Predictable and unpredictable shock: Behavioral measures of aversion and physiological measures of stress.

Abstract

Previous articles have reviewed the behavioral literature and concluded that predictable shock conditions are less aversive than unpredictable shock conditions. This article reviews the literature on predictable and unpredictable shock conditions relative to physiological measures of stressfulness and considers the possible role of stress-induced analgesia in both the physiological and behavioral effects. It finds that unpredictable conditions are physiologically more stressful than predictable conditions when subjects are exposed to them for one or a few sessions and parameters of stress are relatively severe. However, predictable conditions may be more stressful than unpredictable conditions when sessions are long and extend over days and parameters of stress are less severe. The effect of extended stress appears to depend upon the physiological measure used. These findings are discussed in terms of the phasic versus chronic nature of predictable versus unpredictable stress and the organism's ability to adapt physiologically to these conditions. Finally, the data on stress-induced analgesia are reviewed. We conclude that stress-induced analgesia does not significantly contribute to either preference for predictable over unpredictable stress or their differential physiological effects.

Stress, Predictability, and Oral Fentanyl Self-Administration in Female and Male Rats

“…Using an operant paradigm, female and male rats were tested for drug SA with and without predictable or unpredictable acute and repeated stress. Consistent with earlier behavioral, immunological, and physiological reports (Abbott et al , 1984;Arthur, 1986;Glass & Singer, 1972;McKinnon et aI., 1989), predictability had a different effect on drug SA depending on whether the stressor was acute or chronic. Specifically, predictability of the stressor increased fentanyl SA with repeated exposure to the stressor, especially for female subjects.…”

“…For example, Glass and Singer (1972) reported a series of human laboratory studies which found that predictability of a noise stressor attenuated the performance decrements that occurred after cessation of an acute unpredictable nois8 stressor . In contrast, under conditions of chronic stressor exposure, predictability potentiated behavioral , physiological, biochemical, and immunological stress responses (Abbott, Schoen, & Badia, 1984;Arthur, 1986;McKinnon, Weisse, Reynolds, Bowles, & Baum, 1989). This increase with repeated exposure to a stressor might reflect: (1) sensitization to the stressor; or (2) classical conditioning between the stimuli that predict the stressor and the stressor itself ( Pavlov, 1906;Rescorla, 1966;Rescorla, 1967).…”

“…Rationale: It has been reported that, under conditions of repeated stressor exposure or chronic stress, predictability of a stressor may enhance stress responses (Abbott, Schoen, & Badia, 1984;Arthur, 1986;McKinnon, Weisse, Reynolds, Bowles, & Baum, 1989). Therefore, animals in the predictable stress conditions should SA more fentanyl in response to the experience of higher stress.…”

“…Rationale: Under chronic conditions of stressor exposure, predictability has been reported to potentiate responses to stress (Abbott, Schoen, & Badia, 1984;Arthur, 1986). Body weight and water consumption were measured daily throughout the experiment.…”

Stressed out: providing laboratory animals with behavioral control to reduce the physiological effects of stress

“…Jay Weiss in the 1970s cleverly illustrated the importance of psychological factors, such as predictability and outlets for frustration, on the overall effect of a stressor 47 . When negative stimuli are predictable, animals know when to worry and when to relax [48][49][50] . Control, or the perception of control, over a stressor also has a big part on the physiological effect.…”