Two visual systems and their eye movements. CogSci 2005

The existence of two distinct visual pathways in the primate brain is a persistent theme for evolutionary, neurophysio-logical, motor control and neuropsychological research. As one of the most widely cited results in cognitive neuroscience, this distinction has survived decades of critical analysis under different guises (e.g. ambient vs. focal or visuomotor vs. cognitive). However, the interplay between these two processing streams in the solution of everyday tasks remains to be an unresolved issue. In particular, how do they guide eye movements, their most immediate output? Results from our recent study on hazard perception in a simulated driving environment demonstrated that specific combinations of eye movement parameters are indicative to an involvement of either of the two systems. In a further experiment, we tried to validate these parameters by testing assumptions about memory representations related to these two modes. After a short presentation of various real world scenes, subjects had to recognize cut-outs from them, which were selected according to their fixation parameters. Random cut-outs from not seen pictures (catch trials) were also presented. The results confirmed our hypothesis: cut-outs corresponding to presumably focal mode of processing were better recognized than cut-outs similarly fixated in the course of ambient exploration