The evolutionary stability of a bi-stable system of emotions and motivations in species with an open-ended capacity for learning

Abstract - One of the highest evolutionary achievements is the open-ended capacity for learning. This is the ability to acquire a behavioral repertoire which is specifically tailored to the environmental situation(s) an individual happens to live in. This capacity is best exploited if the individual's behavioral organization causes any surplus of energy to be invested in expanding and refining the repertoire, and adapting it to prevailing circumstances. Adaptations of the repertoire are most likely to have survival value if applicable to emergencies and other situations causing high arousal. Experience and skills are therefore maximizing fitness if acquired, and subsequently used, in arousal-evoking, and often risk involving, situations.

Entering high-arousal situation, either voluntarily or involuntarily, however, may be harmful to the individual if the resulting state of high stress lasts too long to allow proper (neuro-)physiological functioning, or if too much risk is involved. An open-ended learning capacity is therefore maximally adding to survival if paired to two distinct tendencies:

1. a tendency to seek high-arousal evoking situations whenever surplus energy is available; and
2. a tendency to seek arousal reducing situations as soon as an emergency occurs or as soon as the surplus energy is exhausted.

This suggests that a bi-stable "telic/paratelic" system of preferred levels of arousal, as described in Apter & Smith's theory of motivational reversals (Apter, 1982), can be considered an Evolutionary Stable Strategy (E.S.S.), as compared to homeostatic systems of arousal and motivation.

Introduction

One of the most recent evolutionary achievements is an open-ended capacity for learning. This is the ability to acquire a behavioral repertoire which is specifically tailored to the environmental situation(s) an individual happens to live in. It will be argued here that this ability is highly enhanced by a bi-stable organization of motivation as described by Apter & Smith in their "reversal theory"(see Smith & Apter, 1975; Apter, 1976, 1982; Apter & Smith, 1976abc, 1977, 1979; and Apter et al., 1985).

In fact, it will be shown that the predisposition for such a bi-modal antagonist system of emotional and motivational reversals constitutes the basis of behavioral flexibility Pelt (this volume) is referring to. The present paper therefore deals with the dynamic structure of the biological substrate of what may be called "memes" (Dawkins, 1976) or "culturgens" (Lumsden & Wilson, 1981). It deals, so to speak, with the interface between "genes" and "memes", between the "hardware""and the "software", as has occurred in man. Here we will deal with the motivational mechanisms taking care of the acquirement and the selection of "software" at the individual level.

Reversal theory

Let us first have a look at what this "reversal theory" is all about. Apter (1982) introduced his reasons for proposing a model of motivational bi-stability as follows and as schematically pictured in Fig. 1.

Let us start by reflecting on a number of different situations in which different levels of arousal, high and low, can be experienced, and see if any pattern or structure can be discerned.

First of all reflect, if you will, on what it is like to be in a dentist's waiting room, about to have a filling. Focus on particular on the kind of arousal which you feel. Now imagine that you are soaking in a hot bath after a hard day's work, and again try to conjure up what the arousal which you experience in this situation feels like. Next, make believe that you are waiting for a bus which is taking a long time to come; you are not in a hurry so that there is no pressure of time, but you have nothing to read or take your attention. Finally, imagine yourself to be in a cinema watching a thriller film and the film has a particularly tense point. I thing you will agree that the arousal feels different in some important sense in each of these cases.

For one thing, of course, the amount of arousal which you feel will be different. If you are like most people, the level of arousal which you experience is likely to be high to some degree or another in two of the cases (waiting for the dentist and watching the film), whereas in the other two cases (waiting for bus and in the bath) it is likely to be rather low.

A second obvious way in which the arousal-experience will be found to differ is in terms of its pleasantness or unpleasantness. Again, two of the situations listed are likely to be found to involve unpleasant arousal (waiting for the bus and waiting for the dentist). Pleasentness and unpleasantness are not, therefore, simple reflections of the amount of arousal.

In terms of just these four examples, high arousal can be pleasant or unpleasant, and so can low arousal. In fact, there would appear to be at least four types of arousal experience. This is corroborated by the fact that there are four widely-used arousal words in everyday language which relate exactly to these four types: anxiety (unpleasant high arousal), excitement (pleasant high arousal), boredom (unpleasant low arousal) and relaxation (pleasant low arousal).

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Fig. 1. The very existance of colloquial labels for our emotions like relaxation, boredom, excitement and anxiety illustrates emotional/motivational bi-modality.

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Apter & Smith (1979) have generalized these and similar findings into a simple but comprehensive theory.