Sebastian & Hernandez-Gil (2012) - Contemporary Flashcards
Aim
- To study the developmental pattern of working memory over time, including changes from ageing or dementia.
- To analyse the developmental pattern of the phonological loop in children aged 5-17 years old. This involved looking at the age at which the digit span stopped increasing in adulthood / adolescence.
- To look at the decline of digit span in older people, including those with two types of dementia – Alzheimer’s and fronto-temporal dementia. (They did this by using previous findings).
- To see if Anglo-Saxon data, which found 15 years to be the age at which digit span stops developing further, were replicated or whether digit span would be higher for Spanish speakers. This is because word length might affect the digit span and Spanish word length differs from Anglo-Saxon.
Procedure (2 parts)
Part 1: primary data gathering to test the hypothesis that there is a difference in digit span which increases with age from 5 – 17 years old.
Sample: 570 volunteers aged 5-17 years, from the Spanish population and from various schools in Madrid. No participants had repeated a school year, had learning difficulties such as in reading and writing or hearing. This created some control of education and cognitive differences.
Participants were split into 5 age groups: age 5, 6-8, 9-11, 12-14 and 15-17years. This covers 13 year groups. Each condition therefore consisted of different ages. Their digit span was measured.
Participants were tested individually in their break time. Sequences of digits were read aloud, one per second. Each time a participant got the sequence right (the right digits in the right order), another digit was added to increase the span and the participants tried again. They started with 3 sequences of 3 digits. Instructions required participants to listen carefully and recall the digits in the same order as presented. The digit span measure was the number of digits in the sequence where they recalled at least two of the three sequences correctly.
Part 2: secondary data (from their previous study in 2010)
25 healthy older people were used to compare against 25 people with Alzheimer’s disease and 9 people with fronto-temporal dementia. Data was gathered about the digit span of the three groups. The digit span task was the same as in the first part.
Results Part 1
The results show that digit span increased with age. The preschool children, aged 5, had very low digit span and showed a significant difference from the others.
Group Age Mean digit span Preschool (5 years) 3.76 (0.52) Primary school (6-8 years) 4.34 (0.58) Primary school (9-11 years) 5.13 (0.81) Secondary school (12-14) 5.46 (0.85) Secondary school (15-17) 5.83 (0.84)
The data was compared with data from an intelligence test for children (they used data from Spanish children), which also showed that digit span increased with age. But the digit span was higher each time than the findings in this study.
Results Part 2
The digit span from the previous study are:
Group Gender Mean digit span
Alzheimer’s dementia 7m / 18f 4.20
Fronto-temporal dementia 5m / 4f 4.22
Healthy older people 6m / 19f 4.44
They compared the results of this study with their previous study. The performance of the elderly participants was compared with the youngest in the first part of the study and showed a higher digit span that both the 5 year olds (sig level 0.0001) and the 6 year olds (sig level 0.03). The performance of the elderly participants did not differ from the other year groups.
Digit span does decline with age when becoming elderly and this is irrespective of whether you have dementia or not.
Conclusion
Digit span increases with age from 5 – 17 years. This contrasts with Anglo-Saxon data as other studies demonstrated that digit span increased to 15 years and then reached an adult level. The adult span is about 7 digits.
They highlighted the idea of differences in word length (how long it takes to say a word, not just the length) between Spanish and English. They highlighted Baddeley et al (1975) finding that that memory span is affected by lists using long words compared to short words. Subvocal rehearsal may be important as the longer it takes to ‘say’ the digit to yourself, the more the trace would decay and so the easier it is to lose the information when rehearsing the digits.
Spanish words are longer than English words. Subvocal rehearsal doesn’t start until age 7 and so there should be less difference between English and Spanish children under 7 compared to over 7. English studies have found a digit span of around 4 for age 5-6years, comparable to Spanish children of that age. Therefore, subvocal rehearsal could be the cause of the difference in older people. From age 7 digit span increases with age for both English and Spanish participants but the digit span is about one digit lower for Spanish because of the effect of word length.
Healthy older people had a digit span similar to 7 year olds, showing that digit span declines with age, although we are unsure at what age the decline starts. The digit span of Alzheimer’s and fronto-temporal dementia is not much different from healthy older people and is similar to a 6 year old. Therefore, dementia did not seem to impact on digit span. The capacity of the phonological loop seems to be affected by age but not dementia.
