Here’s a spin on the depressive realism story. Shiv et al (2005) found that substance abusers and those with brain damage affecting their emotions had enhanced performance on an investment task. According to the authors of the study, the normal controls were actually distracted from making optimum decisions by their emotional involvement in the task.
‘The dark side of emotion in decision-making: When individuals with decreased emotional reactions make more advantageous decisions’ Baba Shiv, George Loewenstein and Antoine Bechara. Cognitive Brain Research, 23(1), April 2005, Pages 85-92. summary here
Abstract:
Can dysfunction in neural systems subserving emotion lead, under certain circumstances, to more advantageous decisions? To answer this question, we investigated how individuals with substance dependence (ISD), patients with stable focal lesions in brain regions related to emotion (lesion patients), and normal participants (normal controls) made 20 rounds of investment decisions. Like lesion patients, ISD made more advantageous decisions and ultimately earned more money from their investments than the normal controls. When normal controls either won or lost money on an investment round, they adopted a conservative strategy and became more reluctant to invest on the subsequent round, suggesting that they were more affected than lesion patients and ISD by the outcomes of decisions made in the previous rounds.
Mind Hacks 
I didn’t read the full paper on this study, but I found it funny to see Bechera who worked with Damasio, talking about the that. Damasio told the importance of emotion in rationnal thinking and on the others hand, the disconnection could be good. Is there to system for the connection between rationnal and emotion ? Or is it the same with different damage, I’ll have to find out !
With a task designed in a particular way you could make any style of cognition advantagous compared to any other. That said, it is interesting that an investment task – one that is presumably close enough in general form to some things we all have to do in our everyday lives – is performed better by the emotionally dysregulated.