Attentional guidance of the eyes by contextual information and abrupt onsets

Age-related contextual cueing features are more evident in reaction variability than in reaction time

Visual-spatial contextual cueing learning underpins the daily lives of older adults, enabling them to navigate their surroundings, perform daily activities, and maintain cognitive function. While the contextual cueing effect has received increasing attention from researchers, the relationship between this cognitive ability and healthy ageing remains controversial. To investigate whether visual-spatial contextual cueing learning declines with age, we examined the contextual learning patterns of older (60-71 years old) and younger adults (18-26 years old) using a contextual-guided visual search paradigm and response variability measurements. We observed significant contextual learning effects in both age groups, impacting response speed and variability, with these effects persisting for at least 24 days. However, older adults required more repetitions and memorised fewer repeated stimuli during initial learning. Interestingly, their long-term memory maintenance appeared stronger, as their contextual facilitation persisted in both response speed and variability, while younger adults only persisted in response speed but not variability. Overall, our results suggest an age-related complex and diverse contextual cueing pattern, with older adults showing weaker learning but stronger long-term memory maintenance compared with younger adults.

Contextual cueing during lethal force training: How target design and repetition can alter threat assessments

Lethal force training requires individuals to make threat assessments, which involves holistic scenario processing to identify potential threats. Photorealistic targets can make threat/non-threat judgments substantially more genuine and challenging compared to simple cardboard or silhouette targets. Unfortunately, repeated target use also brings unintended consequences that could invalidate threat assessment processes conducted during training. Contextually rich or unique targets could be implicitly memorable in a way that allows observers to recall weapon locations rather than forcing observers to conduct a naturalistic assessment. Experiment 1 demonstrated robust contextual cueing effects in a well-established shoot/don't-shoot stimulus set, and Experiment 2 extended this finding from complex scene stimuli to simple actor-only stimuli. Experiment 3 demonstrated that these effects also occurred among trained professionals using rifles rather than computer-based tasks. Taken together, these findings demonstrate the potential for uncontrolled target repetition to alter the fundamental processes of threat assessment during lethal force training.

Eye movements reflect active statistical learning

What is the link between eye movements and sensory learning? Although some theories have argued for an automatic interaction between what we know and where we look that continuously modulates human information gathering behavior during both implicit and explicit learning, there exists limited experimental evidence supporting such an ongoing interplay. To address this issue, we used a visual statistical learning paradigm combined with a gaze-contingent stimulus presentation and manipulated the explicitness of the task to explore how learning and eye movements interact. During both implicit exploration and explicit visual learning of unknown composite visual scenes, spatial eye movement patterns systematically and gradually changed in accordance with the underlying statistical structure of the scenes. Moreover, the degree of change was directly correlated with the amount and type of knowledge the observers acquired. This suggests that eye movements are potential indicators of active learning, a process where long-term knowledge, current visual stimuli and an inherent tendency to reduce uncertainty about the visual environment jointly determine where we look.

Trichotomy revisited: A monolithic theory of attentional control

The control of attention was long held to reflect the influence of two competing mechanisms of assigning priority, one goal-directed and the other stimulus-driven. Learning-dependent influences on the control of attention that could not be attributed to either of those two established mechanisms of control gave rise to the concept of selection history and a corresponding third mechanism of attentional control. The trichotomy framework that ensued has come to dominate theories of attentional control over the past decade, replacing the historical dichotomy. In this theoretical review, I readily affirm that distinctions between the influence of goals, salience, and selection history are substantive and meaningful, and that abandoning the dichotomy between goal-directed and stimulus-driven mechanisms of control was appropriate. I do, however, question whether a theoretical trichotomy is the right answer to the problem posed by selection history. If we reframe the influence of goals and selection history as different flavors of memory-dependent modulations of attentional priority and if we characterize the influence of salience as a consequence of insufficient competition from such memory-dependent sources of priority, it is possible to account for a wide range of attention-related phenomena with only one mechanism of control. The monolithic framework for the control of attention that I propose offers several concrete advantages over a trichotomy framework, which I explore here.

Ready for action! When the brain learns, yet memory-biased action does not follow

Does memory prepare us to act? Long-term memory can facilitate signal detection, though the degree of benefit varies and can even be absent. To dissociate between learning and behavioral expression of learning, we used high-density electroencephalography (EEG) to assess memory retrieval and response processing. At learning, participants heard everyday sounds. Half of these sound clips were paired with an above-threshold lateralized tone, such that it was possible to form incidental associations between the sound clip and the location of the tone. Importantly, attention was directed to either the sound clip (Experiment 1) or the tone (Experiment 2). Participants then completed a novel detection task that separated cued retrieval from response processing. At retrieval, we observed a striking brain-behavior dissociation. Learning was observed neurally in both experiments. Behaviorally, however, signal detection was only facilitated in Experiment 2, for which there was an accompanying explicit memory for tone presence. Further, implicit neural memory for tone location correlated with the degree of response preparation, but not response execution. Together, the findings suggest 1) that attention at learning affects memory-biased action and 2) that memory prepared action via both explicit and implicit associative memory, with the latter triggering response preparation.

