Interactions between attention and perceptual grouping in human visual cortex

PurposeIn daily life, people are adept at extracting task-relevant information from complex visual environment to guide attention more effectively toward the target. This process underpins the contextual cueing effect, where repeated exposure allows individuals to learn associations between contextual cues and targets, thereby enhancing visual search efficiency. However, the cue validity of context —how consistently cues predict target locations—is not always guaranteed in real life. This study focused on cue validity as a critical factor in understanding the contextual cueing effect. Within the study of contextual cueing, cue validity specifically refers to the probability that contextual cues accurately indicate the location of a target.MethodsIn Experiment 1, we manipulated three levels of cue validity (100, 75, and 50%) using a classic contextual cueing paradigm. Experiment 2 examined the potential impact of an imbalanced predictable vs unpredictable trial ratio. In Experiment 3, we explored whether the absence of the contextual cueing effect was due to unsuccessful learning or unsuccessful later expression.ResultsResults from Experiment 1 revealed that higher cue validity (100 and 75%) significantly elicited the contextual cueing effect, resulting in faster responses for repeated displays, whereas lower cue validity (50%) did not result in this effect because the repeated displays could not be effectively learned. Experiment 2 showed that the contextual cueing effect remained robust despite an imbalanced ratio of predictable to unpredictable displays. Experiment 3 further showed that low cue validity affects the early learning phase of context-target associations rather than the later expression in visual search.ConclusionOur study highlights the significant role of cue validity in implicit learning from visual cues. High cue validity enhances learning by providing highly stable context-target associations, while low cue validity does not actively facilitate attention allocation, thereby not promoting the learning process. These findings underscore the importance of cue validity in processing visual information.

The contextual cueing effect is the phenomenon observed when response time (RT) becomes faster in visual search in repeated context compared with a new one. In the present study, we explored whether the mechanisms involved in the effect are age dependent. We investigated it in younger (N = 20, 12 women, 21.2 ± 1.75 years) and older (N = 19, nine women, 67.05 ± 3.94 years) adults. We found a faster target identification in the repeated configurations with similar magnitude in the two age groups, which indicates that this contextual cueing effect remained intact even in the older participants. To shed light on the underlying mechanisms, we measured and compared the amplitude of three event-related potentials: N2pc, P3, and response-locked LRP. In the younger group, the larger contextual cueing effect (novel-minus-repeated RT difference) correlated positively with a larger difference in amplitude for repeated compared with novel configurations for both the N2pc and the P3 components, but there was no correlation with the response-locked lateralized readiness potential (rLRP) amplitude difference. However, in the older group, only the rLRP amplitude difference between novel and repeated configurations showed an enhancement with larger contextual cueing. These results suggest that different mechanisms are responsible for the contextual effect in the two age groups. It has both an early and an intermediate locus in younger adults: effective attentional allocation and successful stimulus categorization, or decision-making confidence are involved; while in older adults, a late locus was identified: a more efficient response organization led to a faster reaction.

Previous research on the mechanisms of contextual cueing effect has been inconsistent, with some researchers showing that the contextual benefit was derived from the attentional guidance whereas others argued that the former theory was not the source of contextual cueing effect. We brought the "stare-in-the-crowd" effect that used pictures of gaze with different orientations as stimuli into a traditional contextual cueing effect paradigm to investigate whether attentional guidance plays a part in this effect. We embedded the letters used in a traditional contextual cueing effect paradigm into the gaze pictures with direct and averted orientation. In Experiment 1, we found that there was a weak interaction between the contextual cueing effect and the "stare-in-the-crowd" effect. In Experiments 2 and 3, we found that the contextual cueing effect was influenced differently when the direct gaze was combined with the target or distractors. These results suggested that attentional guidance played an important role in the generation of a contextual cueing effect and the direct gaze had a special impact on visual search. To summarize the three findings, the direct gaze on target location facilitates the contextual cueing effect, and such an effect is even greater when we compared condition with the direct gaze on target location with condition with the direct gaze on distractor location (Experiments 2 and 3). Such an effect of gaze on a contextual cueing effect is manifested even when the effect of gaze ("stare-in-the-crowd" effect) was absent in the New configurations (search trials without learning).

