Scared stiff: The influence of anxiety on the perception of action capabilities

Influences on the perception of affordances (i.e., opportunities for actions) have been primarily studied by manipulating the functional morphology of the body. However, affordances are not just determined by the functional morphology of the perceiver, but also by the physiological state of the perceiver. States of anxiety have been shown to lead to marked changes in individuals’ physiological state and their behaviour. To assess the influence of emotional state on affordance perception, the perception of action capabilities in near space was examined after participants completed an anxiety-provoking task. Anxiety was induced immediately prior to tasks that assessed participants' perceived reaching ability in Experiment 1, grasping ability in Experiment 2, and the ability to pass their hands through apertures in Experiment 3. Results indicated that those participants who experienced changes in anxiety underestimated their reaching, grasping, and passing ability compared to non-anxious participants. In other words, anxious participants were more conservative in their estimations of their action capabilities. These results suggest that anxiety influences the perception for affordances in near space and are consistent with the notion that anxiety induces withdrawal behaviours.     

Scared stiff: The influence of anxiety on the perception of action capabilities

Influences on the perception of affordances (i.e., opportunities for actions) have been primarily studied by manipulating the functional morphology of the body. However, affordances are not just determined by the functional morphology of the perceiver, but also by the physiological state of the perceiver. States of anxiety have been shown to lead to marked changes in individuals' physiological state and their behaviour. To assess the influence of emotional state on affordance perception, the perception of action capabilities in near space was examined after participants completed an anxiety-provoking task. Anxiety was induced immediately prior to tasks that assessed participants' perceived reaching ability in Experiment 1, grasping ability in Experiment 2, and the ability to pass their hands through apertures in Experiment 3. Results indicated that those participants who experienced changes in anxiety underestimated their reaching, grasping, and passing ability compared to non-anxious participants. In other words, anxious participants were more conservative in their estimations of their action capabilities. These results suggest that anxiety influences the perception for affordances in near space and are consistent with the notion that anxiety induces withdrawal behaviours.     

Visual and haptic perception of postural affordances in children and adults

The present study compared how children and adults perceived affordances for upright stance when information was available either visually or haptically. 12 adults (mean age=26.5 years) and 13 children (mean age=4.5 years) examined an adjustable wooden platform that was randomly set at five different degrees of inclination (17, 22, 27, 33, 39). In the haptic condition, a masking curtain excluded vision of the platform and the surface was explored with a hand-held, wooden dowel. Results showed that for both children and adults there was closer agreement between perceptual judgments and action capabilities in the visual condition. Children overestimated their ability to stand on the steeper slopes, took equal amounts of time to make their judgments across all slopes, and were equally confident in their judgments across all slopes. In contrast, adults were more accurate than children at judging the affordances for upright stance, took longer to respond close to the actual action boundary, and were less confident close to the action boundary. Furthermore, adults took longer to respond and were less confident in the haptic condition whereas children had similar response times and were equally confident in both conditions. These important differences between adults and children in the perception of a basic affordance are discussed with reference to the coupling between perception and action at different phases of the lifespan and to the factors that might influence the organization of this coupling. Finally, implications are drawn for the prevention of accidents and the promotion of basic motor competence in children.     

Detection of the traversability of surfaces by crawling and walking infants

In four studies we investigated the perception of the affordance for traversal of a supporting surface. The surface presented was either rigid or deformable, and this property was specified either optically, haptically, or both. In Experiment 1A, crawling and walking infants were presented with two surfaces in succession: a standard surface that both looked and felt rigid and a deforming surface that both looked and felt nonrigid. Latency to initiate locomotion, duration of visual and haptic exploration, and displacement activity were coded from videotapes. Compared with the standard, the deforming surface elicited longer latency, more exploratory behavior, and more displacement in walkers, but not in crawlers, suggesting that typical mode of locomotion influences perceived traversability. These findings were replicated in Experiment 1B, in which the infant was presented with a dual walkway, forcing a choice between the two surfaces. Experiments 2, 3A and B, and 4A and B investigated the use of optical and haptic information in detecting traversability of rigid and nonrigid surfaces. Patterns of exploration varied with the information presented and differed for crawlers and walkers in the case of a deformable surface, as an affordance theory would predict.     

