke the cognitive visual pathway. Here, net release time was examined without any explicit judgments. The action-specific effect of net size still emerged. Assuming net release time taps into the action pathway, the current studies provide support that action-specific effects occur within both the cognitive and action pathways, possibly because these effects operate on early visual processes prior to the split between the two pathways. [ABSTRACT FROM AUTHOR]

A critical question for theories of spatial vision concerns the nature of the inputs to perception. The action-specific account asserts that information related to action, specifically a perceiver’s ability to perform the intended action, is one of these sources of information. This claim challenges assumptions about the mind in general and perception in particular, and not surprisingly, has been met with much resistance. Alternative explanations include that these effects are due to response bias, rather than genuine differences in perception. Using a paradigm in which ease to block a ball impacts estimated speed of the ball, participants were given explicit feedback about their perceptual judgements to test the response bias alternative. Despite the feedback, the action-specific effect still persisted, thus ruling out a response-bias interpretation. Coupled with other research ruling out additional alternative explanations, the current findings offer an important step towards the claim that a person’s ability to act truly influences spatial perception. [ABSTRACT FROM AUTHOR]

In four experiments, participants estimated the sizes of target objects that were either out of reach, or that could be reached by a tool (a stylus or laser pointer). Objects reachable with the aid of a tool were perceived to be smaller than identical objects without a tool. Participants' responses to questioning rule out demand characteristics as an explanation. This new size illusion may reflect a direct impact of tool use on perceived size, or it may stem from the effects of tool use on perceived distance. Both possibilities support action specific accounts of perception. [ABSTRACT FROM AUTHOR]

The action-specific account of spatial perception asserts that a perceiver's ability to perform an action, such as hitting a softball or walking up a hill, impacts the visual perception of the target object. Although much evidence is consistent with this claim, the evidence has been challenged as to whether perception is truly impacted, as opposed to the responses themselves. These challenges have recently been organized as six pitfalls that provide a framework with which to evaluate the empirical evidence. Four case studies of action-specific effects are offered as evidence that meets the framework's high bar, and thus that demonstrates genuine perceptual effects. That action influences spatial perception is evidence that perceptual and action-related processes are intricately and bidirectionally linked. [ABSTRACT FROM AUTHOR]

Human perception is an outcome of the influence of various factors rather than objective reflection of external environment. Among the factors, action-specific perception is a phenomenon where perception changes in terms of one’s ability to act on the environment. Previous research reported contradictory results regarding whether action-specific perception occurs during performance or after performance due to memory distortion or knowledge about performance results. In this research, we conducted three experiments to determine when action-specific perception occurs. Participants threw darts at different distances and reported perceived size of targets in each trial. The results showed that, in Experiments 1 and 2, participants perceived targets larger when they hit than missed the targets, and the effect was greater when the targets were not visible after each throw. However, because participants had knowledge about the results of their throws, there could have been bias in participants' responses. In Experiment 3, where this possibility was excluded, we also obtained action-specific perception, and therefore concluded that action-specific perception occurs during but not after task performance. [ABSTRACT FROM AUTHOR]

The effects of psychological pressure on perceiving the height of a jump bar just before starting a high jump run was investigated. University students (n = 14) training for a high jump event performed 15 trials (3 practice, 6 high-pressure, and 6 low-pressure) in counterbalanced order in their daily practice environment. The height of the bar was judged as significantly higher on high-pressure trials compared to low-pressure trials (p = 0.030). A regression analysis indicated that participants who reported increased subjective perceived pressure tended to judge the bar to be higher (r = 0.468, p = 0.091). There was no significant difference between high-pressure and low-pressure trials for the performance index, defined as the success rate (p = 0.209). This study provides the first evidence that environmental perceptions prior to executing a motor task under pressure may make performance of the task appear to be more difficult.

