About

Barry Giesbrecht is a Professor in the Psychological & Brain Sciences department at UC Santa Barbara. His research focuses on cognitive neuroscience, visual attention, brain imaging, and systems and circuits neuroscience. He is involved in exploring the neural mechanisms underlying attention and perception, utilizing various brain imaging techniques to advance understanding in these areas. As a faculty member at UCSB, he contributes to the Neuroscience program and leads research initiatives through the UCSB Attention Lab, engaging in studies that deepen insights into how the brain processes visual information and allocates attentional resources.

Research topics

• Computer Science
• Artificial Intelligence
• Data Mining
• Computer vision
• Database
• Medicine
• Neuroscience
• Cardiology
• Internal medicine
• Physics
• Speech recognition
• Anesthesia
• Radiology
• Audiology
• Psychology

Selected publications

• Beyond detection rate: understanding the vigilance decrement using signal detection theory

  Frontiers in Cognition · 2025-01-17 · 5 citations

  articleOpen accessSenior author

  The vigilance decrement has been classically characterized as the decline in performance across time as individuals continuously attend to a task. Errors during these periods of degraded performance are often collectively characterized as failures of attention. Methodologically, the classic characterization of the vigilance decrement relies upon declines in detection rate, a binary measure that is unable to characterize performance beyond a single dimension. Theoretically, using a single construct, such as attention, to describe impaired performance obscures what is likely a range of behaviors. This is a critical issue for the study of vigilance because detection rate can be impacted both by changes in sensitivity and decision criterion. Commonly used tasks do not allow for the reliable computation of these metrics because they elicit a low number of false alarms or because they introduce confounding response demands. To address these shortcomings, we propose the use of a paradigm amenable to the application of the signal detection framework, which permits the reliable and isolated investigation of the vigilance decrement across multiple measures.

  PublisherOA PDFDOI

• Task-irrelevant abrupt onsets differentially impact value-related orienting and maintenance

  Attention Perception & Psychophysics · 2025-05-13

  articleOpen accessSenior author

  Physically salient stimuli are potent influences on behavior, but their negative impacts can be reduced in the presence of explicit goal-related cues. Here, we investigated whether goal-related cues associated with value are capable of insulating information from task-irrelevant abrupt onsets during two stages of information processing. Abrupt onsets were shown either after attention-directing cues and before a target (Experiment 1) or after a target that is to be remembered for later report (Experiment 2). The cues indicated the value associated with upcoming target locations, and they were either different in value, indicating that one was more valuable than the other, or equal in value. In both experiments, subjects were instructed to report the target that would earn them the most points (Experiment 1) or money (Experiment 2). In Experiment 1, performance suffered with equal cues, suggesting that orienting to multiple locations increases susceptibility to distraction from physically salient stimuli. In Experiment 2, the same pattern did not appear for abrupt onsets during the retention period; instead, the impact of the physically salient stimulus was dependent upon working memory capacity. The differential impact of abrupt onsets prior to (Experiment 1) and after (Experiment 2) encoding of value-related target locations suggest that physically salient task-irrelevant stimuli influence value-related information processing differently during orienting and maintenance.

  PublisherOA PDFDOI

• Target Probability, Response Demands, and the Vigilance Decrement

  Journal of Vision · 2025-07-15

  articleOpen accessSenior author

  Vigilance is required when continuously monitoring for rarely occurring signals in the visual environment over time. When engaged in continous monitoring tasks, one robust phenomenon is a decline in detection rate as subjects continuously monitor for signals. One key parameter to this vigilance decrement may be the probability of target occurrence. We utilized the Continuous Temporal Expectancy Task (CTET) to observe performance across three different target probabilities (10%, 15%, 20%) in a within-subjects design. In this task, subjects (n=56) monitored a stream of gray-scale images appearing for brief durations (800 ms) and were instructed to respond when an image appeared for a slightly longer duration (1200 ms, targets). Furthermore, to discriminate between changes in sensitivity and response criterion, a signal detection theory approach was employed. A robust vigilance decrement, indicated by a decline in detection rate (b = -0.031, se = 0.004, p < 0.001), was observed across time. We also observed a decline in d-prime (b = -0.093, se = 0.015, p < 0.001) and an increase in criterion (b = 0.052, se = 0.008, p < 0.001) across time. There was an effect of probability on response rate, such that higher target probability yielded higher response rates (b = 36.030, se = 1.969, p < 0.001). Additionally, there was an effect of probability on d-prime, such that higher target probabilities yielded higher d-prime (b = 0.936, se = 0.409, p < 0.05). These findings together support the idea that the vigilance decrement is associated with both a decrease in sensitivity as well as an increase in criterion — suggesting attentional processes alone do not fully characterize vigilance performance. Furthermore, our results suggest the vigilance decrement is robust to modest changes in target probabilities and concurrent changes in response rate.

