Name: Mark Pillai

School of Psychology – Masters Thesis Defense Meeting

Date: Wednesday, July 23rd, 2025

Time: 2:00 pm - 3:00pm

Location: Virtual, Meeting link click here

Thesis Chair/Advisor:

Randall Engle, Ph.D. (Georgia Tech)

Thesis Committee Members:

Audrey Leroux, Ph.D. (Georgia Tech)

Mark Wheeler, Ph.D. (Georgia Tech)

Title: Task-Evoked Pupillary Reveal a Role for Attentional Intensity in Auditory Discrimination

Abstract: Sensory discrimination has long been theorized to reflect a core cognitive function underlying intelligence. Building on this tradition, we examined whether task-evoked pupil responses, as an index of mental effort, relate to attention control (AC) and auditory discrimination ability. Using a large dataset (N = 336), participants completed three adaptive auditory discrimination tasks (pitch, duration, loudness), a cognitive battery assessing attention control, working memory, and fluid intelligence, and pupillometry during task performance. Structural equation modeling confirmed that attention control predicted auditory discrimination thresholds and fully mediated the relationship between task-evoked pupil dilation and performance. Trial-level multilevel models revealed that higher task difficulty and errors were associated with larger pupil dilations, especially in demanding tasks. Crucially, individuals with greater AC exhibited steeper increases in pupil dilation with rising task difficulty and were more resilient to performance declines. For high-AC individuals, large pupil responses predicted preserved accuracy; for low-AC individuals, they signaled compensatory effort with diminished success. These results suggest that attention control governs both the extent and efficacy of mental effort, determining whether high arousal facilitates or fails to improve performance. This work refines classic resource models by demonstrating that cognitive effort, indexed via pupillometry, supports perception most effectively when guided by strong executive control. Findings support a hierarchical model in which attention control serves as the functional bridge between arousal, sensory discrimination, and higher-order cognition.