Baddeley's Study 1966b

to investigate the influence of acoustic and semantic word similarlity on learning and recall in ST and LTM.

A total of 72 men and women from the Applied Psychology Research Panel in Cambridge took part using an independent measures design.

participant was assigned to one of four word list groups:

• LIST A included 10 acoustically similar words
• LIST B included 10 acoustically dissimilar words
• LIST C included 10 semantically similar words
• LIST D included 10 semantically dissimilar words

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• there were four trials for the same list. words were presented on a slide projector, one word every 3 seconds with 2 second slide change-over.
• participants then completed a distraction task:  6, 8-digit recalls which presented 1 digit per second. 
• the participant then had to recall the words from the list in the order they learnt them.
• this was followed by a 15-minute, self-paced digit copying task before a final surprise of the words in the correct order.

acoustic similarity: there was a tendency for initial learning to be impaired by acoustically similar words cmpared to dissimilar words in the STM. However, once acoustic words were learnt there was no significant difference in the recall between trial 4 and the retest between acoustically similar words and dissimilar words.

semantic similarity: semantically similar words showed slower learning over the 4 trials than semantically dissimilar. semantically similar words had significantly lower level of correct recall in the surprise retest than semantic dissimilar in LTM.

• the LTM is impaired by semantic similarity
• LTM uses semantic coding extensively, although not excusively
• initial information may be encoded acoustically STM for it to be retained there needs to be semantic meaning linked to it.