Positive conditioned suppression: conditioned suppression using positive reinforcers as the unconditioned stimuli

Research has revealed the phenomenon of conditioned suppression in which the rate of responding is reduced during a stimulus that is paired with noncontingent shock. The present study replicated this procedure, but used noncontingent positive reinforcers instead of the aversive shock. The lever-pressing responses of rats were reinforced with food or water. While the rats were responding, a stimulus was occasionally presented and paired with the delivery of a noncontingent positive reinforcer, which was either food, water, or brain stimulation for different rats. The result was a reduction in the rate of responding during the conditioned stimulus. This finding shows that conditioned suppression occurs during a signal for reinforcing as well as aversive stimuli.     

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.     

Conditioned suppression to odorous stimuli in pigeons,

The conditioned suppression technique was employed to establish criterion discrimination of an amyl acetate concentration of 3% of vapor saturation, and to generate differential response rates in the presence of equal concentrations of amyl acetate and butyl acetate. The magnitude of suppression was also recorded as a function of amyl acetate concentration, with the concentrations presented in descending, ascending, and irregular series. The three stimulus presentation procedures generated approximately equivalent suppression versus concentration functions. Amyl acetate suppression thresholds were 0.16%, 0.50%, and 0.73% of vapor saturation for three subjects. Amyl acetate, butyl acetate, and butyric acid thresholds for two additional subjects were approximately 0.10% of vapor saturation. No suppression was recorded during control trials.     

Conditioned acceleration and conditioned suppression in pigeons

Two experiments were performed to investigate the effects on pigeons' keypecking behavior of stimuli that signal different kinds of aversive events: time-out from positive reinforcement, electric shock, loud noise, and loud tone. Behavior maintained by a variable-interval schedule of reinforcement was suppressed by a stimulus before shock, was accelerated by a stimulus before time-out from positive reinforcement, and was unchanged by a stimulus before loud noise or a stimulus before loud tone. Conditioned acceleration with time-out from positive reinforcement and conditioned suppression with shock were obtained regardless of whether a response contingent or response-independent procedure was employed.     

Positive reinforcement and suppression from the same occurrence of the unconditioned stimulus in a positive conditioned suppression procedure

Responding of rats was maintained on a variable-interval schedule of food reinforcement. The same response also produced a blinking light followed by electrical brain stimulation according to a fixed-interval schedule. This conjoint schedule produced two behavioral changes. First, instead of a steady rate of responding throughout the session, which would be characteristic of the variable interval food schedule alone, responding between occurrences of the light-brain stimulation pairings became positively accelerated and thus was more characteristic of the fixed-interval schedule of these pairings. Second, food responding was suppressed during the light that preceded brain stimulation. These results indicate that positive reinforcement and suppression resulted from the same occurrence of the light-brain stimulation combination. This finding suggests that stimuli such as conditioned reinforcers that precede an unconditioned reinforcer may have a suppressive effect upon responding in their presence that is being maintained by another reinforcer.     

Interactions between conditioned and unconditioned flavor preferences

Five experiments investigated how rats' conditioned preferences or aversions for aqueous odors paired with sucrose or salt are affected by their unconditioned response to those tastes. Rats preferred an odor paired with 30% sucrose over an odor paired with 5% sucrose when both were presented in 5% sucrose, but they showed no preference or, if thirsty, showed the reverse preference, when the odors were presented in 30% sucrose. These changes in conditioned preference corresponded to changes in the rats' unconditioned preference for the accompanying sucrose solution. Rats' conditioned aversions for odors paired with salt showed a similar dependence on their reaction to the accompanying salt solution. The results were interpreted as showing that conditioned and unconditioned flavor preferences combine additively, as if mediated by the same sensory representation.     

