Retrieval failure is a type of forgetting that occurs when information that has been previously encoded and stored in long-term memory cannot be accessed or retrieved when needed. This happens because the necessary retrieval cues or triggers are not present. Retrieval cues are external or internal stimuli that help trigger the retrieval of stored information. For example, if you are trying to remember a phone number but cannot recall it, it may be because you are not in the same physical or psychological state as when you first learned the number.

There are several common causes of retrieval failure, including the absence of appropriate retrieval cues, interference from other information, and context-dependent memory. The encoding specificity principle (ESP) is a theory that suggests that memory will be best when a persons physical or psychological state is similar at encoding and retrieval. However, the ESP is difficult to test and leads to circular reasoning.

Retrieval failure is an important concept in psychology because it helps explain why we sometimes forget information that we have previously learned. By understanding the causes of retrieval failure, we can develop strategies to improve memory recall, such as using mnemonic devices or studying in environments similar to the testing environment.