Slides in this set
Aim: To determine the capacity of short term memory using the digit span
Procedure: participants listened to then repeated numbers, starting with 1
digit then adding another each time they got the previous correct. If they
got the sequence wrong they were permitted 1 more attempt. Once the
participant went wrong again the last amount of digits they successfully
recalled were recorded.
Findings: all but 4 participants could successfully recall between 5 and 9
numbers, the 4 that did not fall into this category could recall 4 digits.
Conclusion: this proves that the majority of people fit into the 7 (+ or 2)
theory, showing that the short term memory has a limited capacity.
Criticisms: Strength: sufficient amount of participants involved, validity.
Mundane realism, the situation replicates something you would see in
real life (e.g. remembering a phone number) Weakness: non laboratory
experiment means the external variables may not have been considered
or adequately controlled.…read more
Aim: To distinguish between encoding in the long and short term memory.
Procedure: Each candidate is given set of 10 cards with words on them: 4
sets from acoustically similar to semantically dissimilar. Shown each
card for 3 seconds. After all cards have been shown the candidate has to
write the words down in order.
Findings: In the first four attempts at recalling the word lists in order
participants recalled more words on each successive trial. In the first
trial, the worst performance was by participants who had been givne the
acoustically similar list. After the 20 minute interval the worst
performance was by participants who had been given the semantically
Conclusion: This suggests that the short term memory is acoustically
encoded and the long term memory is semantically encoded
Criticisms: strength: The study is replicable and highly controlled weakness:
Other studies have suggested otherwise, eg Brandimonte et al (1992) have
theorised that the short term memory is visually coded.…read more
Peterson and Peterson 1959
Aim: To measure the effect of inhibiting rehearsal on the duration of Short
Term Memory (STM)
Procedure: Participants hear a list of trigrams (three-letter nonsense words),
and then have to count, aloud, backwards in threes for a certain time (the
IV in this experiment). After the time has completed, participants are
tested on their recall of the trigrams
Findings: There was a marked negative correlation between the delay and
the percentage of trigrams recalled by participants; a delay of three
seconds produced a mean score of almost 80%, but for a delay of
eighteen seconds, the score dropped to 6%.
Conclusion: In the absence of rehearsal, STM's duration is very short.
Criticisms: Strength: These results have replicability; they have been
reproduced many times. Weakness: As Keppel & Underwood (1962)
showed, the fact that Peterson & Peterson ran "practice" tests, it could be
that some of these results were influenced by proactive
interference. Remembering trigrams is not an every day occurrence, and
so it is questionable how much ecological validity these findings have.…read more
Aim: Determine how short-term memory is encoded
Procedure: Ps were presented with sequences of six consonants and then
asked to recall the sequences.
Findings: Letters with similar sounds (e.g. "P", "D", "T") proved more difficult
to recall correctly than letters with different sounds (e.g. "D" "O") even
though the different sounding letters looked more similar ("D" looks like
"O" but sounds different; "D" doesn't look like "T" but sounds similar)
Conclusion: STM encoding is acoustic
Criticisms: Strength: the idea that STM is encoded acoustically is supported
by Baddeley (1966) who found similar effects when testing words that
sounded similar. Weakness: Lacks mundane realism; the use of single
letters does not comprise a reflection of the memory tasks used in
everyday life. Other methods of encoding such as visual (or even by taste
and smell) are also used.…read more
Bahrick et al 1975
Aim: Investigate the duration of LTM
Procedure: Opportunity sample of 392 American ex-high school students
aged 17-74 years tested in free recall the names of as many of their
former classmates; photo recognition test where they were asked to
identify former classmates in a set of 50; name recognition testl name
and photo-matching test.
Findings: Accurate recall was possible for time periods of as much as 50
Conclusion: LTM has seemingly unlimited duration
Criticism: Strength: A high level of mundane realism: remembering faces is
a task relating to real-life settings. Weakness: Familiar faces are a very
specific type of information and therefore these results cannot be
generalised to memory of other material.…read more