Second-order conditioning of the conditioned emotional response: Some methodological considerations

Employing rats in a CER procedure, the present study sought to determine the extent to which the second-order conditioning effects reported by Rizley and Rescorla (1972) represented first-rather than second-order conditioning. Subjects receiving first-order pairings of flashing light (CS₁) and shock followed by second-order pairings of noise (CS₂) and CS₁ displayed greater suppression to CS₂ than did control subjects receiving second-order pairings in the absence of first-order conditioning. This was true whether or not control subjects had experienced unsignaled shock or habituation to CS₁ prior to CS₂CS₁ pairings. Simple stimulus pairings did produce some suppression to CS₂, however. The procedure developed by Rizley and Rescorla (1972) appears to be a reliable means for producing and studying second-order aversive conditioning.     

Short-term retention of “surprising” events following different training conditions

Terry and Wagner (1975) have suggested that short-term retention of information about an event is enhanced if the occurrence of the event is surprising. To investigate this idea, we trained two groups of pigeons in a preparatory-releaser procedure in which half the trials started with the presentation of food (the preparatory event). The preparatory food presensation was signaled by an 8-sec white keylight in the signaled, but not in the unsignaled, group. After a retention interval, varying between 2 and 32 sec, the releaser stimulus (CS_R), a red keylight, was presented for 8 sec in the absence of any reinforcement. The remaining trials were initiated by the presentation of CS_R, and the first peck occurring 8 sec after the onset of CS_R was reinforced by food. The preparatory event controlled responding to CS_R at the short retention interval, with the level of control declining systematically with increasing retention intervals. On probe test trials, the presentation of the preparatory food event was preceded by a stimulus that had previously been paired (CS+) or unpaired with food (CS?). Discriminative responding to CSr was better following CS? than following CS+ in the unsignaled, but not the signaled, group. These results suggest that the enhanced retention following surprising preparatory events reflects a generalization decrement induced by changing the signaling conditions between training and testing.     

The effect of US omission in classical aversive and appetitive conditioning of rabbits

Rabbits (Oryctolagus cuniculus) were given either a 100% or a 50% reinforcement schedule in classical conditioning. Two groups received an aversive US (shock) and two groups received an appetitive US (water to the oral cavity). With parameter estimates for the two-phase model serving as the dependent variables, it was possible to define more precisely the effect of US omission with the intermittent reinforcement schedule. For the aversive preparation, the major effect of intermittent reinforcement was to increase the duration of Phase 1, a phase during which response likelihood remains constant at its initial value. Only a small proportion of subjects reflected the effect of US omission during Phase 2, the “learning” phase, this being a low operator limit following trials on which neither the CR nor the US occurred. The major effect of US omission for the appetitive preparation was in Phase 2, primarily a result of a minority of subjects having a low operator limit following trials on which neither the CR nor the US occurred. Many subjects required separate operators for trials on which the CR did or did not occur. The results were interpreted to pose difficulties for strength theories of conditioning, and the limitation implied for successful application of the Rescorla-Wagner theory are discussed. The implications of the data for response-contingent interpretations and for individual differences are also discussed.     

Postshock learning and conditioned defensive burying

Natural sources of aversive stimuli are frequently well-defined material objects that are present both before and after the aversive event. In the present experiment, rats acquired information about such a source after the aversive event and used this information to guide their subsequent defensive reactions to it. The rats were shocked by one of two possible sources, either a black or a striped prod, mounted on opposite end walls of the test chamber. Immediately following the shock, the houselights were momentarily extinguished and the patterns on the two prods were automatically switched for subjects in the experimental condition or left unchanged for subjects in the control condition. The rats were left in the chamber for another 5 min with the patterns in their new positions before being removed for 2 min while the two prods were mounted on the side walls. During the ensuing test of conditioned defensive burying, the rats in the control condition directed the majority of their burying behavior at the prod exhibiting the pattern displayed by the shock source prior to and during the shock administration. In contrast, the rats in the experimental group buried the prod exhibiting the pattern displayed by the shock source during the postshock period more than they did the prod displaying the pattern present on the shock source prior to and during the shock administration.     

Differential second-order aversive conditioning using contextual stimuli

Two experiments were conducted to determine if contextual stimuli used as S₂ in a higher-order differential conditioning procedure would control the performance of rats. Discrete stimuli were first paired with footshock in a separate training context. During second-order training, a shock-associated discrete stimulus was presented in one of two discriminable observation chambers. Over 4 days of training, subjects engaged in more freezing in the context associated with an excitatory discrete S₁, relative to a context in which no discrete stimulus, or a stimulus that had been explicitly unpaired with shock delivery, was presented. After acquisition of the second-order discrimination, animals were returned to the original training context where they received a “signaled inflation” treatment designed to change the current value of S₁, and the US. This postconditioning manipulation did not selectively affect performance of defensive freezing or conditional analgesia in S₂.     

