Extinction of Pavlovian conditioned inhibition.

Examined 2 procedures with potential for reducing Pavlovian conditioned inhibition in 4 experiments with 72 male Sprague-Dawley rats. The 1st, simple nonreinforced presentation, was suggested by a theory which has been successful with data from the acquisition of conditioned inhibition. However, nonreinforced presentation of a stimulus, either after conditioned inhibition training or intermixed with such training, failed to produce any loss of the inhibition controlled by that stimulus. The 2nd procedure involved removing the negative correlation between inhibitor and reinforcement. When this correlation was altered, in such a way as to continue UCS presentation, loss of inhibition occurred. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparator mechanisms and conditioned inhibition: Conditioned stimulus preexposure disrupts Pavlovian conditioned inhibition but not explicitly unpaired inhibition.

Three conditioned lick-suppression experiments with rats examined the effects of pretraining exposure to the conditioned stimulus (CS) on behavior indicative of conditioned inhibition. After CS-preexposure treatment, subjects received either Pavlovian conditioned inhibition training or explicitly impaired inhibition training with the preexposed CS. The inhibitory status of the CS was then assessed with a retardation (Experiment 1) or a summation (Experiment 2) test. Experiment 3 controlled for the unconditioned stimulus-preexposure effect being a potential confound in Experiments 1 and 2. As predicted by the comparator hypothesis (R. R. Miller & L. D. Matzel, 1988), the CS–context association that developed during the CS-preexposure phase disrupted the expression of Pavlovian conditioned inhibition but not the expression of explicitly impaired inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A reevaluation of Rescorla's early dictums about Pavlovian conditioned inhibition.

R. A. Rescorla's (1969) recommendations concerning the logical and empirical operations for inferring Pavlovian conditioned inhibition were examined in light of modern comparison theories of Pavlovian conditioning and new data that question whether excitation and inhibition are opposite ends of a single continuum of associative strength. This reanalysis confirms Rescorla's dictum that the summation and retardation tests are a sufficient basis for inferring inhibition. No theoretical or empirical challenges since 1969 undermine the heuristic or explanatory power of that concept. However, passing both of the 2 operational tests may not be necessary: A conditioned stimulus/stimuli (CS) may be inhibitory, yet may not pass one or the other test. Recent changes in the conception of inhibition are also reviewed, and it is suggested that there may be other forms of associatively based inhibition that are not at all antagonistic to excitation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pavlovian second-order conditioned analgesia.

Three experiments, with 118 Sprague-Dawley rats, assessed conditioned analgesia in a Pavlovian 2nd-order conditioning procedure by using inhibition of responding to thermal stimulation as an index of pain sensitivity. In Exp I, Ss receiving 2nd-order conditioning showed longer response latencies during a test of pain sensitivity in the presence of the 2nd-order conditioned stimulus (CS) than Ss receiving appropriate control procedures. Exp II found that extinction of the 1st-order CS had no effect on established 2nd-order conditioned analgesia. Exp III evaluated the effects of post 2nd-order conditioning pairings of subcutaneous morphine sulfate (10–20 mg/kg) and the shock unconditioned stimulus/stimuli (UCS). Ss receiving paired morphine–shock presentations showed significantly shorter response latencies during a hot-plate test of pain sensitivity in the presence of the 2nd-order CS than did Ss receiving various control procedures; 2nd-order analgesia was attenuated. Data extend the associative account of conditioned analgesia to 2nd-order conditioning situations and are discussed in terms of the mediation of both 1st- and 2nd-order analgesia by an association between the CS and a representation or expectancy of the UCS, which may directly activate endogenous pain inhibition systems. (52 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Second-order conditioning and Pavlovian conditioned inhibition: Operational similarities and differences.

Procedures for establishing 2nd-order excitation (CS1-unconditioned stimulus [UCS] trials followed by CS2-CS1 trials) are highly similar to those for Pavlovian conditioned inhibition (CS1-UCS trials interspersed with CS2-CS1 trials). Conditioned suppression in rats was used to identify the critical operational differences that result in 2nd-order excitation as opposed to Pavlovian inhibition. No, few, or many CS2-CS1 trials were either interspersed with or given after CS1-UCS trials. CS2 proved excitatory only after few CS2-CS1 trials, either interspersed or sequential (Exp 1). In contrast, CS2 proved inhibitory on both summation (Exp 2) and retardation (Exp 3) tests only after many CS2-CS1 trials, and then only when the excitatory status of CS1 was preserved. Apparently, the critical difference for establishing 2nd-order excitation or Pavlovian inhibition is the number of CS2-CS1 pairings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Within-compound associations modulate the relative effectiveness of differential and Pavlovian conditioned inhibition procedures.