  PublisherDOI

• Catching the wandering mind with real-time triggers

  Journal of Vision · 2025-07-15

  articleOpen accessSenior author

  From moment to moment, our attention fluctuates between optimal and suboptimal states. This flux has been studied using objective indices—such as response time (RT) patterns in laboratory tasks—and subjective measures, like self-reports of task-unrelated thoughts (i.e., mind-wandering). Here, we assessed the predictive utility of a real-time RT-based triggering procedure in capturing both reduced working memory encoding and the phenomenological experience of mind-wandering across various individual differences. Fifty-eight participants completed trait measures of motor impulsivity, mind-wandering propensity, and social desirability bias. Afterwards, they performed a monotonous sustained attention task that demanded a keypress on each trial and lulled them into inattentive responding. When their three-trial RT was one standard deviation above or below their cumulative RT mean, they were interrupted with either a working memory probe to report colors in locations from the previous trial or a mind-wandering probe to report the task-relatedness of their thoughts. Fast RT triggers were associated with reduced working memory encoding compared to slow triggers (b = 0.19, SE = 0.045, p < .0001). Moreover, fast triggers predicted mind-wandering self-reports when controlling for social desirability bias (b = –0.34, SE = 0.14, p = .014). The coupling between these objective and subjective measures of lapsing attention was also weaker among individuals who claimed to have socially desirable traits (b = 0.058, SE = 0.026, p = .027). Together, these findings both 1) reveal a self-presentation bias that obscures attention self-reports and 2) validate the predictive utility of RT-based triggering procedures in anticipating multiple signatures of attentional lapses. We highlight the need for an integrative approach to characterizing the human tendency to decouple from our environment by augmenting subjective techniques with objective ones.

  PublisherDOI

• Social desirability bias obscures mind-wandering reports

  2025-11-19

  articleOpen access

  The study of mind-wandering relies on the assumption that people accurately introspect and report on their attentional state. Yet self-reports may be distorted by extraneous motives, such as a desire to appear attentive. Across two sustained attention tasks, we demonstrate that social desirability bias is systematically linked with task-unrelated thought (TUT). In Experiment 1, higher social desirability bias scores predicted fewer subjective TUT reports during a reaction time task, despite no relationship with objective response times (RTs). This suggests a self-presentation effect rather than true attentional differences. Time pressure during thought probes further weakened RT–TUT coupling. In Experiment 2, controlling for social desirability bias enhanced the ability of an objective, RT-based real-time triggering procedure to predict deeper subjective TUT reports in the Sustained Attention to Response Task (SART). The alignment between objective triggers and subjective reports was strong for low-bias individuals, but weakened for those high in bias. Triggers were also less effective at capturing working memory lapses in participants prone to deliberate mind-wandering, suggesting that intentional off-task thinking manifests differently in behavior. The results show that social desirability bias can obscure TUT reports and should be considered in a science of attention and thought.

  PublisherDOI

• On the Go with AR: Attention to Virtual and Physical Targets while Varying Augmentation Density

  2025-04-24 · 5 citations

  articleOpen access

  Augmented reality is projected to be a primary mode of information consumption on the go, seamlessly integrating virtual content into the physical world. However, the potential perceptual demands of viewing virtual annotations while navigating a physical environment could impact user efficacy and safety, and the implications of these demands are not well understood. Here, we investigate the impact of virtual path guidance and augmentation density (visual clutter) on search performance and memory. Participants walked along a predefined path, searching for physical or virtual items. They experienced two levels of augmentation density, and either walked freely or with enforced speed and path guidance. Augmentation density impacted behavior and reduced awareness of uncommon objects in the environment. Analysis of search task performance and post-experiment item recall revealed differing attention to physical and virtual objects. On the basis of these findings we outline considerations for AR apps designed for use on the go.

  PublisherDOI

• Electrophysiological evidence for differential semantic processing of words and objects presented in augmented reality

