Classic study - Baddeley 1966 Flashcards
Aim
To find out if LTM encodes acoustically (based on sound) or semantically (based on meaning).
Reason for Aim
This is done by giving participants word lists that are similar in the way they sound (acoustic) or their meaning (semantic); if the participants struggle to recall the word order, it suggests LTM is confused by the similarity which means that this is how LTM tends to encode.
Type of Experiment
It was a laboratory experiment.
IV
(1) Acoustically similar word list or acoustically dissimilar;
(2) semantically similar word list or semantically dissimilar;
(3) performance before 15 minutes “forgetting” delay and performance after
Experimental Design
(1) and (2) IV’s are tested using Independent Groups design.
IV (3) is tested through Repeated Measures
DV
(1) Score on a recall test of 10 words; words must be recalled in the correct order.
(2) A test of remembering the word order, not the words themselves)
Sample
(1) 72 mixture of men and women from the Cambridge University subject panel (mostly students); Voluntary Sampling.
(2) 15-20 in each condition (15 in Acoustically Similar, 16 in Semantically Similar).
Procedure -1
(1) Participants split into four groups, according to IV (1) and (2). Each group views a slideshow of a set of 10 words. Each word appears for 3 seconds.
(2) In the Acoustically Similar condition, participants get a list of words that share a similar sound. The Control group had words with Acoustically dissimilar words.
(3) In the Semantically Similar condition, the words share a similar meaning. Control group had semantically dissimilar words.
(4) Four “trials” and (as you would expect) the participants’ got better each time as the words stay the same.
Name the experimental lists used
List A - 10 acoustically similar words
List C - 10 semantically similar words
Name the baseline/control lists used
List B - 10 acoustically dissimilar words matched in terms of frequency of everyday use to list A
List D - 10 semantically dissimilar words matched in terms of frequency of everyday use to list C
How were the words presented?
Words displayed on signs around the room, participants concentrate on getting the ORDER of the words right, not remembering the words themselves.
What was the interference task given?
Participants in all 4 conditions carry out an “interference test” involving hearing then writing down 8 numbers three times. Then recalling the words from the slideshow in order.
How many learning trials were there?
4
How was long term memory tested?
After the 4th trial, the participants get a 15 minute break and perform an unrelated interference task. Then they are asked to recall the list again. This fifth and final trial is unexpected.
Results of the study
-Recall of acoustically similar sounding words was worse than the dissimilar sounding words during the initial phase of learning.
-However, recall of the similar and dissimilar sounding words was not statistically significant.
-This demonstrates that acoustic encoding was initially difficult, but did not affect long term memory recall.
-Participants found the semantically similar words more difficult to learn than the semantically dissimilar word.
-Recalled significantly less semantically similar words in the retest.
Conclusion of the study about STM
The fact that participants found it more difficult to recall list A in the initial stage of learning suggests that short term memory is largely acoustic, therefore acoustically similar sounding words are more difficult to encode in STM. STM gets confused by the similar sounds the way that LTM gets confused by similar meanings.
Conclusion of the study about LTM
Later retest recall of list C was impaired compared to all other lists because they were semantically similar words, suggesting that encoding in long term memory is largely, but not exclusively, semantic so it gets distracted by the semantic similarities and muddles them up.
Generalisability
Baddeley has a large sample of 72. Any anomalies (people will unusually good or bad memories) will be “averaged out” in a sample this size. Only 15 people did the Acoustically Similar condition. An anomaly could make a difference to scores with numbers that small. The sample was made up of British volunteers however, LTM works the same for people from all countries. A volunteer sample might have more people with particularly good memories who enjoy doing memory tests - not representative.
Reliability
(1) It has standardised procedures that can be replicated. Every participant viewed words on slides. Everyone saw the same word for the same amount of time (3 seconds).
(2) Highly controlled nature of the experiment, Baddeley can establish a cause and effect relationship between the independent variable (semantic/acoustic word similarity) and the dependent variable (long term memory).
Application
(1) It has applications for Cognitive Psychologists, investigating LTM in greater depth. Baddeley’s use of interference tasks to control STM has been particularly influential and Baddeley’s & Hitch built on this research, to develop the Working Memory.
(2) Another application is for revision. If LTM encodes semantically, it makes sense to revise using mind maps that use semantic links.
(3) Reading passages out loud over and over (rote learning) is acoustic coding, but LTM doesn’t seem to work this way, so it won’t be as effective.
Validity
(1) Stimulus materials were not naturalistic, thus lacked ecological validity.
(2) Word lists that sound alike are not things we remember in everyday life very often, so results may lack validity.
(3) However, memory researchers would argue that in order to understand memory we have to remove the context and simplify the nature of the to-be-learned information, in order to isolate the aspects of memory we are concerned with.
