Leg Asymmetries and Coordination Dynamics in Walking

Models of interlimb coordination (H. Haken, J. A. S. Kelso, &; H. Bunz, 1985 Haken, H., Kelso, J. A. S. and Bunz, H. 1985. A theoretical model of phase transitions in human hand movements. Biological Cybernetics, 51: 347–356. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; P. N. Kugler &; M. T. Turvey, 1987 Kugler, P. N. and Turvey, M. T. 1987. Information, natural law, and the self-assembly of rhythmic movement, Hillsdale, NJ: Erlbaum.  [Google Scholar]) were tested in walking by examining the role of asymmetries between limbs. Participants walked on a treadmill with and without a metronome. Five asymmetry conditions were created via ankle loads of 0, 3, or 6 kg on either leg. With the metronome, participants matched the target period. Without the metronome, stride rate slowed as the mass was increased on either leg. The loads led to an increase in stride period that was predicted by Huygens’ law and the hybrid pendulum-spring model. In agreement with extended Haken–Kelso–Bunz model predictions, leg asymmetries led to deviations from antiphase coordination. Also, perception–action coordination was influenced by the asymmetry between the legs and metronome. In contrast, no predicted stability effects were observed. These findings reveal that some properties of interlimb coordination, apparent in laboratory-based tasks, can also be observed in human walking.     

Action and Variation in Perception

In her paper, ‘Action and Self‐location in Perception’, Susanna Schellenberg argues that perceptual experience of an object's intrinsic spatial properties, such as its size and shape, requires a capacity to act. More specifically, Schellenberg argues that, to have a perceptual experience of an object's intrinsic spatial properties, a subject needs to have a certain practical conception of space, or a spatial know‐how. That, in turn, requires self‐locating representations, which locate the subject, relative to the perceptual object, as a perceiver and an agent, viz., someone who has a capacity for actions. She also makes two objections, viz., the unification objection and the sentient statue objection, to Alva Noë's sensorimotor view, a different account of how perceptual experience depends on actions. I will argue that her objections jointly render problematic not only Noë's but also her own view.     

Perception and Action Are Inseparable

In her article, Michaels (2000) defined action as "a temporally bounded, observable, goal-directed movement (or non-movement) that entails intention, the detection of information, and a lawful relation between that information and the movement" (p. 251). She defined perception as "the detection of information" (p. 244). This forces one to conclude that it is impossible to study action separately from perception. We argue that perceptual judgments are communicated by movements and that it is impossible to distinguish movements reporting perceptual judgments from other movements, so we conclude that the reverse also is true: It is impossible to study perception separately from action.     

Practical Perception and Intelligent Action

Perceiving things to be a certain way may in some cases lead directly to action that is intelligent (e.g., skillful, wise, clever, astute). This phenomenon has not often been discussed, though it is of broad philosophical interest. It also raises a difficult question: how can perception produce intelligent action? After clarifying the question—which I call the question of “practical perception”—and explaining what is required for an adequate answer, I critically examine two candidate answers drawn from work on related topics: the first, inspired by Hubert Dreyfus's phenomenological analysis of absorbed coping (and of a piece with James Gibson's theory of affordances), focuses on awareness of situational features; the other, suggested by Gilbert Ryle's classic treatment of knowledge‐how, focuses on possession of behavioral dispositions. I argue that neither approach is adequate. Subsequently, I develop and defend an alternative answer that emphasizes the agent's conceptual understanding.     

Embodied Perception and the Economy of Action

ABSTRACT— Perception informs people about the opportunities for action and their associated costs. To this end, explicit awareness of spatial layout varies not only with relevant optical and ocular-motor variables, but also as a function of the costs associated with performing intended actions. Although explicit awareness is mutable in this respect, visually guided actions directed at the immediate environment are not. When the metabolic costs associated with walking an extent increase—perhaps because one is wearing a heavy backpack—hills appear steeper and distances to targets appear greater. When one is standing on a high balcony, the apparent distance to the ground is correlated with one's fear of falling. Perceiving spatial layout combines the geometry of the world with behavioral goals and the costs associated with achieving these goals.     

