Assimilation and contrast: the two sides of specific interference between action and perception.

Perception and action have long been treated as relatively independent and serial processes. More recent views, however, consider perception and action as relying on a common set of processes and/or representations. The present paper will focus on a variety of specific (content-based) perception-action interactions that have been taken as support for such views. In particular, the following aspects will be considered: direction of influence (perception on action vs. action on perception), temporal type (concurrent vs. non-concurrent), functional relation (related/unrelated), and type of movements (biological vs. non-biological). Different extant models of the perception-action interface are discussed and a classification schema proposed that tries to explain when contrast and when assimilation effects will arise.