From shunting inhibition to dynamic normalization: Attentional selection and decision-making in brief visual displays
The relationship between attention and visual masking was investigated in a cued detection task using a factorial masking manipulation. Stimuli were either unmasked, or were masked with simultaneous (integration) masks, or delayed (interruption) masks, or integration-interruption mask pairs. The cuing effects in detection sensitivity were smallest with unmasked stimuli, intermediate with single masks, and largest with integration-interruption pairs. Large cuing effects in RT were found in all stimulus conditions. The results are inconsistent with general mechanisms of contrast gain and response gain, which do not predict interactions with interruption masks. The data were modeled using the integrated system model of visual attention of P. L. Smith and R. Ratcliff (2009), which provides an account of both RT and accuracy. The model fits suggest the action of two independent attentional mechanisms: an early selection mechanism that enhances the perceptual representation of attended, noisy stimuli, and a late selection mechanism that increases the rate of information transfer to visual short-term memory. The results are consistent with a distributed, multi-locus system of attentional control.