head scratching

Scratching the Head.

The gesture of scratching the head is taken to mean that the person is puzzled, has encountered an obstacle in reality or in his thinking about a problem.
The head is perhaps seen as the place where the thoughts are. This is primitive thinking because

a) there are really no such things as thoughts, only thinking processes. Using the language category of nouns, abstract nouns is only a convention, not a reality, see the ideas of Woodworth and Schlosberg.

b) so they are not anywhere, and so specifically not in the head, although the organic physical substrate of the process of thinking is in the head, in the cerebrum.

Facial Expression

When one encounters an obstacle in thinking, in carrying out or forming a plan, one might also frown

The usual reason for scratching some part of the body is that there is an itch, in that body part. The itch is an irritation, a discomfort. The scratching relieves the discomfort because-----

Compare this with the behaviour of CW when she seems to have had a pain in her head or ear. She reacted by hitting the offending body part quite violently with her hand, often causing severe bruising. The body part attacks her, causing her pain, she becomes angry and retaliates by hitting it.
This was apparently the basis in her primitive thinking.

Realistically the slapping or punching would cause tissue damage and adrenaline release, followed by endorphine release, the body's natural opiate. This would make her feel better and so the self-abusing behaviour would be reinforced.
Perhaps CW's pain was deep in 'location', (in Thai 'puat'), and so required rather aggressive 'treatment'. In contrast an itch seems to be a rather superficial skin sensation and so requires a surface 'treatment', e.g. scratching, using the nails or similar.