contemporary study: Sebastian and Hernandez-Gil’s (2012) study of the developmental pattern of digit span

Question 1

what did they want to examine?

Answer 1

• working at University of Madrid, s + hg wanted to examine the developmental pattern of digit span in spanish population* to test the phonological loop component (deals with auditory info) of wmm (Baddeley and hitch)

Question 2

what did they want to investigate?

Answer 2

• the capacity of phonological loop (ie how much it could hold) and to understand whether it would differ in a Spanish population across different ages
• knew that anglo-saxon research (ie British) concluded that digit span increased with age (from age 5-17) so they wanted to investigate whether the same developmental trend occurred in different culture

Question 3

what was the aim of the study?

Answer 3

• investigate the development of phonological loop in children between ages 5-17 using digit span as a measure of phonological capacity
• to look at decline of digit span in older people (normal healthy older people and dementia patients)
• to compare digit span in spanish population with Anglo-Saxon population

Question 4

how many parts are there to this study?

Answer 4

• 2

Question 5

what did the first part of study gather?

Answer 5

• primary data
• data gathered by researchers in an actual study at the time

Question 6

how many ppts did they use in first part of study?

Answer 6

• 570 volunteer ppts
• 5-17
• from various schools in Madrid
• all ppts born in Spain
• impairments in hearing, reading and writing ability were controlled

Question 7

how were ppts divided in groups for first part of study?

Answer 7

• ppts were divided into five different age groups
• average digit span recorded for each age and age group

Question 8

how was the digit span measured in first part?

Answer 8

• ppts tested individually during school break
• sequences of digits were read aloud, one per second
• digits increased in length each time a ppt recalled correctly
• measured by recalling at least two out of three sequences correctly
• started with sequences of three digits
• ppts had to recall digits in the same order they were presented

Question 9

what were the results in the first part? (age group mean digit span)

Answer 9

• preschool (5): 3.76
• primary (6-8): 4.34
• primary (9-11): 5.13
• secondary (12-14): 5.46
• secondary (15-17): 5.83

Question 10

how does digit span change with age? (results of first part)

Answer 10

• increases with age
• pre-school children have low digit span
• rises steadily until around 11 years old
• slows after 11 years
• stable between 15-17 years

Question 11

how do the findings compare to wisc iv data?

Answer 11

• wisc iv (wechsler intelligence scale for children iv) shows digit span increases with age
• researchers compared their findings to wisc iv data

Question 12

what did sebastian & hernandez-gil compare their children’s study results with? (second part)

Answer 12

• compared with research from their 2010 study
• gathered data on adults:
  
  • healthy older people (25 pts)
  • Alzheimer’s (25 pts)
  • dementia (9 pts)

Question 13

what were the mean digit spans of the groups in the 2010 study?

Answer 13

• healthy older people: 4.44
• Alzheimer’s patients: 4.20
• dementia patients: 4.20

Question 14

what did the results show about digit span in healthy older adults compared to younger and dementia patients? (second part)

Answer 14

• older adults had higher digit span than 5 year olds
  
  • older adults’ digit span was similar to 7 year olds
  • no significant difference between older adults and other age groups
• no significant difference between older adults and dementia patients
  
  • suggests digit span decline is due to aging, not dementia

Question 15

why did the spanish study show a lower average digit span compared to the anglo-saxon data?

Answer 15

• spanish words take longer to say than english words
• more sounds in spanish words = more time to say them
• longer word length uses more space in the phonological loop
• this results in a lower digit span in spanish speakers

Question 16

what are the main conclusions from the study on digit span?

Answer 16

• digit span increases with age from 5-17 years
  
  • spanish population continues to show increase in digit span up to 17, unlike anglo-saxon (where it reaches adult average at 15)
• poor digit span in elderly likely due to aging, not dementia
• spanish digit span is about 1 digit shorter than anglo-saxon, likely due to word length effect

Question 17

generalisability - strength

Answer 17

• large sample size tested (public/private schools, age of children, men and women)
  
  • findings considered reliable and generalisable
• comparisons made across different cultures
• study excluded ppts with any hearing, reading or language impairments
  
  • known to diminish digit span

Question 18

generalisability - weakness

Answer 18

• all from madrid
  
  • may not be able to generalise from this

Question 19

reliability - strengths

Answer 19

• researches can compare data with wisc iv data
  
  • very similar pattern shown (interrater reliability)
• careful controls
  
  • standardised procedure for all ppts
  • use of Spanish language + children is form of control
• cultural differences in digit span have been reported by other researchers (Ellis + Hennelley)
  
  • credibility

Question 20

application - strengths

Answer 20

• digit span tests have been reliably linked to performance in reading ability and intelligence
  
  • good measure of verbal memory
• also culture free and meaning free way of measuring pure verbal memory
• helps us understand extent to which wmm is affected by neurological disease and frontotemporal lobe

Question 21

validity - strength

Answer 21

• analyse not only actual age but also for age group
  
  • so they have individual digit span scores for each year + age group
  • they have more info from which to draw conclusions

Question 22

validity - weaknesses

Answer 22

• task is artificial
  
  • we don’t generally recall lists of digits
  • lack of validity (mundane realism)
• assumed that digit span is affected by subvocalising and that’s why under age 7 digit span is lower
  
  • assumption rather than something study showed
  • study states digit span and perhaps low on explanation

Question 23

ethics - strengths

Answer 23

• no major ethical concerns
• ppts under age 18 would need consent from parents
• neither studies used distressing tasks