Visual action control does not rely on strangers--effects of pictorial cues under monocular and binocular vision.

Fast goal-directed actions are supposed to be controlled almost exclusively by bottom-up visual control. This mode of processing has been identified with the so-called dorsal visual stream. It is generally accepted that object recognition, mediated by the ventral stream, must be important for deciding what action to execute depending on the specific object to be grasped and the particular purpose. In contrast, the kinematic parameters of the actual movement itself are supposed to be unaffected by recognition processes. This view was recently challenged by the demonstration of a significant impact of object familiarity on grasping kinematics under binocular visual control (McIntosh & Lashley, 2008). This effect was observed for very well known everyday objects. However, it remained unclear whether the effect was really due to long-term, everyday familiarity of the target objects or whether it was simply mediated by short-term learning during the experiment. Therefore, we examined whether the same effect could also be found with objects that were geometrically identical to the ones used by McIntosh and Lashley (2008) and could be distinguished by a pictorial cue but were not associated with long-term, everyday experience. We only found an effect of familiarity under monocular but not under binocular control. Our observation suggests that indeed familiarity exerts an effect on movements under binocular control only if explicit knowledge about the objects is very stable and salient, e.g. after long-term experience.