Types of memory

Types of memory

1. Definitions

   • STM
     • it is a system for storing information for brief periods of time
   • LTM
     • permanent store which holds unlimited amounts of information.
   • Coding
     • changing the format of information for use in memory.
   • Capacity
     • The amount of information which can be stored
   • Duration
     • the length of time information stays in memory.

2. Short term

   • coding
     • Mainly acoustic
   • Duration
     • 0 - 18 seconds
   • Capacity
     • 7+/-2 items

3. Long term

   • coding
     • Mainly semantic
   • capacity
     • Infinite
   • Duration
     • Infinite

4. what is memory?

   • cognitive psychology

5. Duration of LTM

   • Aim: to test the duration of long term memory through the use of photo recognition.
   • Procedure: Bahrick et al (1975) tested 400 people of various ages on their memory of class mates. A photo recognition test consisted of 50 photos, in a free recall test participants were asked to list names they could remember from their graduating class.
   • Results: Ppts who were tested within 15 years were 90% correct, 48 years 70% were correct.
   • Bahrick et al (1975)

6. Duration of STM

   • Peterson and Peterson (1959).
   • Aim: to study the duration of short term memory using 24 students.
   • Procedure: Each participant was tested over 8 trials and was given a consonant syllable and a three digit number. They were then asked to recall at intervals of 3,6,9,12,15 and 18.
   • Result: 90% at 3 secs, 20% after 9secs, 2% after 18 secs.

7. Capacity - Jacobs’ (1887) Serial digit span

   • Aim: To investigate the capacity of STM.
   • Procedure: Participants were presented with increasingly longer lists of digits or letters, and had to recall them in the right order. When participants fail on 50% of the tasks, they are judged to have reached their capacity.
   • Findings: Participants could generally hold 9 numbers and 7 letters in their STM.
   • Conclusion: STM does have a limited capacity. Memory for numbers may be better (as there are only 10 digits – 0 to 9) whereas there are 26 letters.

8. The magic number 7 +- 2 Miller (1956)

   • Miller reviewed psychological research and concluded that the span of immediate memory is about seven items.
     • This can be applied to musical notes, letters and words.
     • He also found that people can recall five words and letters, through a process of chunking we can remember more.

9. coding of STM

   • AIM – to examine whether coding within STM was acoustic or semantic
   • PROCEDURE - 75 participants were presented with one of 4 word lists, which was repeated 4 times. List A – acoustically similar (cat, hat) List B – acoustically dissimilar (foul, play) List C – semantically similar (large, huge) List D – semantically dissimilar (hot, safe)
   • Participants were then given the words in a list, but in the wrong order. They had to rearrange the words in the correct order.
   • Baddeley (1966)
   • Findings: Participants given List A (acoustically similar words) performed the worst, with 10% recall. They confused similar sounding words (recalling cap instead of cat. Recall for the other lists was better, between 60-80%.