Larger IOR effects following forget than following remember instructions depend on exogenous attentional withdrawal and target localization.

When words are onset in the visual periphery, inhibition of return (IOR) for a subsequent target is larger when those words receive an intervening forget instruction than when they receive a remember instruction Taylor (Quarterly Journal of Experimental Psychology, 58A, 613-629, 2005). The present study manipulated the allocation of endogenous and exogenous attention to assess the source of the forget > remember IOR difference. We determined that the forget > remember IOR difference likely arises from the differential withdrawal of exogenous-rather than endogenous-attention. Furthermore, this forget > remember IOR difference occurs only when a spatially compatible localization response is required; it does not occur when a simple detection response or a perceptual discrimination is required. This suggests that the forget > remember difference in the magnitude of IOR is not due to differences in perceptual/attentional processing. Instead, an instruction to remember or forget biases spatial responses in accordance with whether a location has previously contained relevant or irrelevant information. We suggest that directed forgetting in an item-method paradigm is not accomplished by changes in attention; rather, the changes in attention are coincident with changes in memory and may serve to bias later responses away from a source of unreliable information.