Niko Tinbergen and Konrad Lorenz, proposed that the repertoire of behaviours with which each animal species is equipped is dependent upon innate releasing mechanisms in its central nervous system which are primed to become active when appropriate stimuli – called ‘sign stimuli’ – are encountered in the environment. When these stimuli are met, the innate mechanism is released, and the animal responds with a ‘pattern of behaviour’ which is adapted, through evolution, to the situation.
