- Encoding- placing information into the memory store. Must pay ATTENTION for info to be encoded
- Storage- info must be kept in memory. Memory for skills eg. riding a bike (procedural), facts( semantic) or memories (episodic). Semantic and episodic together is called DECLARATIVE memory. Remembering how info is acquired- EXPLICIT. Not remembering how info is acquired- IMPLICIT.
- Retrieval- ability to recall info when it is needed.
Short term memory:
- limited capacity and duration
- Miller's magic number 7
- Chunking allows info to be combined and increases the capacity of STM
Capacity of STM- Baddeley et al.
- to see if people could remember more short than long words in a serial recall test.
- Pps reading speed was measured
- pps presented with 5 words on a screen. Words were taken from 1 of 2 sets; either a set of one syllable words or a set of polysyllabic words.
- pps asked to write down the 5 words in serial oder immediately after presentation
- pps could recall considerably more short words that long
- able to recall as many words as they could say in about 2 seconds
- strong positive correlation between reading speed and memory span ie immediate memory span represents no. of items that can be said in about 2 seconds
- short words MAY be easier to recall as more familiar
- lack of realism (lab experiment, lists of unconnected words)
Duration of STM- Peterson and Peterson
- test how long STM lasts when rehearsal is prevented
- pps briefly shown a consonant trigram, then asked to count backwards in 3's from specified number to stop rehearsal
- after intervals of 3,6,9,12,15 and 18 seconds, asked to recall original trigram
- procedure repeated several times with different trigrams
- pps able to recall about 80% of trigrams after 3 seconds
- less trigrams remembered as time intervals increased ie STM only able to hold a few items at once and for a brief period of time. Anything needed to be remembered for longer must be transferred to LTM
- preventing rehearsal by interference task, recall poorer
Encoding in STM- Baddeley
- To explore effects of acoustic and semantic encoding in STM
- pps divided into 4 groups. each group heard list of 5 words drawn from one of these categories; acoustically similar/dissimilar words, semantically similar/dissimilar words
- immediately after hearing words, asked to recall them in correct order. Procedure carried out 4 times
- Acoustically similar words harder to recall in correct order (5%) than disimilar (75%)
- causal link can be drawn
- STM may use other forms of encoding
Duration of LTM- Bahrick et al
- to estabilish the existence of VLTM and see if there was difference between recognition and recall
- Investigators tracked down graduates from American high school over 50 year period.
- 392 graduates shown photographs from high school yearbook
- recognition group- pps given group of names, recall group- simply asked to name the people
- in recognition: 90% correct after 14 years of graduation, 60% after 47 years, in recall group; 60% after 7 years, 20% after 47 years