Contextual cueing of visual search reflects the acquisition of an optimal, one-for-all oculomotor scanning strategy

Visual search improves when a target is encountered repeatedly at a fixed location within a stable distractor arrangement (spatial context), compared to non-repeated contexts. The standard account attributes this contextual-cueing effect to the acquisition of display-specific long-term memories, which, when activated by the current display, cue attention to the target location. Here we present an alternative, procedural-optimization account, according to which contextual facilitation arises from the acquisition of generic oculomotor scanning strategies, optimized with respect to the entire set of displays, with frequently searched displays accruing greater weight in the optimization process. To decide between these alternatives, we examined measures of the similarity, across time-on-task, of the spatio-temporal sequences of fixations through repeated and non-repeated displays. We found scanpath similarity to increase generally with learning, but more for repeated versus non-repeated displays. This pattern contradicts display-specific guidance, but supports one-for-all scanpath optimization.

Cross-modal contextual memory guides selective attention in visual-search tasks

Visual search is speeded when a target item is positioned consistently within an invariant (repeatedly encountered) configuration of distractor items ("contextual cueing"). Contextual cueing is also observed in cross-modal search, when the location of the-visual-target is predicted by distractors from another-tactile-sensory modality. Previous studies examining lateralized waveforms of the event-related potential (ERP) with millisecond precision have shown that learned visual contexts improve a whole cascade of search-processing stages. Drawing on ERPs, the present study tested alternative accounts of contextual cueing in tasks in which distractor-target contextual associations are established across, as compared to, within sensory modalities. To this end, we devised a novel, cross-modal search task: search for a visual feature singleton, with repeated (and nonrepeated) distractor configurations presented either within the same (visual) or a different (tactile) modality. We found reaction times (RTs) to be faster for repeated versus nonrepeated configurations, with comparable facilitation effects between visual (unimodal) and tactile (crossmodal) context cues. Further, for repeated configurations, there were enhanced amplitudes (and reduced latencies) of ERPs indexing attentional allocation (PCN) and postselective analysis of the target (CDA), respectively; both components correlated positively with the RT facilitation. These effects were again comparable between uni- and crossmodal cueing conditions. In contrast, motor-related processes indexed by the response-locked LRP contributed little to the RT effects. These results indicate that both uni- and crossmodal context cues benefit the same, visual processing stages related to the selection and subsequent analysis of the search target.

Spatial context target relearning following a target relocation event: Not mission impossible

Our visual system relies on memory to store and retrieve goal-relevant structures and information from the environment for the purpose of optimizing the allocation of attention. This concept, referred to as contextual cueing, has been demonstrated using visual search tasks, wherein repeated visual contexts lead to reduced search times compared with random displays. Subsequently, when an unexpected change occurs in the environment, or memory fails, a cognitive expense is incurred as the mind tries to resolve the conflict with the memory of the previous environmental context. How memory resolves these conflicts and is updated is of great interest. Previous studies showed that, without extensive practice, individuals were unable to associate a secondary target location with a previously learned spatial context following the relocation of the initially learned target. Here, we explored variables that could potentially affect contextual learning and relearning, such as display size, crowding, context color, and whether the target switched to a previously occupied or unoccupied location. In a series of four experiments, we find relearning occurring in all instances. Previous research may have suffered from underpowered designs.

Working memory and active sampling of the environment: Medial temporal contributions

Working memory (WM) refers to the ability to maintain and actively process information-either derived from perception or long-term memory (LTM)-for intelligent thought and action. This chapter focuses on the contributions of the temporal lobe, particularly medial temporal lobe (MTL) to WM. First, neuropsychological evidence for the involvement of MTL in WM maintenance is reviewed, arguing for a crucial role in the case of retaining complex relational bindings between memorized features. Next, MTL contributions at the level of neural mechanisms are covered-with a focus on WM encoding and maintenance, including interactions with ventral temporal cortex. Among WM use processes, we focus on active sampling of environmental information, a key input source to capacity-limited WM. MTL contributions to the bidirectional relationship between active sampling and memory are highlighted-WM control of active sampling and sampling as a way of selecting input to WM. Memory-based sampling studies relying on scene and object inspection, visual-based exploration behavior (e.g., vicarious behavior), and memory-guided visual search are reviewed. The conclusion is that MTL serves an important function in the selection of information from perception and transfer from LTM to capacity-limited WM.

