Figure 1.

a, Apparatus. Somatosensory stimuli were air puffs to the right side of the face, and visual stimuli were presented with fiberoptics attached to the air puff nozzles. These lights were at 45° eccentricity in the right visual field. In each block, visual, somatosensory, or combined bimodal stimuli were presented in one field, either upper or lower. b, Stimulus types in each block. Nontarget standard stimuli, 80% of the stimuli per block, are of 300 ms stimulus duration, while target stimuli (20%) are interrupted by an off gap, 40 ms for light and 120 ms for puff, a double light and double puff. The interval between stimuli was 700–900 ms. In each bimodal block, visual and somatosensory stimuli were presented simultaneously in the same field, either above or below the horizontal meridian, with attention and target detection in one sensory modality. For example, in a Bimodal Visual Attention block the target was a double light, regardless of whether it was paired with a single or a double puff. The illusory stimulus and the nonillusory control stimulus are labeled in magenta and cyan, respectively.