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Some visual relation judgments are limited to a single dimension at a time

36.324, Sunday, May 12, 2:45 - 6:45 pm, Royal Ballroom 6-8
Session: Attention: Divided, resource competition

Audrey G. Lustig¹, Steven L. Franconeri¹; ¹Department of Psychology, Northwestern University

Across the visual system, absolute values are recoded into relative or opponent values for features such as luminance, motion, and color. These types of recoding occur simultaneously for multiple dimensions, perhaps because they only require spatially local processing. Here we ask whether we can simultaneously process relations for multiple dimensions when values are located in spatially separated objects. Previous work shows that we can simultaneously compare multiple values across spatially separated objects (e.g., Santee & Egeth, 1980; whether two shirts differ in both color and stripe pattern), but no existing work tests whether this is possible for relations (e.g., whether one shirt is darker and has wider stripes than the other). We tested this idea by asking participants to detect either value or relation changes for a single dimension and determined whether changes in a second irrelevant dimension influenced performance (dimensions counterbalanced across subjects). Participants detected changes across sequential displays of pairs of circular gratings that varied in both contrast and spatial frequency. In the values task, participants judged whether the two pairs had exactly the same values, and either one or both values could change. Consistent with past work, changes in the second irrelevant dimension interfered (‘same’ responses were slower when values in the other dimension differed), suggesting that values were compared across both dimensions at once. The relation task was identical, except that all absolute values always differed, and instead participants detected changes to the relative values (e.g., is the left object still darker than the right object?). Changes in the second irrelevant dimension no longer interfered, suggesting that only a single relation was recovered at a time. In contrast to local recoding mechanisms, we suggest that when values are spatially separated, extracting their relative values requires the use of far more capacity-limited processes.

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