Check out the article here!
Abstract The neural processes that enable healthy humans to orient attention to sudden visual events are poorly understood because they are tightly intertwined with purely sensory processes. Here we isolated visually guided orienting activity from sensory activity using scalp-recorded event-related potentials (ERPs). By recording ERPs to a lateral stimulus and comparing waveforms obtained under conditions of attention and inattention, we identified an early positive deflection over the ipsilateral visual cortex that was associated with the covert orienting of visual attention to the stimulus. Across five experiments, this ipsilateral visual orienting activity (VOA) could be distinguished from purely sensory-evoked activity and from other top-down spatial attention effects. The VOA was linked with behavioral measures of orienting, being significantly larger when the stimulus was detected rapidly than when it was detected more slowly, and its presence was independent of saccadic eye movements towards the targets. The VOA appears to be a specific neural index of the visually guided orienting of attention to a stimulus that appears abruptly in an otherwise uncluttered visual field. McDonald, J. J., Tay, D., Prime, D. J., & Hillyard, S. A. (in press). Isolating the neural substrates of visually guided attention orienting in humans. Journal of Neuroscience. https://doi.org/10.1523/JNEUROSCI.0205-22.2022
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Congratulations to Jennifer Hoffmeister for her first first-author publication! Check out the article here.
Abstract The control processes that guide attention to a visual-search target can result in the selection of an irrelevant object with similar features (a distractor). Once attention is captured by such a distractor, search for a subsequent target is momentarily impaired if the two stimuli appear at different locations. The textbook explanation for this impairment is based on the notion of an indivisible focus of attention that moves to the distractor, illuminates a nontarget that subsequently appears at that location, and then moves to the target once the nontarget is rejected. Here, we show that such delayed orienting to the target does not underlie the behavioral cost of distraction. Observers identified a color-defined target appearing within the second of two stimulus arrays. The first array contained irrelevant items, including one that shared the target's color. ERPs were examined to test two predictions stemming from the textbook serial-orienting hypothesis. Namely, when the target and distractor appear at different locations, (1) the target should elicit delayed selection activity relative to same-location trials, and (2) the nontarget search item appearing at the distractor location should elicit selection activity that precedes selection activity tied to the target. Here, the posterior contralateral N2 component was used to track selection of each of these search-array items and the previous distractor. The results supported neither prediction above, thereby disconfirming the serial-orienting hypothesis. Overall, the results show that the behavioral costs of distraction are caused by perceptual and postperceptual competition between concurrently attended target and nontarget stimuli. Hoffmeister, J. A., Smit, A. N., Livingstone, A. C., & McDonald, J. J. (2022). Diversion of attention leads to conflict between concurrently attended stimuli, not delayed orienting to the object of interest. Journal of cognitive neuroscience, 34(2), 348-364. Congratulations to Daniel Tay for his second first-author publication! Check out the article here.
Abstract The salience-driven selection theory is comprised of three main tenets: (a) the most salient stimulus within a monitored region of the visual field captures attention, (b) the only way to prevent salience-driven distraction is by narrowly focusing attention elsewhere, and (c) all other goal-driven processes are possible only after the most salient item has been attended. Evidence for and against this theory has been provided from two experimental paradigms. Here, event-related potentials (ERPs) recorded in a novel Go/No-Go paradigm disconfirmed all three of tenets of the theory. Participants were instructed to search cyan-item displays for a salient orientation singleton (Go trials) and to ignore randomly intermixed yellow-item displays that could also contain an orientation singleton (No-Go trials). ERP components associated with attentional orienting (posterior contralateral N2; N2pc), distractor suppression (distractor positivity; PD), and stimulus relevance (P2a) were isolated to test predictions stemming from the salience-driven selection theory. On No-Go trials, the salient oddball elicited a PD rather than an N2pc, indicating that it was suppressed, not attended. Moreover, a P2a emerged before the N2pc on Go trials, demonstrating that observers first evaluated the global color of each display and then decided to search for the oddball (Go trials) or to ignore it (No-Go trials). We conclude that goal-driven processes can lead to the prevention of salience-driven attention capture by salient visual objects within the attentional window. Tay, D., Jannati, A., Green, J. J., & McDonald, J. J. (2022). Dynamic inhibitory control prevents salience-driven capture of visual attention. Journal of Experimental Psychology: Human Perception and Performance, 48(1), 37–51. https://doi.org/10.1037/xhp0000972 Congratulations to Andrea Smit for her first-author publication! Check out the article here.
