Behavioral engineering: control of posture by informational feedback

The effects of informational feedback on a socially undesirable behavior were studied. The feedback was a mild vibrotactile stimulus and the response was slouching. When subjects slouched, a behavioral engineering apparatus provided vibrotactile stimulation to the shoulder. All subjects slouched less when stimulation was provided. A procedural control revealed that slouching will decrease because of the informational aspect of the stimulus consequence and not because of its aversive properties. When the subjects were instructed to slouch, the effects of feedback were reversed: feedback increased, rather than decreased, slouching. These results indicate that the effect of feedback for a response depends on the subject's motivation to perform that response. It is suggested that informational feedback could be used more widely as a therapeutic procedure to modify human behaviors, but only those behaviors that a patient is strongly motivated to change.     

Cardiovascular dynamics during classical appetitive and aversive conditioning in laboratory primates

This report describes changes in the rate of rise of left and right intraventricular pressures during aversive and appetitive conditioning procedures in chair-restrained rhesus monkeys. The conditioning paradigm consisted of a one-minute tone followed, in the one case, by an electric shock, and in the other, by the delivery of Purina monkey pellets. The conditional cardiovascular response was characterized by short latency, highly significant elevations in the derivatives of both ventricular pressures as well as a marked arterial pressor response and tachycardia. The magnitude of the conditional response to the classical aversive procedure was somewhat larger than that to appetitive conditioning. These alterations in the rate of development of intraventricular pressure can be attributed largely to augmentation in the sympathetic neural input to the heart and contribute to an analysis of selective aspects of the nervous regulation of the heart in intact, behaviorally conditioned animals.     

The effects of postconditioning revaluation of CS1 and UCS following pavlovian second-order electrodermal conditioning in humans

An experiment is described which uses various inferential post-conditioning revaluation techniques in order to clarify the associative substructure underlying Pavlovian electrodermal conditioning in human subjects. This study established a second-order skin conductance response (SCR) by pairing a CS₁ with an aversive 115 dB tone (UCS), and then pairing a different stimulus (CS₂) with CS₁. The second-order SCR survived post-conditioning extinction of the response to CS₁, but was abolished when (i) a post-conditioning habituation procedure resulted in a favourable revaluation of the tone UCS, or (ii) when subjects were given instructions which informed them that there would be no more UCS presentations. These results suggest that in the second-order electrodermal conditioning paradigm described, CR₂ is not mediated by S-R links--as it appears to be in second-order aversive conditioning in nonhuman animals--but is affected by manipulations which modify the subject's cognitions concerning the UCS.     

Biphasic constant-current stimulator for whole-animal shocking of marine animals

A constant-current stimulator delivering biphasic pulses was designed and constructed for whole-animal shocking during aversive conditioning of Pleurobrartchaea, a marine gastropod mollusk used for behavioral and neurophysiological research. The advantages of whole-animal stimulation are discussed and results are briefly described with regard to the factors involved in evaluating the procedure. The circuit design and electrode considerations are presented in detail. The basic stimulator design has potential for use as a general instrument for behavioral and physiological research.     

Time-dependent changes in conditioned suppression

Time-dependent changes in a response following aversive conditioning were investigated using a conditioned suppression procedure in a within-subjects design. Four groups of pigeons received Pavlovian conditioning “off the baseline”, immediately followed by an operant task. During the Pavlovian phase, two groups received a forward pairing of a tone with shock, one group received a backward pairing, and one group received a truly random pairing. One of the forward pairing groups also received a delay between the Pavlovian and operant phases. For all groups, key pecking was reinforced on a variable-interval schedule during the operant phase. Testing sessions were identical to training sessions, except that the tone used during Pavlovian conditioning was presented either 0, 15, 30, 45, of 60 minutes after the operant phase began. Testing sessions in which the Pavlovian phase was omitted were also included. The results showed suppression to change as a function of the retention interval, with maximum suppression occurring at intermediate intervals. This U-shaped function was obtained for 11 of the 12 pigeons in the forward-pairing groups and for three of the five in the truly random group. Pigeons in the background pairing group did not show changes in suppression as a function of the retention interval.     

Leverpress escape/avoidance conditioning in rats: Safety signal length and avoidance performance

Leverpress escape/avoidance is an excellent model for assessing coping in rats. Acquisition of the leverpress response is determined by the interstimulus (signal-shock) interval, as well as the type and duration of the aversive event. One factor that has received less research attention is the safety or feedback signal. The safety signal presumably negatively reinforces leverpress responding through fear reduction. Here, we present a parametric manipulation of safety signal length and avoidance performance. All rats were trained with a 60-s tone conditioned stimulus and an intermittent 1-s, 1.0-mA footshock. Training was further accomplished with a 1−, 2−, 4−, or 6-min safety signal. Acquisition of the avoidance response was comparable at all safety signal durations. Rats trained with the shortest safety signal (1 min) exhibited more leverpresses during the safe period, a measure of anxiety. Thus, acquisition of the leverpress avoidance response was efficient regardless of safety signal duration, even though shorter periods were associated with greater anxiety.     

