Fig. 1: Experimental design and fixation patterns in Experiments 1 and 2.

a An example picture for Face, inverted Face (shown as contour here for privacy protection) and a cartoon example of House stimuli (gray-scale pictures were used in the actual experiment; upper panel) and their corresponding fixation patterns which were used for the Fixation Pattern task in Experiment 1 (middle panel) and Experiment 2 (lower panel). The fixation patterns were collected from two subjects (indicated by blue and green, respectively) and pooled over all trials. For Experiment 2, the fixation patterns for houses shown here were normalized to have the same level of spatial dispersion as the fixation patterns for faces (see methods for details). b In the Fixation Pattern task the subjects were instructed always to fixate the fixation dot and to indicate at the end of the trial whether they had detected a target. c Visualization of the correspondence evaluation between fixation dot position and gaze position of the subject by maximizing the cross-correlation. The position (x, y coordinates, indicated by blue and green, respectively) of the fixation dot and the actual eye position (x, y coordinates, indicated by red and turquoise, respectively) of three consecutive trials collected from one subject are shown as a function of time. The x-axis indicates the time (in seconds) relative to the onset of the first trial. The correspondence was measured by calculating the cross-correlation between the time series of the fixation-dot position and the time series of the actual eye position. Note, the data here is only shown as an example to visualize the two time series.