Inhibition of return : dissociating attentional and oculomotor components

The term Inhibition of Return (IOR) describes a performance decrement for stimuli appearing at a recently attended location. It has been hypothesized that one, possibly two, components contribute to the IOR effect: an attentional component and a motor component. In a series of three experiments we demonstrate that both components can contribute to the IOR effect. Using the fixation offset effect (FOE), which can facilitate oculomotor response execution, as a measure of a motor contribution to the IOR effect, we show that the FOE and IOR interact, although not in the manner observed previously. Using changes in target luminance as a measure of an attentional contribution to IOR, we show that IOR and target luminance interact but only when the responses were manual. Together these data reveal two components that can each contribute to IOR. The motorbased component is present when the response is oculomotor, and the attentional component is present when the response is manual.Arts, Faculty ofPsychology, Department ofGraduat