In the context of retrieval failures, the decay theory states that memories fade because of the occurrence of retroactive interference the cerebellum reduces in size over a period of time old memories are constantly replaced by new memories a neurochemical memory trace disintegrates over time

A neurochemical memory trace disintegrates over time

Forgetting from the short term memory is best explained by the trace decay theory. This theory believes that the memory leaves a trace in the nervous system. It can be a physical or chemical trace however, the trace fades away in just a matter of time.