The past, present, and future of selection history

The last ten years of attention research have witnessed a revolution, replacing a theoretical dichotomy (top-down vs. bottom-up control) with a trichotomy (biased by current goals, physical salience, and selection history). This third new mechanism of attentional control, selection history, is multifaceted. Some aspects of selection history must be learned over time whereas others reflect much more transient influences. A variety of different learning experiences can shape the attention system, including reward, aversive outcomes, past experience searching for a target, target‒non-target relations, and more. In this review, we provide an overview of the historical forces that led to the proposal of selection history as a distinct mechanism of attentional control. We then propose a formal definition of selection history, with concrete criteria, and identify different components of experience-driven attention that fit within this definition. The bulk of the review is devoted to exploring how these different components relate to one another. We conclude by proposing an integrative account of selection history centered on underlying themes that emerge from our review.

Local and global context repetitions in contextual cueing

In contextual cueing tasks, participants can use a repeating local context to learn to detect the target, yet most contextual cueing studies have relied on repeating global context properties. We examined whether observers can use local context repetitions in a similar manner as they use global context repetitions. In addition, we examined how reward-predicting context features modulate the use of local and global contexts. Participants searched through contexts in which either the entire context configuration or only a local context around the target repeated, intermixed with novel contexts. Half of the context items appeared in a color signaling either low or high reward. We found that local context repetitions led to comparable benefits in response times and fixation count as global context repetitions did. Surprisingly, reward magnitude did not affect performance in local nor in global contexts. The results suggest that a local chunk of distractors can be used for context learning and attention guidance in a similar manner as the global context configuration. We suggest that the proportion of repeated and novel context trials is crucial for context learning and that our combination of locally and globally repeating contexts provided an environment that facilitated learning in both context types because it allowed predicting the target location from the context in most of the trials.

Contextual cueing is not flexible

Target detection is faster when search displays repeat, but properties of the memory representations that give rise to this contextual cueing effect remain uncertain. We adapted the contextual cueing task using an ABA design and recorded the eye movements of healthy young adults to determine whether the memory representations are flexible. Targets moved to a new location during the B phase and then returned to their original locations (second A phase). Contextual cueing effects in the first A phase were reinstated immediately in the second A phase, and response time costs eventually gave way to a repeated search advantage in the B phase, suggesting that two target-context associations were learned. However, this apparent flexibility disappeared when eye tracking data were used to subdivide repeated displays based on B-phase viewing of the original target quadrant. Therefore, memory representations acquired in the contextual cueing task resist change and are not flexible.

Raising awareness about measurement error in research on unconscious mental processes

Experimental psychologists often neglect the poor psychometric properties of the dependent measures collected in their studies. In particular, a low reliability of measures can have dramatic consequences for the interpretation of key findings in some of the most popular experimental paradigms, especially when strong inferences are drawn from the absence of statistically significant correlations. In research on unconscious cognition, for instance, it is commonly argued that the lack of a correlation between task performance and measures of awareness or explicit recollection of the target stimuli provides strong support for the conclusion that the cognitive processes underlying performance must be unconscious. Using contextual cuing of visual search as a case study, we show that given the low reliability of the dependent measures collected in these studies, it is usually impossible to draw any firm conclusion about the unconscious character of this effect from correlational analyses. Furthermore, both a psychometric meta-analysis of the available evidence and a cognitive-modeling approach suggest that, in fact, we should expect to see very low correlations between performance and awareness at the empirical level, even if both constructs are perfectly related at the latent level. Convincing evidence for the unconscious character of contextual cuing and other effects will most likely demand richer and larger data sets, coupled with more powerful analytic approaches.

Multisensory visuo-tactile context learning enhances the guidance of unisensory visual search

Does multisensory distractor-target context learning enhance visual search over and above unisensory learning? To address this, we had participants perform a visual search task under both uni- and multisensory conditions. Search arrays consisted of one Gabor target that differed from three homogeneous distractors in orientation; participants had to discriminate the target's orientation. In the multisensory session, additional tactile (vibration-pattern) stimulation was delivered to two fingers of each hand, with the odd-one-out tactile target and the distractors co-located with the corresponding visual items in half the trials; the other half presented the visual array only. In both sessions, the visual target was embedded within identical (repeated) spatial arrangements of distractors in half of the trials. The results revealed faster response times to targets in repeated versus non-repeated arrays, evidencing 'contextual cueing'. This effect was enhanced in the multisensory session-importantly, even when the visual arrays presented without concurrent tactile stimulation. Drift-diffusion modeling confirmed that contextual cueing increased the rate at which task-relevant information was accumulated, as well as decreasing the amount of evidence required for a response decision. Importantly, multisensory learning selectively enhanced the evidence-accumulation rate, expediting target detection even when the context memories were triggered by visual stimuli alone.

