CHAPTER II
METHODS OF EXAMINING SENSATION
The value of our work depends in great part on the trustworthiness of the means we have employed to examine sensation. I shall therefore devote this chapter to a description of the tests we have used and the conditions under which they have been carried out.
All the observations on my arm and hand were made with the precautions and safeguards customary in a psychological laboratory. The area to be explored was not extensive and time was no object; on the slightest sign of fatigue the examination was discontinued, and I was allowed a period of freedom and rest.
Such conditions are impossible clinically; and, before we set out on the researches embodied in this work, it was necessary to develop a series of tests which stood midway between the rough-and-ready examination of the clinician and the elaborate observations of the psychologist in his laboratory. Our aim was to find a set of simple tests which would yield measurable results. We were anxious to get rid of those statements of personal opinion which play so large a part in clinical records.
As far as possible, our observations were made in a quiet room, apart from the hospital ward with its distracting sights and sounds. On the rare occasions when this was impossible, owning to the difficulty in transporting the patient, his bed was carefully screened and every method adopted to secure his undivided attention. Whenever the patient was in bed the parts to be tested were exposed as little as possible. Anything that produces a "feeling of coldness," anything that causes shivering or the appearance of "goose skin," greatly diminishes the accuracy of the answers to most tests. A damp, misty or foggy day is peculiarly unfavourable for testing sensation. The most satisfactory conditions are a warm day of early summer, or a bright, cool winter morning in a well-warmed room.
It is important that the patient should be free from all visceral discomfort; he must not be hungry or suffer from a desire to empty his bladder. The following instance shows how potently such conditions may affect the results of even the grossest sensory tests. During the examination of R. A. H. (p. 458) it was noticed that his answers became much less accurate than they had been earlier in the day; for he failed on the right forearm in eight out of twenty attempts to tell the head from the point of a pin. He was
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