Explanations for forgetting : Interference

Interference

Forgetting because one memory blocks another, causing one or both memories to be distorted or forgotten

Proactive interference ( PI)

Forgetting occurs when older memories, already stored, disrupt the recall of newer memories. The degree of forgetting is greater when the memories are similar

Retroactive interference (RI)

Forgetting occurs when newer memories disrupt the recall of older memories already stored. The degree of forgetting is again greater when the memories aare similar

What did Mcgeoch and Mcdonald study

In both RI and PI, interference is worse when memories are similar.

They studied RI by changing amount of similarity between two sets of materials. participants had to learn a list of 10 words until they could remember them with 100% accuracy, then learned a new list.

Group 1 synonyms wordswith same meaning as original

Group 2 Antonyms words with opposite meaning to original

Group 3 Words unrelated to original

Group 4 consonant syllables

Group 5 Three digit numbers

Group 6 No new list - these participants rested (control condition)

What did mcgeoch and mcdonald find

When participants were asked to recall original list, most similar material (synonyms ) produced the worst recall. Shows interference is strongest when memories are similar.

Real world interference

Baddeley and Hitch (1977) supported interference theory by asking rugby players to recall the names of teams they had played against over a season. Players who had played the most games (and thus experienced the most data interference) showed the worst recall, proving that interference can actively operate in everyday environments.

Counterpoint: the conditions required for severe interference are relatively rare in daily life. Unlike controlled lab settings, two everyday memories must be highly similar to truly conflict with each other. This suggests that the majority of day-to-day forgetting might be better explained by alternative theories, such as retrieval failure due to an absence of cues.

Interference and cues

A limitation of interference theory is that its effects appear to be temporary and can be easily overcome using environmental cues. Tulving and Psotka (1971) gave participants categorized word lists; recall progressively worsened with each additional list learned due to proactive interference. However, when participants were later given a cued recall test (being told the category names), their recall scores jumped back up to roughly 70%. This demonstrates that interference causes a temporary loss of informational accessibility rather than a permanent loss of storage, a nuance the core theory fails to predict.

Support from drug studies

Another distinct strength of the theory comes from biological evidence of retrograde facilitation in drug research. Coenen and van Luijtelaar (1997) found that when a list of words was learned before taking the drug diazepam, the participants' long-term recall a week later was significantly better than a placebo control group.

John Wixted (2004) suggested this happens because the drug temporarily blocks the brain from processing new, incoming information, preventing it from retroactively interfering with the memories already stored. This strongly reinforces the idea that forgetting is actively caused by material interference; if you reduce the opportunity for new interference, you directly reduce forgetting.