The phenomenon of 'flapping'

Some severely mentally handicapped children occasionally flap their arms, especially when excited, perhaps when running around, or engaging in some other type of gross motor activity.
If we look at the second feature of frank U.M.N. damage or dysfunction, flexion of the upper limbs, we will see the basis of our flapping.
Since the behaviour is a repeated flexing of the arms, and not a sustained posture, it is clear that the U.M.N. dysfunction is a slight and variable one.
From the observation that the behaviour is especially associated with excitement and gross bodily activity we may describe it as a fluctuating manifestation of a normally only sub-clinical and latent condition.
We might also describe the behaviour as a pattern of pathological associated movements. These are abnormal movements which do not usually show themselves but occur when the neurological patient engages in some normal type of activity.

Associated movements accompany voluntary movements, especially fast gross motor movements, when the individual exerts himself physically . They are also to be seen when the individual is excited, and we can see that the common thread behind excitement and fast movement or exertion must be a high level of activity, perhaps of the A.N.S., especially the S.N.S. and a high level of substances such as adrenalin etc.
This behaviour might become linked with, and triggered by, specific stimuli, and be reinforced/rewarded by specific consequences. So, for example, C.W would run and flap, or just stand and flap,
i. in proximity to ducks and other birds; the resulting scattering of these creatures, as with normal young children, being very rewarding for her
ii. when close to bubbles produced for her amusement