Neural Evidence Suggests Both Interference and Facilitation from Embedding Regularity into Visual Search

In this work, we relied on electrophysiological methods to characterize the processing stages that are affected by the presence of regularity in a visual search task. EEG was recorded for 72 participants while they completed a visual search task. Depending on the group, the task contained a consistent-mapping condition, a random-mapping condition, or both consistent and random conditions intermixed (mixed group). Contrary to previous findings, the control groups allowed us to demonstrate that the contextual cueing effect that was observed in the mixed group resulted from interference, not facilitation, to the target selection, response selection, and response execution processes (N2-posterior-contralateral, stimulus-locked lateralized readiness potential [LRP], and response-locked LRP components). When the regularity was highly valid (consistent-only group), the presence of regularity drove performance beyond general practice effects, through facilitation in target selection and response selection (N2-posterior-contralateral and stimulus-locked LRP components). Overall, we identified two distinct effects created by the presence of regularity: a global effect of validity that dictates the degree to which all information is taken into account and a local effect of activating the information on every trial. We conclude that, when considering the influence of regularity on behavior, it is vital to assess how the overall reliability of the incoming information is affected.

Contextual Cueing Effect Under Rapid Presentation

In contextual cueing, previously encountered context tends to facilitate the detection of the target embedded in it than when the target appears in a novel context. In this study, we investigated whether the contextual cueing could develop at early time when the search display was presented briefly. In four experiments, participants searched for a target T in an array of distractor Ls. The results showed that with a rather short presentation time of the search display, participants were able to learn the spatial context and speeded up their response time overall, with the learning effect lasting for a long period. Specifically, the contextual cueing effect was observed either with or without a mask after a duration of 300-ms presentation of the search display. Such a context learning under rapid presentation could not operate only with the local context information repeated, thus suggesting that a global context was required to guide spatial attention when the viewing time of the search display was limited. Overall, these findings indicate that contextual cueing might arise at an "early," target selection stage and that the global context is necessary for the context learning under rapid presentation to function.

Intact Contextual Cueing for Search in Realistic Scenes with Simulated Central or Peripheral Vision Loss

Purpose

Search in repeatedly presented visual search displays can benefit from implicit learning of the display items' spatial configuration. This effect has been named contextual cueing. Previously, contextual cueing was found to be reduced in observers with foveal or peripheral vision loss. Whereas this previous work used symbolic (T among L-shape) search displays with arbitrary configurations, here we investigated search in realistic scenes. Search in meaningful realistic scenes may benefit much more from explicit memory of the target location. We hypothesized that this explicit recall of the target location reduces visuospatial working memory demands on search considerably, thereby enabling efficient search guidance by learnt contextual cues in observers with vision loss.

Methods

Two experiments with gaze-contingent scotoma simulation (Experiment 1: central scotoma, Experiment 2: peripheral scotoma) were carried out with normal-sighted observers (total n = 39/40). Observers had to find a cup in pseudorealistic indoor scenes and discriminate the direction of the cup's handle.

Results

With both central and peripheral scotoma simulation, contextual cueing was observed in repeatedly presented configurations.

Conclusions

The data show that patients suffering from central or peripheral vision loss may benefit more from memory-guided visual search than would be expected from scotoma simulation and patient studies using abstract symbolic search displays.

Translational Relevance

In the assessment of visual search in patients with vision loss, semantically meaningless abstract search displays may gain insights into deficient search functions, but more realistic meaningful search scenes are needed to assess whether search deficits can be compensated.

How Attentional Guidance and Response Selection Boost Contextual Learning: Evidence from Eye Movement

The contextual cueing effect (CCE) refers to the learned association between predictive configuration and target location, speeding up response times for targets. Previous studies have examined the underlying processes (initial perceptual process, attentional guidance, and response selection) of CCE but have not reached a general consensus on their contributions to CCE. In the present study, we used eye tracking to address this question by analyzing the oculomotor correlates of context-guided learning in visual search and eliminating indefinite response factors during response priming. The results show that both attentional guidance and response selection contribute to contextual learning.

