Second-order conditioning in a licking-based conditioned suppression situation

Abstract

Two experiments were conducted to investigate second-order conditioning in a licking-based conditioned suppression situation. Experiment I and the first half of Experiment II demonstrated that substantial second-order conditioning could be obtained in this situation. The second half of Experiment II provided a fact that the ability of S2 to elicit the (second-order) CR could be reduced by the extinction of the response to SI and augmented by the paired presentation of Si and the augmented US. The results were interpreted from the affirmative point of view concerning the S2-S I hypothesis that the association formed between S2 and SI might be involved in second-order conditioning.

The effect of on‐ or off‐line extinction of a first‐order conditioned stimulus on a second‐order conditioned response in rats

“…Water was available throughout the experiment, including the CR1 extinction phase (we term this an "on-line" procedure). As far as we know, there is only one published study besides Fujii's (1981) that tested CR2 after the extinction of CR1 in conditioned licking suppression in rats (Barnet et al, 1991). In that study, CR1 extinction was conducted "off-line" (i.e., water not available during the extinction phase) and there was no attenuation of CR2, which is consistent with the general finding but not with Fujii's.…”

“…The results were essentially the same as Fujii's (1981), namely, attenuation of CR2 after the extinction of CR1.…”

“…As in Fujii's (1981) study and our unpublished experiments, the extinction of CR1 attenuated CR2 when the extinction was conducted "online." When the extinction was conducted "off-line," however, the extinction of CR1 had no effect on CR2, as also found by Barnet et al (1991), which suggests a CS2-CR1 connection.…”

“…However, one exception to this general finding was reported from our laboratory by Fujii (1981). In a study of the conditioned suppression of licking in rats, he used serial presentation of CS2 followed by CS1 for second-order conditioning, and the modalities of these stimuli were different (auditory and visual).…”

“…In Fujii's (1981) research, as well as in our replication study, the conditioned suppression of licking in thirsty rats was used, and the conditioned response (CR) to the conditioned stimulus (CS) was measured in terms of the suppression of ongoing water licking by that CS. Water was available throughout the experiment, including the CR1 extinction phase (we term this an "on-line" procedure).…”