Name: Jiwon Yeon
Dissertation Defense Meeting
Date: Thursday, July 8, 2021
Time: 9:00 AM
Location: Virtual, https://bluejeans.com/257276793/9737

Advisor: Dobromir Rahnev, Ph.D. (Georgia Tech)

Dissertation Committee Members:
Thackery Brown, Ph.D. (Georgia Tech)
Audrey Duarte, Ph.D. (Georgia Tech)
Kobe Desender, Ph.D. (KU Leuven)
Brian Odeggard, Ph.D. (University of Florida)

Title: Dissociating the brain regions involved in processing objective and subjective performance

Abstract: When making perceptual decisions, easier tasks produce higher task accuracy and, naturally, higher confidence levels. We recognize the two distinctive cognitive processes, but it is challenging to judge exactly how decision and confidence processes affect different brain regions. In the current study, I aimed to reveal which brain regions are activated by objective and subjective performance, respectively. The experiment was a 2 x 2 factorial design, where one factor was task difficulty (i.e., Easy and Difficult conditions) and the other was the number dots presented for the visual stimulus (i.e., High and Low conditions). Different from what observed in the pilot test, the main experiment did not dissociate task performance and confidence level in High and Low conditions. Contrast tests revealed different patterns of activation for Easy > Difficult and Low > High comparisons. However, because behavioral responses for decision and confidence were not clearly separated, it is hard to interpret what those activated regions are associated with. Moreover, none of the regions were able to distinguish either task difficulty or confidence level in the planned MVPA analysis. Meanwhile, I found weak dissociation in the behavioral responses between Difficult-High and Difficult-Low conditions. When contrasting the two conditions each other, I found left middle temporal gyrus (MTG) and right SPL were activated more in Difficult-Low condition compared to Difficult-High condition. Importantly, the right SPL cluster was similar to the right SPL observed in Low > High contrast test. The current study was unfortunately not able to draw a strong conclusion about the task performance and confidence level, and the brain regions associated with those cognitive processes. Nevertheless, partial data of the study showed weak dissociation effect. To understand how the brain computes two cognitive processes that are seemingly separable, it is important to create stable conditions where task performance and confidence level are dissociated and investigate how the brain differently associated with those processes.