Personality and Choice Behaviour

Background

A key theory in personality psychology suggests that extraversion is linked to how sensitive someone is to rewards. Within clinical psychology, a similar perspective is offered for trait anhedonia (the reduced capacity to experience pleasure), which dimensional approaches to psychopathology identify as a narrow facet of extraversion. To date, few studies have investigated both extraversion and anhedonia in relation to behavioural tasks assessing reward sensitivity. One exception is a study by Blain et al. (2021), which found that broad extraversion (but not anhedonia) predicted reward sensitivity in a probabilistic reward task. In our study, we aimed to investigate whether these findings would replicate by using the same reward task and administering self-report questionnaires on extraversion at different levels of the trait hierarchy, along with comprehensive assessments of trait anhedonia.

Research Questions / Hypotheses

1. Does extraversion predict reward sensitivity?
2. Do specific facets of extraversion predict reward sensitivity?
3. Does anhedonia predict reward sensitivity?
4. What is the relationship between extraversion, anhedonia, and reward sensitivity?

Participants

A total of 551 participants completed the study. Of these, 131 participants were removed for providing poor-quality data on the questionnaire, and 48 were removed for failing attention checks in the behavioural task. The final sample comprised 372 participants.

Methods

Participants completed a computerised probabilistic reward task. In the task, participants were presented with a cartoon face that had eyes but no mouth. A line representing a mouth was quickly flashed onto the face, and participants were required to press a key to indicate whether they saw the short mouth (shorter line) or the long mouth (longer line). Before beginning the task, participants were informed that they would receive 4 cents for correct responses and that not all of their correct responses would be rewarded. For each participant, correct identification of one mouth stimulus was randomly chosen to be rewarded three times as often as the other, but participants were not informed of this. Once the task was complete, participants completed a survey consisting of Big Five personality questionnaires and trait anhedonia measures.

Results

We conducted two-way repeated measures ANOVAs and found that both assertiveness and hedonism (facets of extraversion) as well as anticipatory pleasure (an anhedonia scale) had significant interactions with task block in predicting reward sensitivity. Therefore, the relationship between these self-reported traits and response bias varied across the three blocks of the task. We also used structural equation modelling and found that, contrary to Blain et al. (2021), broad extraversion was not a significant predictor of reward sensitivity. In contrast, we found that the narrow facet of Assertiveness, and two anhedonia scales were significant predictors of reward sensitivity. We plan to use a computational model designed for this probabilistic reward task for further analyses.

Implications

Ultimately, this study did not replicate the finding that extraversion predicts reward sensitivity. Instead, we found that a specific, narrow trait of extraversion, as well as anhedonia, may predict reward sensitivity. These results reflect the complex relationship between extraversion, anhedonia, and reward sensitivity and highlights the need for further investigation. These findings will be addressed in a PhD level thesis and will also be presented at a Personality Psychology conference in December, 2024.