Perception of elliptic biological motion

Universität Ulm, Ulm, Baden-Württemberg, Germany
Perception (Impact Factor: 0.91). 02/2006; 35(8):1137-47. DOI: 10.1068/p5482
Source: PubMed


We tested the ability of the mature visual system for discrimination between types of elliptic biological motion on the basis of event kinematics. Healthy adult volunteers were presented with point-light displays depicting elliptic motion when only a single dot, a moving point-light arm, or a whole point-light human figure was visible. The displays were created in accordance with the two-thirds power kinematic law (natural motion), whereas the control displays violated this principle (unnatural motion). On each trial, participants judged whether the display represented natural or unnatural motion. The findings indicate that adults are highly sensitive to violation of the two-thirds power kinematic law. Notably, participants can easily discriminate between natural and unnatural motions without recognising the stimuli, which suggests that people implicitly use kinematic information. Most intriguing, event recognition seems to diminish the capacity to judge whether event kinematics is unnatural. We discuss possible ways for a cross-talk between perception and production of biological movement, and the brain mechanisms involved in biological motion processing.

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Available from: Christel Bidet-Ildei, Sep 15, 2014
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    • "Moreover, this theory could explain the reason why humans tend to prefer stimuli that share common kinematics properties with their own motor productions, i.e., those which conform to motor rules (Fitt's law, isochrony principle, two-third power law) [4] [22] [35] [36]. However, the idea that the motor system is systematically involved in the visual perception of human movements was recently challenged by results obtained in infants and in patients with impaired motor functions. "
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    ABSTRACT: The aim of this experiment was to show that the visual preference for isochronic movements does not necessarily imply a motor simulation and therefore, does not depend on the kinematics of the perceived movement. To demonstrate this point, the participants' task was to adjust the velocity (the period) of a dot that depicted an elliptic motion with different perimeters (from 3 to 60 cm). The velocity profile of the movement conformed ("natural motions") or not ("unnatural motions") to the law of co-variation velocity-curvature (two-thirds power law), which is usually observed in the production of elliptic movements. For each condition, we evaluated the isochrony principle, i.e., the tendency to prefer constant durations of movement irrespective to changes in the trajectory perimeter. Our findings indicate that isochrony principle was observed whatever the kinematics of the movement (natural or unnatural). Therefore, they suggest that the perceptive preference for isochronic movements does not systematically imply a motor simulation.
    Neuroscience Letters 02/2008; 430(3):236-40. DOI:10.1016/j.neulet.2007.10.040 · 2.03 Impact Factor
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    ABSTRACT: Not Available
    Ultrasonics Symposium, 2005 IEEE; 10/2005
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    ABSTRACT: The ability of human observers to detect 'biological motion' of humans and animals has been taken as evidence of specialized perceptual mechanisms. This ability remains unimpaired when the stimulus is reduced to a moving array of dots representing only the joints of the agent: the point light walker (PLW) (G. Johansson, 1973). Such stimuli arguably contain underlying form, and recent debate has centered on the contributions of form and motion to their processing (J. O. Garcia & E. D. Grossman, 2008; E. Hiris, 2007). Human actions contain periodic variations in form; we exploit this by using brief presentations to reveal how these natural variations affect perceptual processing. Comparing performance with static and dynamic presentations reveals the influence of integrative motion signals. Form information appears to play a critical role in biological motion processing and our results show that this information is supported, not replaced, by the integrative motion signals conveyed by the relationships between the dots of the PLW. However, our data also suggest strong task effects on the relevance of the information presented by the PLW. We discuss the relationship between task performance and stimulus in terms of form and motion information, and the implications for conclusions drawn from PLW based studies.
    Journal of Vision 03/2009; 9(3):28.1-11. DOI:10.1167/9.3.28 · 2.39 Impact Factor
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