A neural signature of rapid category-based target selection as a function of intra-item perceptual similarity, despite inter-item dissimilarity

Abstract

Previous work on visual search has suggested that only a single attentional template can be prioritized at any given point in time. Grouping features into objects and objects into categories can facilitate search performance by maximizing the amount of information carried by an attentional template. From infancy to adulthood, earlier studies on perceptual similarity show that consistent features increase the likelihood of grouping features into objects (e.g., Quinn & Bhatt, 2009) and objects into categories (e.g., shape bias; Landau et al., 1988). Here we ask whether lower-level intra-item similarity facilitates higher-level categorization despite inter-item dissimilarity. Adults participated in four visual search tasks where targets were defined as either one item (a specific alien) or a category (any alien) with similar features (e.g., circle belly shape, circle back spikes) or dissimilar features (e.g., circle belly shape, triangle back spikes). Using behavioral and neural measures (i.e., N2pc ERP component which typically emerges 200 milliseconds post-stimulus), we found that intra-item feature similarity facilitated categorization, despite dissimilar features across category items. Our results demonstrate that feature similarity builds novel categories and activates a task-appropriate abstract categorical search template. In other words, grouping at the lower item level facilitates grouping at the higher category level, which allows us to overcome efficiency limitations in visual search.

Emergence of the benefits and costs of grouping for visual search

“…This moderate attrition rate was primarily due to a difficult experimental task and training new undergraduate research assistants to conduct the study. This attrition rate is consistent with our prior studies in which difficult tasks were employed and undergraduates were trained to test participants (e.g., Wu et al, ; Wu, Pruit et al, 2017). Participants in the assemble and disassemble conditions were paid $25 after finishing the experiment at University of Rochester, whereas participants in the no training condition were provided course credit at University of California, Riverside.…”

“…Thus, prior knowledge of a category increases search efficiency for multiple objects within that category. The cognitive benefits from grouping features and objects also have been documented in studies on categorization, chunking, associative learning, and statistical learning, which show that grouping leads to increased efficiency in attention, learning, and working memory from infancy to adulthood (e.g., Blair, Watson, & Meier, ; Brady, Konkle, & Alvarez, ; Chun & Jiang, ; Gobet et al, ; Nako, Wu, & Eimer, ; Wolfe & Horowitz, ; Woodman, Vecera, & Luck, ; Wu, Gopnik, Richardson, & Kirkham, ; Wu et al, ; Xu & Chun, ; see Kruschke, ).…”

“…In particular, there are costs and benefits to prior knowledge on visual search. In terms of the benefits, recent visual search studies using ERP measures have shown that prior knowledge of grouping features into objects and objects into categories increases search efficiency, as reflected in the N2pc ERP component (e.g., Nako, Wu, & Eimer, ; Nako, Wu, Smith, & Eimer, ; Wu et al, ; Wu, Pruitt, Runkle, Scerif, & Aslin, ). The N2pc ERP is the established marker of target selection in visual search studies, emerging 200 ms after stimulus onset in retinotopic occipitotemporal areas contralateral to the target hemifield (Eimer, ; Luck & Hillyard, ).…”

“…This “foil effect” is similar to other findings on capture by semantically related objects (De Groot, Huettig, & Olivers, ; Telling, Kumar, Meyer, & Humphreys, ), objects of expertise in particular categories (e.g., cars, McGugin, McKeeff, Tong, & Gauthier, ), and objects with similar known features (e.g., the color red for a stop sign target, even when the stop sign is in grayscale during the experiment, Olivers, Peters, Houtkamp, & Roelfsema, ). Interestingly, visual search studies have shown that novel objects and categories do not tend to elicit foil effects during a 1‐hr experimental session (e.g., novel Chinese characters, Wu, Scerif, Aslin, Smith, Nako, & Eimer, ; novel alien families, Wu et al, ).…”

“…The N2pc, in particular, is a useful marker indicating the costs and benefits of grouping on visual search. Two N2pc studies have used novel categories (e.g., Chinese characters, Wu et al, ; alien families, Wu et al, ) in which the training procedure was the search task itself (Wu et al, ) or the category was obvious enough to verbalize as a rule (same vs. different shapes, Wu et al, ). In both cases, no training procedure separate from the visual search task itself was used.…”