Abstract Evening‐type individuals often perform poorly in the morning because of a mismatch between internal circadian time and external social time, a condition recognized as social jet lag. Performance impairments near the morning circadian (~24 hr) trough have been attributed to deficits in attention, but the nature of the impairment is unknown. Using electrophysiological indices of attentional selection (N2pc) and suppression (PD), we show that evening‐type individuals have a specific disability in suppressing irrelevant visual distractions. More specifically, evening‐type individuals managed to suppress a salient distractor in an afternoon testing session, as evidenced by a PD, but were less able to suppress the distractor in a morning testing session, as evidenced by an attenuated PD and a concomitant distractor‐elicited N2pc. Morning chronotypes, who would be well past their circadian trough at the time of testing, did not show this deficit at either test time. These results indicate that failure to filter out irrelevant stimuli at an early stage of perceptual processing contributes to impaired cognitive functioning at nonoptimal times of day and may underlie real‐world performance impairments, such as distracted driving, that have been associated with circadian mismatch. Smit, A. N., Michalik, M., Livingstone, A. C., Mistlberger, R. E., & McDonald, J. J. (2020). Circadian misalignment impairs ability to suppress visual distractions. Psychophysiology, 57(2), e13485. On October 1st, the psychology department at SFU hosted their third annual Lab fair! The fair is a great place to showcase the current research we are doing, as well as speak to students who are interested in being a part of our work, either as a participant or as a volunteer. The first picture shows post-doc Andrea and honours student Victoria, and the second picture shows MA student Daniel.
HEL members Andrea Smit, Jennifer Hoffmeister, and David McInytre presented their poster titled: "Caffeine fix?: Neurophysiological measures of visual attention on the world’s most popular drug" at the World Sleep Congress 2019 in Vancouver BC.
World Sleep 2019 is a full scientific congress on sleep medicine and research taking place from September 20-25, 2019 in Vancouver, Canada. The sleep congresses bring sleep professionals from more than 75 countries together to advance sleep health worldwide. The congress will feature the most current, world-class scientific content in the field of sleep medicine and research. Congratulations to Daniel Tay for his first-author publication! It is now available online. Be sure to check it out!
Abstract Identifying a fixed‐feature singleton that pops out from an otherwise uniform array of distractors elicits an ERP component called the N2pc over the posterior scalp. The N2pc has been used to track attention with millisecond accuracy, inform theories of visual selection, and test for specific attention deficits in clinical populations, yet it is still unclear what neuro‐cognitive process gives rise to the component. One hypothesis is that the N2pc reflects a spatial filtering process that suppresses irrelevant distractors. In support of this hypothesis, Luck and Hillyard (1994a) showed that the N2pc is eliminated when the features of the target and distractors switch unpredictably across trials (so that participants cannot prepare to filter out irrelevant items). The present study aimed to replicate Luck and Hillyard’s singleton detection experiment but with modifications to enhance the N2pc signal and to gain statistical power. We show that orientation singletons do, in fact, elicit the N2pc as well as an earlier‐onset and longer‐lasting singleton detection positivity over the occipital scalp when the target and distractor orientations swap randomly across trials. We conclude that spatial filtering might not play a major role in the generation of the N2pc and that the selection processes required to search for fixed‐feature targets (in feature‐search mode) are also engaged in the detection of variable‐feature singletons (in singleton detection mode). Tay, D., Harms, V., Hillyard, S. A., & McDonald, J. J. (2019). Electrophysiological correlates of visual singleton detection. Psychophysiology, e13375. This past year has been an exciting one for our HEL EEG lab! We had some renovations in our lab and thought we would document the process as well as look back down memory lane. To start, here are a few photos of our setup from many years ago in the early years of HEL. Here are some photos of the lab before the renovations began, as well as during the process! Finally, our finished lab! It feels much more open and welcoming with out new shelves and booth set ups.
Congratulations to John Gaspar for his first-author publication! This article just been made available online!
Abstract Individuals with high levels of anxiety are hypothesized to have impaired executive control functions that would otherwise enable efficient filtering of irrelevant information. Pinpointing specific deficits is difficult, however, because anxious individuals may compensate for deficient control functions by allocating greater effort. Here, we used eventrelated-potential indices of attentional selection (the N2pc) and suppression (the PD) to determine whether high trait anxiety is associated with a deficit in preventing the misallocation of attention to salient, but irrelevant, visual search distractors. Like their low-anxiety counterparts (n = 19), highly anxious individuals (n = 19) were able to suppress the distractor, as evidenced by the presence of a PD. Critically, however, the distractor was found to trigger an earlier N2pc in the high-anxiety group but not in the low-anxiety group. These findings indicate that, whereas individuals with low anxiety can prevent distraction in a proactive fashion, anxious individuals deal with distractors only after they have diverted attention. Gaspar, J. M., & McDonald, J. J. (2018). High level of trait anxiety leads to salience-driven distraction and compensation. Psychological Science. Advance online publication. doi: 10.1177/0956797618807166 Congratulations to our HEL honours students Katelyn Baertsch and David McIntyre for completing the Honours program and their undergraduate degrees!
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