figure 5b, but only for the first and second saccade. This plot indicates that a facilitation of return saccades did not appear during these first three fixations. 

## Influence of starting position and image type on exploration behavior 

The most important aim of the current study was to investigate the influence of starting position on scanpath statistics. Therefore we introduced a measure of the mean horizontal distance (MHD) to the starting position at time t , denoted by X$_{MHD}$ ( t ) (see Methods ). 

This measure was computed for each combination of image type and starting position (Fig. 6a). The blue horizontal line indicates the horizontal center of the image. There are three important main effects in the plots of X$_{MHD}$ ( t ). First, for the long term behavior in the balanced images and pattern images, X$_{MHD}$ ( t ) approaches the midline, while there are obvious deviations for images with left or right focus. 

Second, the transient behavior induced by the starting position lasts to about 3 s to 5 s (depending on condition). This observation is in strong contrast to our finding that saccade amplitudes are only affected for the first saccade, which translates into a transient phase of the mean first fixation duration, equivalent to 609.01 ms. This untypically long first fixation indicates that it took the participants a long time to process that the fixation cross had disappeared. 

Third, in a time of approximately 1.5 s to 2 s almost all curves cross the midline and show a local maximum of MHD. The existence of such a maximum lends support for inhibition at the starting position, i.e., the eye is actively driven to the opposite image side. This is most evident for the conditions in which observers started in the image side opposite to the focus (starting from the right in left-focus images and starting from the left in right-focus images), but the effect is also visible for balanced images. Additionally, an interaction 

