Action goal selection and motor planning can be dissociated by tool use

The preparation of eye or hand movements enhances visual perception at the upcoming movement end position. The spatial location of this influence of action on perception could be determined either by goal selection or by motor planning. We employed a tool use task to dissociate these two alternatives. The instructed goal location was a visual target to which participants pointed with the tip of a triangular hand-held tool. The motor endpoint was defined by the final fingertip position necessary to bring the tool tip onto the goal. We tested perceptual performance at both locations (tool tip endpoint, motor endpoint) with a visual discrimination task. Discrimination performance was enhanced in parallel at both spatial locations, but not at nearby and intermediate locations, suggesting that both action goal selection and motor planning contribute to visual perception. In addition, our results challenge the widely held view that tools extend the body schema and suggest instead that tool use enhances perception at those precise locations which are most relevant during tool action: the body part used to manipulate the tool, and the active tool tip.     

Affordances,context and sociality

Affordances, i.e. the opportunity of actions offered by the environment, are one of the central research topics for the theoretical perspectives that view cognition as emerging from the interaction between the environment and the body. Being at the bridge between perception and action, affordances help to question a dichotomous view of perception and action. While Gibson’s view of affordances is mainly externalist, many contemporary approaches define affordances (and micro-affordances) as the product of long-term visuomotor associations in the brain. These studies have emphasized the fact that affordances are activated automatically, independently from the context and the previous intention to act: for example, affordances related to objects’ size would emerge even if the task does not require focusing on size. This emphasis on the automaticity of affordances has led to overlook their flexibility and contextual-dependency. In this contribution I will outline and discuss recent perspectives and evidence that reveal the flexibility and context-dependency of affordances, clarifying how they are modulated by the physical, cultural and social context. I will focus specifically on social affordances, i.e. on how perception of affordances might be influenced by the presence of multiple actors having different goals.

     

Performance and ease influence perceived speed

According to the action-specific perception account, perception is a function of optical information and the perceiver's ability to perform the intended action. While most of the evidence for the action-specific perception account is on spatial perception, in the current experiments we examined similar effects in the perception of speed. Tennis players reproduced the time the ball traveled from the feeder machine to when they hit it. The players judged the ball to be moving faster on trials when they hit the ball out-of-bounds than on trials where they successfully hit the ball in-bounds. Follow-up experiments in the laboratory showed that participants judged virtual balls to be moving slower when they played with a bigger paddle in a modified version of Pong. These studies suggest that performance and task ease influence perceived speed.     

Action-specific effects in a social context: others' abilities influence perceived speed

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.     

What a car does to your perception: Distance evaluations differ from within and outside of a car

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.     

The Marginality of Phenomenology

The essence of Husserl’s intentionality does not lie in any object, but in the marginal horizon presupposed by intentional acts. This characteristic can be seen whether on the level of intensional act or that of noema (intentional object). The reason is that all intentional act and noema come from the stream of internal time consciousness, and thus have Zeithof (time halo or time aureole), while the original meaning constituted by such a halo is prior to the object they are concretized into, and the noema that contains the possibility of meaning will also be intuited together with the perceived adumbration. Using Husserl’s idea that the meaning of non-objectification is prior to the object, Scheler breaks through Husserl’s dogma that the presentation of an object must precede the giving of value to the object, and thus puts forward the new train of thought that the feeling of value is not later than the objectification, or even prior to it. Heidegger deepens and expands the sense of the marginal horizon, revealing in all human behaviors and world presentation such an ontological structure, that is, halo-like meaning or the act of Being itself precedes objects and beings created by the separation of subject and object. Maurice Merleau-Ponty states that the body field is prior to the separation of body and mind, and the body’s perception of external phenomena is first carried out in the manner of field rather than definite objects, therefore, it must have the original ambiguity and be realized in the form of body schema instead of a causal chain. So, the philosophical vitality of phenomenology does not significantly lie in the explanation of the levels and functions of intentional objects, but in the construction premise of such objects, namely, the spatio-temporal halo manifested as marginal horizon, time stream, and the displaying of existential vista.     

