Context dependent latent inhibition in adult humans.

Abstract

Learning the association between one stimulus (a condition stimulus, CS) and another (unconditioned stimulus, US) can be impaired by prior exposure to the CS alone--latent inhibition (LI). Current theories attempting to elucidate the cognitive deficit in schizophrenia have used the abolition of LI in schizophrenia as an indicator of attentional dysfunction. However, it has always been unclear if human and animal LI are measuring the same psychological processes. It is obviously important to clarify this relationship so that theoretical and experimental developments in the rat do not mislead the investigation of brain-behaviour relationships in schizophrenia. LI in the rat is strongly dependent upon context. Our aim was to examine the context specificity of LI in humans and specifically to: (1) investigate whether participants' belief that they are in a different context is sufficient to abolish LI, even though there is no physical change in the environment; (2) produce a context manipulation that is immune to alternative interpretation in terms of stimulus generalization decrement; and (3) investigate whether a "tonic" change of context reduces or abolishes human LI, thus complementing previous reports using a "phasic" change of context. In two experiments we manipulated context in either the real world or a virtual world, and showed that LI is abolished by a change of context in adult humans.