Two tests of all-or-none learning and retention

A number of recent experiments have seemed to imply that the basic associations of learning are formed in an all-or-none manner. However, the evidence provided by these experiments has been essentially indirect since the presence of an association has been assessed by an all-or-none method, viz. simple recall. By allowing the subject more than one attempt at recall or recognition more direct evidence can be obtained. All-or- none learning implies that the probability of success during further attempts will be at the chance level. The experiments described show that this is not the case for the stimulus materials used. On the other hand the uncertainty in bits during further attempts was a fairly high proportion of the uncertainty expected on the all-or-none hypothesis. For this reason the results may indicate only a minor breakdown of the hypothesis. In a retention test administered after a week, fewer first-attempt successes were achieved than in the immediate test but, despite this, the uncertainty after a first- attempt failure was about the same as in the immediate test. The experiments also incorporated a second test of the all-or-none hypothesis. This involved comparing 2-choice and 4-choice recognition scores and recognition scores with recall scores. After corrections for guessing, these scores should be identical, if the hypothesis is correct. Results of this corrected-comparisons test tended to support those of the further-attempts test.