On interference effects in concurrent perception and action

Abstract

Recent studies have reported repulsion effects between the perception of visual motion and the concurrent production of hand movements. Two models, based on the notions of common coding and internal forward modeling, have been proposed to account for these phenomena. They predict that the size of the effects in perception and action should be monotonically related and vary with the amount of similarity between what is produced and perceived. These predictions were tested in four experiments in which participants were asked to make hand movements in certain directions while simultaneously encoding the direction of an independent stimulus motion. As expected, perceived directions were repelled by produced directions, and produced directions were repelled by perceived directions. However, contrary to the models, the size of the effects in perception and action did not covary, nor did they depend (as predicted) on the amount of perception-action similarity. We propose that such interactions are mediated by the activation of categorical representations.

Fig. 1

Depiction of the Hamilton model (see text for details)

Fig. 2

The experimental setup used in the current study (see text for details)

Fig. 3

Example trial sequences for a motion trial (a) and a no-motion trial (b). In no motion trials no reference or test stimuli were shown indicated by a blank gray frame in the figure (see text for details)

Fig. 4

Depiction of the different reference stimulus and hand movement directions, and how the angles were coded for each type of configuration (horizontal, vertical). For the purpose of illustration, two required movement directions are presented for each configuration. In the experiments, only one movement was produced on a given trial. When no reference or test stimulus was shown (no motion trials) a blank gray frame is depicted in the figure

Fig. 5

Expected perceived angles for upward and downward movements when a CE in perception occurs (a). Expected produced directions for motion and no-motion trials if a CE in production occurs (b). The angular differences are exaggerated for the purpose of illustration

Fig. 6

Mean upward and downward produced and required movement trajectories as a function of trial type (motion, no motion) for one exemplary participant in Experiment 1

Fig. 7

Size of the CE in production and perception as a function of the absolute value of the required movement angles for Experiments 1 (25°) and 2 (10° and 35°). Required movement angles are coded relative to the horizontal axis. Whiskers indicate 95% confidence intervals

Fig. 8

Size of the CE in perception as a function of the size of the CE in production for Experiment 1. Each data point corresponds to one participant

Fig. 9

Size of the CE in perception as a function of the absolute value of the required movement angles for Experiments 3 (30° and 80°) and 4 (10° and 100°). Required movement angles are coded relative to the vertical axis. Whiskers indicate 95% confidence intervals