Sense of Agency - Determinants in Personality and Substance Use

Sense of agency entitles the feeling of control over the own actions. The strength of this sense varies inter-individually. This means, people differ in the perception concerning the intensity of their intentions and actions. The current study aims to determine factors influencing this sense of agency on a personality level. Furthermore, it gives insight into the correlative relation between the strength of the sense of agency and substance use. Therefore, 210 participants have been tested for the experiment (intentional binding paradigm for sense of agency, hand paradigm for intentionality bias, questionnaires FAD-Plus, NI-20, substance use). Significant determinants in personality were narcissism (vulnerable subtype) and substance use (consume in general beyond cannabis, and particularly for the substances cannabis, ecstasy or cocaine). Both groups were associated with a weaker sense of agency compared to controls. For both results, alterations in the dopaminergic system need to be discussed. The present results confirm prior hypotheses that dopamine seems to play a crucial role in perception of agency. Possibly, a higher accessibility of dopamine increases sense of agency (hyper-binding), whereas a lower accessibility of dopamine decreases sense of agency (hypo-binding). A second aim of the study was to see, whether there is a connection between sense of agency and intentionality bias. The perception of intention in others differs widely – some people tend to see arbitrary or accidental actions as unintentional, others quickly label ‘intentional’ although the information is not distinct for a categorization. This cognitive error is called intentionality bias. Results could not confirm a relationship between the two constructs - one’s own intention and judging intention in others - in this study. This may be due to lack of connection between the two constructs or due to methodical aspects. Further directions and limitations are discussed