Correlations Between Inhibition and Memory Components of Executive Function and Measures of Autistic Traits in the General Population

Abstract

This thesis comprises two studies (with the second study building upon the first) to assess core components of executive function orthogonally. Executive function can be defined as the combination of goal representation in working memory and the inhibition of goal-irrelevant responses stimuli. Both studies employed a paradigm with two tasks assessing working memory and inhibitory control processes concurrently. The modified Flanker task measured working memory and interference control, while the modified Spatial Conflict task measured working memory and response inhibition. The thesis aimed to examine main effects of memory and inhibitory load in each task when assessed concurrently, explore potential over-additive interactions between these executive function components, and investigate correlations between autistic traits in the general population and task performance.
In each study with 100 participants aged 18-25, Study 1 found that in the Flanker task, how quickly people reacted was significantly affected by the demands on working memory and inhibitory control. In the Spatial Conflict task, the time it took to react was strongly influenced by whether the presented information matched or conflicted (congruency). There's some suggestion that memory played a role, especially in incongruent trials (when the information conflicted). When it came to accuracy, congruency had a strong impact, but memory didn't seem to affect it.
In Study 2, significant progress was achieved through the implemented modifications. In the Spatial Conflict task, effects on reaction time were observed due to both memory and congruency load, and accuracy showed meaningful influence from congruency. Moderate evidence supporting a memory effect, particularly in congruent trials, was noted in accuracy. The Flanker task revealed
a memory effect in both reaction time and accuracy. However, there was no evidence of a congruency effect in accuracy, and the congruency effect in reaction time was only evident in the low memory condition. Interactions between executive function components were not observed, and over-additive interactions were not supported.
Furthermore, Bayesian linear regression and correlation analyses found no meaningful evidence of an increasing correlation between task performance and ASC traits with increasing memory and inhibitory load. These tasks hold potential for future research in concurrently measuring core executive function components.

Date of Award	19 Mar 2024
Original language	English
Awarding Institution	University of Bristol
Supervisor	Chris Jarrold (Supervisor) & Karla Holmboe (Supervisor)