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

Recent work on contextual cueing has shown that reward can facilitate context learning, e.g., when salient but task-irrelevant context features signal reward magnitude. Whether task-relevant context features yield a similar facilitating effect is unclear. Also, emergence and persistence of context learning for contexts associated with different reward magnitudes remains unclear. The present study investigated whether reward increases the speed with which context learning emerges, resulting in an earlier but asymptotically similar contextual cueing effect, or whether reward persistently increases context learning, visible as a larger contextual cueing effect on an asymptotical level. Reward was associated to the predominant orientation of the L-distractors, and the number of context repetitions was increased considerably. Results showed contextual cueing, i.e., faster responses and fewer fixations in repeated compared to novel contexts for all reward magnitudes. Moreover, a high reward led to a more pronounced contextual cueing effect. We developed a model-based approach to explicitly assess the non-linear decline and asymptotic level of the response time curves and to quantify how they were altered by reward. A hierarchical Bayesian parameter estimation revealed that reward decreased the asymptotic level of the repeated contexts' response times. Our results therefore show that reward leads to a persistent advantage in contextual cueing rather than to earlier but asymptotically similar context learning.

Contextual cueing facilitation arises early in the time course of visual search: An investigation with the `speed-accuracy tradeoff task

Visual search is expedited in a spatial context encountered repeatedly. A much-debated question is how early the facilitation by contextual memory arises. The current study examined the possibility of the facilitation of early attentional processing by constructing a descriptive model of the time course of visual search and its facilitation by contextual cueing. Participants in this experiment engaged in a speed-accuracy tradeoff (SAT) task after learning the spatial contexts in a standard visual search task in which they searched for a rotated T target among Ls. In the SAT task, they were required to search for the target and respond immediately when a sound probe was presented, even if they did not find or identify the target when the inter-stimulus interval between the search display and the probe varied from 40 ms to 2,000 ms. Participants completed two blocks of the SAT task, in which they searched in learned and new contexts. The results of the SAT procedure showed that responses were more accurate in repeated contexts than in new contexts, even when only a brief period of time elapsed after presenting the search display (> 90 ms). We conducted an analysis of the time course of contextual-cueing effects with Bayesian hierarchical modeling, which demonstrated that the rate of increase in accuracy was higher for the repeated than for the new contexts. These findings suggest that early attentional processing is enhanced by learning the contexts, and this enhancement arises very early in the time course of the visual search.

Introducing a Bayesian model of selective attention based on active inference

Information gathering comprises actions whose (sensory) consequences resolve uncertainty (i.e., are salient). In other words, actions that solicit salient information cause the greatest shift in beliefs (i.e., information gain) about the causes of our sensations. However, not all information is relevant to the task at hand: this is especially the case in complex, naturalistic scenes. This paper introduces a formal model of selective attention based on active inference and contextual epistemic foraging. We consider a visual search task with a special emphasis on goal-directed and task-relevant exploration. In this scheme, attention modulates the expected fidelity (precision) of the mapping between observations and hidden states in a state-dependent or context-sensitive manner. This ensures task-irrelevant observations have little expected information gain, and so the agent - driven to reduce expected surprise (i.e., uncertainty) - does not actively seek them out. Instead, it selectively samples task-relevant observations, which inform (task-relevant) hidden states. We further show, through simulations, that the atypical exploratory behaviours in conditions such as autism and anxiety may be due to a failure to appropriately modulate sensory precision in a context-specific way.

Predictive visual search: Role of environmental regularities in the learning of context cues

Repeatedly searching through invariant spatial arrangements in visual search displays leads to the buildup of memory about these displays (contextual-cueing effect). In the present study, we investigate (1) whether contextual cueing is influenced by global statistical properties of the task and, if so, (2) whether these properties increase the overall strength (asymptotic level) or the temporal development (speed) of learning. Experiment 1a served as baseline against which we tested the effects of increased or decreased proportions of repeated relative to nonrepeated displays (Experiments 1b and 1c, respectively), thus manipulating the global statistical properties of search environments. Importantly, probability variations were achieved by manipulating the number of nonrepeated (baseline) displays so as to equate the total number of repeated displays across experiments. In Experiment 1d, repeated and nonrepeated displays were presented in longer streaks of trials, thus establishing a stable environment of sequences of repeated displays. Our results showed that the buildup of contextual cueing was expedited in the statistically rich Experiments 1b and 1d, relative to the baseline Experiment 1a. Further, contextual cueing was entirely absent when repeated displays occurred in the minority of trials (Experiment 1c). Together, these findings suggest that contextual cueing is modulated by observers' assumptions about the reliability of search environments.

Reward expectation facilitates context learning and attentional guidance in visual search

Modulations of visual attention due to expectation of reward were frequently reported in recent years. Recent studies revealed that reward can modulate the implicit learning of repeated context configurations (e.g., Tseng & Lleras, 2013). We investigated the influence of reward expectations on context learning by associating colors to different reward magnitudes. Participants searched through contexts consisting of spatially distributed L-shaped distractors and a T-shaped target, with half of these objects appearing in a color associated with low, medium, or high reward. Half of these context configurations were repeatedly presented in every experimental block, whereas the other half was generated newly for every trial. Results showed an earlier and more pronounced contextual cueing effect in contexts associated with high reward compared with low reward contexts. This was visible as faster decline of response times to targets in repeated contexts associated with high reward compared with repeated low reward and novel contexts, and was reflected in the eye movement pattern as shorter distance of the first fixation to the target location. These results suggest that expectation of high reward magnitude facilitates subsequent learning of repeated context configurations. High reward also increases the efficiency of attention guidance toward the target location.

