The Role of tDCS and Subjective Beliefs in

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Approach-avoidance behaviours play a big role in various parts of our daily life and can range from more controlled, explicit behaviours to more automatic, implicit tendencies. Controlled approach behaviour has been associated with relative greater left than right activity in the dorsolateral prefrontal cortex, with studies inducing this pattern of brain activity finding an increase in controlled approach behaviour. However, it is not known whether or not this also holds true for more implicit approach-avoidance behaviours. It is therefore not known if brain stimulation can increase implicit approach behaviour. Furthermore, subjective beliefs about interventions such as brain stimulation techniques have been shown to influence the results of the interventions. Therefore, it is also not known if inducing the subjective belief that the stimulation increases approach behaviour, actually leads to increased approach behaviour. We expected active compared to sham tDCS and the subjective belief induction compared to control instructions to results in increased approach behaviour, measured in reaction times. In order to test this, 39 healthy volunteers were assigned to either a manipulation condition in which a subjective belief about the transcranial direct current stimulation was induced, or a control condition which did not receive this manipulation. Both groups completed two blocks of a joystick task measuring implicit approach-avoidance behaviour. The first block of the task was accompanied by sham stimulation and the second block was accompanied by active stimulation. The results showed that neither stimulation nor subjective beliefs influenced implicit approach-avoidance behaviour. However, active stimulation led to an overall reduction in reaction times. It is possible that tDCS and subjective beliefs cannot influence implicit approach behaviour.
Faculteit der Sociale Wetenschappen