Effect of signaling intertrial unconditioned stimuli in autoshaping.

Abstract

Context-unconditioned-stimulus (US) associations have been suggested as the mediator of the response decrement that occurs when extra USs are added to the intertrial intervals (ITIs) of an otherwise standard Pavlovian conditioning situation. The present autoshaping experiments were concerned with the effect of signaling those extra USs, since such signaling might be expected to lessen their ability to condition the context. Experiments 1 and 2 showed that signaling the ITI USs did reduce their detrimental effects on responding to the conditioned stimulus (CS). To determine whether that reduction was due to an impact of signaling on the target-CS-US association or on performance to the target-CS, Experiment 3 examined responding to differentially trained CSs in a common context, as well as responding to identically trained CSs in differentially trained contexts. Whether the CS was tested in a context of relatively high or low associative strength, more responding occurred to the CS trained with signaled, as compared with unsignaled, ITI USs; further, there was more responding to that CS in the more highly valued context. The pattern of results suggests that contextual value does interact with CS-US learning and may also affect performance to the CS.

The Cover-Stimulus Effect: Role of Similarity in Durations of The CS and Cover Cues

“…The present results are quite similar to those of Cooper et al (1990) who studied pigeon autoshaped responding, as in the present study. Durlach (1983) also studied autoshaped behavior and reported comparatively high levels of responding; however, unique to that study was cover-cue pretraining.…”

“…In conformity to previous studies , a cover cue pretraining phase similar to that of Durlach (1983) was instituted in Experiment 2 to establish the cover cue as an effective conditioned stimulus which might, in turn, permit higher levels of responding to the CS .…”

“…For example, Durlach (1983) showed that the competition model of Rescorla and Wagner (1972) provided a good account for her data. In contrast, Cooper et al (1990) presented data that were not readily accounted for by the Rescorla-Wagner model, but that could be accommodated by the deletion comparator model, a version of Scalar Expectancy Theory (Gibbon & Balsam, 1981).…”

“…Under the signaled random procedure (Cooper, Aronson, Balsam, & Gibbon, 1990;Durlach, 1982Durlach, , 1983Williams, 1994), a random temporal relation between the CS and US is arranged such that the CS and US are occasionally paired, but p(USICS) = p(USIGS). All unpaired US presentations, however, are preceded by a second cue, called the cover stimulus.…”

“…All unpaired US presentations, however, are preceded by a second cue, called the cover stimulus. Durlach (1983) exposed two groups of pigeons to a random arrangement between a CS and an US under an autoshaping procedure. For both groups, 25% of the US presentations were preceded by the CS.…”