WHAT ARE INDIVIDUAL DIFFERENCES IN MEMORY?
Individual Differences refers to variables that make one person different from another.
The cognitive theories of memory tend to ignore these individual differences, focusing instead on processes that are universal and apply to everyone. A few unusual individuals (like H.M. and Clive Wearing) are studied, but only to help researchers understand better how "normal memory" works.
Cognitive theories explain how individuals may pay different levels of attention to events, may rehearse what they attend to to different degrees and may employ different strategies for encoding memories (like "chunking" or Elaborative Rehearsal). Individuals may have different schemas, which cause them to sharpen or level their memories differently.
Memory processes seem to be universal - all human beings have workng memory, short term and long term memory, etc. However, schemas are exactly the sort of thing that differs from culture to culture. This means that what people choose to remember and how they remember it will be affected by culture.
Mary Mullen (1994) carried out the first cross-cultural research into memory. She asked more than 700 Caucasian and Asian students to describe their earliest autobiographical memories (memories of things that happened to them). Asian students' first memories happened six months later than the Caucasian students' first memories - the earliest memory being from around age 4 for Asians and 3 years 6 months for Caucasians.
Katherine Nelson (2004) links this to upbringing and how our parents talk to us. As children, we encode our memories as we talk over those events with the adults in our life. The more those adults encourage us to spin "an elaborate narrative tale", the more likely we are to remember details about the event later.
In Western culture, over-reliance on computers might be affecting memory: this is "digital amnesia" brought about by a habit of looking up information rather than bothering to remember it. Maria Wimber (2015) points out that when we "outsource" our long term memory to mobile phones and the internet, the brain's ability to make long term memories decreases.
Our brain appears to strengthen a memory each time we recall it, and at the same time forget irrelevant memories that are distracting us... In contrast, passively repeating information, such as repeatedly looking it up on the internet, does not create a solid, lasting memory trace in the same way - Maria Wimber
Memory improves with age, peaking in middle life and declining with old age.
A study by Loftus et al. (1992) demonstrates this by showing museum visitors a film then questioning them later. Loftus found that average accuracy was 74%. 26-35 year-olds were most accurate (77%) and the elderly (age 65+) group were the least accurate (56%).
Not only did children (age 5-10) and the elderly (age 65+) get the lowest scores for accuracy, they were also the most suggestible - when there was a "leading question" they were more likely to produce a false memory.
There don't seem to be significant gender differences when it comes to memories, although schemas may be different between men and women and this might affect what they remember and how they remember it. For example, Wang (2013) found that women were better than men at recognising photographs of faces they had seen before - but only female faces; when it came to male faces they scored the same as the men.
In Loftus' study of individual differences, males and females scored similarly, except in the elderly group, where females were much more accurate than males (69% versus 43%).
There is some evidence that introverts have better long term memory (LTM) because they experience more cortical arousal when stressed but extroverts have lower cortical arousal and better short term memory (Cox-Fuenzalisa et al., 2006).
However, a cognitive explanation would be that introverts spend more time thinking about the past (they like to brood) and so they rehearse memories more; extroverts are more focused on the present and so pay more attention to sensory experiences.
Freud's psychodynamic theory of personality is entirely based around memory. Freud argues that people's personalities form when they repress painful childhood memories and create defence mechanisms to deal with unresolved issues in their past. This explains what Freud calls "childhood amnesia" - how we can't recall clearly events in our past from before the age of 5 or 6.
OTHER DIFFERENCES: PHOTOGRAPHIC MEMORY
Another aspect of individual differences is people who have very unusual memory abilities: the so-called "photographic memory" of the person who can recall every minute detail of what they see, read or hear.
For example, Kim Peek was born with brain damage that caused him to suffer many problems but gave him the strange ability to make mental calculations astonishingly quickly and read at speed, recalling in detail everything he read. Peek read 12,000 books in his life and could recall them all.
Although Kim didn't suffer from autism, he inspired the character of Raymond Babbitt in the Oscar-winning film Rain Man (1988). Dustin Hoffman, the actor who played Raymond Babbitt, visited Kim to get an understanding of his abilities and his disabilities.
Photographic memory is sometimes found in people with autism, called autistic savants. For example, Stephen Wiltshire can draw detailed landscapes from seeing a view once.
A condition called eidetic memory occurs in 2-10% of children, who can recall lots of details in something they see once, like car registration plates or book covers. This fades after age 6 and is unknown in adults.
Savantism and eidetic memory seem to be unconnected with IQ.
Adults may have hyperthymesia, also known as Highly Superior Autobiographical Memory (HSAM). James McGaugh (2006) reports the case study of A.J., a woman who could recall every detail of her life from the age of 14.
"Starting on February 5th, 1980, I remember everything. That was a Tuesday."
However, although A.J. could recall her own experiences in detail, she wasn't particularly good at recalling learned material, like information from a book.
A.J. later revealed her identity as Jill Price, a school administrator. She has explained how the inability to forget anything is a source for her of depression and stress.
Another person with HSAM is Aurelien Hayman, a student from Cardiff. Hayman was the subject of a Channel 4 documentary called The Boy Who Can't Forget. Like A.J., Aurelien Hayman can recall every day of his life; however, unlike A.J., he regards his memory as a gift rather than a burden.
APPLYING PSYCHOLOGY TO INDIVIDUAL DIFFERENCES IN MEMORY
EVALUATING INDIVIDUAL DIFFERENCES IN MEMORY (AO3)