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Simon Thorpe, Magaly Alonzo, Jacob Martin; Can eye movements anticipate the laterality of an unpredictable stimulus? . Journal of Vision 2014;14(10):1204. doi: 10.1167/14.10.1204.
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It was recently claimed that humans can perform above chance at guessing where on a screen an image will appear, even when the location is determined by a hardware random number generator (RNG) after the subject has made their response (Bem, 2011, J Pers Soc Psychol, 100, 407). If true, such results would have serious implications for out own work on ultra-rapid visual processing. Studies using a saccadic choice task have shown that eye-movements towards face targets can be initiated just 100 ms after stimulus onset (Crouzet et al, 2010, J Vis) and face localization can be determined from around 50 ms on the basis of ERP recordings (Martin et al, VSS, 2014). Here, we specifically investigated whether fast eye movements might involve anomalous anticipatory responses of the type reported by Bem. After a variable delay, a central fixation cross was replaced by two crosses located on the left and right, and subjects had to saccade to one of them. Once the saccade was underway, a hardware RNG selected left or right at random. If the saccade direction matched the direction selected by the RNG, a well-known and surprising image was presented beyond the location of the target cross, coupled with a lateralized matching audio stimulus (e.g. "Bugs Bunny" coupled with "What's up Doc?"). If the saccade direction differed from the one selected by the computer, no image or sound was presented. Clearly, subjects should not normally be able to perform above chance on such a task and reliable performance over 50% would imply some sort of anomalous anticipation of unpredictable events. Initial results suggest that at least some subjects may be able to perform at above chance, but conclusive results will require extensive additional testing with large numbers of subjects.
Meeting abstract presented at VSS 2014
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