GENERAL CONTROLS OF CONDUCT 3
ments are reflexive actions in response to the sensations arising from their physical circumstances. Especially is this true of children, who have little power to restrain these reflexive tendencies. But far more important are
II. The instincts. Instincts may be defined either in terms of structure or of function. First, as to structure. If we think of a reflex as a direct connection or co-ordina tion of a nerve which receives a sensation with a nerve which controls the movement of a muscle, so that the stim ulation of the first causes an immediate contraction of the second, then the best way to think of an instinct on its physical side is as a combination or complication of a number of reflexes; so that the stimulation of a nerve which receives the sensation is followed by a series of re flex actions terminating finally in an adaptive movement of the body. The dividing line between the reflex and the in stinct is not easy to draw. Perhaps it is better to say that the one gradually merges into the other. But the char acteristic mark of the first is simplicity, and of the second, complexity of nervous co-ordination. Second, as to func tion, it may be defined " as the faculty of acting in such a way as to produce certain ends, without foresight of the ends, and without previous education in the performance." 1 " Instincts are functional correlations of structure." An- gell says : " If the activity involves a number of acts, each one of which, considered singly and alone, is relatively use less, but all of which taken together lead up to some adap tive consequence, such as the building of a nest, the feeding of young, etc., it will be safe to call the action instinctive." 2 McDougall defines an instinct " as an inherited or innate psycho-physical disposition which determines its possessor to perceive, and to pay attention to, objects of a certain class, to experience an emotional excitement of a particular quality upon perceiving such an object, and to act in regard to it in a particular manner, or, at least, to experience an
1 James, " Psychology, Briefer Course," p. 391.
2 " Psychology," p. 288.
�� �
