Intentional control of visual processing benefits from referential objects

Arguments have been made that enhanced visual processing occurs in the area of the palms of the hands due to greater density of bimodal neurons. An alternative is that the hands serve as reference objects relative to which attentional resources are allocated. Two experiments were conducted to determine whether the palms are unique in speeding responses in an Eriksen flanker-type task compared with other parts of the hands and objects used as barriers. In Experiment 1, the hands were crossed and positioned so that the palms faced outward toward letters located in the outer positions. Trial blocks differed in whether the centrally located letter or outer letters were designated as the target for responding. Results yielded reductions in flanker interference much as obtained when the palms face inward. This reduction occurred regardless of whether the center or outer positions of the letters were designated as the target. Experiment 2 replicated these results using as reference objects wooden blocks that mimicked the hands' physical contours, positioned with a curve-edge facing outwards. The results lend support to the referential coding account of the reduction of flanker interference.