Mountain high, valley low: direction-specific effects of articulation on reaching.

Representations underpinning action and language overlap and interact very closely. There are bidirectional interactions between word and action comprehension, semantic processing of language, and response selection. This study extends our understanding of the influence of speech on concurrent motor execution. Participants reached-to-grasp the top or bottom of a vertically oriented bar in response to the location of a word on a computer screen (top/bottom). Words were synonyms for "up" or "down", and participants were required to articulate the word during movement. We were particularly interested in the influence of articulated word semantics on the transport component of the reach. Using motion capture to analyse action kinematics, we show that irrespective of reach direction, saying "up" synonyms led to greater height of the hand, while saying "down" synonyms was associated with reduced height. This direction-specific influence of articulation on the spatial parameters of the hand supports the idea that linguistic systems are tightly integrated and influence each other.