Affordances and the Nature of Perceptual Content

Abstract

According to John McDowell, representational perceptual content is conceptual through and through. This paper criticizes this view by claiming that there is a certain kind of representational and non‐conceptual perceptual content that is sensitive to bodily skills. After a brief introduction to McDowell’s position, Merleau‐Ponty’s notion of body schema and Gibson’s notion of affordance are presented. It is argued that affordances are constitutive of representational perceptual content, and that at least some affordances, the so‐called ‘conditional affordances’, are essentially related to the body schema. This means that the perceptual content depends upon the nature of the body schema. Since the body schema does not pertain to the domain that our conceptual faculties operate upon, it is argued that this kind of perceptual content cannot be conceptual. At least some of that content is representational, yet it cannot feature as non‐demonstrative conceptual content. It is argued that if it features as demonstrative conceptual content, it has to be captured by private concepts. Since McDowell’s theory does not allow for the existence of a private language, it is concluded that at least some representational perceptual content is non‐conceptual.     

Visuospatial perspective taking in a dynamic environment: Perceiving moving objects from a first-person-perspective induces a disposition to act

Spatial perspective taking is an everyday cognitive process that is involved in predicting the outcome of goal directed behavior. We used dynamic virtual stimuli and fMRI to investigate at the neural level whether motion perception interacts with spatial perspective taking in a life-like design. Subjects were asked to perform right-left-decisions about the position of either a motionless, hovering (STATic) or a flying ball (DYNamic), either from their own (1PP) or from the perspective of a virtual character (avatar, 3PP). Our results showed a significant interaction of STIMULUS TYPE and PERSPECTIVE with significantly increased activation in right posterior intraparietal sulcus (IPS) for 1PPDYN condition. As the IPS is critically involved in the computation of object-directed action preparation, we suppose that the simple perception of potentially action-relevant dynamic objects induces a ‘readiness for (re)action’, restricted to the 1PP. Results are discussed against the background of current theories on embodiment and enactive perception.     

Catching ease influences perceived speed: Evidence for action-specific effects from action-based measures

According to the action-specific account of perception, people perceive the environment in terms of their ability to act. Here, we directly tested this claim by using an action-based measure of perceived speed: Participants attempted to catch a virtual fish by releasing a virtual net. The net varied in size, making the task easier or harder. We measured perceived speed by using explicit judgment-based measures and an action-based measure (time to release the net). Participants released the net later when playing with the big as compared with the small net, indicating that the fish looked to be moving more slowly when participants played with the big net. Explicit judgments of fish speed were similarly influenced by net size. These results provide converging evidence from both explicit and action-based measures that a perceiver’s ability to act influences a common underlying process, most likely perceived speed, rather than postperceptual processes such as response formation.     

The generalization of deliberative and automatic behavior: The role of procedural knowledge and affective reactions

Individuals’ goal-directed activity in one situation can affect their behavior in a later, ostensibly unrelated situation. This effect can depend on whether the latter behavior is also goal-directed or is performed automatically. Three studies showed that participants’ rate of speaking in the course of performing a speech shadowing task has a positive influence on the speed with which they later complete an ostensibly unrelated marketing survey. Furthermore, when participants’ attention is called to the goal of working rapidly on the survey, the effect of their past behavior depends on their perception of the goal's desirability. When the time to complete the survey is not mentioned, however, participants’ speed of working on the survey is influenced by their speed of speaking in the earlier situation without their awareness and it does not depend on the desirability of the goal with which their behavior is associated. An additional experiment showed that the relative impact of goal-directed and automatic processes also depends on the cognitive resources that people have available to construe the evaluative implications of their decisions.     

