Explanations for Forgetting (AQA A-Level Psychology): Revision Notes
Interference Theory (IT)
What is interference theory?
Interference Theory (IT) provides an explanation for why we forget information that has been successfully stored in our long-term memory. The theory proposes that forgetting occurs when information in the LTM becomes confused or disrupted by other similar information during the encoding or retrieval process. This interference leads to inaccurate recall, where we either cannot access the correct information or retrieve the wrong details.
Rather than memories being lost from storage, the information remains in our LTM but becomes difficult to access due to competition from similar material. This makes interference theory a form of retrieval failure explanation for forgetting.
Types of interference
Interference theory identifies two distinct types of interference that can occur:
Proactive interference
Proactive interference happens when previously learned information disrupts our ability to recall newer material. The interference works forwards through time, meaning older memories interfere with the formation or retrieval of more recent ones.
Real-life example: Difficulty remembering a new phone number because the memory of your old phone number keeps interfering with your attempts to recall the new digits.
Retroactive interference
Retroactive interference occurs when newly acquired information disrupts the recall of previously learned material. This type works backwards through time, where recent learning interferes with accessing older memories.
Real-life example: Learning a new car registration number, which then makes it harder to remember your previous car's registration details.
Research methods in interference studies
Standard Research Methodology
Researchers typically investigate interference using controlled laboratory experiments involving word pair lists. Participants learn two sets of word pairs, where the first word (the cue) remains the same in both lists, but the second word (the response) differs. After memorising both lists, participants receive the first word of a pair and must recall which second word accompanied it.
This method allows researchers to measure both types of interference:
- When participants recall words from the first list instead of the second (proactive interference)
- When participants recall words from the second list instead of the first (retroactive interference)
Key research studies
Research Study: Schmidt et al. (2000) - Street names and childhood memories
This study investigated interference in a real-life setting by examining how learning new street names affects memory for childhood neighbourhood streets.
Participants: 1,700 former students of a Dutch elementary school, with 211 responding to the questionnaire, aged 11-79 years.
Aim: To assess the influence of retroactive interference on memory for street names learned during childhood.
Procedure: Participants received a map of their childhood neighbourhood (Molenberg) with all 48 street names replaced by numbers. They were asked to recall as many original street names as possible. Researchers collected personal details including how many times participants had moved house and their current living arrangements.
Findings: A clear positive correlation emerged between the number of times participants had moved to other neighbourhoods and the number of childhood street names they had forgotten. Participants who had moved frequently showed significantly poorer recall of their original neighbourhood street names.
Conclusions: Learning new street name patterns when moving house creates retroactive interference, making it harder to recall older street name memories. This demonstrates that interference theory can explain forgetting in genuine real-life situations.
Evaluation:
- Strengths: High ecological validity due to real-life setting; large sample size; demonstrates practical applications of interference theory
- Weaknesses: Multiple extraneous variables (time spent in neighbourhood, frequency of visits, walking vs driving to school) could have influenced results; methodology could be adapted to test proactive interference as well
Research Study: Baddeley and Hitch (1977) - Rugby team memories
This study compared interference theory with trace decay theory by examining rugby players' memories of team matches.
Procedure: Researchers tested participants who had played varying numbers of rugby union games on their ability to remember teams they had played against. They assessed whether forgetting was more related to the number of intervening games played (supporting interference theory) or the amount of time that had passed (supporting trace decay theory).
Findings: Forgetting was more strongly associated with the number of games played between matches rather than the time elapsed, providing support for interference theory over trace decay explanations.
Research Study: Abel and Bauml (2013) - Sleep and interference
This research examined how sleep affects interference between competing memories.
Procedure: Participants learned either single word pair lists or dual lists that would create interference conditions. After a 12-hour interval of either wakefulness or sleep, their memory for the word pairs was tested.
Findings: Sleep significantly reduced both proactive and retroactive interference effects compared to remaining awake. This suggests that sleep helps strengthen and stabilise memory content, making it less susceptible to interference during recall.
Evaluation of interference theory
Limitations:
Limited scope of explanation: The primary criticism of interference theory is that it only effectively explains forgetting when two sets of information share similarities. For instance, interference readily occurs when simultaneously learning French and Welsh vocabulary at school, but this situation is relatively uncommon in everyday life. Most real-life forgetting cannot be attributed to interference between similar materials.
Laboratory artificiality: Much interference research relies on laboratory experiments using artificial tasks like memorising word pair lists. These studies may lack mundane realism and fail to represent how interference operates in natural memory situations outside controlled environments.
Incomplete explanation: Although studies demonstrate that interference represents a genuine phenomenon, they do not clearly identify the specific cognitive processes responsible for creating interference effects. The theory describes what happens but provides limited insight into the underlying mechanisms.
Alternative explanations: Substantial research evidence supports cue-dependent forgetting and other explanations for memory failure. Since multiple explanations for forgetting exist, interference theory cannot account for all instances of retrieval failure.
Strengths:
Real-world applications: Studies like Schmidt et al. demonstrate that interference effects can be observed and measured in genuine life situations, not just laboratory conditions.
Empirical support: Numerous controlled studies have consistently demonstrated both proactive and retroactive interference effects, providing robust evidence for the theory's core principles.
Practical implications: Understanding interference has led to improved learning strategies, such as spacing out the learning of similar materials to reduce interference effects.
Key Points to Remember:
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Interference theory explains forgetting as competition between similar memories in long-term memory, not memory loss
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Proactive interference occurs when old information disrupts recall of new material, while retroactive interference happens when new learning interferes with old memories
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Laboratory studies using word pair lists consistently demonstrate both types of interference, but real-world applications like the Schmidt street names study show interference operates in everyday life
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The theory's main limitation is that it only explains forgetting when similar information competes - most everyday forgetting involves dissimilar materials
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Sleep appears to reduce interference effects by helping to consolidate and stabilise memory content