Four conditioned suppression experiments with 98 male albino rats compared the inhibitory strength of a Pavlovian conditioned inhibitory stimulus (CS–) and a differential CS– and identified some postconditioning manipulations that modulate the measured effectiveness of the CS–. In Exp I, more inhibition was detected to a differential inhibitor than to a Pavlovian inhibitor in summation and retardation tests. Exps II–IV provided evidence that some inhibition conditioned to the Pavlovian CS–, but not to the differential CS–, was masked by a within-compound association. In Exp II, postconditioning extinction presentations of the Pavlovian conditioned excitatory stimulus (CS+) increased the inhibition observed to its CS–. In Exp III, postconditioning pairings of the Pavlovian CS+ with a more powerful UCS than that used for conditioning reduced the inhibition observed to its CS–. In Exp IV, nonreinforced postconditioning presentations of the Pavlovian CS– increased the inhibition observed to that CS–. The unmasking and masking of inhibition conditioned to the Pavlovian CS– by operations that modulate the strength of the within-compound association also changed the relative effectiveness of the Pavlovian and differential procedures. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Facilitation of instrumental behavior by a Pavlovian appetitive conditioned stimulus.

In Exp I, 16 New Zealand white rabbits were trained to perform an instrumental head-raising response for sucrose reward. A jaw-movement CR was established to a 2-sec CS by pairing it with sucrose; a control stimulus was unpaired with sucrose. Instrumental responding maintained by a VI 40-sec schedule was enhanced during 10-sec presentations of the paired, but not the unpaired, CS. Responding on a VR 15 schedule was unaffected except on trials on which the pre-CS baseline response rate was low; in such cases the paired CS caused a long-lasting acceleration of responding. Noncontingent presentation of the sucrose reinforcer itself briefly suppressed responding but had no long-term effect. In Exp II (6 Ss), a CS that had been conditioned at a 10-sec duration produced the same pattern of effects as in Exp I, indicating that facilitation resulted from CS presentation rather than from the frustrative effects of nonreinforcement of the CS. In Exp III (16 Ss), an inhibitory CS blocked facilitation by the excitatory CS but did not itself affect instrumental responding. (53 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Amphetamine-induced conditioned activity is insensitive to perturbations known to affect Pavlovian conditioned responses in rats.

Psychostimulant-induced conditioned activity is characterized by the presence of a hyperactivity in drug-free rats exposed to an environment previously paired with the effects of a psychostimulant. This phenomenon is thought to result from a Pavlovian conditioning process. This hypothesis predicts that conditioned activity will be sensitive to perturbations known to affect classical conditioned responses. In direct contrast with this prediction, the authors report here that conditioned activity is insensitive to (a) the temporal order between the stimulant injection and the exposure to the environment, (b) unsignaled stimulant injections between drug-environment pairings, and (c) drug preexposures before the start of drug-environment pairings. It is concluded that the stimulant effects responsible for the establishment of conditioned activity may not be amenable to a Pavlovian associative process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acquired appetitive responding to intravenous nicotine reflects a Pavlovian conditioned association.

Recent research examining Pavlovian appetitive conditioning has extended the associative properties of nicotine from the unconditioned stimulus or reward to include the role of a conditional stimulus (CS), capable of acquiring the ability to evoke a conditioned response. To date, published research has used presession extravascular injections to examine nicotine as a contextual CS in that appetitive Pavlovian drug discrimination task. Two studies in the current research examined whether a nicotine CS can function discretely, multiple times within a session using passive iv infusions. In Experiment 1, rats readily acquired a discrimination in conditioned responding between nicotine and saline infusions when nicotine was selectively paired with sucrose presentations. In Experiment 2, rats were either trained with nicotine paired with sucrose or explicitly unpaired with sucrose. The results showed that rats trained with explicitly unpaired nicotine and sucrose did not increase dipper entries after the infusions. Nicotine was required to be reliably paired with sucrose for control of conditioned responding to develop. Implications of these findings are discussed in relation to tobacco addiction, learning theory, and pharmacology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioned stimulus determinants of conditioned response form in Pavlovian fear conditioning.

Four experiments using barpress conditioned suppression in rats found that tone evoked more freezing (immobility) than did light. Still, tone and light appeared to have similar conditioned value as assessed by suppression in Experiments 1, 2, and 3, and by blocking, second-order conditioning, and overconditioning assays in Experiments 1, 2, and 3, respectively. Experiment 4 arranged for tone to evoke less suppression than light but more freezing. Results suggest that in fear conditioning, the nature of the conditioned stimulus affects the form of conditioned responding (strong vs. weak freezing). This conclusion extends one drawn by P. C. Holland (see record 1977-12147-001) on the basis of his work in appetitive conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparator view of Pavlovian and differential inhibition.

