Ethology notes -Motivation

Motivation.

Motivation is an intervening variable used to account for factors with in the organism that arouse, maintain and channel behaviour towards a goal. Motivated behaviour is a drive that leads to goal oriented behaviour and satiation.

The term motivation defines some kind of internal variable which influences the relationship between stimulus and response. Motivation was previously described as drives, which build up, the animals threshold of response to functionally related groups of environmental stimuli. (Thus the build up of feeding drive resulted in an increased responsiveness to stimuli connected with food, like the sight or smell of prey). Motivation or drive was resulted in rise or fall in threshold levels of responsiveness to functionally related stimuli. Behaviours which depend on an internal state are said to be motivated, and the study of animal motivation is an important part of ethology. Motivated behaviour has 3 distinct phases, (1) searching phase or phase of appetitive behaviour, (2) orientation phase or phase of consummatory behaviour and (3) quiescent phase..

Lorenz' psychohydraulic model.

Lorenz’s hydraulic model, one of the earliest attempts to model motivation used the analogy of a hydraulic flow system. The fluid in its resting state, the valve blocks the next centre in the hierarchy and inhibits the performance of behaviours beyond that point. When it is excited, the block is removed and the centre is freed for propagation. Impulses can now travel down to lower centres controlling for e g; brood care, resting and fighting but each of these centers is blocked until their appropriate or key stimulus appears. In the case of fighting the key stimulus would be a rival. The rival must be then providing a range of further key stimuli to elicit particular fighting behaviours like biting or chasing, etc.

Deutsch’s model.

An early attempt at the kind of motivational model which has proved very powerful in recent years is the loop system proposed by deutsch. Although deutsch’s model was designated to cover much wider aspects of behaviour, only the part representing motivation is reproduced here. The model operates in the following way. A deficit or imbalance in the animals physiology is detected by and excites ‘central structure ‘or ‘link’. The persistence and strength of this excitation depends on the magnitude of the imbalance. The excited link then activated an appropriate motor system which makes corrective behaviour in motion. As a result of the animal’s behaviour some aspect of its internal and external environment changes. (For example it has eaten and its stomach is now full of food), the change in the environment is registered by the analyzer which inhibits the link so that it no longer responds to inputs from the internal/external environment. This inhibition slowly decays until the link is once again sensitive to excitation.