Susan Mineka

Unpredictable and uncontrollable events: A new perspective on experimental neurosis.

Recent work has shown that unpredictable and/or uncontrollable events can produce a variety of cognitive, affective, and somatic disturbances to the organism. These disturbances are compared to and found to be quite similar to the symptoms of the classic cases of experimental neurosis described by Pavlov, Gantt, Liddell, Masserman, and Wolpe. The hypothesis is then developed that the common thread running through the entire experimental neurosis literature is that in each case important life events become unpredictable or uncontrollable, or both. This interpretation is contrasted with the earlier physiological, psychodynamic, and behavioral interpretations made by the investigators themselves. The implications of this analysis of experimental neurosis for various issues in the predictability-controllability literature are discussed—for example, the interaction between unpredictability and uncontrollability, the threshold for response to lack of predictability or controllability, and the lack versus the loss of predictability and controllability. Finally, the possible clinical relevance of this new perspective on experimental neurosis is discussed.

Determinants of fear over the course of avoidance learning

Abstract Most theorists have explained attenuation of fear over the course of avoidance learning by assuming that fear extinguishes with repeated nonreinforced avoidance trials. Experiment 1 replicates the finding that rats trained to a criterion of 27 consecutive avoidance responses (CARs) show less fear during the CS than rats trained to a criterion of 3 or 9 CARs. This attenuation of fear cannot, however, be accounted for by simple Pavlovian fear extinction, because yoked partners receiving the exact same pattern of CSs and USs did not show this attenuation and did not differ from yoked partners receiving only reinforced CS presentations. Experiment 2 found that feedback from the master avoidance learners response is sufficient to produce this attenuation in yoked animals; “control” per se is not necessary. Several possible explanations are discussed regarding the mechanism underlying this role of feedback in diminishing fear of the CS in the avoidance learning context.

Fear of snakes in wild- and laboratory-reared rhesus monkeys (Macaca mulatta)

Experiment 1 compared the responses of 10 laboratory-reared and 10 wild-reared rhesus monkeys (Macaca mulatta) to a real snake and to a range of snake-like objects. Most wild-reared monkeys showed considerable fear of the real, toy, and model snakes, whereas most lab-reared monkeys showed only very mild responses. Fear was indexed by unwillingness to approach food on the far side of the snake and by behavioral disturbance. Experiment 2 examined the effectiveness of seven flooding sessions in reducing snake fear in 8 wild-reared rhesus monkeys. Mean latency to reach for food, trials to criterion (four consecutive short latency responses), and total exposure time to criterion declined significantly across flooding sessions. Behavioral disturbance declined within sessions but not across sessions. Results of a final behavioral test revealed that substantial long-lasting changes had occurred in only 3 of the 8 monkeys. The results are discussed in the context of dissociation between different indices of fear.

Some New Perspectives on Conditioned Hunger.

One theory holds that appetitive drives such as hunger and thirst are not conditionable because of their slow onset. However, recent evidence has shown only transitory conditioning of appetitive drives even with rapid onset. Such experiments may have failed because: (a) Exteroceptive conditioned stimuli (CSs) used in past experiments may be less easily accociated with the internal hunger drive than are interoceptive taste cues. Experiments 1-3 provided some support for this hypothesis. (b) The dependent measures used in past experiments may not be valid. Experiments 4 and 5 suggested that changes in the rate of bar pressing on an operant extinction curve following probe CSs for hunger may be a more sensitive and valid index of conditioned appetitive drive. However, the elusive and transitory nature of these results demands a reexamination of the basic difference between appetitive and aversive drives, which lies in the mode of their onset and control and which, given adaptive considerations, can account for their widely different conditionability.