Aims: Human physical and psychological features influence perceptions of the environment during activity. If during exercise an individual over-estimates time, they may interpret this as spending longer than necessary under a potentially aversive state of exertion. This may in turn decrease one’s sense of exercise success and tendency to persevere with exercise. We tested if experimentally manipulating sense of exercise self-efficacy would affect time perception during standardised physical exertion. Method: Exercise Self-Efficacy (ESE) of 18 -73 year olds (N=51) was measured before and after an exercise challenge of moderate intensity. Height, weight and body fat composition were measured before participants were randomly allocated to one of three groups. After a 4-minute treadmill fitness test, participants were presented with either bogus feedback about their performance (positive or negative) or no feedback (control). Before and during exercise, participants estimated a prescribed 2-minute time interval. Ratings of perceived exertion were also measured periodically. Results: Feedback on performance had no significant effect on time perception, even when controlling for individual exertion level. Reported ESE was also unaffected by whether someone received positive, negative or no feedback. Age was again found to be significantly correlated with VO2max, r(51) = .62, p < .001, but in contrast to prior findings, estimates of general fitness such as VO2max, BMI and waist circumference were unrelated to changes in time perception due to exertion. Conclusions: These findings failed to support prior findings and anecdotal evidence suggesting that exertion might alter one’s perception of time. We also failed to find any support for effects on ESE when participants were given explicit performance feedback. Finally, participants’ physical characteristics appear to be unrelated to time perception whilst exercising at moderate intensity.

Proponents of the action-specific account of perception and action posit that participants perceive their environment relative to their capabilities. For example, softball players who batted well judge the ball as being larger compared to players who did not hit as well. In the present study, we examined this issue in the context of a well-known speed-accuracy movement task that can be examined in the laboratory, repetitive Fitts aiming. In the Fitts task, a performer moved as quickly and as accurately as possible between two targets, D units of distance apart (between 2.5 and 20.0 cm) and of W width (1.0 cm or less). In the Fitts task, we posited that individuals do not have access to performance quality. Thus, we asked whether individual differences in Fitts task performance was related to perception of target width. If Fitts task performance is related to perception of target width, then the action-specific effect on perception does not require explicit knowledge of performance and, furthermore, these effects reside during on-line visual control of the task. We show that only when subjects were provided with a performance score was there a relation between Fitts task performance and target width judgment error. We interpret this result to mean that action-specific effects do not occur during perceptual processing of the task, but action-specific effects are the result of postperformance evaluation processes. [ABSTRACT FROM AUTHOR]

Almost a century ago it was first suggested that cars can be interpreted as tools, but consequences of this assumption were never tested. Research on hand-held tools that are used to manipulate objects in the environment suggests that perception of near space is extended by using tools. Literature on environment perception finds perception of far space to be modulated by the observer's potential to act in the environment. Here we argue that a car increases the action potential and modulates perception of far space in a way similar to how hand-held tools modulate perception of near space. Five distances (4 to 20 meters) were estimated by pedestrians and drivers before and after driving/walking. Drivers underestimated all distances to a larger percentage than did pedestrians. Underestimation was even stronger after driving. We conclude that cars modulate the perception of far distances because they modulate the driver's perception, like a tool typically does, and change the perceived action potential. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The action-specific perception account holds that people perceive the environment in terms of their ability to act in it. In this view, for example, decreased ability to climb a hill because of fatigue makes the hill visually appear to be steeper. Though influential, this account has not been universally accepted, and in fact a heated controversy has emerged. The opposing view holds that action capability has little or no influence on perception. Heretofore, the debate has been quite polarized, with efforts largely being focused on supporting one view and dismantling the other. We argue here that polarized debate can impede scientific progress and that the search for similarities between 2 sides of a debate can sharpen the theoretical focus of both sides and illuminate important avenues for future research. In this article, we present a synthetic review of this debate, drawing from the literatures of both approaches, to clarify both the surprising similarities and the core differences between them. We critically evaluate existing evidence, discuss possible mechanisms of action-specific effects, and make recommendations for future research. A primary focus of future work will involve not only the development of methods that guard against action-specific postperceptual effects but also development of concrete, well-constrained underlying mechanisms. The criteria for what constitutes acceptable control of postperceptual effects and what constitutes an appropriately specific mechanism vary between approaches, and bridging this gap is a central challenge for future research. [ABSTRACT FROM AUTHOR]