Temporal perception is enhanced for goal-directed biological actions

ABSTRACT

Research into the visual perception of goal-directed human action indicates that human action perception makes use of specialized processing systems, similar to those that operate in visual expertise. Against this background, the current research investigated whether perception of temporal information in goal-directed human action is enhanced relative to similar motion stimuli. Experiment 1 compared observers’ sensitivity to speed changes in upright human action to a kinematic control (an animation yoked to the motion of the human hand), and also to inverted human action. Experiment 2 compared human action to a non-human motion control (a tool moved the object). In both experiments observers’ sensitivity to detecting the speed changes was higher for the human stimuli relative to the control stimuli, and inversion in Experiment 1 did not alter observers’ sensitivity. Experiment 3 compared observers’ sensitivity to speed changes in goal-directed human and dog actions, in order to determine if enhanced temporal perception is unique to human actions. Results revealed no difference between human and dog stimuli, indicating that enhanced speed perception may exist for any biological motion. Results are discussed with reference to theories of biological motion perception and perception in visual expertise.     

Action goals influence action-specific perception

We examined the processes that mediate the emergence of action-specific influences on perception that have recently been reported for baseball batting and golf putting (Witt, Linkenauger, Bakdash, & Proffitt, 2008; Witt & Proffitt, 2005). To this end, we used a Schokokusswurfmaschine: Children threw a ball at a target, which, if hit successfully, launched a ball that the children then had to catch. In two experiments, children performed either a throwing-and-catching task or a throwing-only task, in which no ball was launched. After each task, the size of the target or of the ball was estimated. Results indicate that action-specific influences on perceived size occur for objects that are related to the end goal of the action, but not for objects that are related to intermediate action goals. These results suggest that action-specific influences on perception are contingent upon the primary action goals to be achieved.     

Infants’ grip strength predicts mu rhythm attenuation during observation of lifting actions with weighted blocks

Research has established that the body is fundamentally involved in perception: bodily experience influences activation of the shared neural system underlying action perception and production during action observation, and bodily characteristics influence perception of the spatial environment. However, whether bodily characteristics influence action perception and its underlying neural system is unknown, particularly in early ontogeny. We measured grip strength in 12‐month‐old infants and investigated relations with mu rhythm attenuation, an electroencephalographic correlate of the neural system underlying action perception, during observation of lifting actions performed with differently weighted blocks. We found that infants with higher grip strength exhibited significant mu attenuation during observation of lifting actions, whereas infants with lower grip strength did not. Moreover, a progressively strong relation between grip strength and mu attenuation during observation of lifts was found with increased block weight. We propose that this relation is attributable to differences in infants’ ability to recognize the effort associated with lifting objects of different weights, as a consequence of their developing strength. Together, our results extend the body's role in perception by demonstrating that bodily characteristics influence action perception by shaping the activation of its underlying neural system.     

Awareness of one's body as subject and object

Abstract

This paper rejects Hume's famous claim that we never perceive our selves, by arguing that, under conditions specified, our perception of our bodies is perception of our selves. It takes as its point of departure Quassim Cassam's defence of a position to a similar effect but puts a different interpretation on the distinction between perceiving the body as an object, having spatial attributes, and perceiving it as a self or subject of experiences.     

Effects of movement distance,duration, velocity,and type on action prediction in 12-month-olds

The goal of the present study was to test the influence of the spatial and temporal dynamics of observed manual actions on infants’ action prediction. Twelve-month-old infants were presented with reach-and-transport actions performed by a human agent. Movement distance, duration, and – resulting from the two – movement velocity were systematically varied. Action prediction was measured via the latency of gaze arrival at target in relation to agent’s hand. The results showed a general effect of all parameters on the infants’ perception of goal-directed actions: Infants were more likely to predict the action goal the longer the movement distance was, the longer the movement duration was, and the slower the movement velocity was. In addition, they were more likely to predict the goal of a reaching than a transport action. The present findings extent previous findings by showing that infants are not only sensitive to differences in distances, durations, and velocities at early age but that these factors have a strong impact on the prediction of the goal of observed actions.     