SummaryThe neural responses that distinguish novel from familiar items in recognition memory tasks are remarkably fast in both humans and nonhuman primates. In humans, the earliest onsets of neural novelty effects emerge at about ∼150–200 ms after stimulus onset [1–5]. However, in recognition memory studies with nonhuman primates, novelty effects can arise at as early as 70–80 ms [6, 7]. Here, we address the possibility that this large species difference in onset latencies is caused experimentally by the necessity of using reward reinforcement to motivate the detection of novel or familiar items in nonhuman primates but not in humans. Via magnetoencephalography in humans, we show in two experiments that the onset of neural novelty signals is accelerated from ∼200 ms to ∼85 ms if correct recognition memory for either novel or familiar items is rewarded. Importantly, this acceleration is independent of whether the detection of the novel or the familiar scenes is rewarded. Furthermore, this early novelty effect contributed to memory retrieval because neural reward responses, which were contingent upon novelty detection, followed ∼100 ms later. Thus, under the contextual influence of reward motivation, behaviorally relevant novelty signals emerge much faster than previously held possible in humans.

Reward-predicting distractor orientations support contextual cueing: Persistent effects in homogeneous distractor contexts

Three experiments explored how the repetition of a visual search display guides search during contextual cuing under conditions in which the search process is interrupted by an instructional (endogenous) cue for attention. In Experiment 1, participants readily learned about repeated configurations of visual search, before being presented with an endogenous cue for attention towards the target on every trial. Participants used this cue to improve search times, but the repeated contexts continued to guide attention. Experiment 2 demonstrated that the presence of the endogenous cue did not impede the acquisition of contextual cuing. Experiment 3 confirmed the hypothesis that the contextual cuing effect relies largely on localized distractor contexts, following the guidance of attention. Together, the experiments point towards an interplay between two drivers of attention: after the initial guidance of attention, memory representations of the context continue to guide attention towards the target. This suggests that the early part of visual search is inconsequential for the development and maintenance of the contextual cuing effect, and that memory representations are flexibly deployed when the search procedure is dramatically interrupted.

Perception Matches Selectivity in the Human Anterior Color Center

Repetition of context can facilitate search for targets in distractor-filled displays. This contextual cueing goes along with enhanced event-related brain potentials in visual cortex, as previously demonstrated with depth electrodes in the human brain. However, modulation of the BOLD-response in striate and peristriate cortices has, to our knowledge, not yet been reported as a consequence of contextual cueing. In an event-related fMRI experiment with 16 participants, we observed a selective reduction of the BOLD onset latency for repeated distractor configurations in these areas. In addition, the same onset latency reduction was observed in posterior inferior frontal cortex, a potential source area for feedback signals to early visual areas. These latency changes occured in the absence of differential BOLD time-to-peak and BOLD-amplitude for repeated versus new displays. The posterior part of left inferior frontal cortex has previously been linked to repetition priming, however in the form of repetition suppression. These studies differ from ours in many respects, such as awareness of stimulus repetition and semantic processing. The overlap of activation found in previous priming studies and in the current experiment does not allow the reverse inference that the same mechanisms are involved in contextual cueing and priming. However, future experiments may investigate the mechanisms that lead to repetition suppression versus BOLD-onset reduction in left posterior inferior frontal cortex and visual cortex, thereby elucidating the commonalities or differences between repetition priming and contextual cueing.

Neural responses to visual stimuli are modulated by spatial and temporal context. For example, in primary visual cortex (V1), responses to an oriented target stimulus will be suppressed when embedded within an oriented surround stimulus. This suppression is orientation-specific, with the largest suppression observed when stimuli in the neuron's classical receptive field and surround are of similar orientation. In human psychological experiments, the tilt illusion and tilt aftereffect demonstrate an effect of context on perceived orientation of a target stimulus. Similar to the neurophysiological data, the strength of these effects is modulated by the orientation difference between the target stimulus and context. It has been hypothesized that the neural mechanism underlying both the tilt illusion and tilt aftereffect involves orientation-tuned inhibition in V1. However, to date there is no direct evidence linking human perception of these illusions with measurements of inhibition from human visual cortex. Here, we measured context-induced suppression of neural responses in human visual cortex using functional magnetic resonance imaging (fMRI). In the same participants, we also measured magnitudes of their tilt illusion and tilt aftereffect. Our data revealed a significant relationship between the magnitude of neural suppression in V1 and size of the tilt illusion and tilt aftereffect. That is, participants who showed stronger blood oxygenation level dependent (BOLD) suppression in V1 also perceived stronger shifts in illusory tilt. This agreement between perception and neural responses in human V1 suggests a shared inhibitory mechanism that mediates both spatial and temporal effects of context in human perception.

We usually perceive things in our surroundings as unchanged despite viewpoint changes caused by self-motion. The visual system therefore must have a function to process objects independently of viewpoint. In this study, we examined whether viewpoint-independent spatial layout can be obtained implicitly. For this purpose, we used a contextual cueing effect, a learning effect of spatial layout in visual search displays known to be an implicit effect. We investigated the transfer of the contextual cueing effect to images from a different viewpoint by using visual search displays of 3D objects. For images from a different viewpoint, the contextual cueing effect was maintained with self-motion but disappeared when the display changed without self-motion. This indicates that there is an implicit learning effect in environment-centered coordinates and suggests that the spatial representation of object layouts can be obtained and updated implicitly. We also showed that binocular disparity plays an important role in the layout representations.

