Baddeley (1966)
Today I did a lot of revision and one of the subjects I covered was cognitive psychology. Since I am a science student, I’m eager to drop psychology and concentrate on what I love, but to do this I must first pass my exam. I’ve been producing fact sheets for many psychology experiments so maybe this one will help you!
The Influence of Acoustic and Semantic Similarity on Long-Term Memory for Word Sequences – Baddeley (1966)
Aim
To find out if LTM encodes acoustically (based on sound) or semantically (based on meaning).
Done by giving participants word lists that are similar in their sound or meaning – struggle to recall word order is then due to confusion in the similarity (and the variable which causes the confusion is how LTM encodes).
Procedure
A lab experiment with several independent variables:
- Acoustically similar or acoustically dissimilar words
- Semantically similar or semantically dissimilar
- Performance before 15 minutes of “forgetting” and performance after
Independent groups are in italics; the final one is repeated measures.
Dependent variable was the score of a recall test on 10 words (their order, not the words themselves).
The sample was made up of 72 participants, men and women from Cambridge University Subject Panel (mostly students).
15 participants in the acoustically similar condition; 20 in the acoustically dissimilar.
16 participants in the semantically similar; 21 in the semantically dissimilar.
Method
Participants were split into the four groups described above. The experiment consisted of a presentation of the 10 word list, followed by a task involving STM for 6 sequences of 8 digits.
Words were shown on a slide projector – visible for 3 sec – with a changeover time of 2 seconds. The intervening digit sequences were read out at a 1 second rate and subject were allowed 8 seconds to write out each sequence. After this they had 1 minute to write out the 10 word sequence.
In the acoustically similar condition, participants had words with a similar sound (man, cab, can etc). The control group had one syllable words that didn’t sound the same (pit, few, cow, pen etc).
In the semantically similar condition, the words had similar meaning (great, large, big, huge etc) but the control group had unconnected words (good, huge, hot, safe etc).
After four trials, the participant’s scores got better since the words are the same each time. The words are displayed on signs around the room so that only the order was the main focus. They then had a 15 minute break and had to perform an unrelated interference task (self-paced digit copying) before being asked to recall the word sequence again.
Results
The acoustic similarity list is harder during early learning but the participants soon caught up. LTM is not confused by acoustic similarities because the scores on the last test are similar to the 4th trial, suggesting no forgetting has taken place.
The semantic similarity list was confusing to learn and lags behind the dissimilar list. Little forgetting takes place but the scores are lower overall.
Conclusion
LTM must code semantically – earlier experiments show that STM must code acoustically. The evidence for this is how the LTM gets confused when it has to retrieve the order of words which sound the same. It concentrates on how they mean the same and muddles them up – it has no problem retrieving acoustically similar words because LTM pays no attention to how words sound.
In the acoustically similar condition, there is a slow start due to the fact that the interference task doesn’t 100% block STM so some words linger in the rehearsal loop. In most conditions, the LTM is getting help from the STM. However, in the acoustically similar condition, STM gets confused by the similar sounds in the same way that LTM gets confused by similar meanings. This group then lags behind the controls until the words are encoded in LTM (shown by the scores levelling out).
Evaluation
Generalisability
A strength of the study is that Baddeley uses a large sample of 72 participants. This means that anomalies can be averaged out, e.g. extremely high or low scores. The participants were also British volunteers, which could be a problem (e.g. differences down to culture) but LTM is a universal cognitive function so the sample could still represent a wider population.
However, a weakness of the study is that each group only had a small amount of people in each group (roughly 15-20) so anomalies could still affect the averages. The volunteer sample may also have more people who enjoy memory tests so may not be representative of all kinds of people of all abilities.
Reliability
A strength of the study is that it is reliable. This is because we know details about standard procedures Baddeley used such as the duration words were shown (3 seconds), which words were used (mad, cab, max, mat etc) and how many participants were used (72 participants from Cambridge, a mix of genders). He also increased the reliability by using a slideshow so the results weren’t affected by people with hearing difficulties. This is useful because it can be easily repeated (without any specialist equipment) to find the same results.
Application
Baddeley’s study has primarily been used to develop the Working Memory model and within school environments e.g. revision with semantic links will be more effective than learning acoustically.
Validity
A strength of the experiment was the internal validity because of the amount of controls used, such as using word order (so participants wouldn’t forget the actual words and therefore the risk of words being harder or easier to recall due to familiarity or unfamiliarity was reduced). Baddeley also used a slideshow to help those with hearing difficulties. This controls led to a good procedure which means behaviour is likely true to life.
A weakness of the experiment is that there is reduced ecological validity. Recalling lists of words would’ve been more realistic since you do it sometimes (such as recalling a shopping list or a group of people on an invite list) but recalling word order is very artificial and therefore behaviour shown may be specific to this one scenario.
Ethics
Ethics are not evaluated in the cognitive approach.
Happy studying!
