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Assessment of Auditory Cognitive Resource Deployment on the Modified Paced Auditory Serial Addition Task using Pupillometry and fNIRS

Poster Session B - Sunday, March 8, 2026, 8:00 – 10:00 am PDT, Fairview/Kitsilano Ballroom

Jeremy Loebach¹ (loebach@stolaf.edu), Mary Hendrickson², Aaron Thomsas Rejimon³, Amara Geibel⁴, Alexis Long⁵, Elizabeth Pederson⁶; ¹St. Olaf College

The Modified Paced Auditory Serial Addition Task (mPASAT) continuously presents spoken digits at a fixed rate requiring listeners to sum subsequent digits. Difficulty varies by increasing presentation rates from 5-4-3-2-1 seconds across blocks. Here we compare behavioral data (accuracy and reaction time), pupillometric data (Pupil Labs) and functional near infrared spectroscopy (Artinis Brite, 10-20 system) measures of BOLD activity in 28 individuals to assess how neural resource management converges across methods. Preliminary analysis reveals that accuracy decreases across ISIs (93%-92%-57%-50%-0%, from 5 to 1 second trials). For correct trials, reaction times decreased from 2.32 seconds at 5 second ISIs to 1.31 seconds at 2, giving participants more time to recover before subsequent stimuli at longer ISIs. Performance related pupil dilation changes were observed across correct trials, with smaller dilations for easier trials, and larger dilations for difficult trials. An s-shaped polynomial dilation pattern was observed over time for 5 and 4 second ISIs showing greater resource use pre-response, and a drip after, leading to better recovery before the next stimulus. The 3 and 2 second ISI trials lacked this recovery phase, explaining the drop in performance. fNIRS data showed increasing hemodynamic response (OHb-hHb) with difficulty. At F8, F7 and Fz optodes, higher accuracy trials (5 second ISI) had the lowest hemodynamic values, which increased as accuracy decreases (4-3-2 second ISIs). Overall, these preliminary findings provide further validation of the mPASAT and demonstrate convergence across the pupillometric and fNIRS measurements of neural resource management.

Topic Area: ATTENTION: Auditory