Blocking between landmarks during 2-D (touchscreen) and 3-D (ARENA) search tasks with pigeons

Many studies investigating cue competition have focused on the blocking effect. We investigated the blocking effect with pigeons using a landmark-based spatial search task in both a touchscreen preparation (Exp. 1a) and an automated remote environmental navigation apparatus (Exp. 1b). In Phase 1, two landmarks (LMs: A and Z) appeared on separate trials as colored circles among a row of eight (touchscreen) or six (ARENA) identical response units. Subjects were rewarded for pecking at a target response unit to the right of LM A and to the left of an extraneous LM, Z. During the blocking trials in Phase 2, LM X was presented in compound with a second LM (A) that had been previously trained. On control trials, LM Y was presented in compound with LM B and a target in the same manner as in the trials of AX, except that neither landmark had previously been trained with the target. All subjects were then tested with separate trials of A, X, B, and Y. Testing revealed poor spatial control by X relative to A and Y. We report the first evidence for a spatial-blocking effect in pigeons and additional support for associative effects (e.g., blocking) occurring under similar conditions (e.g., training sessions, spatial relationships, etc.) in 3-D and 2-D search tasks.     

Self-punitive avoidance behavior in the mouse

Mice were trained to avoid shock by leaving a startbox and traversing a straight alley. During the first extinction phase (Phase I), two groups were given 30 regular extinction (RE) trials, while another two received punished extinction (PE) trials in the center of the alley. During the last 50 extinction trials (Phase II), conditions were reversed for one of the two groups receiving the same treatment in Phase I. This resulted in two nonshifted groups (RE-RE and PE-PE) and two shifted groups (RE-PE and PE-RE). PE treatment led to higher running speed in both phases and reversed an extinction trend. Furthermore, punishment-induced facilitation was greater for the group receiving PE following RE than for the group receiving PE immediately after avoidance training.

     

Effects of sucrose concentrations on single-alternation performance in rats

In Experiment 1, rats received single-alternation training with 32% or 4% sucrose reward (Phase 1) followed by a shift in reward from 32% to 4%, and vice versa (Phase 2). In Phase 1, high reward facilitated alternation performance over low reward. In Phase 2, performance on rewarded trials increased as reward increased but was unchanged as reward decreased. Performance on nonrewarded trials showed negligible effects of shifts in reward. In Experiment 2, rats received goalbox placements with 32% or 4% sucrose alternated with nonreward in Phase 1; and in Phase 2, they received alternation runway training with the same or the opposite reward from that of placements. Performance on rewarded trials was faster, the higher the reward in runway training; performance on nonrewarded trials was slower, the higher the reward in placements. In Experiment 3, Phase 1 provided placements with 64%, 32%, 16%, or 4% sucrose or dry mash alternated with nonreward; Phase 2 provided alternation runway training with dry mash reward. Alternation prerformance developed more rapidly, the higher the sucrose concentration in placements. Only 64% sucrose produced performance superior to that for dry-mash placements.     

Replacement of event-generated memories of nonreinforcement with signal-generated memories of reinforcement during partial reinforcement training: Effect on resistance to extinction

Event-generated memory refers to the memory of a reinforcement (R) or nonreinforcement (N) event from an immediately preceding trial;signal-generated memory refers to the memory of a temporally remote R or N, retrieval of which is generated by presentation of a signal with which the memory is associated (Haggbloom, 1988). In each of three experiments, Group Signal-R received runway discrimination training in Phase 1 to establish a stimulus as a signal for R, and partial reinforcement training in Phase 2. An extinction test measured learning about the memory of nonreward (S^N)—learning that occurs when S^N is retrieved on R trials that follow N trials. In Group Signal-H, those R trials were accompanied by the signal for R, a treatment we hypothesized would generate retrieval of the memory of reinforcement (S^R) so that signal-generated S^R would replace event-generated S^N as the operative memory, thereby eliminating the increased resistance to extinction normally produced by PRF training. In each experiment, Group Signal-R was less resistant to extinction than was a control group conditioned to respond to-event-generated S^N. Extinction was as rapid in Group Signal-R as it was in a consistent reinforcement control group (Experiment 1) and in a group given intertrial reinforcements to interfere with learning about S^N (Experiment 3). Experiment 2 tested two alternative interpretations of the failure to learn about S^N in Group Signal-R. Those alternatives were found to be less viable than the hypothesis that the signal for R actively recruited retrieval of a competing memory.     

