An Examination of the Multi-Faceted Motivation System in Healthy Young Adults

Abstract

Background: Amotivation is a prevalent symptom in schizophrenia (SZ) and depression (MDD), and is linked to poor functional outcomes in affected individuals. Conceptualizations of motivation have outlined a multi-faceted construct comprised of reward responsiveness, reward expectancy, reward valuation, effort valuation, and action selection/preference-based decision making. To date, findings from studies utilizing variable-centered approaches to examining isolated facets of motivation in SZ and MDD have been inconsistent. Thus, the present study adopted a person-centered approach, and comprehensively examined the reward system in a non-clinical sample in an attempt to explore potential subtypes of motivation impairments, while minimizing the effects of illness-related confounds. Methods: Ninety-six healthy undergraduate students were evaluated for amotivation, schizotypal traits, depressive symptoms, and cognition, and administered objective computerized tasks to measure the different facets of motivation. Cluster analysis was performed to explore subgroups of individuals based on similar motivation task performance. Additionally, correlational analyses were conducted in order to examine inter-relationships between motivation facets, and relations between clinical measures and facets of motivation. Results: Cluster analysis identified two subgroups of individuals with differential motivation performance profiles. Correlational analyses revealed that reward responsiveness was associated with amotivation, depressive symptoms, and negative schizotypy. Further, significant inter-correlations were found between reward responsiveness and reward expectancy, as well as between reward valuation and effort valuation. Conclusions: Our results mark important steps forward in understanding motivation in a non-clinical sample, and guide future dimensional and comprehensive analyses of the multi-faceted reward system. It remains to be seen whether these patterns of results will be similar in clinical populations such as SZ and MDD.

Keywords: RDoC; amotivation; depressive symptoms; reward system; schizotypal traits.

Figure 1

Schematic representation of a single trial in the International Affective Picture Rating System (IAPS) task (36). In this example, pleasantness and arousal ratings must be made for a positive-valence image.

Figure 2

Schematic depicting the trial sequence in the Cued Reinforcement Reaction Time (CRRT) task (38). In this example, 100 points are awarded for a fast response on a high probability reinforcement trial.

Figure 3

Examples of items utilized in the Kirby Delay Discounting questionnaire [Kirby DD; (40)].

Figure 4

Schematic depicting the trial sequence in the Effort Expenditure for Rewards Task [EEfRT; (24)]. In this example, the hard task was selected and successfully completed on a high reward magnitude and high probability trial.

Figure 5

Screenshots of the virtual city in the Multitasking in the City Test [MCT; (45)].

Figure 6

Motivation performance profiles across clusters. Significant differences are denoted by ^**p < 0.01. Error bars represent standard error of the mean.