The data for the Potsdam Spatial Frequency Search can be found in an OSF repository under
In this OSF repository you will find fixation data, images, and a corresponding readme-file.
Please refer to the following article when using the data or for more information:
Rothkegel, L. O. M., Schütt, H. H., Trukenbrod, H. A., Wichmann, F. A., & Engbert, R. (2018). Searchers adjust their eye movement dynamics to the target characteristics in natural scenes. arXiv preprint arXiv:1802.04069.
The data in the OSF repository come from a large Search expeimrnet of 10 participants who each searches artificial targets on natural images in 1200 trials.
As natural image backgrounds we chose 25 images taken by the authors and an additional member of the Potsdam lab in the area surrounding Potsdam. The images contained neither faces nor text.
As targets we designed 6 different low-level targets with different orientation and spatial frequency content (See paper for more information). Participants were instructed to search for one of 6 targets for the upcoming block of 25 images. To do so, the target was presented on a 26th demonstration image, marked by a red square. Each session consisted of 6 blocks of 25 images for each of the 6 different targets. The 25 images within a block were always the same presented in a new random order.
Trials began with a black fixation cross presented on grey background at a random position within the image borders. After successful fixation, the image was presented with the fixation cross still present for 125 ms. This was done to assure a prolonged first fixation to reduce the central fixation tendency of the initial saccadic response. After removal of the fixation cross, participants were allowed to search the image for the previously defined target for 10 s. Participants were instructed to press the space bar to stop the trial once a target was found. In ∼ 80% of trials the target was present.
At the end of each session participants could earn a bonus of up to 5€ additional to a fixed 10€ reimbursement, depending on the number of points collected divided by number of possible points. If participants correctly identified a target, they earned 1 point. If participants pressed the bar although no target was present, one point was subtracted.
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