[Developmental and individual differences in delayed response task performance (A-not-B task) in 7- to 12-month-old infant twins].
The purpose of the study was to explore developmental and individual differences in the working memory that was assessed by performance of the A-not-B task in 7- to 12-month-old infant twins. The sample included 150 infant twins participating in genetic project, 18 of them were tested at 8 and 11 months of age. Information concerning birth weight and gestational age was collected from birth records. All infants were tested using Bayley Scales of Mental and Psychomotor Development. The infant's working memory (WM) was tested during A-not-B task performance, which was shown to depend on the maturity of the prefrontal cortex. The behavioral data were analyzed off-line using videotape records. The one-way ANOVA revealed that the AB performance improves with age. A highly significant improvement of the ability to tolerate the delay in A-not-B task was observed between 9 and 10 months of life. There was no longitudinal stability in individual infant performance of A-not-B across the period of 7-12 months of age. The AB delay was significantly correlated with psychomotor and mental development only after the crucial period of the rapid increase in the AB delay (9-10 months). The analysis of intraclass mono- and dizygotic correlations showed that individual differences in the WM (tolerance to AB delay) at 7-9 months and at 10-12 months are of different nature. There was a significant effect of shared environment on AB delay variance in 10-12-month-old group, whereas down to this age no systematic influence on individual variability was observed. These findings suggest that the ability to tolerate the AB delay can be provided by different brain mechanisms in 7-9 and 10-12-month-old infants.
N N
NN
Pushina
E V
EV
Orekhova
T A
TA
Stroganova
D000367:Age Factors; D001835:Body Weight; D005260:Female; D047109:Fetal Development / Q000502:physiology; D005838:Genotype; D005865:Gestational Age; D006801:Humans; D007223:Infant; D018730:Infant Behavior / Q000502:physiology*; D008568:Memory / Q000502:physiology; D017397:Prefrontal Cortex / Q000502:physiology*; D011247:Pregnancy; D011597:Psychomotor Performance / Q000502:physiology; D014427:Twins / Q000235:genetics*