Abstract
Ample evidence indicates that different neural mechanisms support the efficiency of processing global and local levels of hierarchical stimuli (Navon patterns), although the nature of these mechanisms is debated. Some studies have associated global versus local perception with the use of relatively low versus relatively high spatial frequencies, respectively (e.g., Ivry & Robertson, 1998). Others have implicated differences in saliency of the two levels as the relevant variable (e.g., Mevorach et al., 2006). However, both camps agree that hierarchical perception is at least partially flexible, and perceptual strategies can be applied to the low-level visual characteristics of the display depending on the demand characteristics of the task. We explored the nature of this relationship and asked if imposing a global or local bias would induce a subsequent bias to process low or high spatial frequencies, respectively. Participants viewed pairs of hierarchical Navon displays and were asked to make same/different judgments on the global and local levels in separate blocks. Following each hierarchical display, compound spatial frequency gratings appeared, and participants made orientation judgments on either the low or high spatial frequencies. The association between global versus local perception and the processing of low versus high spatial frequencies was corroborated. Participants were faster at reporting the orientation of low than high spatial frequency gratings during the global attention block, and they were faster at reporting the orientation of the high than low spatial frequency gratings during the local attention block.