6.5 The regression phenomenon in learning systems.
By growth and differentiation, every child keeps increasing it's possibilities to interact with the world. It constantly adds new "layers" to it's personal behavioural equipment, the latest of which are vulnerable and not yet stable. As the new behaviour is exposed to the environment it can be put to severe tests. In the case of a massive aversive stimulation for which it is not yet prepared, the new behaviour may fail and be discontinued. Progression stops and regression takes its place.
People differ as to their nervous excitability and their immune vigilance. On the one hand we see individuals who have a neuronal constitution with high excitation thresholds (we label these persons extroverts). Only when repeatedly or strongly stimulated do they respond with arousal and attention. In the ancient terms of Heymans they would belong to the phlegmatic temperament. The analogous property of the immune system is low vigilance and low reactivity. On the other hand there are people with an overly sensitive and/or overly reacting neuronal and autonomous constitution (introverts). They react strongly to stimulation and easily become overexcited. The analogous immune temperament is high vigilance and overreaction.
Anxiety and excitement can incapacitate the faculty of focussed attention and of accurate observation. Overreacting with nervousness and tenseness is a cause for inhibitory or blocking stress-reactions. If overreactions occur frequently they become a hazard for cognitive development. Educators at home and in the schools should be aware of the differences in emotional temperament between children (Chapter 7).
Since life is full of unpredictable events, system-overload cannot always be prevented. J.G.Miller (1965) presented a thesis about hierarchically ordered systems, that predicts the hazards we have just mentioned. If a high organisation level of the system reaches the limits of its competence to handle information (= overflow), the next lower level will take over the coordinating task. This has consequences for the systems we have discussed: the genetic system, the immune, the neuronal and the language systems. Genetic regression may secure the survival of a species when dramatic and long lasting changes in the environment put heavy demands on adaptability. Since this subject is beyond the scope of this book we'll limit the discussion to the three remaining systems of adaptation and defence. By keenly observing the effect of overflow, the hierarchical order in the systems may reveal itself. Regression to an organized response of a lower order is often reinforced by its immediate beneficial effects and, by learning, may become a permanent feature. It seems plausible that habit formation can take place in the lymphoid, as well as in the neuronal and the language system. This will be illustrated in the paragraphs that follow.