When experience with scenes foils attentional orienting: ERP evidence against flexible target-context mapping in visual search.

Visual search is speeded when a target is repeatedly presented in an invariant scene context of nontargets (contextual cueing), demonstrating observers' capability for using statistical long-term memory (LTM) to make predictions about upcoming sensory events, thus improving attentional orienting. In the current study, we investigated whether expectations arising from individual, learned environmental structures can encompass multiple target locations. We recorded event-related potentials (ERPs) while participants performed a contextual cueing search task with repeated and non-repeated spatial item configurations.

ERPs and alpha oscillations track the encoding and maintenance of object-based representations in visual working memory.

When memorizing an integrated object such as a Kanizsa figure, the completion of parts into a coherent whole is attained by grouping processes which render a whole-object representation in visual working memory (VWM). The present study measured event-related potentials (ERPs) and oscillatory amplitudes to track these processes of encoding and representing multiple features of an object in VWM. To this end, a change detection task was performed, which required observers to memorize both the orientations and colors of six "pacman" items while inducing configurations of the pacmen that systematically varied in terms of their grouping strength.

Environmental regularities mitigate attentional misguidance in contextual cueing of visual search.

Visual search is faster when a fixed target location is paired with a spatially invariant (vs. randomly changing) distractor configuration, thus indicating that repeated contexts are learned, thereby guiding attention to the target (contextual cueing [CC]). Evidence for memory-guided attention has also been revealed with electrophysiological (electroencephalographic [EEG]) recordings, starting with an enhanced early posterior negativity (N1pc), which signals a preattentive bias toward the target, and, subsequently, attentional and postselective components, such as the posterior contralateral negativity (PCN) and contralateral delay activity (CDA), respectively.

Learning-Induced Plasticity Enhances the Capacity of Visual Working Memory.

Visual working memory (VWM) is limited in capacity, though memorizing meaningful objects may refine this limitation. However, meaningful and meaningless stimuli typically differ perceptually, and objects' associations with meaning are usually already established outside the laboratory, potentially confounding experimental findings. Here, in two experiments with young adults ( = 45 and = 20), we controlled for these influences by having observers actively learn associations of (for them) initially meaningless stimuli: Chinese characters, half of which were consistently paired with pictures of animals or everyday objects in a learning phase.

Mission impossible? Spatial context relearning following a target relocation event depends on cue predictiveness.

Visual search for a target is faster when the spatial layout of distractors is repeatedly encountered, illustrating that statistical learning of contextual invariances facilitates attentional guidance (contextual cueing; Chun & Jiang, 1998, Cognitive Psychology, 36, 28-71). While contextual learning is usually relatively efficient, relocating the target to an unexpected location (within an otherwise unchanged search layout) typically abolishes contextual cueing and the benefits deriving from invariant contexts recover only slowly with extensive training (Zellin et al., 2014, Psychonomic Bulletin & Review, 21(4), 1073-1079).

Changes in attentional breadth scale with the demands of Kanizsa-figure object completion-evidence from pupillometry.

The present study investigated whether the integration of separate parts into a whole-object representation varies with the amount of available attentional resources. To this end, two experiments were performed, which required observers to maintain central fixation while searching in peripheral vision for a target among various distractor configurations. The target could either be a "grouped" whole-object Kanizsa figure, or an "ungrouped" configuration of identical figural parts, but which do not support object completion processes to the same extent.

Feedback from lateral occipital cortex to V1/V2 triggers object completion: Evidence from functional magnetic resonance imaging and dynamic causal modeling.

Illusory figures demonstrate the visual system's ability to integrate disparate parts into coherent wholes. We probed this object integration process by either presenting an integrated diamond shape or a comparable ungrouped configuration that did not render a complete object. Two tasks were used that either required localization of a target dot (relative to the presented configuration) or discrimination of the dot's luminance.

EEG evidence for enhanced attentional performance during moderate-intensity exercise.

Research on attentional control within real-world contexts has become substantially more feasible and thus frequent over the past decade. However, relatively little is known regarding how these processes may be influenced by common naturalistic behaviors such as engaging in physical activity, which is thought to modulate the availability of neurometabolic resources. Here, we used an event-related potential (ERP) approach to determine whether various intensities of aerobic exercise might affect the concurrent performance of attentional control mechanisms.

The nationality benefit: Long-term memory associations enhance visual working memory for color-shape conjunctions.

Visual working memory (VWM) is typically found to be severely limited in capacity, but this limitation may be ameliorated by providing familiar objects that are associated with knowledge stored in long-term memory. However, comparing meaningful and meaningless stimuli usually entails a confound, because different types of objects also tend to vary in terms of their inherent perceptual complexity. The current study therefore aimed to dissociate stimulus complexity from object meaning in VWM.

Affective Modulation of Working Memory Maintenance: The Role of Positive and Negative Emotions.

The present study investigated the impact of task-irrelevant emotional images on the retention of information in spatial working memory (WM). Two experiments employed a delayed matching to-sample task where participants had to maintain the locations of four briefly presented squares. After a short retention interval, a probe item appeared and participants were required to indicate whether the probe position matched one of the previously occupied square positions.

Why Are Acquired Search-Guiding Context Memories Resistant to Updating?

Looking for goal-relevant objects in our various environments is one of the most ubiquitous tasks the human visual system has to accomplish (Wolfe, 1998). Visual search is guided by a number of separable selective-attention mechanisms that can be categorized as bottom-up driven - guidance by salient physical properties of the current stimuli - or top-down controlled - guidance by observers' "online" knowledge of search-critical object properties (e.g.

Attention capture by salient object groupings in the neglected visual field.

