Context control of negative transfer induced by preexposure to irrelevant stimuli: Latent inhibition in humans

New associations to formerly irrelevant stimuli are made more slowly than to the same stimuli when they are novel. This negative transfer phenomenon, termed latent inhibition (LI), has been extensively investigated in the animal literature. The present set of studies examines LI in humans and, in particular, the effects of several types of context manipulations on LI. Four experiments were conducted. LI was produced when the context in which stimulus preexposure occurred was the same as the test context (Experiments 1, 3, and 4). LI was attenuated when the stimulus preexposure and test contexts were different (Experiment 1). LI attenuation also occurred as a function of change of context from preexposure to test when additional context preexposure preceded stimulus preexposure in that context (Experiment 2). An explicit context extinction procedure failed to reduce the amount of LI (Experiment 3). Finally, it was shown that stimulus and context preexposures must occur conjointly in order for LI to develop (Experiment 4). The effects of the different context manipulations on LI are similar to those obtained in animals and congruent with the notion that preexposure context serves as an occasion setter for the activation of a stimulus-no consequence association.