Multiunit changes in hippocampus and medial geniculate body in free-behaving rats during acquisition and retention of a conditioned response to a tone

Multiunit activity (MUA) was recorded chronically in the hippocampus (CA3) and the medial geniculate body (mMG) during habituation to a tone followed by conditioning (tone paired with footshock) or pseudoconditioning (tone/footshock unpaired) in rats previously trained in a lever-pressing for food task (VI 60). In the conditioned group pairing tones with footshocks rapidly induced an increase in the initial CS-evoked response in the mMG, followed by the emergence of a hippocampal response and a marked conditioned suppression of lever-pressing to the tone. In contrast, in the pseudoconditioned group, the stimulus induced only transient cellular changes in the hippocampus and in the mMG, while no behavioral suppression to the tone could be seen. Moreover, presentations of the CS 45 days later induced multiunit and behavioral responses in both structures, only in the conditioned group. These results are used for discussion of the role of learning-induced changes in the sensory structure (mMG) as compared with changes in an associative structure (hippocampus), during acquisition and retention of a conditioned response.     

Avoidance responding as a function of stimulus duration and relation to free shock

Response-independent pairings of a tone and a brief shock were superimposed on uncued avoidance responding in four groups of rhesus monkeys. For one group, tone presentations were immediately followed by an unavoidable electric shock; for the remaining groups, gaps of 5, 20, and 80 sec intervened between tone termination and shock delivery. These temporal values subsume paradigms usually treated as discrete procedures; the conditioned emotional response procedure (0-sec gap between tone and shock), trace procedure (5-sec gap) and safety-signal training (80-sec gap). Within each group, tone durations of 10, 20, 40, and 80 sec were examined. A response pattern marked by maximum response rate in the initial 5 sec of the tone followed by deceleration before shock was observed when shock immediately followed the tone, but not when gaps were interposed between the tone and shock. Response rates in the first 5 sec of the tone were a function of both tone duration and duration of the gap. When the gap was 0 to 5 sec, initial response rates were highest in longer duration tones; this relationship between tone duration and initial tone response rate was not observed for longer gaps.     

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.     

Acquisition and discrimination of appetitively and aversively conditioned heart rate responses in rhesus monkeys

This report describes the acquisition of a conditional heart rate response to both classical aversive and appetitive conditioning in eight rhesus monkeys(Macaca mulatta). The behavioral paradigm consisted of two discrete one minute tones followed by the corresponding unconditional stimuli,i.e., electric shock or Purina monkey chow. A third tone followed by neither food nor shock served as a discriminative stimulus (DS). The conditional heart rate responses developed in two phases. The first phase was characterized by similar responses to both conditional stimuli and the DS. Control heart rate rose during this period. During the second phase, control heart rate decreased (five animals), the DS response disappeared, and different conditional heart rate patterns to food and shock emerged. The existence of distinct conditional response patterns indicates probable differences in the autonomic nervous regulation of the heart during aversive and appetitive conditioning.     

Self-punitive behavior in humans: Effects of a self-fulfilling prophecy

Human subjects were exposed to contingencies which programmed aversive tones (100 db). Two types of contingencies were employed: self-confirming (i.e., self-fulfilling prophecies), in which the aversive tone was occasioned by the prediction it was about to occur; and self-disconfirming, in which the tone was probable when subjects predicted it would not occur. Experiments 1 and 2 used a modified classical conditioning paradigm, and demonstrated that a self-confirming contingency maintained reliable self-punitive responding, i.e., subjects consistently predicted and therefore obtained tones on every trial. Subjects in Experiment 3 were instructed to express predictions continuously throughout four sessions to ensure adequate sampling of the various predictions. Subjects exposed to a self-disconfirming contnngency reliably evidenced awareness of the contingency in effect (judged by answers on a postexperimental questionnaire), whereas subjects exposed to a self-confirming contingency failed to show effective avoidance behavior or contingency awareness. Experiment 4 investigated free-operant self-punitive behavior, utilizing a single prediction response button, which subjects depressed repeatedly. Subjects were exposed to either periodic or aperiodic punishment schedules over as many as four sessions. In general, more persistent self-punitive responding was found in the groups receiving periodic punishment. The results from the four experiments show that self-confirming contingencies can effectively prolong self-punitive responding in human subjects. The findings are consistent with a blocking interpretation of self-punitive behavior, which asserts that when an aversive event is already predicted by stimuli in the situation (including temporal cues), the association between a response and punishment is impaired, and self-punitive responding is likely to be maintained. An integration of human and animal self-punitive research is proposed.     

