  Understanding the affective, cognitive and behavioural processes involved in
risk taking is essential for treatment and for setting environmental conditions
to limit damage. Using Temporal Difference Reinforcement Learning (TDRL) we
computationally investigated the effect of optimism in risk perception in a
variety of goal-oriented tasks. Optimism in risk perception was studied by
varying the calculation of the Temporal Difference error, i.e., delta, in three
ways: realistic (stochastically correct), optimistic (assuming action control),
and overly optimistic (assuming outcome control). We show that for the gambling
task individuals with 'healthy' perception of control, i.e., action optimism,
do not develop gambling behaviour while individuals with 'unhealthy' perception
of control, i.e., outcome optimism, do. We show that high intensity of
sensations and low levels of fear co-occur due to optimistic risk perception.
We found that overly optimistic risk perception (outcome optimism) results in
risk taking and in persistent gambling behaviour in addition to high intensity
of sensations. We discuss how our results replicate risk-taking related
phenomena.
