SAFETY SIGNALS AND THE ACQUISITION AND EXTINCTION OF LEVER-PRESS DISCRIMINATED AVOIDANCE IN RATS.

Rats learned a discriminated avoidance response more rapidly when a safety signal occurred following an escape or avoidance response. Two extinction procedures were used: complete omission of shock or delivery of an unavoidable shock at the end of the warning period. Under the latter procedure, avoidance-extinction responding was initially higher but subsequently declined to the same level as under the omission procedure. Under each extinction procedure, animals were divided into two subgroups: safety signal and no-safety signal. The safety signal did not significantly effect avoidance responses in extinction per se, but it did result in fewer extra responses during the inter-trial and safety periods following an avoidance-extinction response. With no-safety signal there was an increase over extinction sessions in the numbers of such extra responses, especially in the shock delivery subgroup. [ABSTRACT FROM AUTHOR]