Acquisition of habitual visual attention and transfer to related tasks

Extensive research has shown that statistical learning affects perception, attention, and action control; however, few studies have directly linked statistical learning with the formation of habits. Evidence that learning can induce a search habit has come from location probability learning, in which people prioritize locations frequently attended to in the past. Here, using an alternating training-testing procedure, we demonstrated that the initial attentional bias arises from short-term intertrial priming, whereas probability learning takes longer to emerge, first reaching significance in covert orienting (measured by reaction times) after about 48 training trials, and in overt orienting (measured by eye movements) after about 96 training trials. We further showed that location probability learning is persistent after training is discontinued, by transferring from a letter search task to a scene search task-emulating another characteristic feature of habits. By identifying the onset of probability learning and investigating its task specificity, this study provides evidence that probability cuing can induce habitual spatial attention.

Conscious and unconscious memory differentially impact attention: Eye movements, visual search, and recognition processes

A hotly debated question is whether memory influences attention through conscious or unconscious processes. To address this controversy, we measured eye movements while participants searched repeated real-world scenes for embedded targets, and we assessed memory for each scene using confidence-based methods to isolate different states of subjective memory awareness. We found that memory-informed eye movements during visual search were predicted both by conscious recollection, which led to a highly precise first eye movement toward the remembered location, and by unconscious memory, which increased search efficiency by gradually directing the eyes toward the target throughout the search trial. In contrast, these eye movement measures were not influenced by familiarity-based memory (i.e., changes in subjective reports of memory strength). The results indicate that conscious recollection and unconscious memory can each play distinct and complementary roles in guiding attention to facilitate efficient extraction of visual information.

Response time modeling reveals multiple contextual cuing mechanisms

Contextual cuing refers to a response time (RT) benefit that occurs when observers search through displays that have been repeated over the course of an experiment. Although it is generally agreed that contextual cuing arises via an associative learning mechanism, there is uncertainty about the type(s) of process(es) that allow learning to influence RT. We contrast two leading accounts of the contextual cuing effect that differ in terms of the general process that is credited with producing the effect. The first, the expedited search account, attributes the cuing effect to an increase in the speed with which the target is acquired. The second, the decision threshold account, attributes the cuing effect to a reduction in the response threshold used by observers when making a subsequent decision about the target (e.g., judging its orientation). We use the diffusion model to contrast the quantitative predictions of these two accounts at the level of individual observers. Our use of the diffusion model allows us to also explore a novel decision-level locus of the cuing effect based on perceptual learning. This novel account attributes the RT benefit to a perceptual learning process that increases the quality of information used to drive the decision process. Our results reveal both individual differences in the process(es) involved in contextual cuing but also identify several striking regularities across observers. We find strong support for both the decision threshold account as well as the novel perceptual learning account. We find relatively weak support for the expedited search account.

Anodal and Cathodal tDCS Over the Right Frontal Eye Fields Impacts Spatial Probability Processing Differently in Pro- and Anti-saccades

Learning regularities that exist in the environment can help the visual system achieve optimal efficiency while reducing computational burden. Using a pro- and anti-saccade task, studies have shown that probabilistic information regarding spatial locations can be a strong modulator of frontal eye fields (FEF) activities and consequently alter saccadic behavior. One recent study has also shown that FEF activities can be modulated by transcranial direct current stimulation, where anodal tDCS facilitated prosaccades but cathodal tDCS prolonged antisaccades. These studies together suggest that location probability and tDCS can both alter FEF activities and oculomotor performance, yet how these two modulators interact with each other remains unclear. In this study, we applied anodal or cathodal tDCS over right FEF, and participants performed an interleaved pro- and anti-saccade task. Location probability was manipulated in prosaccade trials but not antisaccade trials. We observed that anodal tDCS over rFEF facilitated prosaccdes toward low-probability locations but not to high-probability locations; whereas cathodal tDCS facilitated antisaccades away from the high-probability location (i.e., same location as the low-probability locations in prosaccades). These observed effects were specific to rFEF as tDCS over the SEF in a separate control experiment did not yield similar patterns. These effects were also more pronounced in low-performers who had slower saccade reaction time. Together, we conclude that (1) the overlapping spatial endpoint between prosaccades (i.e., toward low-probability location) and antisaccades (i.e., away from high-probability location) possibly suggest an endpoint-selective mechanism within right FEF, (2) anodal tDCS and location probability cannot be combined to produce a bigger facilitative effect, and (3) anodal rFEF tDCS works best on low-performers who had slower saccade reaction time. These observations are consistent with the homeostasis account of tDCS effect and FEF functioning.

