memory

• Cognitive psychology


  The study of how people learn, structure, store and use knowledge - essentially how people think about the world around them
• Memory


  The mental process used to encode, store and retrieve information
• Types of memory


  • Short term memory
  • Long term memory
• Short term memory


  • Its capacity can be tested
  • Its duration can be measured
• Long term memory


  • Its capacity is unlimited
  • Its duration has the potential to last a lifetime
• Jacobs (1887) digit span technique

  1. Use a laboratory experiment

  2. Ask participants to recall lists of digits or letters in the same order they were presented

  3. Pace matched to half second metronome

  4. Repeat over a number of trials to establish participant's digit span
• The average digit span (number of items recalled) was between 5 and 9
• Digits were recalled better than letters
• Digit span increases with age
• Chunking


  Organising information into groups (or chunks) to make the most efficient use of short term memory's limited capacity
• Short term memory can hold up to 7 chunks of information at any one time</b>
• Chunking is even more effective if the chunks have meaning
• Brown (1938) and Peterson & Peterson (1939) Brown-Peterson technique


  1. Briefly show participants a trigram of consonants

  2. Ask participants to count backwards in 3s from a given number

  3. After intervals of 3, 6, 9, 12, 15 or 18 seconds, ask participants to recall the original trigram
• Participants could recall 80% of trigrams after a 3 second interval, 50% after 6 seconds, and under 10% after 18 seconds
• Brown-Peterson effect


  The rapid loss of information in short term memory when rehearsal is prevented
• Bahrick et al. (1975) yearbook photographs study

  1. 400 student participants of various ages

  2. Shown their old school yearbook and asked to recall names of classmates

  3. Tested on photo recognition, name recognition, and name and photo matching
• After up to 34 years, participants could remember up to 90% of their classmates, declining to 70% after 48 years
• Free recall was less accurate, 60% after 15 years and 30% after 48 years
• Acoustic encoding


  Encoding information based on how it sounds
• Semantic encoding


  Encoding information based on its meaning
• Baddeley (1966) acoustic vs semantic encoding study


  1. Participants asked to immediately recall in serial order a list of 5 words

  2. Words were either acoustically similar, acoustically dissimilar, semantically similar, or semantically dissimilar
• In short term memory, words that sound similar were harder to recall than acoustically dissimilar words, but meaning had little effect
• In long term memory, recall of semantically similar words was much worse than semantically dissimilar words, but recall was the same for acoustically similar and dissimilar words
• Maintenance rehearsal


  Repeating information to keep it in short term memory
• Elaborative rehearsal


  Engaging in more meaningful analysis of information (e.g. creating images, making associations) to aid transfer to long term memory
• Sperling (1960) iconic store study


  1. Used a tachistoscope to flash a grid of 12 symbols for 50ms

  2. Participants asked to report as many symbols as possible
• Participants could only recall around 4 symbols, even though they reported seeing more
• Sperling's partial report technique

  Participants asked to report only the symbols in a specific row of the grid
• Maintenance rehearsal


  The process of storing information in the STM. Eventually it will lead to it being transferred to the LTM.
• Elaborative rehearsals


  Involves more meaningful analysis (e.g. images, association) of information and leads to better recall
• Sperling (1960) studied the sensory memory for vision (the iconic store) by using a tachistoscope
• Sperling's procedure


  1. Exposed a grid of 12 symbols for 50ms

  2. Asked subjects to remember as many letters as they could

  3. Found subjects could only recall around 4 symbols before the grid faded from their sensory memory
• Sperling's partial report technique

  1. Exposed the grid for 150ms

  2. When the grid disappeared, a tone indicated a row of 4 letters

  3. In the partial report condition, recall was on average just over 3 out of 4 symbols from any row
• The iconic store can retain approximately 76% of all data received
• More information was lost over time - only 50% was available after 0.3 sec and only 30% after 1 sec delay
• Glanzer and Cunitz found that words at the beginning and end of a list were better remembered than words in the middle
• Semantic memory


  Memory for general knowledge and facts not time-stamped
• Episodic memory


  Memory for personal experiences and events that are time-stamped
• Procedural memory


  Memory for skills, actions and how to do things
• Baddeley and Hitch's working memory model

  • Emphasises the active nature of short-term memory
  • Consists of a central executive, the phonological loop, the visuospatial sketchpad, and the episodic buffer