ABSTRACT
When recognising attention or mental activity one should perhaps first consider the distinction between the external world of objective reality and the reflection of this in the internal world of psychical reality. In electro-physiological experiments Hernandez-Peon recorded the occipital responses to single light flashes using subcortical electrodes and found that the response amplitude became larger with the increased intensity of the light. It may be said that subjective factors influenced some facet of the "attention" paid by the patient to the light flashes and this determined the variations in the occipital responses. The application of attention to one thing at a time necessitates the simultaneous withdrawal of attention from everything else that is not attended to. The problem, however, remained as to whether recorded changes might have been due to "attention" or "inattention" or due to the process of redistribution of cathectic energy. From 1934, Adrian made exhaustive examinations of the alpha rhythm on himself and his co-workers.
