Anorexia nervosa as a case of complex instrumental conditioning

Anorexia nervosa (AN) can be considered a result of complex instrumental conditioning. It is postulated that in healthy nonsatiated individuals, the sight and smell of the preferred food, acting as a conditioned stimulus (food CS), activates a memory pattern of associations "eating--desirable sensory input" (approach pattern). This leads to the instrumental reaction of eating which is reinforced by sensory satisfaction. In victims of AN, in addition to the approach pattern the food CS activates another pattern of associations consisting of such components as "eating--obesity--failure" and " noneating --thinness--success" (avoidance pattern). The establishment of the avoidance pattern depends on such factors as social preferences and pressures to be slim, inborn dispositions, and personal psychological problems. If the activation of the avoidance pattern prevails over the activation of the approach pattern, the individual refrains from eating. The refusal to eat is here an instrumental avoidance reaction; its performance is reinforced by satisfaction derived from successful self-control and losing weight. A prolonged activation of the avoidance pattern leads to malnutrition and ultimately to death. In cases in which the approach pattern and the avoidance pattern are frequently activated simultaneously to the same degree, a neural conflict may develop. In a variation called "bulimia nervosa," an activation of the approach pattern alternates with the activation of the avoidance pattern. First, overeating takes place; it is reinforced by oral-gastric satisfaction. Then, the avoidance reaction of self-induced vomiting or purging follows; it is reinforced by satisfaction derived from preventing weight gain.