One more example, perhaps even more trivial in the eyes of some people, may be given. A duckling a few hours old will scratch the side of his head. It is true he may topple over in the process, through insufficient powers of balance, for the simultaneous performance of poising on one leg and having a good scratch with the other is no easy matter. But let not either our familiarity with such behaviour, nor some observed and laughable failure on the part of the duckling, blind us to the fact that this is a congenital activity, and one of no little complexity, indicating a definite organic nexus. A local irritation sets agoing movements of the hind limb of that side through which just that particular spot is scratched in the absence of any previous practice, any learning to localize the spot. There can be no question that such inherited co-ordinations, whether perfect from the first, or with deferred perfection and some aid from acquisition, afford ready-made data to consciousness, which are of the utmost service in the guidance of subsequent behaviour. The two-days-old chick, with the aid of this instinctive co-ordination, performs well a number of actions, which, had she to consciously learn them all, would probably be still but half mastered when she was a skinny old hen.
Our whole treatment of instinctive behaviour has been based on the assumption, already to some extent justified, that experience is not inherited. If it be hereditary, how comes it that chicks show no recognition of still water, which must have been familiar to the experience of generation after generation of birds? How comes it that they do not even seem to recognize their natural parent and protector, the hen? Two chicks ten days old were taken to the yard whence were derived the eggs from which they were hatched, and were placed about two yards from a hen which was clucking to her brood. They were not in a frightened condition, for they stood on my hand and ate grain from it, scratching at the palm. But of the clucking of the hen they took no notice whatever. The same results were obtained with other chicks thirteen days old. Was this due, as Spalding suggested, to loss of the instinctive response which was perhaps present at an earlier age? Seemingly not. For a chick was taken at the age of two and a half days to its own mother, which had three chicks. These followed her about, and ran at once to her when she clucked and pecked on the ground. The little stranger, however, took no notice, nor did he show any tendency either to go to the hen or to follow the three chicks, having been purposely brought up alone. When the hen took her little brood under her wing, the stranger was placed close to her. She clucked, and seemed anxious to entice and welcome the little fellow, seizing an oat-husk and dropping it before him; but he remained indifferent, walking away and standing in the sunshine. After about forty minutes he seemed more inclined to go with the other chicks, but still ignored the existence of the hen. The natural instinctive tendency seems to be from the first to nestle under anything; and there is the hen provided by nature for the purpose. By experience the chicks grow accustomed to her fussy ways, as they grow accustomed to the ways of such a foster-parent as the writer of these pages. Still, though there is, apparently, no instinctive knowledge of the hen as their natural protector, and though I have seen no observable response to the clucking sound, this must not be taken as necessarily implying that there is no instinctive response to any of her modes of behaviour. There is such a response to her pecking on the ground; there is probably such a response to her danger-note; and there may be many other such instinctive modes of behaviour related to her actions. How far they extend can only be ascertained by patient observation; and such responsive behaviour need not imply any instinctive knowledge begotten of inherited experience.
We may now summarize some of the general conclusions which may be drawn from observations of instinctive behaviour in young birds.
1. That which is inherited is essentially a motor response or train of such responses. Mr. Herbert Spencer’s description of instinct as compound reflex action is thus justified.
2. These often show very accurate and nicely-adjusted hereditary co-ordinations.
3. They are evoked by stimuli, the general type of which is fairly definite, and may in some cases be in response to particular objects.
4. They are also generally shown under conditions which lead us to infer the presence of an internal factor, emotional or other.
5. There does not seem to be any evidence of inherited knowledge or experience.
IV.—The Conscious Aspect of Instinctive Behaviour
In our definition of instinctive behaviour all positive reference to the presence of conscious states was omitted. By some writers, however, the fact that it is accompanied by consciousness is regarded as a distinguishing feature of instinct. Romanes introduced his definition with the words:[38] “Instinct is reflex action into which there is imported the element of consciousness.” And he emphasized the conscious aspect when he said: “The term comprises all those faculties of mind which are concerned with conscious and adaptive action, antecedent to individual experience.” Professor Wundt also lays some stress on the conscious accompaniments of instinctive activities which, he says,[39] “differ from the reflexes proper in this, that they are accompanied by emotions in the mind, and that their performance is regulated by these emotions.” The definitions of other writers express or imply the presence of consciousness in differing modes and degrees, culminating in the hypothesis of inherited knowledge. Douglas Spalding, for example, said[40] that “animals can forget the instinctive knowledge which they never learned!”