How does neural architecture constrain attentional selection?
Professor George Alvarez Harvard University
(Dept. of Psychology Faculty Candidate)
The world presents a rich, and continuously changing stream of visual information. With attention, we take an active role in how we experience this stream of input as meaningfully segmented objects and events, selecting a subset of that stream for enhanced processing and awareness. Although attentional selection is generally considered to be a high-level cognitive function, there appear to be important low-level, anatomical constraints on attention. I will present a series of behavioral experiments showing that our ability to select and track objects is constrained by boundaries in the visual field, such as the separation between left and right hemifields, or the quadrants of the visual field. These constraints appear to be linked to the known hemifield and quadrantic representations in lower-level regions of the visual cortex (e.g., V2-V3). Further experiments suggest that these visual field effects are a signature of location-based, but not feature-based, attentional selection. Finally, I will describe several cognitive training experiments suggesting that attentional enhancement is limited to trained locations in the visual field. Combined, these results support a model of attentional capacity in which competition within visual maps places a significant bottleneck on attentional selection. More generally, these results suggest that cognitive models must take into account the important role of visual anatomy (neural/representational architecture) to explain the limits on attention and perception.