The human pulvinar and attentional processing of visual distractors.

The processing of a target is degraded when noise is present in proximity, and performance increases as the target-noise distance increases. We tested a group of healthy volunteers and a group of patients, who suffered strokes in the posterior thalamus, in a task where the target-noise distance was manipulated. Whilst controls exhibited the expected pattern of results, thalamic patients exhibited little signs of noise interference. Interference occurred when the target-noise distance was 0 degrees (the target and noise were superimposed), but it was absent for distances equal to and bigger than 1 degree. The results suggest that the coarse grain of visual attention reported previously might be due to some aspects of attention processing underlain by the pulvinar and acting to grab the visual context or background of a target.