2 research outputs found
Decision making under time pressure: an independent test of sequential sampling models
No full textChoice probability and choice response time data from a risk-taking decision-making task were compared with predictions made by a sequential sampling model. The behavioral data, consistent with the model, showed that participants were less likely to take an action as risk levels increased, and that time pressure did not have a uniform effect on choice probability. Under time pressure, participants were more conservative at the lower risk levels but were more prone to take risks at the higher levels of risk. This crossover interaction reflected a reduction of the threshold within a single decision strategy rather than a switching of decision strategies. Response time data, as predicted by the model, showed that participants took more time to make decisions at the moderate risk levels and that time pressure reduced response time across all risk levels, but particularly at the those risk levels that took longer time with no pressure. Finally, response time data were used to rule out the hypothesis that time pressure effects could be explained by a fast-guess strategy
Intentional inhibition of actions in humans
No full textA crucial component of human behavioural flexibility is the capacity to inhibit actions at the last moment before action execution. This behavioural inhibition is often not an immediate reaction to external stimuli, but rather an endogenous ‘free’ decision. Knowledge about such ‘intentional inhibition’ is currently limited, with most research focused on stimulus-driven inhibition. This thesis will examine intentional inhibition, using several different experimental approaches. The behavioural experiments reported in the initial chapters found that intentional inhibition directly alters sensory processing during decision-making. In addition, there were unique effects of prior event sequences on subsequent decisions to either act or inhibit. Brain imaging methods using EEG and fMRI showed distinct neural mechanisms associated with intentional inhibition, which did not apply to rule-based inhibition. Work with Tourette syndrome patients indicated that the intentional inhibition of involuntary motor tics affects brain activity associated with voluntary actions. Furthermore, attentional manipulation strategies were shown to be highly effective in reducing tics, which may open up alternative behavioural treatment approaches for tic disorders. This thesis concludes by demonstrating that intentional inhibition is a bona fide cognitive function worth studying. It also develops a cognitive model in which behavioural inhibition varies along a continuum from ‘instructed inhibition’ to ‘intentional inhibition’. This model may be useful as a guide for future work
