Are two hands better than one? A follow-up to Davoli & Brockmole's(2012) "shielding" effect


Davoli & Brockmole (2012; AP&P), in the context of a classic Eriksen “flanker” task, observed that positioning one’s hands around a target item reduced interference from incongruent flankers, despite the flanking items still being perfectly visible. Herein we asked whether this “shielding” effect would still be observed if instead participants only placed a single hand to one side of the target. More importantly, if shielding is still observed, is it sensitive to where flankers appear in relation to the hand (i.e. palm or backhand)? To do this, we had participants perform a flanker task while varying which hand was placed on-screen, as well as a no-hand control. Critically, within each trial we allowed flankers to individually vary in their compatibility with the target (ex: incongruent flanker on left, congruent on right). This allowed us to probe whether the degree of interference (and possible reductions thereof) elicited by incongruent flankers was modulated by their position with respect to the hand. Our results are discussed from an embodied cognition perspective in relation to classical attentional concepts such as orienting and set.