abstract Erik Van der Burg

Erik Van der Burg (University of Sydney, Australia)

Evolving the stimulus to fit the brain: A genetic algorithm reveals the brain's feature priorities in visual search.

Finding a target in clutter is a common task studied for 30 years using the visual search paradigm. A reliance on factorial experimental designs, however, has limited visual scene complexity to impoverished displays. Here we examine search in complex displays using a genetic algorithm (GA). Participants searched a series of complex displays and those supporting fastest search were selected to reproduce ('survival of the fittest'). Their display properties ('genes') were crossed and combined to create a new generation of 'evolved' displays. Displays evolved quickly over generations towards a stable, efficiently searched array. Contrary to current models, evolution was serial, not parallel: colour evolved first, followed by orientation. The evolved displays also contained spatial patterns suggesting a coarse-to-fine search strategy not predicted by current models. The GA, therefore, not only simplifies evaluation of complex search spaces, it adapts the display to the brain and reveals its own search strategies.