7 Influence of initial fixation position anism and dynamical model (SceneWalk) which uses inhibitory tagging as a mechanism for saccade planning (Engbert et al., 2015). Stimuli . A set of 64 color photographs was presented to human observers. Pictures were presented on a 20 inch CRT monitor (Mitsubishi Diamond Pro 2070; frame rate 120 Hz, resolution 1280 × 1024 pixels; Mitsubishi Electric Corporation, Tokyo, Japan). Images showed either natural object-based scenes (48) or abstract natural patterns (16). Object- based scenes were further devided into three categories as balanced, left focus, or right focus, yielding a total of 4 categories (Fig. 1). The Pattern images were chosen to obtain a more homogenous fixation distribution because of the lack of objects present. Systematic oculomotor biases were expected to be stronger in these images. For the categorization we used an objective test by computing visual saliency by the graph based visual saliency model (Harel, Koch, & Perona, 2006) and the Judd saliency model (Judd et al., 2009) without distance to center weighting and face or object detection. As posthoc measure, the density map of the observers’ fixations for each of the 48 natural scenes was evaluated so that an empirical measure of left and right bias of the images was included. Figure 2 shows an example of an image with right focus compared to the output of the two saliency models and the kernel density estimate of the fixation density (excluding the initial fixation) from all observers. To obtain a quantitative measure for the presence of a left, or right focus, we computed the horizontal position of a vertical line, so that there was equal saliency/intensity on each side of the line. If the horizontal position of this line differed by more than 5 percent from the center (for the average Experiment Method