Effect of delay interval on classical eyeblink conditioning in 5-month-old human infants
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Updated: Sep 28, 2026
Classical Short-Delay Eyeblink Conditioning in One-Year-Old Children
Published on: September 1, 2018
Dragana I Claflin1, Mark E Stanton, Jane Herbert
1Department of Psychology and Integrated Toxicology Curriculum, Duke University, Durham, NC, USA.
Insights
Human infants learned through classical conditioning, with optimal associative eyeblink timing occurring at a 650-ms delay. This suggests a developmental shift in conditioning delays during early infancy.
Area of Science:
- Developmental Psychology
- Cognitive Neuroscience
- Behavioral Science
Background:
- Associative learning is fundamental to cognitive development.
- Classical eyeblink conditioning is a key paradigm for studying infant learning.
- Understanding optimal timing in conditioning is crucial for developmental research.
Purpose of the Study:
- To evaluate associative learning in 5-month-old infants using classical eyeblink conditioning.
- To determine the effect of different conditioned stimulus-unconditioned stimulus (CS-US) delay intervals on infant conditioning.
- To compare the delay function in infants with that of adults.
Main Methods:
- Human infants (5 months old) were conditioned using a tone (CS) paired with an airpuff (US).
- Three delay intervals (250, 650, 1,250 ms) were tested across different infant groups.
- Conditioning was assessed by comparing paired groups with unpaired control groups.
Main Results:
- Associative conditioning occurred at 650 ms and 1,250 ms delays, but not at 250 ms.
- Adaptive eyeblink timing to avoid the airpuff was observed only at the 650 ms delay.
- The delay function in 5-month-olds was sharper than in adults, indicating a narrower optimal interval.
Conclusions:
- Infant associative learning is sensitive to CS-US timing, with an optimal delay around 650 ms at 5 months.
- The optimal delay interval for eyeblink conditioning shifts downward between 1 and 6 months of age.
- Infant conditioning delays are longer than those typically reported in adult populations.
Abstract:
Associative learning was evaluated in human infants with simple delay classical eyeblink conditioning. A tone conditioned stimulus (CS) was paired with an airpuff unconditioned stimulus (US) at three different delay intervals (250, 650, and 1,250 ms). Independent groups of healthy, full-term 5-month-old human infants were assigned to these three paired conditions and received two identical training sessions 1 week apart. The two longer delays resulted in associative conditioning, as confirmed by comparison with unpaired control groups. However, only at the 650-ms delay were associative eyeblinks adaptively timed to avoid the airpuff. The delay function at 5 months of age appears much sharper than is observed in adults. Together with the findings of A. H. Little, L. P. Lipsitt, and C. Rovee-Collier (1984), the present study suggests a downward shift in the optimal delay interval for associative eyeblink conditioning between 1 and 6 months of age. However, this delay remains longer than what is typically reported in adults.
