The levels of processing framework proposed by Fergus I.M. Craig and Robert S. Lockhart in 1972, refers to three levels of encoding of information: visual encoding (concerned with visual stimuli), phonemic encoding (concerned with visual and auditory stimuli) and semantic encoding (concerned with meaning). Shallow processing, (visual and phonemic processing), leads to a fragile memory trace that is susceptible to rapid decay, and deep processing (semantic processing) results in a more durable memory trace.