Related Experiment Video
Updated: Aug 14, 2026
The 5-Choice Serial Reaction Time Task: A Task of Attention and Impulse Control for Rodents
Published on: August 10, 2014
Age-related and individual differences in the performance of a delayed response task (the A-not-B task) in infant
N N Pushina1, E V Orekhova, T A Stroganova
1Psychological Institute, Russian Academy of Education, Moscow.
Insights
Infant working memory, assessed via the A-not-B task, improves significantly between 9-10 months. Early differences are environmental, while later differences involve systematic environmental factors.
Area of Science:
- Developmental Psychology
- Cognitive Neuroscience
- Behavioral Genetics
Background:
- Working memory development in infants is crucial for cognitive growth.
- The A-not-B task is a standard measure for assessing object permanence and working memory in infants.
- Understanding the factors influencing early working memory development is essential.
Purpose of the Study:
- To analyze age-related changes in the A-not-B task performance in infants aged 7-12 months.
- To investigate the nature of interindividual differences in working memory capacity during this period.
- To explore the genetic and environmental influences on working memory development.
Main Methods:
- A cohort of 150 infants (7-12 months) from twin pairs (monozygotic and dizygotic) participated.
- Working memory was assessed using the A-not-B task, measuring the maximum tolerable delay.
- The Bayley scale was used to assess mental development.
Main Results:
- Performance on the A-not-B task improved with age, with a notable increase in delay tolerance between 9 and 10 months.
- Significant correlation between mental development and working memory delay emerged after 9-10 months.
- Infant twin analysis revealed environmental determination of differences at 7-9 months, shifting to systematic environmental influences at 10-12 months.
Conclusions:
- Working memory development shows distinct age-related trajectories and differing underlying mechanisms.
- Environmental factors play a significant role in shaping early working memory, with a shift in influence over time.
- The findings highlight the dynamic interplay of genetics and environment in infant cognitive development.
Abstract:
The aim of the present work was to analyze the age-related dynamics and nature of interindividual differences in performing the A-not-B task, which addresses working memory in children aged 7-12 months. The cohort consisted of 150 children aged 7-12 months from mono- and dizygotic twin pairs. Working memory was assessed in terms of the maximum delay which the children could tolerate in a delayed response test (the A-not-B task). Performance of the task improved with age, such that a sharp change in the ability to tolerate the delay occurred between nine and ten months of age. Mental development as assessed using the Bayley scale showed a significant correlation with the duration of the delay in the task only after a threshold period (9-10 months of age) in the development of working memory. Analysis of intrapair correlations in mono- and dizygotic twins showed that interindividual differences in the A-not-B task delay at age 7-9 months were completely determined by individual environmental factors (including measurement errors), while at age 10-12 months the leading role in the interindividual variability in this measure was taken by the systematic environment. These results show that the abilities to tolerate delays at the beginning and end of the second six months of life are based on different mechanisms.