Conditioned suppression and conditioned enhancement with the same positive UCS: an effect of CS duration

Previous experiments have shown that positively reinforced operant responding is suppressed during a conditioned stimulus terminated with an electric shock (conditioned suppression). In the present experiment, the conditioned stimulus was terminated with a positive unconditioned stimulus, and it was found that the duration of the conditioned stimulus was a key factor in determining whether response suppression or response enhancement was observed during the stimulus. The lever-pressing responses of rats were maintained by a variable-interval schedule of food reinforcement. While the rats were pressing the lever, a light was occasionally turned on, its offset coincident with a brief period of access to a sucrose solution. In consecutive blocks of sessions, the light duration was 40 sec, 12 sec, or 120 sec. Results showed that the rate of lever pressing was substantially suppressed during the 12-sec stimulus, slightly suppressed during the 40-sec stimulus, and enhanced during the 120-sec stimulus.     

Changes in pain reactivity induced by unconditioned and conditioned excitatory and inhibitory stimuli

In three experiments we investigated the effects of aversive-conditioning components on the reactivity of rats to pain. After training in Experiment 1 with a discrete conditioned stimulus (CS) for a shock unconditioned stimulus (US), different groups were exposed to the CS, US, CS/Us compound, just the training context, or none of those immediately prior to a hot-plate test assessing the latency of a paw-lick response. Relative to no exposure and context alone, the CS produced a shorter latency--that is, an apparent sensitization effect--whereas the US produced a longer latency--that is, a hypoalgesic effect--that was actually augmented by the CS/US compound. Furthermore, whereas the US-induced hypoalgesia was unaffected by the opiate antagonist, naloxone, hypoalgesia produced by the CS/US compound was appreciably decremented by the drug. Experiment 2 showed the same effects with parameters more typical of conditioning research. Experiment 3 compared signals for the presence (CS+) and absence (CS-) of the US. The CS- did not itself affect pain reactivity, but in inhibited the effects of the CS+, US, and CS+/US compound. Collectively, the results suggest that a CS+sensitizes the animal to imminent events and also potentiates an opioid reaction that supplants the less effective nonopioid hypoalgesia induced by the US. In contrast, a CS- functions as a general moderator of excitation, inhibiting both sensitization and hypoalgesic effects, whether opioid or nonopioid.     

Evaluative conditioning in the picture-picture paradigm with random assignment of conditioned stimuli to unconditioned stimuli

Human participants were allocated to 1 of 3 groups. In the conditioning group, each conditioned stimulus (CS)-unconditioned stimulus (US) pair was presented 7 times during the acquisition phase. Participants who were assigned to the extinction group saw 5 additional presentations of each CS in isolation after the 7 presentations of each CS-US pair. In the latent inhibition group, the CS-only trials were presented before the CS-US trials. Overall, a significant evaluative conditioning effect was observed. This effect cannot be dismissed on the basis of the arguments developed by A. P. Field and G. C. L. Davey (1997, 1998, 1999), and the results thus provide strong evidence for the associative nature of evaluative conditioning. The results are also in line with other findings, which showed that evaluative conditioning is resistant to extinction.     

Evaluative conditioning without directly experienced pairings of the conditioned and the unconditioned stimuli

Evaluative conditioning (EC) is the valence change of a stimulus (conditioned stimulus, CS) that is due to the previous pairing with another stimulus (unconditioned stimulus, US). We investigated whether EC can occur also when the CS-US pairings are not experienced directly by the participant but are implied by other events that the participant encounters. In two experiments, positive USs were presented in some trials and negative USs in other trials. Afterwards, participants were given information from which it was possible to conclude that CSs were covertly present during these trials. Finally, the valence of these CSs was registered using both implicit (Implicit Association Test, affective priming) and explicit measures (valence ratings). In line with the assumption that EC effects can be based on CS-US pairings that are not directly experienced, the valence of the CSs changed in the direction of the US with which they were covertly paired. This effect was observed both on explicit and on implicit measures. We argue that several aspects of our results are in line with propositional models of EC and fit less well with association formation models.     

