those of the head. The variations in the two processes have been
measured by Münsterberg and Campbell[1] in reference to a single
condition, namely, the relation of attention to and interest in the
objects observed to the direction of sight in the closed eyes after
movement of the head. But apart from the influence of such secondary
elements of ideational origin, there is reason to believe that the
mere movement of the head from its normal position on the shoulders up
or down, to one side or the other, is accompanied by compensatory
motion of the eyes in an opposite direction, which tends to keep the
axis of vision nearer to the primary position. When the chin is
elevated or depressed, this negative reflex adjustment is more
pronounced and constant than when the movement is from side to side.
In the majority of cases the retrograde movement of the eyes does not
equal the head movement in extent, especially if the latter be
extreme.

[1] Münsterberg, H., and Campbell, W.W.: PSYCHOLOGICAL REVIEW,
I., 1894, p. 441.

The origin of such compensatory reactions is connected with the
permanent relations of the whole bodily organism to the important
objects which surround it. The relations of the body to the landscape
are fairly fixed. The objects which it is important to watch lie in a
belt which is roughly on a horizontal plane with the observing eye.
They move or are moved about over the surface of the ground and do not
undergo any large vertical displacement. It is of high importance,
therefore, that the eye should be capable of continuous observation of
such objects through facile response to the stimulus of their visual
appearance and movements, in independence of the orientation of the
head. There are no such determinate spatial relations between body