Influences of luminance contrast and ambient lighting on visual context learning and retrieval

Contextual facilitation: Separable roles of contextual guidance and context suppression in visual search

Visual search is facilitated when targets are repeatedly encountered at a fixed position relative to an invariant distractor layout, compared to random distractor arrangements. However, standard investigations of this contextual-facilitation effect employ fixed distractor layouts that predict a constant target location, which does not always reflect real-world situations where the target location may vary relative to an invariant distractor arrangement. To explore the mechanisms involved in contextual learning, we employed a training-test procedure, introducing not only the standard full-repeated displays with fixed target-distractor locations but also distractor-repeated displays in which the distractor arrangement remained unchanged but the target locations varied. During the training phase, participants encountered three types of display: full-repeated, distractor-repeated, and random arrangements. The results revealed full-repeated displays to engender larger performance gains than distractor-repeated displays, relative to the random-display baseline. In the test phase, the gains were substantially reduced when full-repeated displays changed into distractor-repeated displays, while the transition from distractor-repeated to full-repeated displays failed to yield additional gains. We take this pattern to indicate that contextual learning can improve performance with both predictive and non-predictive (repeated) contexts, employing distinct mechanisms: contextual guidance and context suppression, respectively. We consider how these mechanisms might be implemented (neuro-)computationally.

Invariant contexts reduce response time variability in visual search in an age-specific way: A comparison of children, teenagers, and adults

Contextual cueing is a phenomenon in which repeatedly encountered arrays of items can enhance the visual search for a target item. This is widely attributed to attentional guidance driven by contextual memory acquired during visual search. Some studies suggest that children may have an immature ability to use contextual cues compared to adults, while others argue that contextual learning capacity is similar across ages. To test the development of context-guided attention, this study compared contextual cueing effects among three age groups: adults (aged 18-33 years, N = 32), teenagers (aged 15-17 years, N = 41), and younger children (aged 8-9 years, N = 43). Moreover, this study introduced a measure of response time variability that tracks fluctuations in response time throughout the experiment, in addition to the conventional analysis of response times. The results showed that all age groups demonstrated significantly faster responses in repeated than non-repeated search contexts. Notably, adults and teenagers exhibited smaller response time variability in repeated contexts than in non-repeated ones, while younger children did not. This implies that children are less efficient at consolidating contextual information into a stable memory representation, which may lead to less stable attentional guidance during visual search.

Task-Irrelevant Context Learned Under Rapid Display Presentation: Selective Attention in Associative Blocking

In the contextual cueing task, visual search is faster for targets embedded in invariant displays compared to targets found in variant displays. However, it has been repeatedly shown that participants do not learn repeated contexts when these are irrelevant to the task. One potential explanation lays in the idea of associative blocking, where salient cues (task-relevant old items) block the learning of invariant associations in the task-irrelevant subset of items. An alternative explanation is that the associative blocking rather hinders the allocation of attention to task-irrelevant subsets, but not the learning per se. The current work examined these two explanations. In two experiments, participants performed a visual search task under a rapid presentation condition (300 ms) in Experiment 1, or under a longer presentation condition (2,500 ms) in Experiment 2. In both experiments, the search items within both old and new displays were presented in two colors which defined the irrelevant and task-relevant items within each display. The participants were asked to search for the target in the relevant subset in the learning phase. In the transfer phase, the instructions were reversed and task-irrelevant items became task-relevant (and vice versa). In line with previous studies, the search of task-irrelevant subsets resulted in no cueing effect post-transfer in the longer presentation condition; however, a reliable cueing effect was generated by task-irrelevant subsets learned under the rapid presentation. These results demonstrate that under rapid display presentation, global attentional selection leads to global context learning. However, under a longer display presentation, global attention is blocked, leading to the exclusive learning of invariant relevant items in the learning session.