Perception is believed to scale the world to reflect one's own capabilities for action--objects that are more effortful to obtain are perceived as further away. Somewhat surprisingly, perception is also influenced by observing another person attempt an action, even though others cannot directly alter one's own capabilities. It is unknown, however, whether the effects of observation reflect a simulation of one acting as if from the perspective of the actor, or whether they reflect simulation of the potential effects of the actor on the environment, but from the observer's own point of view. In 2 experiments, we had an actor and an observer view a scene from opposing viewpoints. Enhancement of the actor's capabilities to reach a target object caused the target to appear further from the observer. Thus, in addition to indexing one's own capabilities, the perceptual system also scales the world to account for the potential effects of others. [ABSTRACT FROM AUTHOR]

In perceptual-motor tasks such as dart throwing, those who hit the target more successfully report the target to be bigger than those who hit less successfully. While initial evidence seemed to support the recent contention that the variability in performance (rather than the amount of successful hits) may scale reported target size, here we provide counterevidence for this hypothesis. We systematically manipulated performance outcomes in a shuffling task by means of magnetic fields. Participants were asked to slide a disk on a wooden board towards a circular target. Using a within-subjects design, in two conditions throw outcomes were manipulated to produce either high or low variability in performance outcome, while the mean success of performance (i.e., the mean error) remained constant across conditions. Despite the successful manipulations of high and low variability in the performance outcomes, results revealed that size estimates of the target remained stable. [ABSTRACT FROM AUTHOR]

A growing empirical literature has demonstrated that perceptions of the physical environment are influenced by the perceiver's behavioral ability. However, prior research has focused only on the perceptual consequences of individual behavior, despite the fact that individuals regularly take part in cooperative social interaction. To test whether similar effects occur as a result of engaging in joint action, we asked participants to estimate anticipated walking distance to a target location when expecting to carry a heavy object either alone or jointly with a confederate. Surprisingly, even though carrying with another person requires less physical effort, on certain carrying tasks participants estimated distances to be farther when expecting help. However, this effect was reversed when participants were asked to focus on the difficulty of the task or told about the alternative experimental condition, thereby making salient for joint carders the potential, presumably negative, counterfactual of having to work alone. Findings are explained in terms of an ecological approach, which conceptualizes perception as the detection of information specifying affordances. These results highlight the limitations of purely effortful accounts of such phenomena and demonstrate the unique way in which social factors relevant to coordination can alter how people relate to their physical environments. [ABSTRACT FROM AUTHOR]

Abstract: We examined whether perception of a threatening object – a spider – was more accurate than of a non-threatening object. An accurate perception could promote better survival than a biased perception. However, if biases encourage faster responses and more appropriate behaviors, then under the right circumstances, perceptual biases could promote better survival. We found that spiders appeared to be moving faster than balls and ladybugs. Furthermore, the perceiver's ability to act on the object also influenced perceived speed: the object looked faster when it was more difficult to block. Both effects – the threat of the object and the perceiver's blocking abilities – acted independently from each other. The results suggest effects of multiple types of affordances on perception of speed. [Copyright &y& Elsevier]

Given the flexible organization of locomotion evidenced in the many ways the limbs can be coordinated, the authors explored the potentially correspondingly flexible organization of nonvisual (kinesthetic) distance perception. As kinesthetic distance perception is known to be affected by how the limbs are coordinated, the authors probed the potential perceptual contribution of the arms during locomotion by manipulating arm–leg coordination patterns in blind-walked distance-matching tasks. Whereas manipulation of arm–leg coordination for walking with free-swinging arms had no observable perceptual consequences, comparable manipulation for walking with hiking poles did affect distance matching. These results suggest that under conditions in which the arms act to propel the body (e.g., crawling or stair-climbing) a person's nonvisual sense of movement is conveyed in the coordinated actions of all four limbs. [ABSTRACT FROM PUBLISHER]

According to the action-specific perception account, spatial perception is affected by the specific energetic costs required to perform an action. In the current experiments, we examined the effect of age on distance perception. Older and younger adults were asked to verbally estimate distance to a target placed in a hallway. Results showed that older adults estimated distances to be farther compared to younger adults. Additionally, older and younger adults estimated distances on a surface that was easier to walk on (carpet) and on a surface that was more difficult to walk on (carpet covered by a plastic tarp). For older adults, distances looked farther on the plastic surface than on the carpet. These differences across surfaces were not found for able, younger adults. These results suggest that the type of floor surface available influences perception of distances. Furthermore, the results suggest that perception is still sensitive to environmental differences that affect ability even as a perceiver ages. [ABSTRACT FROM AUTHOR]

