Extinction of Comparator Stimuli during and after Acquisition: Differential Facilitative Effects on Pavlovian Responding

The mechanisms of extinction were examined by reducing the intensity of the unconditioned stimulus (US) after acquisition training to determine whether such reductions lie on a continuum with CS-alone extinction. The experiments revealed that reductions in US intensity yielded extinction-like effects. Specifically, there were proportional reductions in the daily mean level of responding across sessions. There were also persistent within-session declines and between-session increases of responding analogous to spontaneous recovery. Surprisingly, even when US intensity was held constant, within-session declines and between-session increases were apparent. The results are discussed with respect to possible contributions from unlearning, new learning, generalization decrement, and nonassociative loss, especially CS-specific attentional changes and CR-specific reactive inhibition. EXTINCTION AND US INTENSITY 97the conditioned response (CR) with a 4-mA shock US, each of four groups was presented with a lower US intensity. In addition to CS-alone extinction (no US), three reduced US intensities were used: 0.5, 1, and 2 mA. The latter two values are known to produce reliable CR acquisition in the rabbit nictitating membrane (NM) preparation (Napier, Macrae, & Kehoe, 1992;Smith, 1968). Method

Section: A Hybrid Modelmentioning

confidence: 99%

Extinction revisited: Similarities between extinction and reductions in US intensity in classical conditioning of the rabbit’s nictitating membrane response

Kehoe

White

2002

“…Evidence for both retrieval-interference theory and comparator theory has come from experiments that subjected CS A to extinction following training of the AX compound (e.g., Blaisdell et aI., 1999;Cole, Barnet, & Miller, 1995;Harris & Westbrook, 1998;Kaufman & Bolles, 1981;Matzel, Schachtman, & Miller, 1985;Matzel, Shuster, & Miller, 1987;Yin, Grahame, & Miller, 1993). Such extinction should weaken X's comparator, A-US, association according to comparator theory and should weaken the source of retrieval interference according to retrieval-interference theory.…”

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confidence: 99%

Conditioned inhibition training of the competing cue after compound conditioning does not reduce cue competition

Rauhut

McPhee

Dipietro

et al. 2000

In each of two experiments, we studied Pavlovian fear conditioning (as assessed by barpress conditioned suppression) in 32 albino rats. Following a two-stage cue-competition procedure (A+ then AX+), we subjected the competing cue (A) to conditioned inhibition training (B+, BA-) before testing the target cue (X). Conditioned inhibition training was designed to weaken the putative A-unconditioned stimulus (US) association, perhaps changing it to an A-no-US association. Performance-deficit theories of cue competition, such as comparator theory and retrieval-interference theory, predict that such procedures should weaken cue competition, causing Conditioned Stimulus X (CS X) to evoke strong responding. The same prediction can be deduced from recent acquisition-focused models (Dickinson & Burke, 1996;Van Hamme & Wasserman, 1994). In opposition to this prediction, however, we found in both experiments that conditioned inhibition training had no detectable effect on cue competition even though it successfully abolished conditioned responding to CS A. In Experiment 2, moreover, we found evidence against the hypothesis that the weak response to CS Xwas due to generalization decrement rather than to cue competition. Results favor early learning-deficit theories of cue competition over performance-deficit theories and over the recent acquisition-focused models.

“…On the one hand, these studies have failed to observe a decrease in conditioned performance to A when reinforced exposures to an AB compound were followed by reinforced exposures to B (e.g., Kalat & Rozin, 1972;Schweitzer & Green, 1982). On the other hand, there are numerous studies, using fear conditioning in rats, that have shown that overshadowing of one element (A) ofa reinforced AB compound can be reversed by posttraining extinction of B (Kaufman & Bolles, 1981;Matzel, Schachtman, & Miller, 1985;Yin, Grahame, & Miller, 1993). Similarly, latent inhibition ofa CS was attenuated by extensive exposure to the training context (i.e., context extinction) following CS-US pairings (Grahame, Barnet, Gunther, & Miller, 1994).…”

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confidence: 99%

“…Thus, the detection ofevidence for retroactive revaluation may depend on whether A borrows associative strength from B on test. For example, in several ofthe experiments by Miller and his colleagues (e.g., Grahame et a!., 1994;Yin et a!., 1993), retroactive revaluation of a discrete CS was brought about by extinction of the training context. In these experiments, the critical CS-context associations would have been relatively weak in comparison with the strong odor-taste associations established in the experiment reported by Durlach and Rescorla (1980).…”

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confidence: 99%

Retroactive revaluation of an odor-taste association

Harris

Westbrook

1998

Rats showed an increase or decrease in preference for an aqueous odor conditioned stimulus (CS) presented in compound with a palatable (sucrose) or unpalatable (quinine) taste unconditioned stimulus (US), respectively. Four experiments then studied the consequences for odor preference of presenting water in the context where the odor-taste compound had previously occurred (i.e., no-CSno-US experience). Exposure to that context increased the preference for the odor associate of sucrose and decreased preference for the odor associate of quinine. The increased preference for the odor associate of sucrose was contingent on reexposure to the context where the odor-sucrose compound had occurred (i.e., retroactive revaluation) and was reduced by preexposure to the context where the odor-sucrose compound was to occur (Le.,latent inhibition of the context). The retroactive revaluation of within-event learning caused by exposures to the associated context is discussed in terms of (1) the modified version of the SOP model (Wagner, 1981) proposed by Dickinson and Burke (1996)and (2) the comparator model (Miller & Matzel, 1988).Contemporary theories ofassociative learning have been strongly influenced by demonstrations that responding to a target conditioned stimulus (CS) is modulated by the status of that and other CSs present during training. Interference effects such as overshadowing, blocking, and latent inhibition have inspired theories that describe the mechanisms by which CSs compete for attentional processing and for associative strength with the unconditioned stimulus (US) (Mackintosh, 1975;Pearce & Hall, 1980;Rescorla & Wagner, 1972;Wagner, 1981). Thus, these theories typically attribute variations in conditioned responding to differences in the acquisition ofassociations during CS-US pairings. Moreover, these theories assume that modulation of CS-US associations can occur only when the animal is directly exposed to the CS.However, this view has been challenged by demonstrations that performance to a CS can be increased or decreased retroactively by changing the associative strength between other CSs and the US. For example, studies investigating learning of stimulus-outcome relations in human subjects have shown that performance to an overshadowed stimulus can be retroactively increased by posttraining exposures to the paired stimulus. Specifically, if subjects learn the association between a compound cue, AB, and a particular outcome, then the predictive value accorded A can be retroactively decreased by paired presentations of B and the outcome (Chapman, 1991;Dickinson