Appetitive Behaviour, Consummatory Act, and the Hierarchical Organisation of Behaviour- With Special Reference To the Great Tit (Parus Major 1)

Abstract

1. Appetitive behaviour and consummatory act differ only in degree, and no absolute distinction can be made between them. In particular, both share the characteristic of spontaneity, and in both cases the behaviour has restricted variability. 2. Certain activities (singing, courting, nest-building, reproductive fighting, etc.) are grouped together as reproductive activities because there appear to be relationships between the causal mechanisms underlying them. 3. These activities depend on a hierarchical system of causal factors, basically similar to those demonstrated by TINBERGEN (l.c.) and BAERENDS (l.c.) for other animals. All the activities belonging to a major instinct have some causal factors in common: those belonging to a sub-instinct have some causal factors which they share with the other sub-instincts, and some which are specific to them; and so on. This hierarchial system of causal factors is exhibited in the behaviour of the bird as a hierarchy of moods, each mood having a certain definite type of behaviour associated with it. Each form of appetitive behaviour is characterised by motor pattern, orientation component and/or by the stimuli to which the animal is particularly responsive while showing it. Each type must therefore depend on a particular nervous mechanism. Thus there must be a hierarchy of nervous mechanisms corresponding to the hierarchy of causal factors. 4. There seems to be no generalised territorial appetitive behaviour, as observed by TINBERGEN in the Stickleback, in the Great Tit. The bird may change from one mood to another without any apparent change in the external situation. 5. A preliminary analysis of the feeding instinct of the Great Tit is made in a similar way, the activities involved being those associated with hunting for, preparing and eating food, and, probably, food fighting. Each of these apparently has its own sources of motivation, as well receiving motivation from above. 6. There are a number of types of fighting behaviour, which are motivated from different higher centres (feeding, reproductive, etc.). Fighting may also occur independently of any superordinated mechanism. There are relationships between the different types of fighting. 7. The different instincts of an animal may utilise the same motor patterns. The behavioural organisation of the whole animal must thus be pictured as a set of closely interwoven hierarchial systems. 8. Some neurophysiological evidence is cited to show that, at any rate in mammals, the various nervous mechanisms may, but do not always, have any very precise anatomical localisation. 9. The principle characteristics of the 'centres' are summarised.