Low sensitivity to reward enhances learning in a latent inhibition task.

A68
In Latent Inhibition (LI), the association between a target conditioned stimulus (CS) and unconditioned stimulus (US) is weakened through pre-
exposure (PE) to the CS prior to learning. Typically this results in reduced ability to learn the association between the CS and US compared to a non
pre-exposed (NPE) group. LI has long been established as a test of selective learning that is sensitive to personality variables that can be measured
psychometrically. In healthy participants, individual differences in the tendency to show LI should be related to personality measures of reward
sensitivity such as those measured by the BAS subscales of the BIS/BAS (Carver & White, 1994, J Pers Soc Psychol, 67, 319-333). The present study
therefore examined the effects of BAS Fun Seeking, BAS Drive, and BAS Reward Responsiveness on learning the association between a CS and US in
a computerised LI task. The pharmacological basis of BAS is theorised to be dopaminergic and since LI is sensitive to dopaminergic treatments it was
predicted that participants with high BAS would learn the CS-US association faster and that this might be particularly evident in the PE group.
51 neurotypical participants were tested, aged between 18 and 33. In the LI task the CS was white noise that was pre-exposed (without consequence)
or not, in stage one, and was immediately followed by the US (which was the increment of a number counter) in stage two. In addition to the measures
of LI, baseline levels of conditioning were measured. In all cases, responding was measured as pressing ‘z’ on a computer keyboard. Testing was
followed by administration of the BIS/BAS. Analysis of variance was used to identify main effects and interactions which were explored further using
independent t-tests, where required.
As expected, there was an LI effect with the PE group taking a greater number of trials overall to learn the CS-US association. BAS Drive, BAS Reward
and BIS had no significant effect on LI. There was a clear effect of BAS Fun Seeking, but contrary to prediction, this was manifested as faster learning
in the low Fun Seeking group across both PE and NPE groups.
Findings are not accounted for by differential baseline levels of conditioning. One account of findings might be that being less reward sensitive improves
learning in the LI task because fewer attentional resources are focused on the US outcome.