People perceive individual objects as being closer when they have the ability to interact with the objects than when they do not. We asked how interaction with multiple objects impacts representations of the environment. Participants studied multiple-object layouts, by manually exploring or simply observing each object, and then drew a scaled version of the environment (Exp. 1) or reconstructed a copy of the environment and its boundaries (Exp. 2) from memory. The participants who interacted with multiple objects remembered these objects as being closer together and reconstructed smaller environment boundaries than did the participants who looked without touching. These findings provide evidence that action-based perceptual distortions endure in memory over a moving observer's multiple interactions, compressing not only representations between touched objects, but also untouched environmental boundaries. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

According to an action-specific account of perception, the perceived speed of a ball can be a function of the ease to block the ball. Balls that are easier to stop look like they are moving slower than balls that are more difficult to stop. This was recently demonstrated with a modified version of the classic computer game Pong (Witt & Sugovic, 2010). However, alternative explanations can also explain these results without resorting to nonoptical effects on perception. To examine whether blocking ease influences perception, we conducted several experiments. We examined whether the apparent effects were due to the type of perceptual judgment, the timing of the judgment, and the effectiveness of the paddle. The results are consistent with a perceptual explanation, and help build a case that blocking ease can influence perceived speed. [ABSTRACT FROM AUTHOR]

According to the action-specific account of perception, perceivers see the environment relative to their ability to perform the intended action. For example, in a modified version of the computer game Pong, balls that were easier to block looked to be moving slower than balls that were more difficult to block (Witt & Sugovic, 2010). It is unknown, however, if perception can be influenced by another person's abilities. In the current experiment, we examined whether another person's ability to block a ball influenced the observer's perception of ball speed. Participants played and observed others play the modified version of Pong where the task was to successfully block the ball with paddles that varied in size, and both the actor and observer estimated the speed of the ball. The results showed that both judged the ball to be moving faster when it was harder to block. However, the same effect of difficulty on speed estimates was not found when observers watched a computer play, suggesting the effect is specific to people and not to the task. These studies suggest that the environment can be perceived relative to another person's abilities. [ABSTRACT FROM AUTHOR]

Targets presented just beyond arm's reach look closer when observers intend to touch them with a reach-extending tool rather than without the tool. This finding is one of several that suggest that a person's ability to act influences perceived distance to objects. However, some critics have argued that apparent action effects were actually due to effects on the judgments rather than on the perception. In other words, the target does not actually look closer, but participants report that it is. To help counter this argument, the current experiments used an indirect measure of perceived distance: Participants reported perceived shape or perceived parallelism. The results revealed that triangles looked shorter and lines looked more horizontal to participants who reached with a tool, and therefore could reach the targets, than they did to participants who reached without the tool. These results demonstrate convergence across multiple types of judgments, a finding that undermines alternative, judgment-based accounts and suggests that the ability to reach an object changes the perceived distance to the object. [ABSTRACT FROM AUTHOR]

We typically misestimate the dimensions of our body e.g., we perceive our fingers as shorter, and our torso as more elongated, than they actually are. It stands to reason that those metric biases may also extend to objects that we interact with, to facilitate attunement with the environment. To explore this hypothesis, we compared the metric representations of seven objects and the subjects' own hand using the Line Length Judgment task, in six experiments involving 152 healthy subjects. We evaluated the size estimation errors made for each target (hand or previously observed objects) by asking subjects to compare the vertical or horizontal dimension of a specific target against the length of a vertical or horizontal line. As expected, we showed that the hand is misperceived in its dimensions. Interestingly, we found that metric biases are also present for daily-life objects, such as a mobile phone and a coffee mug, and are not affected by familiarity with the objects. In contrast, objects that are less likely to be manipulated, either because they are potentially harmful or disgusting, were differently represented. Furthermore, the propensity to interact with an object, rated by an independent sample of subjects, best predicted the pattern of metric biases associated with that object. Taken together, these findings support the hypothesis that biases affecting the hand representation extend to objects that elicit action-oriented behavior, highlighting the importance of studying the body as integrated and active in the environment. [ABSTRACT FROM AUTHOR]