What leads us to pay attention to some things in the visual world and ignore others? The research plan examines the factors affecting the capacity of graspable objects to automatically draw visual attention to their locations. In question is the degree to which the implicit recognition of an object's motor affordance can bias visual attention. Viewing tools, pictures of tools, and even the names of tools have all been shown to activate motor-related regions of cortex independent of an observer's intention to act. This suggests that when a tool's representation is primed by visual input, the motor schema used for grasping that tool becomes primed as well. The experiments outlined here address whether such selection for an object-specific motor program can have a feedback influence on the orienting of visual attention to the location of that object. The paradigm is based on an object competition model, where participants view two task-irrelevant objects--one a """"""""TOOL"""""""" and one a """"""""NON-TOOL""""""""--while waiting for a target to be presented in one of the two object locations. Using event-related potentials (ERPs), we have found systematic increases in sensory-level visual attention at the location of the TOOL when it was in the right visual field. Using event-related fMRI, we have confirmed that TOOLs in the right visual field preferentially activated motor schemata in dorsal regions of premotor and prefrontal cortex, relative to TOOLs in the left visual field.
The aim of the research plan is to examine the basis of this visual field asymmetry. In particular, does it reflect a differential sensitivity to low-level object properties between the two visual hemifields, a differential time course of attentional biases between the hemifields, an asymmetry in the sensitivity to the grasping orientation of an object, or a combination of these factors? Given that spatial attention research has long-focused on understanding how attention aids perception, the current research plan is novel in studying how implicit action processing biases visual attention. Beyond this basic question of cognitive function, the broader objective is to provide the normative foundation for understanding how attention-visuomotor interactions may be impaired in psychiatric populations known to have disorders of attention and motor function.
