BY R. A. HINDE Field Station for the Study of Animal Behaviour, Cambridge University Department of Zoology
The problem of motivation is central to the understanding of behaviour. Why, in the absence of learning and fatigue, does the response to a constant stimulus change from time to time? To what is the apparent spontaneity of behaviour due? This paper is concerned with one type of model which has been developed to help answer such questions--namely that in which changes in the organism's activity are ascribed to changes in the quantity or distribution of an entity comparable to physical, chemical or electrical energy.
Such models have been developed by theoreticians with widely differing backgrounds, interests and aims, and the frameworks of ideas built round them diverge in many respects; but in each case the energy treatment of motivation is a central theme (cf. Carthy, 1951; Kennedy, 1954). They have had a great influence on psychological thought, and although they are unlikely to continue to be useful, it is instructive to examine their nature, their achievements and their limitations.
The four models or theories to be discussed here are those of Freud, McDougall, Lorenz and Tinbergen. They are only four of many in which energy concepts are used, but in them the energy analogy is made explicit in terms of a mechanical model, instead of being merely implied by a 'drive' variable which is supposed to energize behaviour. The models were designed to account for many features of behaviour in addition to the phenomena of motivation, and here it will be necessary to extract only those aspects relevant to the present theme.
In the psycho-analytic model ( Freud, 1932, 1940) the id is pictured as a chaos of instinctive energies which are supposed to originate from some source of stimulation within the body. Their control is in the hands of the ego, which permits, postpones or denies their satisfaction. In this the ego may be dominated by the super-ego. The energy with which Freud was particularly concerned--the sexual energy or libido--is supposed not to require immediate discharge. It can be postponed, repressed, sublimated, and so on. The source of this energy lies in different erogenous zones as the individual develops, being successively oral, anal and phallic, and it is in relation to these changes that the individual develops his responses to the external world.