Time,change, and motion: The effects of stimulus movement on temporal perception

The effects of stimulus motion on time perception were examined in five experiments. Subjects judged the durations (6–18 sec) of a series of computer-generated visual displays comprised of varying numbers of simple geometrical forms. In Experiment 1, subjects reproduced the duration of displays consisting of stationary or moving (at 20 cm/sec) stimulus figures. In Experiment 2, subjects reproduced the durations of stimuli that were either stationary, moving slowly (at 10 cm/sec), or moving fast (at 30 cm/sec). In Experiment 3, subjects used the production method to generate specified durations for stationary, slow, and fast displays. In Experiments 4 and 5, subjects reproduced the duration of stimuli that moved at speeds ranging from 0 to 45 cm/sec. Each experiment showed that stimulus motion lengthened perceived time. In general, faster speeds lengthened perceived time to a greater degree than slower speeds. Varying the number of stimuli appearing in the displays had only limited effects on time judgments. Other findings indicated that shorter intervals tended to be overestimated and longer intervals underestimated (Vierordt’s law), an effect which applied to both stationary and moving stimuli. The results support a change model of perceived time, which maintains that intervals associated with more changes are perceived to be longer than intervals with fewer changes.     

Perception of Affordances for Walking Under a Barrier From Proximal and Distal Points of Observation

We investigated perception of affordances for a given behavior from points of observation other than that from which the behavior is to be performed. Participants viewed a horizontal barrier from different points of observation and reported whether they would be able to walk under that barrier. In Experiment 1, they viewed the barrier both while standing on the floor and while sitting on the floor. In Experiment 2, they viewed the barrier both while standing on the floor and while standing on a step stool. The results show that although perception of this affordance is body-scaled regardless of point of observation, there are subtle differences in the perceptual boundaries in each case. Such differences are likely due to differential attunement to the information specifying the affordance at each point of observation.     

The Role of Anxiety in Perceiving and Realizing Affordances

Three experiments were conducted to examine the role of anxiety in perceiving and realizing affordances in wall climbing. Identical traverses were situated high and low on a climbing wall to manipulate anxiety. In Experiment 1, participants judged their maximal overhead reachability and performed maximal reaches on the climbing wall. Anxiety was found to reduce both perceived and actual maximal reaching height. In Experiment 2, participants climbed from right to left and back again on the high and low traverses, which now entailed an abundance of holds. Consistent with the reduction of perceived and actual maximal reaching height found in Experiment 1, anxiety led to the use of more holds. Finally, in Experiment 3, points of light were sequentially projected around the participants while they were climbing to measure attention. As participants detected fewer lights in the high-anxiety condition, it was concluded that anxiety narrowed attention. In general, the results underscored that the actor's emotional state plays an important role in perceiving and realizing affordances and that the perception of affordances changes as the accompanying action capabilities change.     

The influence of athletic experience and kinematic information on skill-relevant affordance perception

Humans can perceive affordances both for themselves and for others, and affordance perception is a function of perceptual–motor experience involved in playing a sport. Two experiments investigated the enhanced affordance perception of athletes. In Experiment 1, basketball players and nonbasketball players provided perceptual reports for sports-relevant (maximum standing-reach and reach-with-jump heights) and non-sports-relevant (maximum sitting height) affordances for self and other. Basketball players were more accurate at perceiving maximum reach-with-jump for another person than were nonbasketball players, but were no better at perceiving maximum reach or sitting heights. Experiment 2 investigated the informational basis for this enhanced perceptual ability of basketball players by evaluating whether kinematics inform perceivers about action-scaled (e.g., force-production dependent), but not body-scaled (i.e., geometrically determined), affordances for others, and whether basketball experience enhances sensitivity to kinematic information. Only basketball players improved at perceiving an action-scaled affordance (maximum reach-with-jump), but not body-scaled affordances (maximum standing-reach and sit) with exposure to kinematic information, suggesting that action-scaled affordances may be specified by kinematic information to which athletes are already attuned by virtue of their sport experience.     

The influence of athletic experience and kinematic information on skill-relevant affordance perception

Humans can perceive affordances both for themselves and for others, and affordance perception is a function of perceptual-motor experience involved in playing a sport. Two experiments investigated the enhanced affordance perception of athletes. In Experiment 1, basketball players and nonbasketball players provided perceptual reports for sports-relevant (maximum standing-reach and reach-with-jump heights) and non-sports-relevant (maximum sitting height) affordances for self and other. Basketball players were more accurate at perceiving maximum reach-with-jump for another person than were nonbasketball players, but were no better at perceiving maximum reach or sitting heights. Experiment 2 investigated the informational basis for this enhanced perceptual ability of basketball players by evaluating whether kinematics inform perceivers about action-scaled (e.g., force-production dependent), but not body-scaled (i.e., geometrically determined), affordances for others, and whether basketball experience enhances sensitivity to kinematic information. Only basketball players improved at perceiving an action-scaled affordance (maximum reach-with-jump), but not body-scaled affordances (maximum standing-reach and sit) with exposure to kinematic information, suggesting that action-scaled affordances may be specified by kinematic information to which athletes are already attuned by virtue of their sport experience.     