Object contextual cueing is an implicit learning paradigm in which the repeated co-occurrence of certain objects facilitates target detection, even when their spatial arrangement varies. In three experiments - where participants performed a visual search task in which the target was accompanied by either consistently repeated or randomly varying distractors - we attempted to replicate Chun and Jiang's (1999) study. In Experiment 1 (using faces; N=25, M=20.8years) and Experiment 2 (using abstract figures; N=25, M=20.8years), although participants became faster and more accurate over time, no significant difference emerged between repeated and new configurations. Thus, using the same experimental design, we were unable to replicate the object contextual cueing effect. In Experiment 3, we tested whether search strategy influences the effect by instructing one group to adopt an active search strategy and another to use a passive one (N=20 per group, M=21.8 and 21.7years, respectively; active: actively search for the target, passive: let the unique item pop out). However, the manipulation had no effect: the contextual cueing effect did not emerge in either group. Importantly, within each group we observed substantial individual differences - some participants showed a facilitation effect, others no effect, and some even showed a reverse pattern. These findings suggest that object contextual cueing may not be a robust or universal phenomenon and may instead depend on individual cognitive styles or learning tendencies.

Repeatedly encountering a visual search display with the target located at a fixed position relative to the distractors facilitates target detection, relative to novel displays – which is attributed to search guidance by (acquired) long‐term memory (LTM) of the distractor ‘context’ of the target. Previous research has shown that this ‘contextual cueing’ effect is severely impeded during learning when participants have to perform a demanding spatial working memory (WM) task concurrently with the search task, though it does become manifest when the WM task is removed. This has led to the proposal that search guidance by LT context memories critically depends on spatial WM to become ‘expressed’ in behaviour. On this background, this study, of two experiments, asked: (1) Would contextual cueing eventually emerge under dual‐task learning conditions if the practice on the task(s) is extended beyond the short training implemented in previous studies? and given sufficient practice, (2) Would performing the search under dual‐task conditions actually lead to an increased cueing effect compared to performing the visual search task alone? The answer is affirmative to both questions. In particular, Experiment 1 showed that a robust contextual cueing effect emerges within 360–720 dual‐task trials as compared to some 240 single‐task trials. Further, Experiment 2 showed that when dual‐ and single‐task conditions are performed in alternating trials blocks, the cueing effect for the very same set of repeated displays is significantly larger in dual‐task blocks than in single‐task blocks. This pattern of effects suggests that dual‐task practice eventually leads to direct, or ‘automatic’, guidance of visual search by learnt spatial LTM representations, bypassing WM processes. These processes are normally engaged in single‐task performance might actually interfere with direct LTM‐based search guidance.

This study examines the effects of contextual cueing on the remote memory of alcoholic Korsakoff patients and normal subjects. Naming of personalities who became famous in each of the five decades beginning 1935 was tested under two conditions: "no-context", in which minimal extraneous cues to identification were provided, and "context", where clear extraneous cues were available. Normal subjects performed better than Korsakoff patients, showed no evidence of a temporal gradient, and exhibited a contextual cueing advantage across all decades. In contrast, Korsakoff patients demonstrated a marked temporal gradient, and the contextual cueing advantage declined systematically as more recent decades were sampled. Further analyses demonstrated that the differential pattern of deficits shown by Korsakoffs and controls was not attributable to absolute differences in performance level. Theoretical implications of these data for explanations of Korsakoff retrograde amnesia are discussed.

The present study examined the extent to which learning mechanisms are deployed on semantic-categorical regularities during a visual searching within real-world scenes. The contextual cueing paradigm was used with photographs of indoor scenes in which the semantic category did or did not predict the target position on the screen. No evidence of a facilitation effect was observed in the predictive condition compared to the nonpredictive condition when participants were merely instructed to search for a target T or L (Experiment 1). However, a rapid contextual cueing effect occurred when each display containing the search target was preceded by a preview of the scene on which participants had to make a decision regarding the scene's category (Experiment 2). A follow-up explicit memory task indicated that this benefit resulted from implicit learning. Similar implicit contextual cueing effects were also obtained when the scene to categorize was different from the subsequent search scene (Experiment 3) and when a mere preview of the search scene preceded the visual searching (Experiment 4). These results suggested that if enhancing the processing of the scene was required with the present material, such implicit semantic learning can nevertheless take place when the category is task irrelevant.

Cortical Inhibition in Alcohol Dependence