Dissociative effects of different types and amounts of nonreinforced CS exposure on avoidance extinction and the CER

Abstract Two experiments examined the effectiveness of two amounts of flooding or response-prevention on hastening avoidance response extinction and on reducing CS-produced suppression of bar-pressing for food. In Experiment 1, 20 and 30 flooding trials were both shown to be effective in hastening the extinction of a well-learned shuttlebox avoidance response. In Experiment 2, rats trained under comparable conditions to those in Experiment 1 were tested following flooding for the CER in a different apparatus. The results indicated that 30, but not 20, flooding trials were sufficient to reduce the CER. In each experiment the results of additional control groups equated with the flooded groups for nonreinforced CS exposure also revealed a dissociation between the effectiveness of this CS time control procedure in hastening avoidance response extinction and in reducing the CER. Further comparisons showed that although 30 flooding trials did reduce the CER, the same total duration of nonreinforced CS Exposure in the form of avoidance extinction trials did not. Thus the context in which CS exposure occurs may affect the dynamics of extinction of the CER. The experiments are discussed in the broader context of dissociation of various indices of fear in humans.

Inconsistency and possible habituation of CCK-induced satiety.

Abstract Rats injected daily with cholecystokinin initially inhibited food intake in the first 30 min after injection, but after several days showed an increase in food ingested to an amount that approached their preinjection baseline food intakes and that did not differ from that of rats injected with isotonic saline. This effect occurred with the synthetic C-terminal octapeptide of cholecystokinin and to a lesser extent with injections of natural cholecystokinin extract. It occurred with wet mash and to a lesser extent with liquid diets. When injections were spaced at twice per week, there was an inconsistent response to cholecystokinin but no evidence of habituation. This finding of possible habituation and inconsistent responding to repeated injections of cholecystokinin questions its role as a physiological satiety signal.

Dissociation between conditioned emotional response and extended avoidance performance

Abstract The present experiments examined the dissociation between the strength of a shuttlebox avoidance response (AR) and one index of fear of the avoidance CS. Avoidance response strength was indexed by resistance to extinction of the AR and by changes in response latency, and fear of the CS was indexed by the conditioned emotional response (CER) technique. Experiments 1, 2A, and 3A all found that rats trained to a criterion of 27 consecutive avoidance responses (CARs) showed response strength comparable or superior to rats trained to a criterion of 9 CARs. Experiments 2B and 3A demonstrated that rats trained to 27 CARs showed less suppression of bar pressing during the avoidance CS (less CER) than rats trained to 9 CARs. Experiment 3A also found that, when extinguished in the shuttlebox to a moderate criterion (5 consecutive trials without a response) before CER testing, rats trained to 9 CARs showed some, although not complete, loss of CER, whereas rats trained to 27 CARs showed no loss of CER. In Experiment 3B rats that took 1 vs 2 days to reach a criterion of 27 CARs were compared for their AR strength and for their CER. Although rats taking 2 days to reach criterion showed somewhat greater resistance to extinction of the AR than rats reaching criterion in 1 day, this variable had no apparent effect on the CER. Implications of the present results for current theories of avoidance learning are discussed.

The effects of overtraining on flooding of jump-up and shuttlebox avoidance responses ☆

Two experiments are reported which test the effects of overtraining (2, 4 or 6 days) on the efficacy of flooding (response-prevention) in hastening the extinction of jump-up and two-way shuttlebox avoidance responses. In the jump-up box, overtraining reduces the effectiveness of flooding in two ways: Rats trained for 6 days and given a flooding treatment are more resistant to extinction than rats trained for only 2 or 4 days and given a flooding treatment. By contrast, rats trained for 6 days and given a control treatment are less resistant to extinction than control rats trained for 2 or 4 days. In the shuttlebox, overtraining neither reduces the effectiveness of flooding in hastening avoidance response extinction, nor reduces the resistance to extinction of control animals. Implications of these different effects of overtraining on jump-up and two-way shuttlebox responses are discussed.

Some further tests of the brief confinement effect and the SSDR account of flooding

Abstract Although brief confinement in novel or fearful places may occasionally produce flooding-like effects with regard to hastening avoidance response extinction, the results of the three experiments reported here indicate that this is not as robust a phenomenon as is flooding. Experiments 1 and 2 found that any tendency for a brief confinement effect to occur is likely to result from the use of a procedure where extinction is started on the grid floor as opposed to on the ledge of a jump-up box. Experiment 3 found no evidence at all that confinement in either a novel or a fearful place can hasten the extinction of a more well-learned jump-up response than that studied in previous experiments, even when the grids extinction procedure was used. Overall these results do not support the SSDR account of flooding, which has derived its chief support from experiments demonstrating a brief confinement effect.