Decision by sampling and rank order effects in value judgement and decision making
Mullett, Timothy L. (2014) Decision by sampling and rank order effects in value judgement and decision making. PhD thesis, University of Nottingham.
This thesis uses the Decision by Sampling model as a basis for examining effects of rank order encoding in value judgement and preferential choice. A range of experiments are reported, and these employ a variety of methodologies including behavioural paradigms, eye tracking and functional MRI. The results show that when there are a relatively small number of values used during an experiment, participants encode utility based upon the rank order of a potential outcome within these values. By introducing different decision contexts where the experienced values have a positive or negative skew, an individual’s utility curve can be made concave and risk averse or convex and risk seeking. These different utility curves can be produced within the same individual and same task simply by providing a contextual cue for each trial. Two fMRI experiments demonstrate the neural systems underlying this phenomenon. The results show that all regions of the reward network encode reward as a function of the reward’s rank order within the current context. No region of the brain was found to encode a reward’s absolute financial value.
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