This theory contradicts the multi-store [[Atkinson-Shiffrin memory model]] which represents memory strength as being continuously variable, the assumption being that rehearsal always improves long-term memory. They argued that rehearsal that consists simply of repeating previous analyses (maintenance rehearsal) doesn't enhance long-term memory.<ref>Eysenck, M. (2006). Learning and Long-term memory. In Fundamentals of cognition (Second ed.). Hove, England: Psychology Press</ref>
In a study from 1975 (Craik and Tulving) participansparticipants were given a list of 60 words. Each word was presented along with three questions. The participant had to answer one of them. Those three questions were in one of three categories. One category of questions was about how the word was presented visually ("Is the word shown in ''italics''?"). The second category of questions was about the phonemic qualities of the word ("Does the word begin with the sound 'bee'?"). The third category of questions was presented so that the reader was forced to think about the word within a certain context. ("Can you meet one in the street [a friend]"?) The result of this study showed that the words which contained deep processing (the latter) were remembered better.<ref>Craik, F. I., & Tulving, E. (1975). Depth of processing and the retention of words in episodic memory. ''Journal of experimental Psychology: general'', ''104''(3), 268.</ref>
