only after disappearance of a fixation marker. As a measure of the central fixation bias we computed the distance to center (DTC) of the eyes over time. In all experiments the disappearance of a fixation marker 125 ms after image onset led to an early reduction of the DTC in comparison to trials where the fixation marker disappeared simultaneously to the image onset (original scene viewing paradigm). The reduction of the CFB was particularly pronounced in experiments with pre-trial fixation time as a between subject factor (Exp. 1 & 2). But the reduction of the CFB was even visible when participants started observation at the center of an image (Exp. 4). In a within-subject design with very short pre-trial fixation times (Exp. 3) the manipulation did not significantly reduce the early CFB. A systematic investigation of the disappearance delays of the fixation marker demonstrated that a delay between 125 ms and 250 ms is sufficient for a strong and reliable reduction of the CFB. Shorter delays produced stronger CFBs, whereas longer delays only modestly reduced the CFB but severely changed the time course of the scene viewing paradigm. With long delays the preview time before exploration of an image increased substantially in contrast to the standard scene viewing paradigm. The distance to center of the second fixation was well predicted by the latency of the initial saccade (time from image onset) across experiments. Short saccade latencies led to a strong bias towards the center whereas longer saccade latencies were less systematically directed towards the center. Hence, the latency of the initial response seemed to primarily account for the observed differences of the CFB. 

Our findings are in agreement with the note communicated earlier that a sudden image onset during scene viewing represents an artificial laboratory situation and may cause unnatural saccadic behavior (’t Hart et al., 2009; Tatler et al., 2011). However, the sudden image onset seems to primarily affect the tendency of the first saccade to move the eyes towards the center of an image. Due to the dependence of fixation locations (Engbert 

