Since refractory phase is regarded as a universal post-stimulation phenomenon of sensitive tissues, the question arises whether a similar effect may be observed which is characteristic of voluntary and associative responses. Three sets of experiments were made, using reaction time, judging the longer of two parallel lines, and nonsense syllable-number sequences after the method employed by Thorndike. Variations in the interims between stimulations were introduced. These ranged from ½ sec. to 16 sec. The author's results led him to conclude that in the case of the three processes studied effects are produced in the organism which "serve as a barrier against immediate repetition." The subsequent return to "normality" is comparable to that found in isolated tissues and reflexes, and while it may not be identical with refractory phase in nerve-muscle preparations, it is probably based upon it. (PsycINFO Database Record (c) 2006 APA, all rights reserved)