Compounding discriminative stimuli controlling free-operant avoidance

The performances of three rats were stabilized on a multiple schedule that maintained responding by a free-operant avoidance schedule during independent presentations of tone and light. The simultaneous absence of these stimuli signalled shock-free periods and controlled response cessation. Subsequently, test sessions were administered consisting of independent presentations of each stimulus and these stimuli compounded (tone-plus-light). During an extinction test, additive summation was observed to the compounded stimuli, i.e., more responses were emitted to the compound than to either tone or light. During a series of 28 maintenance-test sessions in which the shock schedule remained operative, the compounded stimuli produced a generally enhanced response rate and fewer pauses terminating with shock than either single stimulus condition. These results extend the generality of free-operant additive summation to responding maintained by aversive control. In addition, a comparison of the present study with previous experiments reporting additive summation of positively reinforced responding indicates that similar variables—rate and aversive differences between training stimulus conditions—should be considered in accounting for response distributions during stimulus compounding when responding is controlled by either positive or negative contingencies.     

Total peripheral resistance changes in dogs during aversive classical conditioning

The arterial pressure, heart rate, stroke volume, cardiac output and total peripheral resistance of laboratory dogs were monitored continuously before and during a 30 min period in which aversive classical conditioning procedures were applied. The experimental stimulation generated inhibition of behavioral activity (“freezing”) together with sustained increases in arterial pressure averaging 30%, and increases in heart rate and cardiac output of 60–70%. The calculated total peripheral resistance decreased by an average of 20%. The behavioral and cardiovascular responses were sustained during the aversive conditioning period. The results suggest that significant peripheral vasodilation occurred under these conditions which was probably not due to metabolic byproducts of behavioral activity, but probably reflected sympathetic cholinergic effects upon blood vessels in the skeletal muscles. These data document the significance of the skeletal muscle circulation in the total peripheral resistance to blood flow in unanesthetized animals.     

Leverpress Escape/Avoidance Conditioning in Rats: Safety Signal Length and Avoidance Performance

Leverpress escape/avoidance is an excellent model for assessing coping in rats. Acquisition of the leverpress response is determined by the interstimulus (signal-shock) interval, as well as the type and duration of the aversive event. One factor that has received less research attention is the safety or feedback signal. The safety signal presumably negatively reinforces leverpress responding through fear reduction. Here, we present a parametric manipulation of safety signal length and avoidance performance. All rats were trained with a 60-s tone conditioned stimulus and an intermittent 1-s, 1.0-mA footshock. Training was further accomplished with a 1-, 2-, 4-, or 6-min safety signal. Acquisition of the avoidance response was comparable at all safety signal durations. Rats trained with the shortest safety signal (1 min) exhibited more leverpresses during the safe period, a measure of anxiety. Thus, acquisition of the leverpress avoidance response was efficient regardless of safety signal duration, even though shorter periods were associated with greater anxiety.     

Emotion, attention, and the startle reflex

This theoretical model of emotion is based on research using the startle-probe methodology. It explains inconsistencies in probe studies of attention and fear conditioning and provides a new approach to emotional perception, imagery, and memory. Emotions are organized biphasically, as appetitive or aversive (defensive). Reflexes with the same valence as an ongoing emotional state are augmented; mismatched reflexes are inhibited. Thus, the startle response (an aversive reflex) is enhanced during a fear state and is diminished in a pleasant emotional context. This affect-startle effect is not determined by general arousal, simple attention, or probe modality. The effect is found when affects are prompted by pictures or memory images, changes appropriately with aversive conditioning, and may be dependent on right-hemisphere processing. Implications for clinical, neurophysiological, and basic research in emotion are outlined.     

Psychophysiological responses during analogue systematic desensitization and non-relaxation control procedures

This investigation tested the hypotheses than an analogue systematic desensitization procedure (SD) would be both more effective and more efficient than a comparable non-relaxation control procedure (NRC) with respect to subjective report, behavioral and psychophysiological variables. Phobic subjects responded to slides depicting a feared aversive stimulus. The SD procedure resulted in significantly less reported fear, fewer trials to a criterion level of decrease in subjective fear, and significantly greater decreases in ANS baseline measures. However, measures of behavioral avoidance and measures of decrease in psychophysiological responsivity to the aversive stimuli revealed significant changes within both SD and NRC groups, and no significant differences between the groups, whether or not the groups were equated for number of stimulus presentations. The results, indicating equivalent efficacy and efficiency for the SD and NRC procedures, suggested a limited role for relaxation in systematic desensitization. An extinction or habituation hypothesis was supported at the expense of a counterconditioning hypothesis.     

