| The Decay Theory of Forgetting
One important question concerns forgetting. Cognitive psychology has addressed this question. One theory of forgetting is decay theory. Decay theory suggest that we forget something because the memory of it fades with time. This theory would suggest that if we do not attempt to recall an event, the greater the time since the event the more likely we would be to forget the event. Thus, this theory suggests that memories are not permanent.
There are other theories of forgetting. Memory for an event may reflect interference. The interference theory of forgetting suggest that we would forget something because other information learned is interfering with our ability to recall it.
One problem with the decay theory of forgetting is that we do not know whether the failure to recall something reflects that it is no longer in our memory, or that it reflects retrieval failure. Perhaps it is still there but we cannot retrieve the memory for some reason.