"The human being may be regarded as an organism possessing certain centralized properties which permit him to respond to many and diverse stimuli in an organized and selective manner. This conception of man, inexplicable in terms of the old Laws of Association, gained firmer ground with experimentation begun in the latter part of the nineteenth century. Reaction-time experiments constituted the major portion of research current at the time." --

"This thesis concerns the question of intellectual loss in schizophrenia. To obtain evidence of such loss, the investigator must demonstrate that an individual with schizophrenia has a lower intelligence than he had at a time when the disorder was presumably absent. The task appears straightforward. A survey of the literature on this subject, however, indicates that it is not. The problem of determining whether intellectual loss occurs in schizophrenia presents certain difficulties, which relate, in general, to an insufficient knowledge concerning the nature of the disorder, and, in particular, to the following factors." --