Aversive smoking therapies: A conditioning analysis of therapeutic effectiveness

Rapid smoking (RS) and a less aversive rapid-puffing (RP) treatment were compared on ability to enhance the impact of a behavioral-counseling (BC) procedure on psychophysiological, attitudinal and behavioral response to cigarettes. Data reveal that both aversive smoking treatments resulted in less smoking once treatment began, reduced smoking in post-treatment taste tests, and superior follow-up performance at 6 months and 1 yr. At 1 yr, RS S s achieved the highest number of days abstinent of any group. Regression analyses showed that Ss' confidence ratings of remaining abstinent were highly predictive of follow-up status, and that these ratings were related to number of cigarettes smoked during treatment and amount of smoking during post-treatment taste tests.     

Testing social acoustic memory in rats: Effects of stimulus configuration and long-term memory on the induction of social approach behavior by appetitive 50-kHz ultrasonic vocalizations

Rats emit distinct types of ultrasonic vocalizations (USVs), which serve as situation-dependent affective signals. In appetitive situations, such as rough-and-tumble-play, high-frequency 50-kHz USVs occur, whereas low-frequency 22-kHz USVs can be observed in aversive situations, such as social defeat. USVs serve distinct communicative functions and induce call-specific behavioral responses in the receiver. While aversive 22-kHz USVs serve as alarm calls and induce behavioral inhibition, appetitive 50-kHz USVs have a pro-social communicative function and elicit social approach behavior, supporting the notion that they serve as social contact calls to (re)establish or maintain contact among conspecifics. The aim of the present study was to use the rat's ability to communicate in the ultrasonic range via high-frequency 50-kHz USVs in order to develop a test for social acoustic memory in rats with relevance for human verbal memory. Verbal learning and memory is among the seven cognitive domains identified as commonly deficient in human schizophrenia patients, but particularly difficult to model. We therefore tested whether the induction of social approach behavior by playback of appetitive 50-kHz USVs is dependent on (1) acoustic stimulus configuration and (2) social long-term memory, and whether (3) social long-term memory effects can be blocked by the administration of scopolamine, a muscarinic acetylcholine antagonist producing amnesia. Results show that social approach behavior in response to playback of natural 50-kHz USVs depends on acoustic stimulus configuration and occurs only when sound energy is concentrated to a critical frequency band in the ultrasonic range. Social approach behavior was detected during the first exposure to playback of 50-kHz USVs, whereas no such response was observed during the second exposure 1week later, indicating a stable memory trace. In contrast, when memory formation was blocked by i.p. administration of scopolamine (0.5mg/kg or 1.5mg/kg) immediately after the first exposure, rats displayed social approach behavior during the second exposure as well. Induction of social approach behavior in response to repeated playback of natural 50-kHz USVs may therefore provide a new and rather unique approach for testing social acoustic memory in rats with relevance to human verbal memory.     

Human, free-operant avoidance of “time out” from monetary reinforcement

To assess the aversive effects of withdrawing monetary reinforcement, human subjects were exposed to a free-operant avoidance procedure in which periods of no reinforcement occurred if the subject failed to respond, and each response postponed withdrawal of reinforcement. Avoidance behavior was developed either through specific instructions about the consequence of responding or through preliminary escape-avoidance training. In all cases, rates of response were found to be a positively accelerated function of decreases in the duration by which responding postponed reinforcement withdrawal. The findings with respect to the function relating avoidance behavior to the interval of postponement were viewed as similar to those obtained when shock is used as the aversive event in free-operant avoidance conditioning.     

Distinguishing BIS-mediated and BAS-mediated disinhibition mechanisms: a comparison of disinhibition models of Gray (1981, 1987) and of Patterson and Newman (1993)

The theoretical framework developed by J. A. Gray (1981, 1987a, 1987b) was used to study disinhibitory behavior. Using a point-scoring reaction time procedure, 4 different experiments were conducted to differentiate 2 disinhibitory mechanisms associated with the behavioral activation system (BAS) and the behavioral inhibition system (BIS). Consistent with the work of C. M. Patterson and J. P. Newman (1993), the BAS-mediated mechanism was related to a lack of inhibition in reward-directed behavior after introducing an occasional aversive contingency and to deficits in learning from aversive cues when responding for reward (Experiments 1-3). The BIS-mediated mechanism was related to a higher ability to extinguish aversive associations (Experiment 1), a lower aversive generalization gradient (Experiment 3), and a lower interference with appetitive behavior in the presence of aversive stimuli (Experiment 4).