Prior knowledge of category size impacts visual search

Interaction of prior category knowledge and novel statistical patterns during visual search for real-world objects

Two aspects of real-world visual search are typically studied in parallel: category knowledge (e.g., searching for food) and visual patterns (e.g., predicting an upcoming street sign from prior street signs). Previous visual search studies have shown that prior category knowledge hinders search when targets and distractors are from the same category. Other studies have shown that task-irrelevant patterns of non-target objects can enhance search when targets appear in locations that previously contained these irrelevant patterns. Combining EEG (N2pc ERP component, a neural marker of target selection) and behavioral measures, the present study investigated how search efficiency is simultaneously affected by prior knowledge of real-world objects (food and toys) and irrelevant visual patterns (sequences of runic symbols) within the same paradigm. We did not observe behavioral differences between locating items in patterned versus random locations. However, the N2pc components emerged sooner when search items appeared in the patterned location, compared to the random location, with a stronger effect when search items were targets, as opposed to non-targets categorically related to the target. A multivariate pattern analysis revealed that neural responses during search trials in the same time window reflected where the visual patterns appeared. Our finding contributes to our understanding of how knowledge acquired prior to the search task (e.g., category knowledge) interacts with new content within the search task.

Neural target selection as a marker of real-world familiarity during search for perceptually distinct objects

Prior studies have shown that behavioral performance is better when detecting specific familiar items based on real-world experience (e.g., an own-age face, a specific bird for bird experts), compared to less familiar items (e.g., an other-age face). These biases emerge from exposure to and interactions with initially less familiar items, which allow for better discrimination and search (e.g., finding an other-age face in a crowd). However, many broad categories in the natural environment (e.g., vintage objects, exotic fruit) contain perceptually distinct items that people can accurately search for individually, even if the objects are not as familiar. How might real-world familiarity impact search in these cases? Recent studies suggest that the N2pc event-related potential (ERP, neural marker of target selection) may be more sensitive than behavioral performance in reflecting prior knowledge, and perhaps familiarity, during visual search. In two experiments, the present study investigated the behavioral effects (Experiment 1) and N2pc effects (Experiment 2) of searching for distinct familiar (modern) versus less familiar (vintage) objects in younger adults. Experiment 1 also included a sample of older adults, who were familiar with both types of objects. Overall, the behavioral results did not reveal robust differences in searching for modern versus vintage objects. However, the N2pc in younger adults was present when searching for modern objects, but not for vintage objects. The N2pc results suggest that this neural marker may be more sensitive than behavioral measures in reflecting familiarity from real-world experiences with object categories.

Category-based attentional capture can be influenced by color- and shape-dimensions independently in the conjunction search task

Attention can be involuntarily attracted by a distractor that matches the current attentional control settings (ACSs). However, it remains unclear whether two category-specific ACSs can operate independently. By defining a target as a combination of two prototype-based categories, the present event-related potential (ERP) study investigated how color-category and shape-category ACSs operate within a search task paradigm and the effects of temporal task demands on these ACSs. The matching level between target and distractor was manipulated to separate the effects of each ACS. The relative position between target and distractor was employed to isolate the attentional processing of the distractor from the target. Furthermore, two display durations were used to manipulate the temporal task demands, including a short fixed window (800 ms) and a dynamic window extended until the user responded. Our results support a two-stage selection scenario. In early stage, the color- and shape-ACS independently guided attention to task-relevant property (N2pc components) and suppressed attention toward task-irrelevant properties (P_D components). In late stage, these two independent ACSs were integrated into a holistic ACS to interfere with the consolidation (contralateral delay activity components) and behavioral performance (accuracy and RTs) of target identification. Moreover, an early N1/P1 component might reflect a preattentive enhancement of relevant information or a preattentive suppression of irrelevant objects. These two category-specific ACSs weights differently in varied temporal task demands. These findings support the idea that independent early processing is followed by integrated late processing, which can be applied to category-based attentional capture with different temporal task demands.

Rapid target selection of object categories based on verbs: Implications for language-categorization interactions

Although much is known about how nouns facilitate object categorization, very little is known about how verbs (e.g., posture verbs such as stand or lie) facilitate object categorization. Native Dutch speakers are a unique population to investigate this issue with because the configurational categories distinguished by staan (to stand) and liggen (to lie) are inherent in everyday Dutch language. Using an ERP component (N2pc), four experiments demonstrate that selection of posture verb categories is rapid (between 220-320 ms). The effect was attenuated, though present, when removing the perceptual distinction between categories. A similar attenuated effect was obtained in native English speakers, where the category distinction is less familiar, and when category labels were implicit for native Dutch speakers. Our results are among the first to demonstrate that category search based on verbs can be rapid, although extensive linguistic experience and explicit labels may not be necessary to facilitate categorization in this case.

Learning What to Attend to: From the Lab to the Classroom

Research in adult cognitive neuroscience addresses the bidirectional relationship between attentional selection and prior knowledge gained from learning and experience. This research area is ready for integration with developmental cognitive neuroscience, in particular with educational neuroscience. We review one aspect of this research area, learning what to attend to, to propose a path of integration from highly controlled experiments based on developmental and adult cognitive theories to inform cognitive interventions for learners across the lifespan. In particular, we review the research program that we have developed over the last few years, describe the constraints that we have faced in integrating adult and developmental paradigms, and delineate suggested next steps to inform educational neuroscience in more applied ways. Our proposed path of integration transitions from basic to applied research, while also suggesting that input from education could inform new basic research avenues that may more likely yield outcomes meaningful for education.

Emergence of the benefits and costs of grouping for visual search

The present study investigated how grouping related items leads to the emergence of benefits (facilitation when related items are search targets) and costs (interference when related items are distractors) in visual search. Participants integrated different views (related items) of a novel Lego object via (a) assembling the object, (b) disassembling the object, or (c) sitting quietly without explicit instructions. An omnibus ANOVA revealed that neural responses (N2pc ERP) for attentional selection increased between pretest to posttest regardless of the training condition when a specific target view appeared (benefit) and when a nontarget view from the same object as the target view appeared (cost). Bonferroni-corrected planned comparisons revealed that assembling the object (but not disassembling the object or no training) had a significant impact from pretest to posttest, although the ANOVA did not reveal any interaction effects, suggesting that the effects might not differ across training conditions. This study is one of the first to demonstrate the emergence of the costs and benefits of grouping novel targets on visual search efficiency.