The integration of fragmentary parts into coherent whole objects has been proposed either to rely on the availability of attentional resources or to arise automatically, that is, from preattentive processing (prior to the engagement of selective attention). In the present study, these two alternative accounts were tested in a group of neglect patients with right-hemisphere parietal brain damage and associated deficits of selective attention in the left (visual) hemispace. The reported experiment employed a search task that required detection of targets in the left and/or right hemifields, which were embedded in configurations that consisted of variants of Kanizsa figures.

Stimulus-driven updating of long-term context memories in visual search.

Visual search for a target is faster when the spatial layout of nontarget items is repeatedly encountered, illustrating that learned contextual invariances can improve attentional selection (contextual cueing). This type of contextual learning is usually relatively efficient, but relocating the target to an unexpected location (within otherwise unchanged layouts) typically abolishes contextual cueing. Here, we explored whether bottom-up attentional guidance can mediate the efficient contextual adaptation after the change.

Automatic Guidance (and Misguidance) of Visuospatial Attention by Acquired Scene Memory: Evidence From an N1pc Polarity Reversal.

Visual search is facilitated when the target is repeatedly encountered at a fixed position within an invariant (vs. randomly variable) distractor layout-that is, when the layout is learned and guides attention to the target, a phenomenon known as . Subsequently changing the target location within a learned layout abolishes contextual cuing, which is difficult to relearn.

Object-based grouping benefits without integrated feature representations in visual working memory.

Visual working memory (VWM) is typically considered to represent complete objects-that is, separate parts of an object are maintained as bound objects. Yet it remains unclear whether and how the features of disparate parts are integrated into a whole-object memory representation. Using a change detection paradigm, the present study investigated whether VWM performance varies as a function of grouping strength for features that either determine the grouped object (orientation) or that are not directly grouping relevant (color).

Distributed attention beats the down-side of statistical context learning in visual search.

Spatial attention can be deployed with a narrower focus to process individual items or distributed relatively broadly to process larger parts of a scene. This study investigated how focused- versus distributed-attention modes contribute to the adaptation of context-based memories that guide visual search. In two experiments, participants were either required to fixate the screen center and use peripheral vision for search ("distributed attention"), or they could freely move their eyes, enabling serial scanning of the search array ("focused attention").

Tracking the completion of parts into whole objects: Retinotopic activation in response to illusory figures in the lateral occipital complex.

Illusory figures demonstrate the visual system's ability to integrate separate parts into coherent, whole objects. The present study was performed to track the neuronal object construction process in human observers, by incrementally manipulating the grouping strength within a given configuration until the emergence of a whole-object representation. Two tasks were employed: First, in the spatial localization task, object completion could facilitate performance and was task-relevant, whereas it was irrelevant in the second, luminance discrimination task.

Resolving the Electroencephalographic Correlates of Rapid Goal-Directed Chunking in the Frontal-Parietal Network.

Previous studies have revealed a specific role of the prefrontal-parietal network in rapid goal-directed chunking (RGDC), which dissociates prefrontal activity related to chunking from parietal working memory demands. However, it remains unknown how the prefrontal and parietal cortices collaborate to accomplish RGDC. To this end, a novel experimental design was used that presented Chinese characters in a chunking task, testing eighteen undergraduate students (9 females, mean age = 22.

Affective modulation of memory-based guidance in visual search: Dissociative role of positive and negative emotions.

Emotions can either facilitate or hamper the allocation of attention and the extraction of statistical regularities from perceptual input. In the present study, we investigated whether context memory of spatial target-distractor relations in visual search is influenced by task-irrelevant affective stimuli. In Phase 1 of the study, positive, negative, or neutral images (randomly selected) were presented in the background of a given repeated (fixed target-distractor arrangement) or nonrepeated (random arrangement) search array.

Kanizsa-figure object completion gates selection in the attentional blink.

Previous work has demonstrated that perceptual grouping modulates the selectivity of attention across space. By contrast, how grouping influences the allocation of attention over time is much less clear. This study investigated this issue, using an attentional blink (AB) paradigm to test how grouping influences the initial selection and the subsequent short-term memory consolidation of a target.

Taking Attention Out of Context: Frontopolar Transcranial Magnetic Stimulation Abolishes the Formation of New Context Memories in Visual Search.

This study investigates the causal contribution of the left frontopolar cortex (FPC) to the processing of violated expectations from learned target-distractor spatial contingencies during visual search. The experiment consisted of two phases: learning and test. Participants searched for targets presented either among repeated or nonrepeated target-distractor configurations.

Amodal Completion of a Target Template Enhances Attentional Guidance in Visual Search.

When searching for a target object in cluttered environments, our visual system appears to complete missing parts of occluded objects-a mechanism known as "amodal completion." This study investigated how different variants of completion influence visual search for an occluded target object. In two experiments, participants searched for a target among distractors in displays that either presented composite objects (notched shapes abutting an occluding square) or corresponding simple objects.

Surface filling-in and contour interpolation contribute independently to Kanizsa figure formation.

To explore mechanisms of object integration, the present experiments examined how completion of illusory contours and surfaces modulates the sensitivity of localizing a target probe. Observers had to judge whether a briefly presented dot probe was located inside or outside the region demarcated by inducer elements that grouped to form variants of an illusory, Kanizsa-type figure. From the resulting psychometric functions, we determined observers' discrimination thresholds as a sensitivity measure.

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.

Attention as the 'glue' for object integration in parietal extinction.

Patients with unilateral, parietal brain damage frequently show visual extinction, which manifests in a failure to identify contralesional stimuli when presented simultaneously with other, ipsilesional stimuli (but full awareness for single stimulus presentations). Extinction reflects an impairment of spatial selective attention, leaving basic preattentive processing unaffected. For instance, access to bilaterally grouped objects is usually spared in extinction, suggesting that grouping occurs at a stage preceding (in the patients: abnormally biased) spatial-attentional selection.