Cognitive load eliminates the global perceptual bias for unlimited exposure durations

In the present study, we used Navon-type Cognitive Psychology 9: 353-383 (1977) hierarchical patterns to demonstrate that cognitive load eliminates a global perceptual bias and enhances the representation of local elements at unlimited exposure durations. We added a cognitive-load manipulation to Kimchi and Palmer's Journal of Experimental Psychology: Human Perception and Performance 8:521-535 (1982) similarity-matching experiment with hierarchical patterns, and presented the stimuli for either unlimited or limited exposure durations. When exposures were unlimited, we demonstrated that observers exhibited a global bias under low, but not under high, cognitive load (Exp. 2). When exposures were limited, however, cognitive load exerted no effect, and the global bias remained (Exp. 1). We suggest that (1) these findings are best reconciled by proposing two stages in the representation of global structure, namely construction and maintenance; (2) the construction and maintenance stages are isolated, respectively, by limited-duration and unlimited-duration paradigms; and (3) cognitive processes play an integral role only in the maintenance stage. Given that real-world vision is not driven by a series of brief stimulus exposures, and is therefore likely to reflect maintenance processes, we argue that unlimited-exposure paradigms are more suitable for addressing real-world perceptual biases. When unlimited-exposure paradigms are used, cognitive load eliminates the commonly reported global bias.