2.3 Studies

2.3 Studies

1. Contemporary

   • Sebastian and Hernandez-Gil (2012)
     • Aim: To investigate the development of the phonological loop in children, between ages of 5 and 17. Using digit span as a measure of phonological capacity.
       • Procedure: Sample of 570 volunteered participants taken from schools in Madrid. Impairments in hearing,reading and writing controlled. Divided into five age groups and average digit span taken for group.
         • Individually tested, increasing sequences of digits. Digit span recorded as the maximum digit recalled in correct order without error.
           • Results: Developmental trend of increasing digit span with age. Rises steadily till around 11 when it slows. Remains fairly stable at 15 and 17 years.
             • Compared to previous research, elderly participants significantly higher than 5 year olds, but not significantly different to other groups. Dementia patients showed similar profile (4.2 digit span) to younger age group.
               • Comparing elderly group to the dementia patients showed no significant difference. Suggests poor digit span was a consequence of ageing rather than dementias.
                 • Consistent with Anglo-saxon research. However overall capacity of digit span was much lower in Spanish population. Due to the word length effect, as Spanish digits tend to be two or more syllables, taking up more time to sub-vocally repeat and rehearse, taking up more space in the phonological loop.
                   • Further word length effect support: Sub-vocal rehearsal does not appear until ages 7-8, no difference between Spanish and Anglo-saxon before age of 7 years. After 9, noticeable difference, suggesting word length effect occurs once sub-vocalisation appears in the phonological development.
                     • Conclusion: digit span increases with age, starting point occurs when children are able to sub-vocalise at around 7. Spanish significantly shorter than Anglo-saxon, due to word length effect. Comparing elderly to dementia participants show that poor digit span is a result of ageing, rather than dementia.
                       • Evaluation: Questionable as to wether digit span reflects everyday use of verbal memory as we rarely use verbal memory to memorise lists of digits. However digit span tests have show to be reliably linked to reading and intelligence, suggesting they're good measure of verbal memory.
                         • Large sample size, therefore findings can be reliable and generalisable to the Spanish population. Sample size gathered was important as comparisons were being made to other cultures. Excluded participants with any impairments to hearing, reading or language, so removing extraneous variables that could have affected results.

2. Classic

   • Baddeley (1966b)
     • Aim: To investigate the influence of acoustic and semantic word similarity on learning and recall in STM and LTM
       • Acoustic = sound. Semantic = meaning
       • Procedure: Lab experiment to test sequential recall of acoustically and semantically similar word lists. Three different experiments were conducted, Experiment three:
         • Four lists of 10 words.
           • List A: 10 Acoustically similar.
           • List B: 10 Acoustically dissimilar. Matches in terms of frequency of everyday use to List A.
           • List C: 10 Semantically similar words.
           • List D: 10 Semantically dissimilar words. Matches in terms of frequency of everyday use to List C.
           • List B and D acted as baseline control groups for List A and C.
         • Participants men and women recruited, assigned one of the four list conditions. INDEPENDENT GROUPS.
           • Presented one word every three seconds, after presentation required to complete six tasks involving memory for digits.
             • One minute to recall by writing down words in order. Followed by 15 minute interference task involving digit sequences, then a surprise retest on the word list.
               • Results: Recall of acoustically similar words worse than dissimilar words during the initial phase of learning. However recall of the similar and dissimilar acoustic sounding, was not significantly different after initial phase.
                 • Semantically similar words more difficult to learn than the dissimilar and recalled significantly fewer words in the retest.
                   • Conclusion: Suggests that STM is largely acoustic, therefore acoustically similar sounding words were more difficult to encode.
                     • Later retest recall of list C was impaired compared to other lists showed that encoding in LTM is largely, but not exclusively semantic.
                       • Evaluation: Lab research, not using memory in an everyday context, therefore difficult to generalise findings. LACKS ECOLOGICAL VALIDITY.
                         • However to understand memory need to remove the context, to isolate aspects of memory we're concerned with.
                         • Relied heavily on the role of rehearsal for information to become established in LTM. Nature of rehearsal is therefore exaggerated this memory process, being an artefact of the experimental procedure. LACKS MUNDANE REALISM.
                           • Scientific as it used controlled lab environment with standerlised procedure. Therefore replicable and high reliability. High control means you can establish cause and effect relationship between the IV and DV.

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