Dopamine, appetitive reinforcement, and the neuropsychology of human learning: An individual differences approach

Personality research is usually perceived as lying towards the " softer " end of psychological inquiry, seemingly far from the " harder " neural mechanisms, processes, and neurological lesions which are the daily stuff of neuropsychology. As biologically-oriented personality psychologists, however, we have always tried to couch our proposals in brain-behavioural terms and have even offered suggestions as to the " neuropsychology " of personality traits such as anxiety and their related clinical conditions (e.g., Gray, 1982). Furthermore, several other personality theorists have also drawn from the rich materials of behavioural neuroscience (e. In this chapter we continue to apply our neuropsychological approach to personality: specifically focusing on the effects of personality traits on learning tasks. The usual reaction of our more traditional neuropsychology colleagues is to express a varying degree of scepticism about any attempt to explore the neuropsychology of personality. It is therefore perhaps worth reflecting at the start of this chapter on the possible reasons for such a reaction. One possible concern is that of severity. The subjects who participate in a personality study are healthy after all and so it might be expected that the range of variation of brain functioning that they would display would be relatively small. There are many studies of the effects of personality on cognitive task performance, for example those focusing on trait anxiety (Eysenck, 1992). These studies show that significant personality-task correlations can be readily obtained. Furthermore, we believe that new neuroscience methods will enable researchers to illuminate the neurobiological bases of these differences between individuals. Another concern, which is potentially more serious, is that of specificity. Neuropsychology traditionally attempts to detect relationships between specific brain functions and the specific brain structures that are damaged in the patients being studied. Personality traits, even when they have a strong biological basis, may reflect mechanisms that are distributed over a wide neural network of structures (e. However, the idea that specific brain structures may act more or less independently, and that the corresponding psychological functions may be empirically isolated, is an oversimplification that does not reflect the richly interconnected nature of the brain. In keeping with this, there has been a detectable shift away from notions of strict localisation of function in contemporary neuropsychology. This trend has been encouraged by connectionist models, which have emphasised distributed processing (e.g., Rumelhart & McClelland, 1986), and by the often widely dispersed patterns of neural activation …