Auditory-visual interactions in the perception of a ball's path

We carried out two experiments to measure the combined perceptual effect of visual and auditory information on the perception of a moving object's trajectory. All visual stimuli consisted of a perspective rendering of a ball moving in a three-dimensional box. Each video was paired with one of three sound conditions: silence, the sound of a ball rolling, or the sound of a ball hitting the ground. We found that the sound condition influenced whether observers were more likely to perceive the ball as rolling back in depth on the floor of the box or jumping in the frontal plane. In a second experiment we found further evidence that the reported shift in path perception reflects perceptual experience rather than a deliberate decision process. Instead of directly judging the ball's path, observers judged the ball's speed. Speed is an indirect measure of the perceived path because, as a result of the geometry of the box and the viewing angle, a rolling ball would travel a greater distance than a jumping ball in the same time interval. Observers did judge a ball paired with a rolling sound as faster than a ball paired with a jumping sound. This auditory-visual interaction provides an example of a unitary percept arising from multisensory input.     

Carrying the height of the world on your ankles: Encumbering observers reduces estimates of how high an actor can jump

The authors investigated how changes in action capabilities affect estimation of affordances for another actor. Observers estimated maximum jumping-reach height for themselves and another actor. Half of the observers wore ankle weights that reduced their jumping ability. The ankle weights reduced estimates of maximum jumping-reach height that observers made for themselves and for the other actor, but only after observers had the opportunity to walk while wearing the weights. Changes in estimates closely matched changes in actual jumping-reach ability. Results confirm and extend recent investigations that indicate that perception of the spatial layout of surfaces in the environment is scaled to an observer's capacity to act, and they link that approach to another embodied cognition perspective that posits a link between one's own action capabilities and perception of the actions of other agents.     

How character goal pursuit “moves” audiences to share meaningful stories

ABSTRACT

Recent research has examined the theme-level determinants of how stories move readers. Our research examined what moves readers in more nuance. Specifically, we examined how readers’ perception of a character’s goal pursuit (i.e., their motivation to complete a goal, goal desire intensity, and goal pursuit struggle) leads to narrative engagement, which we posit is an antecedent to being moved. The degree to which readers are moved should then influence their intention to share the story. Across two studies, character motivation consistently influenced narrative engagement, particularly emotional engagement, which evokes the experience of being moved. Being moved by the story – but not enjoyment – increased readers’ intentions to share it with others. We argue that media psychology researchers should incorporate being moved into their broader models of narrative engagement for both basic and applied research.     

Implied body action directs spatial attention

Research confirms that the body influences perception, but little is known about the embodiment of attention. We investigated whether the implied actions of others direct spatial attention, using a lateralized covert-orienting task with nonpredictive central cues depicting static, right/left-facing bodies poised in midaction. Validity effects (decreased response times for validly compared with invalidly cued trials) indicated orienting in the direction of the implied action. In Experiment 1, we compared action (running, throwing) with nonaction (standing) cues. Only the action cues produced validity effects, suggesting that implied action directs attention. The action cues produced faster responses overall, suggesting that action cues prime motor responses. In Experiment 2, we determined whether action cues shifted attention in a specific direction rather than to a general side of space: Two cues had similar action speed and motor effort but differed in implied direction (jumping, vertical; throwing, horizontal). Validity effects were found only for the throw cues for which the implied motion direction was consistent with lateralized target locations. In Experiment 3, we compared block-like stimuli to the throwing action stimuli to examine whether lower level perceptual information could account for the attention effects alone. Validity effects were found only for the human-action stimuli. Overall, the results suggest that predictive simulations of action shift attention in action-consistent directions.     

Experience matters: the impact of doing versus watching on infants' subsequent perception of tool-use events

Prior work suggests that active experience affects infants' understanding of simple actions. The present studies compared the impact of active and observational experience on infants' ability to identify the goal of a novel tool-use event. Infants either received active training and practice in using a cane to retrieve an out-of-reach toy or had matched observational experience before taking part in a habituation paradigm that we used to assess infants' ability to identify the goal of another person's tool-use acts. Active training alone facilitated 10-month-old infants' ability to identify the goal of the tool-use event. Active experience using tools may enable infants to build motor representations of tool-use events that subsequently guide action perception and support action understanding.