Temporal evolution of the central fixation bias 5 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 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. 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 Participants General Procedure