Melton (1963) argues only one kind of memory storage. Levels-of-processing theory of memory: craik and lockhart (1972); memory depends not on a particular memory store but on the initial processing done to the information at time of acquisition. Focuses on different kinds of cognitive processing that we perform when we encode, and later retrieve, information. Retention and coding of information depend on the kind of perceptual analysis done at encoding. Processing done at a superficial or shallow level does not lead to very good retention. Improvement does not come from rehearsal and repetition but from greater depth of analysis. Incidental learning: retention of information even when it is not required of, or even intended by, the processor. Craik and tulving (1975); people remembered best for words processed semantically. Bower and karlin (1974) found similar results with nonverbal stimuli; people who rated faces for honesty had better memory than those who rated faces for gender.