The potentiation of grasp types during visual object categorization

The close integration between visual and motor processes suggests that some visuomotor transformations may proceed automatically and to an extent that permits observable effects on subsequent actions. A series of experiments investigated the effects of visual objects on motor responses during a categorisation task. In Experiment 1 participants responded according to an object's natural or manufactured category. The responses consisted in uni-manual precision or power grasps that could be compatible or incompatible with the viewed object. The data indicate that object grasp compatibility significantly affected participant response times and that this did not depend upon the object being viewed within the reaching space. The time course of this effect was investigated in Experiments 2-4b by using a go-nogo paradigm with responses cued by tones and go-nogo trials cued by object category. The compatibility effect was not present under advance response cueing and rapidly diminished following object extinction. A final experiment established that the compatibility effect did not depend on a within-hand response choice, but was at least as great with bi-manual responses where a full power grasp could be used. Distributional analyses suggest that the effect is not subject to rapid decay but increases linearly with RT whilst the object remains visible. The data are consistent with the view that components of the actions an object affords are integral to its representation.