Anticipating the terminal position of an observed action: Effect of kinematic, structural, and identity information

Abstract

The ability to visually identify and anticipate motor actions performed by others is thought to be an essential component of social interactions and possibly requires relating visual information with sensorimotor knowledge. Though motor theory of visual perception received convincing evidence from behavioural, neuropsychological, and developmental studies, the nature of the information used for anticipating the terminal location of an observed human action remains still an open issue. In this context, the aim of the present study was to evaluate the role of motor representations on the prediction of the terminal location of an observed manual reaching movement. The stimulus was a two-dimensional point-light display showing the top-view of a right arm moving along the sagittal plane towards targets positioned at different distances. The task was to estimate the terminal location of the reaching movement after the stimulus vanished following 60% of total movement duration. Characteristics of the point-light display could vary according to movement kinematics (biological motion, constant, inverse, or monotonically increased velocity), structural features (all joints visible or only the forefinger tip), and movement identity (self- vs. other-generated action). Results showed that spatial performances improved when presenting “self-generated” actions (identity effect) in the biological motion condition (kinematic effect). Furthermore, reducing the visual stimulus to the forefinger did not affect the performance (structural effect). Considered together, these findings provide further evidence for motor-based visual perception of biological motion and suggest that kinematic but not structural information is crucial to give sense to an observed human action and to anticipate its final location.

Keywords:

• Point light display
• Reaching movement
• Visual prediction

Acknowledgements

This work was supported by the University Lille 3 and national grant ANR “Concepts systèmes et outils pour la sécurité globale” programme from the French Ministry.

Notes

¹Different visuomotor theories have been suggested in the past, including the theory of common representational code (Hommel, Musseler, Aschersleben, & Prinz, 2001; Prinz, 1997), internalized motor simulation triggered by the visual stimulus (Jeannerod, 2001), reciprocal motor and perceptual resonance (Shütz-Bosbach & Prinz, 2007; Viviani, 2002), and mirror neuron system (Rizzolatti & Craighero 2004). Though these theories diverged in some respects, only the general view of the implication of the motor system in the visual perception of biological movement will be referred to here.