Classic Study Baddeley (1966b) Flashcards
Aim
Find out if LTM encodes acoustically or semantically.
Type of experiment
- Lab experiment.
- Independent Groups.
How many participants
75 young servicemen
4 lists of 10 words each
- Hearing test before procedure, 3 people were excluded.
List A- Acoustically Similar
List B - Acoustically Dissimilar
List C - Semantically Similar
List D - Semantically Dissimilar
Procedure
4 separate groups learned one list each.
Each list presented loud on tape, one word every three seconds.
- 40 Seconds to write down as many of 10 words as they could recall, in order heard them.
- Carried out 4 times (learning trials).
- Spent 20 minutes on unrelated task (recalling 8 digit sequences).
Then had to try and recall the ten words again in correct order, they were not told about this.
How was performance measured?
Number of words they recalled in correct position in the list.
Differences in performance in the four lists were compared using Mann-Whitney U.
Findings Learning Trials
Recall of AS was consistently lower than for AD.
No significant differences in recall of two semantic lists
Significant forgetting of SS and SD in recall test.
Findings Recall Test
No significant forgetting of words in the AS list.
No significant differences in recall of two semantic lists.
Significant forgetting of SS and SD in recall test.
Conclusions
- Findings were puzzling.
- Only AS list showed no forgetting - suggests LTM is acoustic.
- Baddeley said some aspect of procedure meant semantic nature of LTM was hidden.
- Led him to carry out two more experiments to clarify nature of LTM encoding
Strength High Internal Validity
All 3 experiments used well controlled procedures.
All lists were matched with each other in terms of frequency appearing in English Language.
Results cannot be from participants remembering more frequent words.
Avoids confounding variables, making cause and effect between IV and DV much clearer.
Competing HIV
Limitation to experiment 1 is that a confounding variable is not controlled.
Did not rule out STM as influence on later recall from LTM because Participants could still rehearse words between trials.
Low External Validity
Tight controls meant results artificial and unlike real life.
IRL STM and LTM probably interact in the way they do in Ex.1 but Baddeley eliminated it as it was a confounding variable.
Only when control increased, LTM semantic encoding became obvious.
Suggests encoding does not represent IRL and study may exaggerate role of semantic encoding in LTM
Application
Understanding that LTM encoding is mostly semantic can help improve long term recall of info.
Useful for students revising for exams, rather than just rehearsal they can think about the info and organise it like mind maps.
Allow process of the meaning of the material matching the form of LTM encoding.
Shows Baddeley’s study has validity to be applicable IRL.
