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AN ELECTROENCEPHALOGRAPHY INVESTIGATION OF THE EFFECTS OF ATTENTION ON CROSSMODAL TEMPORAL ACUITY

Charlotte Babarinsa, Zoey Keeley, Kathryn Hirabayashi, Samantha Papadakis, Zoii Barnes-Scott, Russell Jaffe, Leslie D Kwakye

The ability to accurately integrate sensory information from our environment, a concept known as multisensory integration, is an integral mechanism in information processing that allows us to create a coherent perception of the world around us. The accuracy of this integration is heavily reliant on our ability to precisely distinguish timing differences between unisensory stimuli (crossmodal temporal acuity). Our previous research investigated whether attention alters crossmodal temporal acuity using a crossmodal temporal order judgment (CTOJ) task in which participants were asked to report if a flash or beep occurring at different time intervals appeared first while concurrently completing a visual or auditory distractor task. We found that increasing the perceptual load of the distractor task led to sharp declines in participants’ crossmodal temporal acuity. The current study uses electroencephalography (EEG) to understand the neural mechanisms that lead to decreased crossmodal temporal acuity. Participants completed a CTOJ task as described above while EEG activity was recorded using 64 scalp electrodes. Behavioral results demonstrated that in support of previous research, increasing perceptual load decreased crossmodal temporal acuity regardless of the modality of the distractor task. We found that increasing auditory load led to differences in ERP amplitude approximately 300-1000 ms post onset of the first CTOJ stimulus. In contrast, when increasing visual load, differences in ERP amplitude were found 100-200 ms after the onset of the visual stimulus regardless of which stimulus was presented first. These results indicate that while visual distractors seem to be altering early modality-specific processing, auditory distractors primarily altered integrative or decision-making mechanisms. These findindings demonstrate that visual and auditory distractors may influence crossmodal temporal acuity through differing mechanisms although the behavioral effects of the two distractor tasks were highly similar.

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Supervised Research: Text

FAMILIARIZATION INCREASES FACE INDIVIDUATION MEASURED WITH FAST PERIODIC VISUAL STIMULATION

Sara C.Verosky, Katja A.Zoner, Corinne W. Marble*, Margaret M. Sammon*, Charlotte O.Babarinsa

People are better at recognizing familiar versus unfamiliar faces. The current study investigated whether familiarity would lead to a larger face individuation response as measured via fast periodic visual stimulation (FPVS). While electroencephalography (EEG) was recorded, participants viewed oddball sequences of faces made up of more versus less familiarized faces. In each sequence, a single base face was repeated at a rate of 6 Hz and oddball faces with different identities were presented every fifth face (6 Hz/5 = 1.2 Hz). As in previous studies, significant face individuation responses were observed at 1.2 Hz and its harmonics, with the strongest responses located over right occipito-temporal electrode sites. Despite a relatively minimal learning manipulation, the face individuation response over right occipito-temporal sites was stronger for more versus less familiarized faces. These results suggest that the fast-periodic visual oddball paradigm offers a promising means for investigating face learning.

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Supervised Research: Text

IMPLICIT RESPONSES TO FACE TRUSTWORTHINESS

Sara C. Verosky, Katja A. Zoner, Corinne W. Marble*, Margaret M. Sammon*, & Charlotte O. Babarinsa

People rapidly and spontaneously form trustworthiness impressions based on facial appearance.  Studies using fMRI find that activity in the amygdala and other regions tracks with face trustworthiness, even when participants are not explicitly asked to judge face trustworthiness.  The current study investigated whether it would be possible to detect implicit responses using another method: fast periodic visual stimulation (FPVS). While EEG was recorded, participants viewed sequences of faces where a single base face was presented at a rate of 6 Hz and oddball faces with different identities were presented every fifth face (6 Hz/5=1.2 Hz).  The oddball faces were all either untrustworthy- or trustworthy-looking. The base face was also untrustworthy- or trustworthy-looking, meaning it matched the oddball faces on trustworthiness or did not match. Although participants’ task was unrelated to the faces, the trustworthiness of the oddball faces had a strong influence on the response at 1.2 Hz and its harmonics.  There was a stronger response for sequences with untrustworthy- versus trustworthy-looking oddball faces over bilateral occipito-temporal cortex, medial occipital cortex, and beyond. In contrast, the match in trustworthiness between the base face and the oddball faces had only a minimal effect. The effect of oddball type was observed after a short recording time, suggesting that FPVS offers a useful means of capturing implicit responses to face trustworthiness.

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Supervised Research: Text
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