In 3 experiments using rats as subjects, the authors varied trial spacing to investigate the conditions under which Pavlovian and differential inhibition are observed. Experiment 1 compared Pavlovian and differential inhibition with spaced training trials. Spaced trials resulted in only the Pavlovian inhibitor passing both summation and retardation tests. Conversely, Experiment 2 compared these 2 types of inhibition with massed training trials. This training resulted in only the differential inhibitor passing both tests for conditioned inhibition. Finally, in Experiment 3 all subjects experienced Pavlovian inhibition training with massed trials. Although this training by itself did not result in behavior indicative of inhibition, subjects that also experienced posttraining extinction of the training context did pass both tests for inhibition. Overall, these results are anticipated by the extended comparator hypothesis (Denniston, Savastano, & Miller, 2001) but are problematic for most contemporary associative learning theories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pavlovian appetitive contingencies and approach versus withdrawal to conditioned stimuli in pigeons.

Investigated the directed skeletal movements of 21 female White Carneaux pigeons toward signals of food or no food in 3 experiments. Ss approached and pecked an illuminated key that was positively correlated with food delivery, and positioned themselves relatively far from an illuminated key that was negatively correlated with food delivery. Key illuminations alone, random presentations of key illuminations and food, and backward pairings of key illuminations and food did not produce keypecking or consistent approach-withdrawal. Therefore, directed skeletal behavior-often believed to be conditioned and maintained primarily or exclusively by operant procedures-also emerges on Pavlovian procedures. Several kinds of alternative explanations (e.g., conditioned reinforcement effects, and stimulus substitution) for these phenomena are considered, and some potential implications for operant discrimination learning are briefly explored. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Pavlovian conditioned stimulus-unconditioned stimulus pairings during avoidance response-prevention trials in rats.

Response prevention (blocking) has been shown to hasten extinction of an instrumental avoidance response. One interpretation suggests that the facilitation effect is mediated by Pavlovian fear reduction during conditioned stimulus exposure on blocked trials. To test the fear-reduction hypothesis 30 male Holtzman albino rats received either a typical blocking treatment, blocking with shock, or extinction alone. Results indicate that blocking with the UCS was as effective as regular blocking in facilitating extinction of avoidance. An ancillary part of the experiment to assess the effectiveness of response prevention in 30 immature Ss showed that blocking did not facilitate extinction with the weanlings. Findings suggest that facilitated extinction is not solely attributable to Pavlovian fear reduction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Latent inhibition in the conditioned electrodermal response.

Measured the effects of preexposure to the CS, amount of pre-exposure, and delay between pre-exposure and conditioning in a classical electrodermal conditioning experiment with 139 female nursing students. 3 conditions were investigated: no delay, 1-hr delay, and 24-hr delay. In each of these delay conditions Ss were pre-exposed to either 100 or 50 presentations of the to-be-conditioned stimulus or 100 or 50 presentations of an irrelevant stimulus. Results were analyzed separately for long and short latency responses in terms of amplitude, magnitude, latency, recruitment, and frequency. It was found that CS pre-exposure reduced the frequency of responding regardless of delay or number of pre-exposures. There was a significant CS Pre-exposure main effect for short latency responses and a significant Trial Blocks * CS Pre-exposure interaction effect for long latency responses. Theoretical and methodological implications are discussed. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simultaneous backward conditioned inhibition and mediated conditioning.

Demonstrations of retrospective revaluation suggest that remembered stimuli undergo a reduction in association with the unconditioned stimulus (US) present during learning. Conversely, demonstrations of mediated conditioning in flavor-conditioning experiments with rats suggest that remembered stimuli undergo an increase in association with the US present during learning. In a food allergy prediction task with 23 undergraduates, we demonstrated simultaneous backward conditioned inhibition and mediated conditioning effects. These results are compatible with the hypothesis that the direction of change (decrease or increase) in associative strength depends on whether the remembered stimulus was of a different category (conditioned stimulus/antecedent) or the same category (US/outcome) as the presented US. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Ontogeny of conditioned inhibition in domestic chicks.