  Computers in Human Behavior Reports · 2025-04-25 · 1 citations

  articleOpen accessSenior author

  Head-worn augmented reality (AR) offers exciting possibilities to help users learn new information. By blending digital content with the learner's real-world environment, AR can create engaging and enjoyable experiences that may improve knowledge retention. Electroencephalography (EEG) allows for discreet, continuous monitoring of brain activity at the scalp. This study examined whether the N400 event-related potential (ERP), a brain response linked to semantic processing, could be incorporated into a system combining AR and EEG. While the N400 is reliably elicited by a mismatch in meaning between two sequentially presented stimuli, there are two key outstanding questions. First, how do 3D objects presented in AR impact semantic processing as measured by the N400? Second, is there a reliable N400 to mismatches between an object and its name, in addition to mismatches in meaning? Twenty-four young adults viewed sequential pairs of stimuli through an AR headset while EEG was recorded. We manipulated whether the first stimulus was a 3D object or written word and whether the second stimulus matched or mismatched the first in terms of meaning or name. Participants' reaction times were slower for mismatching pairs when compared to matching pairs in all conditions. Averaged ERP and single-trial classification analyses showed robust differences in brain responses. Additionally, participants were more accurate and exhibited faster behavioral and brain responses for naming compared to meaning judgments. These results suggest the N400 could be used in a combined AR-EEG system to provide feedback on semantic understanding, potentially opening exciting new avenues for enhancing learning. • Augmented reality (AR) offers exciting possibilities to help users learn new information. • Electroencephalography (EEG) is a noninvasive method for monitoring brain activity. • We combined AR and EEG to examine an EEG signal linked to meaning, known as the N400. • We demonstrated robust N400 responses in all conditions. • Results are a first step towards an AR-EEG system for semantic knowledge detection.

  PublisherDOI

• Scene Awareness While Using Multiple Navigation Aids in AR Search

  2025-10-08

  articleOpen access

  Augmented reality (AR) allows virtual information to be presented in the real world, providing support for numerous tasks including search and navigation. Allowing users access to multiple navigation aids may help leverage the benefits of different navigational guidance methods, but may also have negative perceptual and cognitive impacts. In this study, users performed searches for virtual gems within a large-scale augmented environment while choosing to deploy two different navigation aids either independently or simultaneously: world-locked arrows and an on-screen radar. After completing the search, participants were asked to recall objects that may or may not have been present in the scene. The use of navigation aids impacted object recall, with impaired recall of objects in the environment when an aid was switched on. The results point at possible impact factors of object awareness in mobile AR and underscore the potential for adaptable interfaces to support users navigating the physical world.

  PublisherOA PDFDOI

• Full interhemispheric integration sustained by a fraction of posterior callosal fibers

  Proceedings of the National Academy of Sciences · 2025-10-21 · 1 citations

  articleOpen access

  The dynamic integration of the lateralized and specialized capacities of the two cerebral hemispheres constitutes a hallmark feature of human brain function. This interhemispheric exchange of information critically depends upon the corpus callosum. Classical anatomical descriptions of callosal organization outline a topographic gradient from front to back, such that specific transcallosal fibers support distinct aspects of integrated brain function. Here, we present a challenge to this conventional model. Using neuroimaging data obtained from a new cohort of adult corpus callosotomy patients, we leverage modern network neuroscience techniques to show that full interhemispheric integration can be achieved via a small proportion of posterior callosal fibers. Partial callosotomy patients with spared callosal fibers retained widespread patterns of interhemispheric functional connectivity and showed no signs of behavioral disconnection, even with only 1 cm of the splenium intact. Conversely, only complete callosotomy patients demonstrated sweeping disruptions of interhemispheric network architectures, aligning with disconnection syndromes long-thought to reflect diminished information propagation and communication across the brain. These findings motivate an evolving mechanistic understanding of synchronized interhemispheric neural activity for large-scale human brain function and behavior.

  PublisherOA PDFDOI

• No disconnection syndrome after near-complete callosotomy

  Communications Psychology · 2025-12-15

  articleOpen access

  Sensorimotor processing in the human brain is largely lateralized, with the corpus callosum integrating these processes into a unified experience. Following complete callosotomy, this integration breaks down, resulting in disconnection syndromes. We asked how much of the corpus callosum is sufficient to support functional unity-the absence of disconnection syndrome-by comparing three complete callosotomy patients with one retaining only the splenium. Using lateralized tasks across visual, tactile, visuospatial, and language domains, we predicted domain-specific deficits in the splenium-only patient based on established anatomical models of callosal topography. Strikingly, while complete callosotomy patients exhibited disconnection syndromes, the splenium patient demonstrated functional unity across all domains-as if his entire corpus callosum were intact. Our findings highlight the brain's remarkable capacity to maintain behavioral integration through minimal preserved pathways, highlighting how the structure-dependent reorganizational capacity of the human brain may allow to preserve functional unity.

  PublisherOA PDFDOI

Recent grants

• NIH Grant R03MH070638

  NIH · $74k · 2006

• Neural representation of scene context during visual search

  NIH · $417k · 2013–2016

Frequent coauthors

• Scott T. Grafton

  Hologic (Germany)

  44 shared

• Tom Bullock

  University of California, Santa Barbara

  42 shared

• Miguel P. Eckstein

  41 shared

• J. C. Elliott

  38 shared

• Mary H. MacLean

  University of California, Santa Barbara

  32 shared

• Jean M. Vettel

  DEVCOM Army Research Laboratory

  28 shared

• Javier O. Garcia

  17 shared

• Koel Das

  Indian Institute of Science Education and Research Kolkata

  16 shared

Education

• BA, Psychology

  University of Waterloo

  1995