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Elizabeth Walter, Paul Dassonville; In search of the hidden: contextual processing in parietal cortex. Journal of Vision 2007;7(9):1061. doi: 10.1167/7.9.1061.
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© ARVO (1962-2015); The Authors (2016-present)
In the Hidden Figures Task (HFT), observers must search for a simple shape hidden inside the context of a more complex figure. Surprisingly, performance in the HFT is known to be negatively correlated with susceptibility to illusions of spatial orientation in the Rod-and-Frame Task (RFT; Witkin & Asch 1948) and the Roelofs effect (Dassonville, Walter & Lunger, VSS 2006); that is, an observer who struggles with the HFT will tend to have high illusion susceptibilities. This relationship suggests that similar mechanisms are responsible for processing the contextual cues provided in the respective stimuli of these very different tasks. Using fMRI, we have previously demonstrated that regions in intraparietal sulcus (IPS) and superior parietal cortex are involved in the contextual processing associated with the Roelofs effect (Walter & Dassonville, VSS 2006). In our current study (using the same participants), we sought to determine whether these same regions are also involved in contextual processing in the HFT. In the current event-related design, participants were asked to either perform a variant of the HFT, or to match a simple shape to a figure that “popped out” of a complex line drawing. We found a number of areas in superior parietal cortex and IPS that were selectively involved in this hidden figures search task (but not the “popout” matching task). Importantly, some of these areas overlapped with those found to be associated with contextual processing in the Roelofs task. Control studies indicate that the activations in these areas of overlap are not simply caused by differences in the patterns of eye movements across the various tasks. We propose that these parietal areas are selectively involved in processing visuospatial contextual information in these tasks.
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