Short Article: Recognition and Attention Guidance during Contextual Cueing in Real-World Scenes: Evidence from Eye Movements

When confronted with a previously encountered scene, what information is used to guide search to a known target? We contrasted the role of a scene's basic-level category membership with its specific arrangement of visual properties. Observers were repeatedly shown photographs of scenes that contained consistently but arbitrarily located targets, allowing target positions to be associated with scene content. Learned scenes were then unexpectedly mirror reversed, spatially translating visual features as well as the target across the display while preserving the scene's identity and concept. Mirror reversals produced a cost as the eyes initially moved toward the position in the display in which the target had previously appeared. The cost was not complete, however; when initial search failed, the eyes were quickly directed to the target's new position. These results suggest that in real-world scenes, shifts of attention are initially based on scene identity, and subsequent shifts are guided by more detailed information regarding scene and object layout.

Humans, but Not Deep Neural Networks, Often Miss Giant Targets in Scenes

Even with great advances in machine vision, animals are still unmatched in their ability to visually search complex scenes. Animals from bees [1, 2] to birds [3] to humans [4-12] learn about the statistical relations in visual environments to guide and aid their search for targets. Here, we investigate a novel manner in which humans utilize rapidly acquired information about scenes by guiding search toward likely target sizes. We show that humans often miss targets when their size is inconsistent with the rest of the scene, even when the targets were made larger and more salient and observers fixated the target. In contrast, we show that state-of-the-art deep neural networks do not exhibit such deficits in finding mis-scaled targets but, unlike humans, can be fooled by target-shaped distractors that are inconsistent with the expected target's size within the scene. Thus, it is not a human deficiency to miss targets when they are inconsistent in size with the scene; instead, it is a byproduct of a useful strategy that the brain has implemented to rapidly discount potential distractors.

Five Factors that Guide Attention in Visual Search

How do we find what we are looking for? Fundamental limits on visual processing mean that even when the desired target is in our field of view, we often need to search, because it is impossible to recognize everything at once. Searching involves directing attention to objects that might be the target. This deployment of attention is not random. It is guided to the most promising items and locations by five factors discussed here: Bottom-up salience, top-down feature guidance, scene structure and meaning, the previous history of search over time scales from msec to years, and the relative value of the targets and distractors. Modern theories of search need to specify how all five factors combine to shape search behavior. An understanding of the rules of guidance can be used to improve the accuracy and efficiency of socially-important search tasks, from security screening to medical image perception.

Hippocampal gamma-band Synchrony and pupillary responses index memory during visual search

Memory for scenes is supported by the hippocampus, among other interconnected structures, but the neural mechanisms related to this process are not well understood. To assess the role of the hippocampus in memory-guided scene search, we recorded local field potentials and multiunit activity from the hippocampus of macaques as they performed goal-directed search tasks using natural scenes. We additionally measured pupil size during scene presentation, which in humans is modulated by recognition memory. We found that both pupil dilation and search efficiency accompanied scene repetition, thereby indicating memory for scenes. Neural correlates included a brief increase in hippocampal multiunit activity and a sustained synchronization of unit activity to gamma band oscillations (50-70 Hz). The repetition effects on hippocampal gamma synchronization occurred when pupils were most dilated, suggesting an interaction between aroused, attentive processing and hippocampal correlates of recognition memory. These results suggest that the hippocampus may support memory-guided visual search through enhanced local gamma synchrony. © 2016 Wiley Periodicals, Inc.

Independence of long-term contextual memory and short-term perceptual hypotheses: Evidence from contextual cueing of interrupted search

Observers are able to resume an interrupted search trial faster relative to responding to a new, unseen display. This finding of rapid resumption is attributed to short-term perceptual hypotheses generated on the current look and confirmed upon subsequent looks at the same display. It has been suggested that the contents of perceptual hypotheses are similar to those of other forms of memory acquired long-term through repeated exposure to the same search displays over the course of several trials, that is, the memory supporting “contextual cueing.” In three experiments, we investigated the relationship between short-term perceptual hypotheses and long-term contextual memory. The results indicated that long-term, contextual memory of repeated displays neither affected the generation nor the confirmation of short-term perceptual hypotheses for these displays. Furthermore, the analysis of eye movements suggests that long-term memory provides an initial benefit in guiding attention to the target, whereas in subsequent looks guidance is entirely based on short-term perceptual hypotheses. Overall, the results reveal a picture of both long- and short-term memory contributing to reliable performance gains in interrupted search, while exerting their effects in an independent manner.

