The nature of forgetting in short-term and long-term memory

Forgetting occurs when previously learnt information cannot be retrieved from memory. Research into memory often assumes that an inability to recall something means it has been forgotten.

Causes of forgetting in short-term memory

Forgetting from short-term memory (STM) is typically viewed as an availability issue, where the information is no longer present.

This can happen because:

• STM has a limited capacity, so new information can displace older items.
• STM has a limited duration, causing information to fade or decay over time if not rehearsed.

Causes of forgetting in long-term memory

Forgetting from long-term memory (LTM) can also involve decay, making information unavailable.

However, other factors include:

• Accessibility problems - Information is stored but difficult to retrieve without sufficient prompts, such as needing hints to recall details from an article read months ago.
• Interference problems - Confusion arises when similar pieces of information overlap, making it hard to distinguish between them, like mixing up two similar historical dates.

Interference as an explanation for forgetting

Interference theory suggests that the ability to remember is disrupted by learning similar information either before or after the target material. This creates confusion in memory, leading to forgetting. There are two main types: retroactive interference and proactive interference.

Retroactive interference

This occurs when newly learnt information disrupts the recall of older information.

Underwood and Postman (1960) study on retroactive interference

• Method - Participants were divided into two groups and both learnt a list of word pairs (e.g., door-key). The experimental group then learnt a second list with the same first words but different second words (e.g., door-lamp), while the control group received no second list. Both groups were later tested on recalling the first list.
• Results - The control group showed better recall of the first list compared to the experimental group.
• Conclusions - The poorer performance of the experimental group indicated that the second list caused retroactive interference, hindering recall of the original pairs.

Proactive interference

This happens when older information disrupts the recall of newly learnt material.

Underwood (1957) study on proactive interference

• Method - The study examined forgetting over a day by testing recall of word lists. Participants who had previously learnt multiple lists (more than a dozen) were compared to those who had learnt none before the target list.
• Results - Recall of the target list after a day was approximately 25% for those with prior lists, but around 75% for those without prior learning.
• Conclusions - Earlier lists created proactive interference, reducing the ability to remember the later list.

Strengths and limitations of the interference theory

Interference theory provides a framework for understanding why similar memories can conflict, but it has both supporting evidence and notable drawbacks.

Strengths of the interference theory

• Backed by many controlled laboratory experiments, such as those by Underwood and colleagues, which demonstrate consistent effects.
• Applies to real-world scenarios, like difficulty recalling vocabulary from a native language after learning a foreign one due to overlapping words.

Limitations of the interference theory

• Effects are often stronger in artificial lab settings (e.g., using unrelated word lists) than in everyday life.
• The theory has lost some prominence as it explains the occurrence of forgetting but not the underlying cognitive or biological mechanisms.

Retrieval failure and cue-dependent forgetting

Retrieval failure theory views forgetting as a problem of accessing stored information rather than the information being lost. Memories in LTM are available but may not be accessible without appropriate cues, which can be internal (e.g., emotional state) or external (e.g., environmental context). This is known as cue-dependent learning, where recall improves if the retrieval context matches the encoding context, such as remembering more in the same mood or location as when the information was learnt.

Evidence and evaluation of cue-dependent forgetting

Cue-dependent forgetting is often regarded as the strongest explanation for forgetting in LTM, with research suggesting that most LTM information remains available if the right cues are provided.

Tulving and Psotka (1971) study on forgetting in LTM

• Method - The study tested interference versus cue-dependent theories. Participants learnt a varying number of lists (between 1 and 6 lists) of 24 of words organised into categories. Recall was tested in two conditions: free recall (no cues) and cued recall (with category hints).
• Results - Free recall showed evidence of retroactive interference, with poorer performance as more lists were learnt. However, providing cues eliminated these interference effects, restoring high recall levels.
• Conclusions - Forgetting appeared to be due to a lack of cues rather than true loss of information, as memories became accessible again with appropriate prompts.
• Evaluation - The lab-based design allowed tight control over variables but reduced ecological validity, as word lists lack the meaningful context of real-life memories.

Overall evaluation of cue-dependent forgetting

Strengths:

• Substantial evidence indicates that nearly all LTM information is available with the right cue, making this a robust explanation for accessibility issues.

Limitations:

• Much supporting research uses artificial tasks like word lists, which may not reflect everyday forgetting.
• It is hard to empirically test if all LTM content is truly accessible.
• The theory may not fully explain procedural memories, such as skills like swimming or playing a musical instrument, which are less reliant on cues.