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Monica Rosen, Mark Mills, Michael Dodd; Task-Defined Requirements of Attention and Global-Local Processing. Journal of Vision 2016;16(12):693. doi: 10.1167/16.12.693.
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© 2017 Association for Research in Vision and Ophthalmology.
Global precedence refers to the notion that visual information at the global versus local-level is prioritized. This stems from studies showing that the global is identified faster and is more difficult to ignore than the local. Little is known regarding the prevalence of these effects beyond simple classification tasks. The present study explored the relationship between effects of attention (via manipulation of task relevancy) and global/local processing in the context of a higher-level problem solving task. Numerical Navon stimuli were presented as a math equation (e.g., "2 + 3", in which the global 2 and 3 consisted of smaller, homogeneous local numbers) for a variable duration. In one experiment, participants judged whether the number defining the local-level was the true/false answer to the global equation (local is task-relevant). In a second experiment, participants judged whether a single-level number presented after the compound equation was the true/false answer to the global equation (local is task-irrelevant). Response times (RTs) and error rates were considerably higher when the local-level was task-relevant versus task-irrelevant, indicating that task-driven processing of local information is effortful. When the local-level was task-relevant to solving the global equation, RTs increased and errors decreased with exposure to the compound equation, suggesting that participants tried to make greater use of local information the longer it was presented (reflected in longer RTs), which they were successful at (reflected in reduced error). When the local-level was task-irrelevant, RTs and errors decreased with exposure duration. Importantly, this performance benefit leveled off at longer exposures for RT but not errors, suggesting that local information delayed responses as it became more available with exposure. As the local-level was task-irrelevant, this suggests that processing of local information is obligatory with increasing exposure. Together, these findings indicate that processing of local information differs for task-relevant and task-irrelevant information.
Meeting abstract presented at VSS 2016
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