The acquisition of a running response as a function of odor buildup,squad rotation,and introduction of naive subjects

A three-phase experiment was conducted in which rats received a double-alternation schedule of reward and nonreward. During Phase 1, the baseline period, double-alternation behavior was displayed earlier and more strongly by subjects run last in the daily sequence. This finding suggests that both reward and nonreward odor cues are cumulative over subjects. During Phase 2, a subject-rotation procedure was initiated; that is, each day the last subject in the previous day’s running sequence was moved to the first position in the sequence, etc. Rotation to the first position in the group led to an immediate disruption of responding. During Phase 3, two naive rats were inserted at the beginning of the running sequence and two at the end. The results, which showed that the naive animals placed at the end of the sequence acquired the patterning response much faster than those placed in the beginning positions, are interpreted as reflecting preparedness to respond to such intensified odors.     

Need for approval and antisocial behavior moderate the effect of socioemotional cues on adolescent girls’ cognitive control

To examine whether need for approval (NFA) and antisocial behavior (ASB) moderate the effects of socioemotional stimuli on cognitive control, 88 girls (M_age = 16.31 years; SD = 0.84; 65.9% White) completed a socioemotional Go/No-go and questionnaires. At high approach NFA, girls responded more slowly during appetitive than control (b = −8.80, p < .01) and aversive (b = −5.58, p = .01) trials. At high ASB, girls responded more slowly (b = −6.12, p = .02) and less accurately (OR = 1.11, p = .03) during appetitive than aversive trials; at low ASB, girls responded more slowly during aversive than control trials (b = −4.42, p = .04). Thus, both context and individual differences influence adolescents' cognitive control.     

Effects of stress controllability,immunization, and therapy on the subsequent defeat of colony intruders

Three experiments investigated the influence that various stress-controllability manipulations had on the defensive behaviors of rats when they were subsequently tested as intruders in previously established, aggressive colonies of conspecifics. In Experiment 1, naive subjects that had received a session of 80 shocks in a tube showed an enhanced series of defensive responses and received more bites than did a group of restrained nonshocked rats as colony intruders 24 h later. These two measures were also found to be positively correlated within each group. In Experiment 2, a group that was given 80 yoked inescapable shocks, in contrast to a group that had wheel-turn escape training and a restrained nonshocked control group, displayed more defeat and was bitten more frequently when tested as intruders on the following day. In Experiment 3, 60 trials of wheel-turn escape training were given 4 h prior to (i.e., immunization) or after (i.e., therapy) a session of 60 inescapable tube shocks. During resident-intruder testing 24 h later, both of these groups showed less defeat and received fewer bites than did an inescapably preshocked group but did not differ from a restrained nonshocked control group. These findings clearly indicate that stress controllability alters species-typical defensive responses, and their implications concerning other learned helplessness effects and interpretations are discussed.     

Effects of component training and subsequent sequencing of stimuli on shuttlebox avoidance responding of rats

The serial presentation of two different CSs, with each stimulus having an 8-sec duration (S1₈/S2₈), consistently has resulted in most of the shuttlebox avoidance responses being recorded to the S2 component. Experiment 1 attempted to attenuate this serial CS, delayed-response effect by conditioning the separate components of a serial CS prior to ordering them sequentially. Ten component-training trials were administered, with subjects receiving CS-US pairing to S1 only, S2 only, or to both S1 and S2 presented on separate trials. Two CS durations (8 or 16 sec) during this phase also were compared. Subjects were then given 100 avoidance test trials using the standard serial procedure. The 10 best avoidance responders in each group were selected for analysis. Shorter avoidance latencies were obtained only for subjects receiving component conditioning to S1. CS duration was not a factor in establishing the shorter latencies. Component conditioning to S2 resulted in increasing the total avoidances. Experiment 2 increased the number of component-training trials and the generality of the findings by using a different strain of rats and by extending the testing phase of the study so that all subjects could be included in the analysis. Comparable results were obtained. The theoretical implications of these data were discussed.     

Some effects of early social stimulation on the emotional reactivity of ducklings

Newly hatched Khaki Campbell ducklings were housed with a conspecific for 24 h beginning at either 1 or 5 days of age. A third group of ducklings received no social stimulation. When tested on Day 7, ducklings afforded early social stimulation exhibited less distress calling and crouching in a novel open field than ducklings exposed to late or no social stimulation. A second experiment asked whether the above result was due to early social stimulation per se or to the separation which occurred at its termination. Newly hatched ducklings were housed with a conspecific beginning on Day 1. One-half of the birds were separated from their companions on Day 2; the rest were separated on Day 6. On Day 7, the ducklings that were separated early exhibited less crouching and distress calling in a novel open field than the birds that were separated late. This finding implies that the withdrawal of social stimulation, rather than social stimulation perse, was responsible for the reduced emotional behavior observed in Experiment I. It is concluded that early withdrawal of social stimulation generated a strong aversive reaction and that it was the strength and timing of this reaction that mediated the emotionality moderating effects found here. Under these circumstances, the primary function of early social stimulation was to establish a condition whereby the aversive reaction generated by separation would occur early.     

