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.
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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. 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 Greg Christie for his first-author publication! Be sure to check it out online.
Abstract In the present study, we investigated whether salience determines the sequence of selection when participants search for two equally relevant visual targets. To do this, attentional selection was tracked overtly as observers inspected two items of differing physical salience: one a highly salient color singleton, and the other a less salient shape singleton. Participants were instructed to make natural eye movements in order to determine whether two line segments contained within the two singletons were oriented in the same or in different directions. Because both singleton items were task-relevant, participants had no reason to inspect one item before the other. As expected, observers fixated both targets on the majority of trials. Critically, saccades to the color singleton preceded saccades to the less salient shape singleton on the majority of trials. This demonstrates that the order of attentional object selection is largely determined by stimulus salience when task relevance is equated. Christie, G. J., Spalek, T. M., & McDonald, J. J. (2018). Salience drives overt selection of two equally relevant visual targets. Attention, Perception, & Psychophysics, 80(6), 1342-1349. |
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