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 procodures 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.