What is the background of eye accessing cues?
William James (Principles of Psychology, 1890) first suggested that internal representations and eye movements may be related. This observation was not explored further until the 1970's when Richard Bandler, John Grinder, Robert Dilts and others conducted further experimentation in this area.
According to neurological research, eye movement both laterally and vertically seems to be associated with activating different parts of the brain. In the neurological literature, these movements are called lateral eye movements (LEM) and in NLP we call them eye accessing cues because they give us insights as to how people are accessing information.