S-R correspondence effects of irrelevant visual affordance: Time course and specificity of response activation

It has been suggested that representations for action, elicited by an object's visual affordance, serve to potentiate motor components (such as a specific hand) to respond to the most afforded action. In three experiments, participants performed speeded left-right button press responses to an imperative target superimposed onto a prime image of an object suggesting a visual affordance oriented to left or right visual space. The time course of response activation was measured by varying the onset time between the prime and target. Long-lasting and gradually developing correspondence effects were found between the suggested affordance of the prime and the side of response, with little effect of response modality (hands uncrossed, hands crossed, or foot response). We conclude that visual affordances can evoke an abstract spatial response code, potentiating a wide variety of lateralized responses corresponding with the affordance.     

行动语义、客体背景和判断任务对客体动作承载性的影响

客体动作承载性指人们知觉客体时同时激活的针对客体的行动。当Gibson最初提出动作承载性概念时, 他认为客体的这种属性是可以自动激活的。然而近年来越来越多的证据显示, 在知觉和行动的关系中, 行动语义知识和客体所处背景对客体动作承载性具有调节作用, 表现在人们可以根据这些自上而下的信息选择针对客体的适当的行动。此外, 不同的判断任务在引发客体动作承载性效应上具有特异性, 表现在若判断任务仅需知觉客体表层属性时, 不能激活对客体的动作, 进而不能产生客体动作承载性; 若判断任务需要对客体进行深层加工时, 才会激活对客体的动作。未来研究还需要进一步探究行动语义知识和客体所处背景影响客体动作承载性发生的原因和机制, 以及不同判断任务中出现结果特异性的原因。     

动允直接知觉的共鸣原理

传统认知理论认为我们只能间接知觉动允,而生态认知心理学则认为对动允的知觉是个体与环境信息直接共鸣的过程。生态认知心理学首先判定动允并不是存在于我们头脑中的认识,而是实际存在于个体-环境系统中的事实,对动允的直接知觉就是对动允的检测而非推测,是对动允信息的拾取而非对记忆内容的提取。这种直接知觉表现为身体的相关动作机制（动作神经元、肌肉组织等）与环境中动允信息的共鸣。进化与学习在共鸣的形成与发展中具有重要作用。     

Does own experience affect perception of others’ actions in capuchin monkeys (Cebus apella)?

Anticipating another’s actions is an important ability in social animals. Recent research suggests that in human adults and infants one’s own action experience facilitates understanding and anticipation of others’ actions. We investigated the link between first-person experience and perception of another’s action in adult tufted capuchin monkeys (Sapajus apella spp., formerly Cebus apella spp.). In Experiment 1, the monkeys observed a familiar human (actor) trying to open a container using either a familiar or an unfamiliar action. They looked for longer when the actor tried to open the container using a familiar action. In Experiment 2, the actor performed two novel actions on a new container. The monkeys looked equally at the two actions. In Experiment 3, the monkeys were trained to open the container using one of the novel actions in Experiment 2. After training, we repeated the same procedure as in Experiment 2. The monkeys looked for longer when the actor manipulated the container using the action they had practiced than when she used the unfamiliar action. These results show that knowledge derived from one’s own experience impacts perception of another’s action in these New World monkeys.     

Extending the notion of affordance

Post-Gibson attempts to set out a definition of affordance generally agree that this notion can be understood as a property of the environment with salience for an organism’s behavior. According to this view, some scholars advocate the idea that affordances are dispositional properties of physical objects that, given suitable circumstances, necessarily actualize related actions. This paper aims at assessing this statement in light of a theory of affordance perception. After years of discontinuity between strands of empirical and theoretical research, the time is ripe for addressing the question of whether the dispositional interpretation of affordance is in accordance with some recent evidence from cognitive science and neuroscience. Following this line, I clarify that there are some cases of affordance-related effects that neither require the actualization of an action, nor the presence of an action-related property bearer in the environment, and that the identification of affordance with physical properties provides only a partial explanation of the wide range of affordance-related effects. Accordingly, I argue in favor of a more general account of affordance perception based on the ability to directly detect perceptual patterns in the environment.     

