Latent inhibition in human Pavlovian differential conditioning: Effect of additional stimulation after preexposure and relation to schizotypal traits

Latent inhibition has been defined as the retardation of Pavlovian conditioning due to conditioned stimulus (CS) preexposure. The present study investigated (1) the effect of additional stimulation signalling the shift from preexposure to acquisition, and (2) the relationship between "schizotypal traits" and latent inhibition in human electrodermal conditioning. Three groups (48 subjects) were presented with 20 preexposure, 8 acquisition, and 8 extinction trials in a differential conditioning paradigm. One group received different stimuli during preexposure and acquisition, whereas the remaining groups (SAME, SAME + S) received the same stimuli throughout the experiment. In group SAME + S, an additional signal was presented at the end of the preexposure phase. Latent inhibition was evident in electrodermal first interval response conditioning during acquisition and second interval response conditioning during acquisition and extinction. Contrary to results from animal research, latent inhibition was not disrupted by the additional signal in group SAME + S. A covariation of schizotypal traits and latent inhibition was detected in both groups preexposed to the CSs. During acquisition, latent inhibition of electrodermal first interval response conditioning was evident in subjects scoring low in "schizotypy", but not in high scorers. The latter results replicate previous findings obtained from a different latent inhibition paradigm.