Underpowered samples, false negatives, and unconscious learning

The scientific community has witnessed growing concern about the high rate of false positives and unreliable results within the psychological literature, but the harmful impact of false negatives has been largely ignored. False negatives are particularly concerning in research areas where demonstrating the absence of an effect is crucial, such as studies of unconscious or implicit processing. Research on implicit processes seeks evidence of above-chance performance on some implicit behavioral measure at the same time as chance-level performance (that is, a null result) on an explicit measure of awareness. A systematic review of 73 studies of contextual cuing, a popular implicit learning paradigm, involving 181 statistical analyses of awareness tests, reveals how underpowered studies can lead to failure to reject a false null hypothesis. Among the studies that reported sufficient information, the meta-analytic effect size across awareness tests was d_z = 0.31 (95 % CI 0.24–0.37), showing that participants’ learning in these experiments was conscious. The unusually large number of positive results in this literature cannot be explained by selective publication. Instead, our analyses demonstrate that these tests are typically insensitive and underpowered to detect medium to small, but true, effects in awareness tests. These findings challenge a widespread and theoretically important claim about the extent of unconscious human cognition.

Preserved Suppression of Salient Irrelevant Stimuli During Visual Search in Age-Associated Memory Impairment

Previous studies have suggested that older adults with age-associated memory impairment (AAMI) may show a significant decline in attentional resource capacity and inhibitory processes in addition to memory impairment. In the present paper, the potential attentional capture by task-irrelevant stimuli was examined in older adults with AAMI compared to healthy older adults using scalp-recorded event-related brain potentials (ERPs). ERPs were recorded during the execution of a visual search task, in which the participants had to detect the presence of a target stimulus that differed from distractors by orientation. To explore the automatic attentional capture phenomenon, an irrelevant distractor stimulus defined by a different feature (color) was also presented without previous knowledge of the participants. A consistent N2pc, an electrophysiological indicator of attentional deployment, was present for target stimuli but not for task-irrelevant color stimuli, suggesting that these irrelevant distractors did not attract attention in AAMI older adults. Furthermore, the N2pc for targets was significantly delayed in AAMI patients compared to healthy older controls. Together, these findings suggest a specific impairment of the attentional selection process of relevant target stimuli in these individuals and indicate that the mechanism of top-down suppression of entirely task-irrelevant stimuli is preserved, at least when the target and the irrelevant stimuli are perceptually very different.

Selective scanpath repetition during memory-guided visual search

Visual search efficiency improves with repetition of a search display, yet the mechanisms behind these processing gains remain unclear. According to Scanpath Theory, memory retrieval is mediated by repetition of the pattern of eye movements or "scanpath" elicited during stimulus encoding. Using this framework, we tested the prediction that scanpath recapitulation reflects relational memory guidance during repeated search events. Younger and older subjects were instructed to find changing targets within flickering naturalistic scenes. Search efficiency (search time, number of fixations, fixation duration) and scanpath similarity (repetition) were compared across age groups for novel (V1) and repeated (V2) search events. Younger adults outperformed older adults on all efficiency measures at both V1 and V2, while the search time benefit for repeated viewing (V1-V2) did not differ by age. Fixation-binned scanpath similarity analyses revealed repetition of initial and final (but not middle) V1 fixations at V2, with older adults repeating more initial V1 fixations than young adults. In young adults only, early scanpath similarity correlated negatively with search time at test, indicating increased efficiency, whereas the similarity of V2 fixations to middle V1 fixations predicted poor search performance. We conclude that scanpath compression mediates increased search efficiency by selectively recapitulating encoding fixations that provide goal-relevant input. Extending Scanpath Theory, results suggest that scanpath repetition varies as a function of time and memory integrity.

Neural structures involved in visual search guidance by reward-enhanced contextual cueing of the target location

Spatial contextual cueing reflects an incidental form of learning that occurs when spatial distractor configurations are repeated in visual search displays. Recently, it was reported that the efficiency of contextual cueing can be modulated by reward. We replicated this behavioral finding and investigated its neural basis with fMRI. Reward value was associated with repeated displays in a learning session. The effect of reward value on context-guided visual search was assessed in a subsequent fMRI session without reward. Structures known to support explicit reward valuation, such as ventral frontomedial cortex and posterior cingulate cortex, were modulated by incidental reward learning. Contextual cueing, leading to more efficient search, went along with decreased activation in the visual search network. Retrosplenial cortex played a special role in that it showed both a main effect of reward and a reward×configuration interaction and may thereby be a central structure for the reward modulation of context-guided visual search.