THE NATURE OF INTELLIGENT BEHAVIOUR 119 
this is just as much the outcome of heredity as the instinc- 
tive act of pecking. Since, therefore, heredity determines 
what shall be selected and what rejected—since the likes and 
dislikes are themselves instinctive—any essential difference 
between congenital and acquired behaviour seems to be 
evanescent. 
Now, if we apply to the affective qualities of mental states 
—the pleasurable tone or its opposite which characterize such 
states—the term “instinctive,” we do so in reference to the 
broader psychological conception of instinct, rather than in 
accordance with the narrower biological acceptation of the 
term. For the likes and dislikes constitute part of the con- 
ditions under which the behaviour occurs, and not elements in 
the co-ordinated response as such. Hence it is preferable to 
apply to these hereditary qualities the term inate, rather than 
the term instinctive. But, waiving this distinction, it is true 
that such pleasant or unpleasant qualities of the sensory results 
of stimuli are part of the animal’s hereditary outfit, and are 
not acquired in the course of individual experience. What, 
then, is acquired? What part does experience play in the 
development of intelligent behaviour? Let us consider the 
case of the chick and the ladybird, and see whether it helps 
us to answer these questions. The chick is stimulated to the 
instinctive pecking response by a small moving object. That 
is the first scene of the little drama. In the second scene the 
ladybird is seized, sensory centres are unpleasantly stimulated, 
and the insect is dropped or thrown on one side with signs of 
disgust. Let us grant that this aversion with its characteristic 
response is also instinctive. There is no hereditary connection 
between scene 1 and scene 2. After an interval the curtain 
rises on act ii. The characters are the same as in the first 
scene of the previous act. But the action of the drama is 
different. The chick does not seize the ladybird. Why? 
Because there is an acquired connection between scenes 1 and 2 
of the previous act. The chick has gained experience of the 
nauseous character of the insect, and this experience influences 
and modifies his behaviour. The essentially new feature, 