Who is approachable?

The consequences of social interaction can be variable, sometimes harmful, but often rewarding. The adaptive social perceiver must therefore determine which interactions are worthwhile pursuing and which are not. The present research investigated whether subtle but meaningful differences in facial expressions are perceived in terms of the affordance of approachability. Participants engaged in simulated social encounters with targets displaying enjoyment smiles, non-enjoyment smiles or neutral expressions while fluctuations in their posture were measured. The results indicated systematic differences in perceived approachability as a function of facial expression and target sex. These findings are discussed in terms of the functional coupling between social perception and action with respect to the information that specifies the affordance of approachability.     

Action,prediction, and temporal awareness

The brain needs to track changes in the relation between action and effect. In two experiments, participants made voluntary keypress actions. In an adaptation phase, these actions were followed after a fixed interval by a tone. During a subsequent test phase, the duration of the interval was unexpectedly changed. We used time perception as an implicit marker of the experience of participants' control over the effect, and confirmed a temporal binding between actions and effects. On test trials, participants perceived tones to occur as shifted towards their time of occurrence in the preceding adaptation phase. Therefore, the perceived time of a tone was partly based on learning of an internal prediction, rather than on the time of actual sensory input. This predictive model is rapidly updated over a few trials (Experiment 1), and requires attention to the tones (Experiment 2). The brain learns action–effect relations. This predictive learning influences the perception of effects, and underlies some temporal illusions associated with action.     

Searching for Memory Systems

The aim of the present study was to investigate the relationship between the affordance effect (i.e., the advantage for responses corresponding spatially with the location of an object's graspable part) and the Simon effect (i.e., the advantage for responses corresponding spatially with stimulus location) and to assess whether they both occur at the response selection stage. In two experiments participants were required to respond according to the vertical orientation (upward or inverted) of photographs of graspable objects, located to the left or right of fixation, with their handles oriented to the right or left. In Experiment 1 the response was a buttonpress; in Experiment 2 was a reaching movement. Our results showed that both Simon and affordance effects emerged in response times but not in movement times. In Experiment 1, the two effects did not interact, whereas a clear interaction emerged in Experiment 2. These results seem to suggest that the interaction between Simon and affordance effects may depend on the type of required action.     

To Cross or Not to Cross: The Effect of Locomotion on Street-Crossing Behavior

Perception of some affordances requires action scaling rather than simply body (size) scaling. Crossing a road safely is such an affordance. Perceiving accurately whether crossing in front of oncoming traffic is possible entails perceiving the relation between environmental properties (the to-be-crossed distance and the available time) and one's walking abilities. Only while walking is perceptual information about walking abilities available; hence, a more accurate perception of whether crossing is possible is expected than when stationary. We observed crossing behavior (stopping, staying, and crossing) at a crosswalk and related this behavior to the time that was available before the next vehicle arrived. The critical time gap that separated not crossing (stopping or staying) and crossing was smaller, that is, closer to the actual crossing time, when walking than when standing still. Thus, crossing from standstill entailed a larger safety margin. This suggests that information about ongoing action can yield more accurate perception of the affordance in question.     

Doggone affordances: Canine perception of affordances for reaching

Performing any behavior requires perceiving affordances—whether and how that behavior can be performed. Perception of affordances exhibits action scaling—choices about when to transition between two different modes of behavior reflect the fit between action capabilities and environmental properties. The boundary between distances that are perceived to be reachable with an arm-only reach and those that are perceived to be reachable with an arm-plus-torso reach occurs at farther distances for long-armed than for short-armed people, but at the same ratio of object-distance-to-arm length for both groups. To the extent that perception of affordances is supported by detection of invariant stimulation patterns, perception of a given affordance ought to exhibit action scaling regardless of species. We investigated the heights at which dogs chose to transition from reaching with the head only to rearing (i.e., reaching with the head plus torso). This transition occurred at a taller height for tall than for short dogs, but at the same ratio of shoulder-height-to-treat-height for both groups. The results demonstrate a similarity in perception of affordances across species and suggest that perception of affordances is supported by detection of lawfully structured stimulation patterns that may be invariant across species.