Such conceptual representations have tended to differ from logical ones in several respects. One, as already discussed, has been the emphasis by Schank and various other researchers (e.g., Wilks 1978; Jackendoff 1990) on “deep” (canonical) representations and primitives. An often cited psychological argument for primitives is the fact that people rather quickly forget the exact wording of what they read or are told, recalling only the “gist”; it is this gist that primitive decomposition is intended to derive. However, this involves a questionable assumption that subtle distinctions between, say, walking to the park, ambling to the park, or traipsing to the park are simply ignored in the interpretive process, and as noted earlier it neglects the possibility that seemingly insignificant semantic details are pruned from memory after a short time, while major entailments are retained for a longer time.