Rats previously exposed to repeated uncontrollable stressors were shown to be unable to learn how to avoid shocks
Why is it that most of us can have occasional terrible experiences, feel depressed, and then recover, while a few of us collapse into major depression? Certain features dominate as psychologically stressful: a loss of control (Lack of control predicts stress-response) and of predictability (Lack of predictability predicts stress-response) within certain contexts, a loss of outlets for frustration, a loss of sources for support (Having social support is shown to lower the stress-response in primates including humans), a perception of life worsening.
In one style of experiment, pioneered by the psychologists Martin Seligman and Steven Maier, animals are exposed to pathological amounts of these psychological stressors. The result is a condition strikingly similar to a human depression. Although the actual stressors may differ, the general approach in these studies always emphasizes repeated stressors with a complete absence of control on the part of the animal. For example, a rat may be subjected to a long series of frequent, uncontrollable, and unpredictable shocks or noises, with no outlets.
After awhile, something extraordinary happens to that rat. This can be shown with a test. Take a fresh, unstressed rat, and give it something easy to learn. Put it in a room, for example, with the floor divided into two halves. Occasionally, electricity that will cause a mild shock is delivered to one half, and just beforehand, there is a signal indicating which half of the floor is about to be electrified. Your run-of-the-mill rat can learn this “active avoidance task” easily, and within a short time it readily and calmly shifts the side of the room it sits in according to the signal. Simple. Except for a rat who has recently been exposed to repeated uncontrollable stressors. That rat cannot learn the task. It does not learn to cope. On the contrary, it has learned to be helpless. This phenomenon has been dubbed “learned helplessness.” When people believe they have little or no control over their fate, they become anxious. “Something terrible can happen to me at any time and I will be unable to do anything about it.” When the anxiety and sense of helplessness become too great, people become depressed. “There is no use trying; I’m doomed.”
References
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Sapolsky, Robert. (2004). Why Zebras Don’t Get Ulcers Chapter 14. Stress and Depression (p. 423). New York, NY: Henry Holt and Company.
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Gray, Peter. (2013). Free to Learn Chapter 1. What Have We Done to Childhood? (p. 38). New York, NY: Basic Books.
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Type:🔴 Tags: Psychology / Psychiatry Status:☀️