and 40 pixels to the left/right of the image. In Experiments 1, 2 and 4 the images covered 31.1 ◦ of visual angle in the horizontal and 23.3 ◦ in the vertical dimension. In Experiment 3 images covered a larger proportion of the visual field with 36.25 ◦ of visual angle in the horizontal and 27.20 ◦ in the vertical dimension due to a reduced viewing distance. 

## Participants 

Participants were students of the University of Potsdam and of nearby high schools. Num- ber of participants for each experiment is indicated below. They received credit points or a monetary compensation of 8 Euro for their participation in any of the four experiments. The average duration of one experimental session was 40-45 minutes. All participants had normal or corrected-to-normal vision. The work was carried out in accordance with the Declaration of Helsinki. Informed consent was obtained for experimentation by all participants. 

## General Procedure 

Participants were instructed to position their heads on a chin rest in front of a computer screen at a viewing distance of 70 cm (60 cm in Exp. 3). Eye movements were recorded binocularly (monocularly in Exp. 3) using an Eyelink 1000 video-based-eyetracker (SR- Research, Osgoode/ON, Canada) with a sampling rate of 500 Hz (1000 Hz in Exp. 3 and downsampled to 500 Hz for our analysis). Trials began with a black fixation cross presented on gray background. After successful fixation, an image was presented. After onset of the image, the fixation cross remained visible on top of the image for a variable duration. We refer to this duration as the pre-trial fixation time. Participants were instructed to keep their eyes on the fixation cross until it disappeared. If participants moved their eyes before the pre-trial fixation time elapsed, a mask of Gaussian white noise 

