The topic of psychology we are evaluating in this article is ‘forgetting’. We’ll summaries the main theories of forgetting; including encoding failure, decay of memory trace, displacement theory and interference theory. Alongside giving examples of psychological studies to back up each theory.
THEORIES OF FORGETTING
- Encoding failure
- Decay of memory trace
- Displacement theory
- Interference theory (retroactive and proactive)
- Memory for traumatic events
Forgetting can occur at any stage of memory; as we process information we filter, alter and lose much of it. See diagram below, the red arrows illustrate a loss of memory at each stage:
EBBINGHAUS FORGETTING CURVE (1885)
Real world rapid decay of short term memory
You are introduced to somebody new at a party. They ask you how you know the host. You tell them then turn to your friend with the intention of introducing them. Suddenly, you realise you have forgotten the new persons name. An awkward silence ensues…If immediate recall is so good why do we immediately forget some information?
FAILURE TO ENCODE DETAIL
- Who were the characters in the detective film in last class?
- What was the detective wearing?
- Who was murdered?
- What time was the victim murdered?
- What type of plant was the lady planting?
TRACE DECAY IN SHORT-TERM MEMORY
Trace Decay Theory:
- Memories fade or decay gradually if they are unused
- Time plays a crucial role in trace decay
- Your ability to retrieve information declines with time after the original encoding of memory
- Information in short-term memory creates an active trace in the form of an excitation of nerve cells that, unless refreshed by rehearsal would fade away or decay over time
PETERSON & PETERSON (1959) STUDY
- Remember three consonants (e.g. HWB)
- Count back in 3 until cued to recall (suppresses rehearsal)
Results showed 90% of short-term memory information was forgotten after just 18 seconds without rehearsal. The process of rehearsal increases the strength of the memory trace, which increases the chances of memory entering into long-term memory.
ISSUES WITH DECAY THEORY
Memory loss is not just dependent on time…
Jenkins and Dallenbach (1924) Study
The participants learn list of nonsense syllables A) immediately before bed or B) at the beginning of the day. The results showed that sleep causes less memory loss than activity while awake.
“Memories interfering with memories”
- Forgetting is not caused by the mere passage of time
- Caused by one memory competing with or replacing another memory
- What we are currently learning can be disrupted (interfered with) by:
- Previous learning = Proactive Interference (“forwards”)
- Future learning = Retroactive Interference (“backwards”)
RETROACTIVE INTERFERENCE IN EYE WITNESS TESTIMONY
Eye witness testimony can be interfered with in a similar way:
- Similar events experienced by the witness since the crime
- New memories formed in similar situation
- Questioning by the police on topic
All may retroactively interfere with memory of crime
Underwood (1957) Study:
- Participants study a series of nonsense syllable lists
- 24 hours later participant had to remember a new list of nonsense syllables
The results showed the more nonsense syllables the participants had originally learnt, the less they recalled of the 2nd list. The new lists were becoming increasingly confused with those from the old lists.
EVALUATION OF INTERFERENCE THEORY
- The greater the similarity between two sets of material, the greater the interference
- Meaningless material is more susceptible to interference than meaningful material
- Meaning can increase memory strength through association
- The more difficult the distracting task between learning and recall, the more it will interfere with learning
- But it is difficult to dissociate time from interference; in order for new interfering information to be presented, time has to pass
- Memory loss may be due to either or both Trace Decay over time of interference
THE MEMORY OF TRAUMATIC EVENTS
The memory of traumatic events can be highly emotive and therefore you could be more likely to remember ever detail or nothing at all, depending upon the type of trauma.
Most people’s earliest memory is nothing more than when they were 4-5 years old but someone who tragically suffered the death of their father remembers this happening at the age of 2.
Someone involved in a car accident would wake up with no memory of what happened two hours before the event or even anything that happened throughout the entire day of the event.