Differential effects of advance semantic cues on grasping, naming, and manual estimation.

In the three experiments reported here, we systematically investigated when and/or how prior semantic information about a target-object would affect the programming and execution of grasping movements. A name-length association was first created during a practice phase while participants performed one of the three tasks: grasping, naming, or manual estimation of an object's length upon an auditory presentation of its name. In the subsequent test phase, in the majority of trials, these names correctly indicated the upcoming object for a grasping task or a control naming task (Experiment 1A and 1B), and a grasping task or a manual estimation of object length (Experiment 2). In both experiments, a name was occasionally incongruent or a neutral cue (a burst of white noise) was presented instead. Although in the grasping task, semantic cues (both congruent and incongruent) consistently facilitated movement-onset time (indicating a preparatory-set like effect), the impact of these cues on the formation of grasping aperture was less consistent or absent. The experiments also demonstrated that naming and perceptual estimation of object length were affected differently from grasping by the same semantic cues, with the congruent cues facilitating and the incongruent cues slowing down response onset. These findings reinforce and extend the proposal that the transformations of visual and semantic information for perceptually-driven tasks are quite different from the transformations of the same information for the programming and control of object-directed action.