The Social Nature of Perception and Action

ABSTRACT— Humans engage in a wide range of social activities. Previous research has focused on the role of higher cognitive functions, such as mentalizing (the ability to infer others' mental states) and language processing, in social exchange. This article reviews recent studies on action perception and joint action suggesting that basic perception–action links are crucial for many social interactions. Mapping perceived actions to one's own action repertoire enables direct understanding of others' actions and supports action identification. Joint action relies on shared action representations and involves modeling of others' performance in relation to one's own. Taking the social nature of perception and action seriously not only contributes to the understanding of dedicated social processes but has the potential to create a new perspective on the individual mind and brain.     

Egocentric Spatial Representation in Action and Perception*

Neuropsychological findings used to motivate the “two visual systems” hypothesis have been taken to endanger a pair of widely accepted claims about spatial representation in conscious visual experience. The first is the claim that visual experience represents 3‐D space around the perceiver using an egocentric frame of reference. The second is the claim that there is a constitutive link between the spatial contents of visual experience and the perceiver’s bodily actions. In this paper, I review and assess three main sources of evidence for the two visual systems hypothesis. I argue that the best interpretation of the evidence is in fact consistent with both claims. I conclude with some brief remarks on the relation between visual consciousness and rational agency.     

Task-Specific Dynamics and the Study of Perception and Action: A reaction to von Hofsten (1989)

In a recent discussion of motor development, von Hofsten (1989) distinguished two approaches which he called the perception-action and dynamic systems ap- proaches, respectively. In this reaction, we suggest that the proposed distinction is inappropriate. We argue that research on perception and action in terms of task-specific dynamics is uniquely suited to the characterization of problems inherent to the coupling of perception and action. The problems discussed include the problem of stability and transitions in behavior; the problem of perceptual information about physical properties of the action system; and the role of the brain in the context of the degrees of freedom problem, the problem of multiple scales of analysis, and the heterogeneity of the components of the human action system including the brain.     

Enactivism and the Unity of Perception and Action

This paper contrasts two enactive theories of visual experience: the sensorimotor theory (O’Regan and Noë, Behav Brain Sci 24(5):939–1031, 2001; Noë and O’Regan, Vision and mind, 2002; Noë, Action in perception, 2004) and Susan Hurley’s (Consciousness in action, 1998, Synthese 129:3–40, 2001) theory of active perception. We criticise the sensorimotor theory for its commitment to a distinction between mere sensorimotor behaviour and cognition. This is a distinction that is firmly rejected by Hurley. Hurley argues that personal level cognitive abilities emerge out of a complex dynamic feedback system at the subpersonal level. Moreover reflection on the role of eye movements in visual perception establishes a further sense in which a distinction between sensorimotor behaviour and cognition cannot be sustained. The sensorimotor theory has recently come under critical fire (see e.g. Block, J Philos CII(5):259–272, 2005; Prinz, Psyche, 12(1):1–19, 2006; Aizawa, J Philos CIV(1), 2007) for mistaking a merely causal contribution of action to perception for a constitutive contribution. We further argue that the sensorimotor theory is particularly vulnerable to this objection in a way that Hurley’s active perception theory is not. This presents an additional reason for preferring Hurley’s theory as providing a conceptual framework for the enactive programme.     

A Systems Approach to Perception and Action

ABSTRACT

On the 50th anniversary of its publication, we look back on some of the intellectual contributions of Gibson's (1966) The Senses Considered as Perceptual Systems. This work is often seen as contributing a new perspective to our understanding of the 5 senses. In this paper, we explore another intellectual contribution: Gibson's treatment of perception–action as an irreducible, functional system. We review select examples of systems thinking from the physical, animal, and human social domains. Our suggestion is that a systems-level approach to social interactions would have been a natural extension of Gibson's ideas.     

