Ultimate Psychology Guide
The process of forgeting
An early explanation for why we forget is the decay theory. This theory asserts that information is forgotten because of the gradual disappearance of the memory trace. Thus decay theory views the original piece of information as gradually disappearing unless something is done to keep it intact.
A much modern theory is interference theory. This theory refers to the view that forgetting occurs because recall of certain words interferes with recall of other words. There are two basic types of interference:
1-Retroactive interference: happens when new information interferes with old information. Let us say for example that you decide to learn a new language if this kind of inhibition happens then you will find yourself saying some words from the new language while talking with the language you already know.
2-Proactive interference: occurs when the interference material occurs before rather than after. For example when you change your phone password it is highly possible that when you try to inter the password you enter the old one, which means that the old password interfered with the new one.
Robert J. Sternberg (2008). Cognitive Psychology, Fifth Edition.