| Abstract: | In the blocking paradigm, prior training to one conditioned stimulus (CSA) blocks the ability to attend to a second conditioned stimulus (CSB) when the two form a compound (CSAB) in subsequent training. Blocking is an associative process by which animals learn to ignore CSB because it contains no new information regarding the reinforcing event. In Experiment 1, dopamine (DA) receptor supersensitivity was induced in rats by prolonged pretreatment with haloperidol. The animals with DA receptor supersensitivity failed to show blocking by responding equivalently to both elements of the CSAB compound. This effect was replicated in Experiment 2, which also tested for an arousal interpretation of disrupted blocking by introducing a novel stimulus following training. Supersensitive rats were no more responsive to this novel stimulus than were control animals, which supports a selective attention deficit interpretation of disrupted blocking with DA receptor supersensitivity. This attentional deficit resembles behavioral perseverations induced by DA agonists. |
