Interference

Interference

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

Proactive interference

Forgetting occurs when older memories, already stored, disrupt the recall of newer memories.

The degree of forgetting is greater when the memories are similar

E.g. Giving your old phone number to someone after changing to a new one.

Retroactive interference

Forgetting occurs when newer memories disrupt the recall of older memories already stored.

The degree of forgetting is greater when memories are similar.

E.g. A teacher learning the student names of a new class may have trouble remembering the student names of an older class

McGeoch + McDonald

PROCEDURE

Studied retroactive interference by changing the amount of similarity between 2 sets of materials.

Participants had to learn a list of 10 words until they could remember them 100% accuracy.

There were 6 groups of participants who had to learn different types of new lists:

1. Synonyms

2. Antonyms

3. Words unrelated to original list

4. Consonant syllables

5. 3-digit syllables

6. No new list (control condition)

McGeoch + McDonald

FINDINGS

When participants were asked to recall the original lists of words, the group with synonyms had the worst recall. Shows that interference is strongest when the memories are similar.

Supports both types of interference.

Explanation of effects of similarity

2 possible reasons why similarity affects recall.

Could be due to PI - previously stored information makes new similar information more difficult to store.

Or it could be due to RI - new information overwrites previous similar memories because of similarity

PI Keepel + Underwood

Same study as Peterson and Peterson

Gave participants a trigram to remember. Asked them to count backwards in threes. The length of time doing this gradually increased.

Number of trigrams recalled decreased with the increased time spent on the task

Proactive interference could explain this as earlier trigrams entered LTM and this interfered with the newer trigrams.

RI Schmidt

Investigated ability to remember street names learnt in childhood.

200+ participants 11-79 years old, former students of Dutch primary school

Sent a questionnaire about how many times they moved, where they lived and how long for.

Sent a map of the neighbourhood where they lived, street names replaced with numbers.

Interference measured by number of times they moved to other neighbourhoods

Positive association between number of moves and number of street names they forgot.

Retroactive interference had occurred, the new learnt street names interfered with the ability to recall the old ones.

W Experimental methods

Research was done in laboratories.

Subjects had to learn numbers, syllables and word lists in the McDonald study. Not fully representative of how memory operates.

Artificial environment. Low in ecological validity and hard to generalise.

S Baddeley + Hitch

Real-world application.

Rugby players recalling the names of teams they played against in a rugby season.

All had the same amount of time played, some missed matches so interference was different for everyone.

Players who played the most games had the most interference and had the worst recall.

Increases validity

W Vogel

People are more resistant to interference than others

Gave participants tasks to test their working memory capacity.

Highest and lowest scorers were given more tasks to create proactive interference.

High WMC = less likely to be affected by PI.

High WMC associated with enhanced filtering ability, helps prevent irrelevant information from disrupting working memory.

They can focus on relevant information more.

Limited explanation as it doesn’t apply to everyone.

W Tulving and Psotka

Interference is temporary and can be recovered using cues.

Gave participants lists of words with categories.

Recall ≈ 70% for the first list. Got worse for each additional list.

Given a cued recall test after the procedure with the names of the categories given. Rose to 70% again.

Shows that interference causes a temporarily loss of material that is still in LTM.