Types of memory

Types of memory

1. Sensory Register

   • Very large capacity
     • Sperling (1960) - Showed participants a 3x4 grid of letters for 50 milliseconds then asked to recall a row. He concluded that the information is there in our brains even wit such a quick image, therefore the capacity for visual information must be large.
     • Picks up all information from our senses.
   • The information you get from your senses gets filtered by your brain and stored here briefly. The sensory register is made up of 5 different stores for different types of information.
     • Echoic store - Auditory information
     • Iconic store - Visual information
     • Haptic store - Tactile (touch) information
     • Gustatory store - taste information
     • Olfactory store - smell information
   • Short duration (500 milliseconds)
     • Walsh and Thompson - Found that the duration of the sensory register is 500m/s but gets worse with age.
   • Unless we pay attention then most of the information disappears quickly through spontaneous decay

2. Memory: The process of maintaining information over time, drawing on our past experiences.

3. Coding: the format in which the information is stored ie. sound (acoustic), picture (visual), word (semantic)

4. Capacity: The amount of information a store can hold.

5. Duration: The length of time information can be stored for.

6. Short term memory (STM)

   • Short term memory is usually coded acoustically (sound)
   • Limited capacity (7 +/- 2 pieces of information)
     • Serial digit spa method (Jacobs) - Method of assessing the capacity of STM, it consists of asking someone to recall a string of digits.
       • Miller - Identified the capacity of STM was 7 piece of information +/- 2. Concluded that 7 was the average digit span people can recall but it ranged from 5-9 digits.
     • The capacity increasing if people 'chunk' the information together.
   • Limited duration (18-30 sec0nds)
     • Peterson and Peterson - Particicants had to read a list of consonant tiagrams (3 random consonants ie. DTH) and asked them to recall them after differnt lengths of time (3, 6, 9, 12, 15 or 18 seconds). In between they had to count back in threes from a given number to stop them internally recalling them. After 3 seconds - 90% recalled correctly, after 18 seconds - only 5% recalled correctly. Concluded that STM's duration is between 18-30 seconds.

7. Long term memory (LTM)

   • Large duration (some cannot be recalled though)
     • Bahrick - 400 participants were asked to list the names of their ex-classmates from free re-call and photos. Those who had left school in the last 15 years recalled 90% of names/faces. After 48 years - name recognition was 80% and photo-recognition was 40%
   • Unlimited capacity
     • Wagenaar - Wrote a diary for 6 years and tested himself on the recall of events. Found that he had excellent recall for past events. If he struggled to recall he used cues (what/when/where/who) and found he could recall when prompted. Conclusion - LTM's capacity is unlimited.
   • Types of LTM
     • Coding is usually semantic (the meaning of information) in the long term memory. However LTM can also be coded acoustically or visually to.
     • Episodic Memory (Explicit/concious)
       • An autobiographical record of personal experiences - the event, the context and the emotions experienced.
       • Tulving - Injected 6 volunteers with radio-active gold and performed either episodic or semantic tasks (whilst being brain scanned) - 3 results showed that during episodic tasks the frontal lobe was active.
         • Suggests different parts of the brain are involved, LTM isn't one central store.
     • Procedural memory (Implicit/unconcious)
       • Our memory of action based performance of motor skills/tasks. Allows you to perform learnt tasks with little need for conscious processing. Learnt through repetition and practice.
       • Finke et al - Reported on the case of PM, a 68 year old professional cellist. He has severe amnesia following a brain infection and found he couldn't remember musical facts but was able to read and play music (even learning new complex pieces)
         • Suggests the brain stores different coded LTM information in different areas.
     • Semantic memory (Explicit/conscious)
       • Contains all knowledge, facts, concepts and meanings.
       • Vicari et al - Reported on a case of an 8 year old girl who had brain damage after a brain tumour was removed. She was unable to form new episodic memories but was able to create and recall semantic ones.
         • Suggests the semantic LTM is stored in a separate area to the brain to the episodic LTM.