IS INTERFERENCE IN GRASPING PRODUCED WHEN COVERT ATTENTION IS DIRECTED TO NON-TARGET OBJECTS?

Abstract

Previous literature has shown that when covert attention is directed to a non-target object while grasping a target fruit, the non-target’s size can influence the peak grip aperture for the target fruit (Castiello, 1996). Castiello’s study is heavily cited but no replications have even been published. For this reason, the current study first aimed to replicate the interference effect found by Castiello (1996), and then explores the role that binocular vision might play in moderating the effect. Experiment 1 was a strict methodological replication of Castiello’s (1996) main experiment. The results revealed a robust effect of the target fruit’s size on peak grip aperture, but no effect of the size of the non-target flanking fruit. In Experiment 2, a similar paradigm was used to determine if the effect of the flanking fruit would increase when binocular vision was restricted, based on the idea that actions controlled with binocular vision have privileged access to the dorsal visual pathway which is known to produce metrically precise actions. As in Experiment 1, no evidence was found for an effect of the size of the flanking fruit under binocular or monocular viewing conditions, suggesting that grasping actions are quite robust to interference from concurrently attended non-target objects.