Developing Anticipation Skills in Tennis Using On-Court Instruction: Perception versus Perception and Action

On-court instruction involving either Perception–action training or Perception-only training was used to improve anticipation skill in novice tennis players. A technical instruction group acted as a control. Participants' ability to anticipate an opponent's serve was assessed pre- and posttest using established on-court measures involving frame-by-frame video analysis. The perception–action and perception-only groups significantly improved their anticipatory performance from pretest to posttest. No pretest-to-posttest differences in anticipation skill were reported for the technical instruction group. The ability to anticipate an opponent's serve can be improved through on-court instruction where the relationship between key postural cues and subsequent performance is highlighted, and both practice and feedback are provided. No significant differences were observed between the perception–action and perception-only training groups, implying that either mode of training may be effective in enhancing perceptual skill in sport.     

Perception And Action: Alternative Views

A traditional view of perception and action makestwo assumptions: that the causal flow betweenperception and action is primarily linear or one-way,and that they are merely instrumentally related toeach other, so that each is a means to the other.Either or both of these assumptions can be rejected.Behaviorism rejects the instrumental but not theone-way aspect of the traditional view, thus leavingitself open to charges of verificationism. Ecologicalviews reject the one-way aspect but not theinstrumental aspect of the traditional view, so thatperception and action are seen as instrumentallyinterdependent. It is argued here that a betteralternative is to reject both assumptions, resultingin a two-level interdependence view in whichperception and action co-depend on dynamicallycircular subpersonal relations and as a result may bemore than merely instrumentally interdependent. Thisis illustrated by reference to motor theories ofperception and control theories of action.     

Corporeal Objects and the Interdependence of Perception and Action

This paper is about how action and perception are related in self–awareness. The main positive claim is that bodily awareness may consist in perceptual experiences that are sufficient to provide corporeal objects with introspective self–awareness. The short–term goal is to examine the grounds and motivations for strong versions of the claim that the self–awareness of corporeal objects is dependent on the exercise of their agency. As examples of 'patient perceivers' show, we should not underestimate the resources that perceptual experience alone offers to corporeal selves.     

The Limits of Attention for Visual Perception and Action in Aging

ABSTRACT

This study aimed to investigate whether aging results in an increased attentional blink effect in older adults as compared to young adults. A rapid serial visual presentation (RSVP) paradigm was employed in which participants were asked to identify two targets (dual-task condition) presented in rapid succession. These targets were separated by various intervals in a stream of stimuli. The performance for identifying the second target was normally diminished as compared to identification of a single-task target. Various combinations of tasks, such as two perceptual tasks or one perceptual and one action task, as well as different types of pointing action, such as pointing to a displaced target, pointing to a stationary target or pointing to a disappeared target, were manipulated in this study to see if aging may further impact these variables. The results of this study showed that in young adults, successful identification of the first target interfered with identifying the second target, as well as the initiation time (action planning) of pointing to the second target. However, identification of the first target did not interfere with pointing movement time and pointing accuracy, even when the target was displaced, which required online control of action. Conversely, for older adults, successful central identification not only interfered with identifying the second target and with the pointing initiation time, but also interfered with pointing movement time for a displaced target. This suggests that older adults seem to be unable to concurrently identify the first target and correct their already-initiated pointing movement compared to young adults.     

Interaction of Perception and Action in Discrete and Continuous Rapid Aiming Tasks

Previously, we have shown that discrete and continuous rapid aiming tasks are governed by distinct visuomotor control mechanisms by assessing the combined visual illusion effects on the perceived and effective index of difficulty (ID). All participants were perceptually biased by the combined visual illusion before they performed the rapid aiming tasks. In the current study, the authors manipulated the order of performing perceptual and motor tasks to examine whether perceptual or motor experience with the illusory visual target would influence the subsequent perceived and effective ID in discrete and continuous tapping tasks. The results supported our hypothesis showing that perceptual experience with the illusory visual target in the discrete condition reduced the effective ID in the subsequent discrete tapping task, and motor experience with the illusory visual target in the continuous condition reduced the illusion effects on the perceived ID in the subsequent perceptual judgment task. The study demonstrates the coinfluence of perception and action, and suggests that perception and action influence one another with different magnitude depending on the spatial frame of reference used to perform the perceptuomotor task.