2.1.3 Long Term Memory

Long-term memory:

• There are three types of long-term memory (LTM):
  • Episodic
  • Procedural
  • Semantic 

Episodic memory

• This is the part of LTM that relates to experiences a person has had or events from their life.
• Examples of episodic memory:
  • A 16th birthday party
  • The first time someone sees the sea
  • Someone's first psychology lesson

Procedural memory

• This is the part of LTM involved in knowing how to do certain actions or skills
• Examples of procedural memory:
  • Knowing how to ride a bicycle
  • Knowing how to swim
  • Knowing how to make a cup of tea

Semantic memory

• This is the part of LTM that involves knowing and recalling facts, concepts and meanings
• Examples of semantic memory:
  • Knowing that Paris is the capital of France
  • Knowing that the number 3 is between the numbers 2 and 4
  • Knowing that the word 'bank' has two meanings: A place where money is stored, or the edge of a river

• Long Term Memory (LTM) is the part of the memory that holds information indefinitely, having a longer duration and larger capacity than Short Term Memory (STM)
• As far as is known, long-term memory has an unlimited capacity
• There is no way to test this as people often forget facts and information
• There has never been a known case of someone not being able to learn something new or retain a memory because their LTM is full

Duration of long-term memory

• Research from studies as well as anecdotal evidence suggests people can recall facts from childhood in their later life
• The duration of LTM is as long as a person’s lifetime
• The only time in a person’s life that may not be open for the recall is an early childhood
• Most people cannot recall episodes from their life before the age of two
• This known as Childhood or Infantile amnesia

Evidence for the duration of long-term memory

• Bahrick (1975) investigated the duration of LTM in several studies using a field study method
• One of his most famous experiments was asking 392 American graduates to identify people from their high school yearbook
• The participants were given a list of names and had to select the photograph that matched that name
• In some cases, the graduates were going back 47 years to their graduation and the yearbook photographs
• Those recalling from 14 years ago could accurately match the name to the face 90% of the time
• Those recalling from 47 years were accurate 60% of the time
• This suggests LTM lasts a lifetime as such strong recall after 47 years is not likely to fade too much a few decades later

 Evaluating research into duration and long-term memory

• Bahrick's study has good ecological validity as looking at old photographs and trying to recall names is a task most people do in real life
• However, Bahrick would have had less control over the variables in the study
• Some people may have had better recall as they were still in the same town and maybe still in contact with the people in the yearbook
• Others may have had poor recall as they never really knew the names of the people in the yearbook in the first place as they were less social in high school
• The study never really explains why recall becomes worse over time, is it a side effect of old age or that there is some limit to duration which impacts the memory as we get old and continue to make more memories

What is encoding in long-term memory?

• Encoding is how the information is processed from the senses into the memory itself
• This is how the information will be stored and ultimately recalled
• Encoding is always in the form of a modality or one of the senses
• Long-term memory encodes semantically or by meaning
• We know this from a study by Baddeley (1966)

What is the evidence for encoding in long-term memory?

• Baddeley considered encoding in short-term memory and long-term memory but here we will look at LTM only
• He gave participants four lists of words to learn:
  • Acoustically similar: words that sounded the same such as cat, bat, rat
  • Acoustically dissimilar: words that did not sound the same such as laugh, bear, pencil
  • Semantically similar:  words that mean the same such as large, huge, enormous
  • Semantically dissimilar: words that do not mean the same such as police, computer, chair
• The words were all presented visually, on a screen as part of a slideshow
• They had to be recalled in the order presented: Free recall was not allowed
• For the long-term memory part of the experiment he asked for recall after 20 minutes
• He found the semantically similar words had the worst recall: Getting them in the correct order was incredibly difficult as they all meant the same thing
• There was no difference in LTM for the acoustically similar and dissimilar words
• From this, he concluded that LTM relied on semantic encoding to process information

How can we evaluate the research into encoding in long-term memory?

• Once again, this is a lab experiment so is highly controlled, with extraneous variables taken care of
• However, this also means that it lacks ecological validity as the tasks do not relate to real life
• The words had little to no meaning for participants and so they were harder to recall
• Information that has to be recalled in reality often has meaning and significance, making recall easier