Evaluative conditioning without directly experienced pairings of the conditioned and the unconditioned stimuli

Evaluative conditioning (EC) is the valence change of a stimulus (conditioned stimulus, CS) that is due to the previous pairing with another stimulus (unconditioned stimulus, US). We investigated whether EC can occur also when the CS–US pairings are not experienced directly by the participant but are implied by other events that the participant encounters. In two experiments, positive USs were presented in some trials and negative USs in other trials. Afterwards, participants were given information from which it was possible to conclude that CSs were covertly present during these trials. Finally, the valence of these CSs was registered using both implicit (Implicit Association Test, affective priming) and explicit measures (valence ratings). In line with the assumption that EC effects can be based on CS–US pairings that are not directly experienced, the valence of the CSs changed in the direction of the US with which they were covertly paired. This effect was observed both on explicit and on implicit measures. We argue that several aspects of our results are in line with propositional models of EC and fit less well with association formation models.     

On conditioned reinforcing effects of negative discriminative stimuli

Observing responses by pigeons were studied during sessions in which a food key and an observing key were available continuously. A variable-interval schedule and extinction alternated randomly on the food key. In one condition, food-key pecking during extinction decreased reinforcement frequency during the next variable-interval component, and in the other condition such pecking did not affect reinforcement frequency. Observing responses either changed both keylight colors from white to green (S+) or to red (S−) depending on the condition on the food key, or the observing responses never produced the S+ but produced the S− when extinction was in effect on the food key. Observing responses that produced only S− were maintained only when food-key pecking during extinction decreased reinforcement frequency in the subsequent variable-interval component. The red light conformed to conventional definitions of a negative discriminative stimulus, rendering results counter to previous findings that production of S− alone does not maintain observing. Rather than offering support for an informational account of conditioned reinforcement, the results are discussed in terms of a molar analysis to account for how stimuli acquire response-maintaining properties.     

Conditioned suppression of bar-pressing behavior by stimuli associated with drugs

Ten naive male albino rats were trained to press a bar under a variable-interval 30-sec schedule with water as the reinforcer in two experiments. This behavior was disrupted by chlorpromazine in Experiment I (two rats) and by lysergic acid diethylamide (LSD) in both Experiment I (two rats) and Experiment II (six rats). The administration of the drug was paired with an originally neutral white light. After several pairings with either drug, the light also depressed behavior. When the light was no longer paired with drug, the depression effect extinguished much faster than is usually observed in conditioned suppression studies.     

Spontaneous emotion regulation to positive and negative stimuli

The ability to regulate one’s emotions is an integral part of human social behavior. One antecedent emotion regulation strategy, known as reappraisal, is characterized by cognitively evaluating an emotional stimulus to alter its emotional impact and one response-focused strategy, suppression, is aimed at reducing behavioral output. People are capable of using these specific emotion regulation strategies when instructed to do so; however, it is equally important to investigate natural and self-selected strategy use. This study was designed to determine to what extent people spontaneously regulate their emotions and the emotion regulation strategies they choose to achieve their regulatory goals. Participants were given no instructions to regulate their emotions before they were shown a negative and a positive film clip, but were instead asked afterwards about the specific strategies that they had used. Participants reported regulating their emotions more to the negative film than to the positive film. Reappraisal was more frequently selected as an emotion regulation strategy than suppression. As expected, participants with high baseline respiratory sinus arrhythmia (RSA) adopted reappraisal strategies more than those with low RSA but, surprisingly, RSA was not associated with facial expressivity. Suggestions for future research in this relatively young field of spontaneous emotion regulation are offered.     

Factors influencing responding under multiple schedules of conditioned and unconditioned reinforcement

Two experiments examined pigeons' responses under multiple schedules of conditioned and unconditioned reinforcement. In one component, responses produced food according to a fixed-interval schedule; in a second component, responses produced brief stimuli according to a fixed-ratio schedule. When brief-stimulus presentations were paired with food in the first component, rates in the second component were usually higher than 10 responses per minute. When pairing in the first component was eliminated, responding continued to be maintained in the second component. Elimination of food presentation from the first component substantially decreased responding in the second component, even though the brief stimulus had not been paired with food. Experiment II demonstrated that response rate was affected by the duration of both the second component and the brief stimulus. The results suggest that three conditions are important in maintaining responding with brief-stimulus presentations: (1) pairing the brief stimulus, at least initially, with food, (2) maintaining unconditioned reinforcement in one component, and (3) employing optimal brief-stimulus and component durations.