Second-order conditioning using a contextual stimulus as S1

Three experiments investigated the question of whether a spatial stimulus, a context, could function as S₁ in a second-order conditioning procedure. In each experiment, rat subjects were presented with S₁-US pairings by being given footshocks in one of two contexts. Forty-eight hours later, the experimental groups received S₂-S₁ pairings, during which a tone was presented in the training context. As measured by a lick-suppression test administered in a third context, rats were more fearful of the tone if it occurred in the context in which they had previously been shocked. The training context in each experiment apparently served to establish second-order fear conditioning to the tone.     

Context specificity of sensory preconditioning: Implications for processes of within-event learning

A variant of the taste aversion procedure for sensory preconditioning, as used by Rescorla and Cunningham (1978), was employed in a study of the context dependency of within-event learning. In two experiments, rats received Phase 1 exposure to a simultaneous flavor compound, AX; flavor X was paired with illness during Phase 2, and any tendency for the resulting aversion to be elicited by A was measured. It was found that subjects were less likely to shun flavor A as a consequence of this training if the Phase 1 and test episodes were conducted in distinctively different contexts. This effect was evident both when the change of context occurred just before the test with flavor A (Experiment 1) and when it occurred before Phase 2 (Experiment 2). These results were taken to imply that, as is often found with serial associations, the retrieval of within-event associations is subject to contextual control. The implications of these findings for the interpretation of perceptual learning effects are discussed.     

An opponent-process interpretation of postshock bursts in appetitive responding

While eight food-deprived rats pressed a lever for food during daily 1-h sessions, four CS-Shock₂ trials were presented. Trials were preceded by either a Shock₁ of .25, .50, .75 mA or no Shock₁. It was found that the rate of appetitive responding during the CS was greater on Shock₁-CS-Shock₂ trials relative to CS-Shock₂ trials. The data indicate that the phenomenon of postshock bursts in responding can occur in the absence of a signal for safety after shock. The results conform to the predictions of the opponent-process theory of motivation.     

Differential effects of a retention interval on latent inhibition and the habituation of an orienting response

In Experiment 1, rats experienced presentations of a discrete visual stimulus (Stage 1) until habituation of the orienting response (OR) occurred. On a test session given after an interval of 16 days (Stage 2) the OR reappeared. For control subjects that received no Stage 1 training but presentations of the light in Stage 2, habituation persisted during the test. All subjects then received conditioning trials on which the light preceded the delivery of food. They showed latent inhibition, acquiring the conditioned response less readily than control subjects that had not previously experienced the light. Experiment 2 confirmed that the latent inhibition effect survived the retention interval for subjects that received no habituation test session. This pattern of results implies that habituation of the OR and latent inhibition are determined by different mechanisms.     

Second-order sexual conditioning in male Japanese quail (Coturnix japonica)

Second-order conditioning of social approach to a female conspecific in male Japanese quail was investigated in four experiments. Subjects that received paired first- and second-order trials acquired second-order conditioning in both Experiments 1 and 2. In contrast, subjects that received paired first-order but unpaired second-order trials, and subjects that received unpaired first-order but paired second-order trials, did not acquire second-order conditioning. In Experiment 3, subjects for whom the first-order conditioned stimulus was presented in extinction showed second-order conditioning comparable to that shown by subjects in a control group that did not receive the extinction procedure. In Experiment 4, subjects approached a second-order stimulus less when sexually satiated than when sexually deprived. These findings suggest that second-order sexual conditioning in quail is mediated by an association of the second-order stimulus with a representation of the unconditioned stimulus.     

Aversive conditioning of naturally produced reward and nonreward odors in rats

Past experiments have reported that rats encountering reward (R) or nonreward (N) goal events emit odors that can be utilized as discriminative stimuli for instrumental behavior by conspecifics. In the present study, thirsty male rats were aversively conditioned by ingestional toxicosis to R and N odors, and their suppression of water consumption in the presence of these odors was measured. Thirsty trained donors were placed into chambers containing R or N goal events to generate, respectively, the R or N odors. Test animals were given eight differential conditioning trials (four with one odor as CS+; four with the other as CS?), involving placement into an odorcontaining chamber with water available, followed by a LiCl injection on CS+ trials. Animals tested in their CS+ odor consumed significantly less water than did CS? and control subjects. Both R and N odors were conditioned by aversive means and readily discriminable from each other. This represents the first laboratory demonstration of aversive conditioning of such naturally produced odors, and it suggests that aversive conditioning may be useful in the study of odorous emissions generally. Implications for innate meanings of R and N odors are discussed.