Evaluation of Trace Decay Theory of Forgetting

There is evidence to support the trace decay theory of forgetting. For example, the Peterson and Peterson (1959) experiment demonstrated that participants recalled fewer items the longer the delay before recall. Similarly Ebbinghaus (1885) found that memory deteriorated over time. He found that forgetting is fastest in the first hour after learning which supports the argument of trace decay operating on short term memory. He also found that there was some loss of memory after a day demonstrating trace decay from long term memory.

One of the main problems with trace decay theory is that it is very difficult to test objectively. It is possible that other factors such as interference or lack of available cues may have an effect on forgetting rather than trace decay. Perhaps the ideal way to test the decay of a memory trace would be to have participants receive information and then do nothing, physical or mental for a period of time. If recall was poor after a period of time then it could be said that decay has occurred.

There is evidence that challenges trace decay theory. Jenkins and Dallenbach (1924) tested whether time between encoding and recall led to forgetting. Participants had to learn a list of nonsense syllables. Some participants went to sleep immediately (the equivalent of doing nothing) while the remainder went about their usual routine. During several intervals the participants were tested on their recall. If forgetting was due to decay it would be expected that both sets of results would show a similar pattern. However, participants who remained awake forgot more than those who slept. This would indicate that forgetting may be due to events that happen between learning and recall interfering with ability to recall rather than decay.