The decoupling of attention and eye movements during multiple fixation search

Introduction: Many studies have investigated how attention can be deployed to the visual periphery while observers maintain central eye fixation, but less is known about attentional deployment during multiple fixation search. Although a transient decoupling of attention and eye fixation supposedly mediates peripheral processing guiding subsequent saccades (e.g., Kowler et al., 1994), it is widely believed that the perceptual decision to choose a target location during search is mostly determined by visual information acquired during its fixation in which the observer attends to the foveated location (for a review, Findlay & Gilchrist, 2003). Here, we use temporally modulated noise and the classification movie technique to test this hypothesis. Methods: Three observers used natural eye movements to search for a bright Gaussian target (6.8 cd/m) among four dim distractor Gaussians (4.7 cd/m2) spaced along a circumference (6.9 deg). The intensity of the target and distractors varied every 25 ms (stdev = 1.5 cd/m2). Eye position and perceptual localization decisions were recorded. The temporal sequences of noise values at incorrectly chosen target locations were aligned with respect to saccade execution and averaged across trials. Results: For all three observers, the classification movies show that the information presented at the periphery during the initial central fixation strongly influenced the observers' decisions to choose a location as the target despite the occurrence of several subsequent saccades. Conclusion: Perceptual decisions after search are driven not only by visual information at the point of eye fixation but also by attended information in the visual periphery.