Used the combined-cue test to measure age-dependent changes in learned stimulus inhibitory control in 40 young Vantress * Arbor Acre chicks trained to key peck for heat reinforcement. Both 1- and 4-day-old chicks were given either 96 or 384 discrete trials in a successive discrimination test, and then their response latencies to the novel combined cue (S+, S-) and the prior S+ cue were compared with those of age-matched controls during extinction. Major findings are as follows: (a) One-day-old chicks showed significant response suppression to the combined cue only after receiving 384 discrete trials, whereas 4-day-old chicks showed significant response suppression after both 96 and 384 trials. (b) While control chicks (S+ training only) of both age groups pecked more quickly at the novel cue than at the prior S+ cue during extinction, only the younger chicks pecked more quickly at the novel cue as the number of their prior S+ responses increased. The main conclusion from these experiments is that even the 1-day-old chick has the capacity to acquire learned inhibitory stimulus control but does so at a slower rate than the 4-day-old chick. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Food-reinforced inhibition of conditioned salivation in dogs.

12 mongrel dogs salivated to a tone that was followed by food, but not to a noise for which there was an added response dependency. The noise was followed by food if and only if they did not salivate. The addition of this response dependency vitiated the classically conditioned response to the noise. A yoked-control group of 6 Ss receiving the same sequences of stimuli and food salivated to both the tone and noise stimuli. It is generally concluded that neither the effects of stimulus-dependent reinforcement nor the effects of response-dependent reinforcement are restricted to either skeletal or autonomic responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transfer of negative occasion setting and conditioned inhibition across conditioned and unconditioned stimuli.

The transfer of negative occasion setting and conditioned inhibition across conditioned stimuli (CSs) and unconditioned stimuli (USs) was examined in four experiments that used Pavlovian appetitive feature negative discrimination training procedures with rats. After training with simultaneous compounds (A+, XA–), X inhibited conditioned responding (CRs) elicited by other CSs and CRs supported by other appetitive USs that had not been involved in discrimination training. After training with serial compounds (A+, X→A–), X's power to set the occasion for nonresponding transferred across CSs and USs only if those events had also been involved in serial feature negative discrimination training. The results supported the suggestion that the acquisition of negative occasion setting involves the representation of individual events in a higher order memory system, separate from that involved in simple association, and that negative occasion setters act only on events that are represented in that system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Facilitation of instrumental behavior by a Pavlovian appetitive conditioned stimulus". Correction to Lovibond.

Reports an error in the article, "Facilitation of Instrumental Behavior by a Pavlovian Appetitive Conditioned Stimulus" by Peter F. Lovibond (Journal of Experimental Psychology: Animal Behavior Processes, 1983, Jul, Vol. 9, No. 3, pp. 225-247)." Part of the second sentence on page 227 was omitted, and the correction is presented here. (The following abstract of this article originally appeared in record 1984-08705-001.) In Exp I, 16 New Zealand white rabbits were trained to perform an instrumental head-raising response for sucrose reward. A jaw-movement CR was established to a 2-sec CS by pairing it with sucrose; a control stimulus was unpaired with sucrose. Instrumental responding maintained by a VI 40-sec schedule was enhanced during 10-sec presentations of the paired, but not the unpaired, CS. Responding on a VR 15 schedule was unaffected except on trials on which the pre-CS baseline response rate was low; in such cases the paired CS caused a long-lasting acceleration of responding. Noncontingent presentation of the sucrose reinforcer itself briefly suppressed responding but had no long-term effect. In Exp II (6 Ss), a CS that had been conditioned at a 10-sec duration produced the same pattern of effects as in Exp I, indicating that facilitation resulted from CS presentation rather than from the frustrative effects of nonreinforcement of the CS. In Exp III (16 Ss), an inhibitory CS blocked facilitation by the excitatory CS but did not itself affect instrumental responding. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Disconnection of the basolateral amygdala complex and nucleus accumbens impairs appetitive Pavlovian second-order conditioned responses.

There is considerable evidence that the basolateral complex of the amygdala (ABL) is involved in learning about the motivational value of otherwise neutral stimuli. The authors examined the role in this function of the ABL and one of its major efferent structures, the nucleus accumbens. Male Long-Evans rats received either sham, ipsilaterally. or contralaterally placed unilateral lesions of the ABL and accumbens and were trained in an appetitive Pavlovian second-order conditioning task. Sham-lesioned and ipsilaterally lesioned rats acquired the task normally, but contralaterally lesioned rats, in which the ABL and accumbens were functionally disconnected, failed to acquire second-order conditioned responses (although they did acquire second-order conditioned orienting responses). The results suggest that the ABL and accumbens are part of a system critical for processing information about learned motivational value. (PsycINFO Database Record (c) 2010 APA, all rights reserved)