Alpha rhythms and mental imagery

Abstract

1. 1. Active vision and visual recall are associated with blocking or attenuation of the alpha rhythms, active vision producing the greater degree of change. Non-visual imagery is associated with their persistence. Alpha activity is also blocked non-specifically by anxiety. 2. 2. All the EEGs in this series were of the R type, almost certainly due to the fact that the subjects were a highly selected group with versatile modes of thought, whereas the Bristol series (1943) consisted of an unselected group. 3. 3. The EEGs showed every grade of change between the M and P types, suggesting that these simply represent the two extremes of a continuous gradation of changes. 4. 4. Individuals use different types of imagery with differing degrees of ease and preponderance. Just as the M, P, and R types of record are correlated with distinct varieties of thinker, so, within certain limits, the several properties of the alpha rhythms, in a “resting” record can be correlated with a subject's ease and habitual use of visual imagery. 5. 5. In correlating mental activity with changes in the EEG, as much attention must be paid to analysing the individual properties of a person's mental processes (psychological information) as to the features of the EEG.