Representing and anticipating human actions in vision

Verfaillie, Karl; Daems, Anja

doi:10.1080/13506280143000403

Cited by 104 publications

(83 citation statements)

References 35 publications

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“…This result goes along with findings on RM effects in the literature, indicating that an observer's memory for a moving object (Hubbard, 1995) or for a photograph with implied motion (Freyd, 1983) is distorted in the direction of the suggested motion. This finding is also compatible with the hypothesis of an anticipation of the future posture in biological motion perception (Verfaillie & Daems, 2002) and indicates that when a visual stimulation such as a PLC movement is abruptly stopped, its dynamics survive.…”

Section: Resultssupporting

confidence: 80%

Optical flow and viewpoint change modulate the perception and memorization of complex motion

Jarraya

Amorim

Bardy

2005

Perception & Psychophysics

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Participants observed a point-light character (PLC) performing a gymnastic movement. They either memorized the final PLC orientation from the initial viewpoint, to match it to a test posture (memory task), or judged whether the biological motion appeared continuous (perceptual task), despite a viewpoint change. The observer could be either static or virtually in motion (pan or track) while looking at the movement from the initial viewpoint. The presence of a spatial layout during virtual self-motion induced a global optical flow specifying the translational component of the PLC movement, rendering the event more predictable for the participants. A representational momentum effect was observed in the memory task, suggesting that when a visual stimulation, such as a PLC motion, is abruptly stopped, its dynamics survive. In contrast, structural and transformational invariants specifying the PLC motion were sufficient to solve the perceptual task accurately. Finally, both the remembering of the final posture and the perception of continuity degraded with an increase in viewpoint change due to tilt/slant posture orientation matching, indicating that orientation processes interfered with event perception.

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Section: Resultssupporting

confidence: 80%

Optical flow and viewpoint change modulate the perception and memorization of complex motion

Jarraya

Amorim

Bardy

2005

Perception & Psychophysics

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“…This function, which can be derived from an occluder time Â pose time interaction, is in line with previous findings showing that action prediction involves internal models that run in real time to the observed action (Graf et al, 2007;cf. Flanagan & Johansson, 2003;Verfaillie & Daems, 2002). Performance was best when occluder time and pose time matched because the internal model of the last-seen action pose prior to occlusion was internally updated in real time, thus matching the actual test pose.…”

Section: Discussionmentioning

confidence: 99%

Motor execution affects action prediction

Springer

Brandstädter

Liepelt

et al. 2011

Brain and Cognition

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a b s t r a c tPrevious studies provided evidence of the claim that the prediction of occluded action involves real-time simulation. We report two experiments that aimed to study how real-time simulation is affected by simultaneous action execution under conditions of full, partial or no overlap between observed and executed actions. This overlap was analysed by comparing the body sides and the movement kinematics involved in the observed and the executed action. While performing actions, participants observed point-light (PL) actions that were interrupted by an occluder, followed by a test pose. The task was to judge whether the test pose depicted a continuation of the occluded action in the same depth angle. Using a paradigm proposed by Graf et al., we independently manipulated the duration of the occluder and the temporal advance of the test pose relative to occlusion onset (occluder time and pose time, respectively). This paradigm allows the assessment of real-time simulation, based on prediction performance across different occluder time/pose time combinations (i.e., improved task performance with decreasing time distance between occluder time and pose time is taken to reflect real-time simulation). The PL actor could be perceived as from the front or back, as indicated by task instructions. In Experiment 1 (front view instructions), evidence of action simulation was obtained for partial overlap (i.e., observed and performed action corresponded either in body side or movement kinematics), but not for full or no overlap conditions. The same pattern was obtained in Experiment 2 (back view instructions), ruling out a spatial compatibility explanation for the real-time pattern observed. Our results suggest that motor processes affect action prediction and real-time simulation. The strength of their impact varies as a function of the overlap between observed and executed actions.

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“…Verfaillie, De Troy, and Van Rensbergen (1994) presented point-light walker figures, and in some conditions, transsaccadic memory for the figures was consistent with a representational momentumlike extrapolation from the posture of the walker at the initiation of a saccade to the posture of the walker at the completion of that saccade. Verfaillie and Daems (2002) presented observers with an animated sequence of a humanlike figure performing some action, and then the observers viewed a static picture of a humanlike figure and judged whether the picture portrayed a possible or an impossible pose. When the static picture presented a possible pose that was an extension of the movement of the just-viewed animated sequence, the observers were faster in their judgments, and this priming effect is consistent with representational momentum in memory for the actions (or postures) depicted in the animated sequence.…”

Section: Characteristics Of the Targetmentioning

confidence: 99%

Representational momentum and related displacements in spatial memory: A review of the findings

Hubbard

2005

Psychonomic Bulletin & Review

294

417

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Memory for the final location of a moving target is often displaced in the direction of target motion, and this has been referred to as representational momentum. Characteristics of the target (e.g., velocity, size, direction, and identity), display (e.g., target format, retention interval, and response method), context (landmarks, expectations, and attribution of motion source), and observer (e.g., allocation of attention, eye movements, and psychopathology) that influence the direction and magnitude of displacement are reviewed. Specific conclusions regarding numerous variables that influence displacement (e.g., presence of landmarks or surrounding context), as well as broad-based conclusions regarding displacement in general (e.g., displacement does not reflect objective physical principles, may reflect aspects of naive physics, does not solely reflect eye movements, may involve some modular processing, and reflects high-level processes) are drawn. A possible computational theory of displacement is suggested in which displacement (1) helps bridge the gap between perception and action and (2) plays a critical part in localizing stimuli in the environment. DISPLACEMENT IN SPATIAL MEMORY 823Given the issues associated with the term representational momentum, Hubbard (1995c) has suggested that the broader term displacement should be used to refer to general mislocalizations in memory for the final position of a target, and the more specific term representational momentum should be used only to refer to that component of displacement that is attributed to the implied momentum of the target. The momentum of a physical object is defined as the product of that object's mass and velocity (i.e., momentum ϭ mass ϫ velocity), but neurons representing the motion of a physical object would not themselves actually be in motion (just as neurons representing a mental rotation would not themselves actually be rotating), and so mental representations would not be expected to possess physical momentum per se. In the following discussion, the term representational momentum is used to describe that component of displacement consistent with how physical momentum would influence a physical object, but such a use is necessarily more abstract and metaphorical than concrete and literal (i.e., more consistent with second-order isomorphism than with first-order isomorphism; Hubbard, in press-b). Similarly, the terms representational gravity, representational friction, and representational centripetal force abstractly and meta- 824HUBBARD phorically describe components of displacement consistent with how physical gravity, friction, and centripetal force would influence a physical object. Displacement in the Direction of Motion (Representational Momentum)The initial demonstration of a forward displacement in memory for the final position of a previously viewed moving target was provided by Freyd and Finke (1984; see panel A in Figure 1), who presented observers with computer-animated displays consisting of three concentric sequential pr...

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Representing and anticipating human actions in vision

Cited by 104 publications

References 35 publications

Optical flow and viewpoint change modulate the perception and memorization of complex motion

Optical flow and viewpoint change modulate the perception and memorization of complex motion

Motor execution affects action prediction

Representational momentum and related displacements in spatial memory: A review of the findings

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