Fear-potentiated startle responses in temperamentally different human infants

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L A Schmidt1, N A Fox

  • 1Department of Psychology, McMaster University Hamilton, Ontario, Canada.

Developmental Psychobiology
|April 4, 1998
PubMed

Insights

Infant temperament predicts toddler behavior. High motor activity with negative affect at 4 months linked to behavioral inhibition, while positive affect linked to exuberance, with differences seen in fear-potentiated startle responses at 9 months.

Area of Science:

  • Developmental Psychology
  • Neuroscience
  • Infant Behavior

Background:

  • Early temperament, characterized by motor activity and affect, predicts later behavioral styles.
  • Previous research linked infant temperament to toddler behavioral inhibition or exuberance.

Purpose of the Study:

  • To examine fear-potentiated startle eyeblink responses in 9-month-old infants based on their 4-month temperament.
  • To investigate the neurobiological underpinnings of early behavioral styles.

Main Methods:

  • Assessed baseline and fear-potentiated startle eyeblink responses during a stranger-approach paradigm at 9 months.
  • Categorized infants based on high motor activity and either negative or positive affect at 4 months.

Main Results:

  • Infants with high motor activity and negative affect at 4 months showed a significantly greater increase in fear-potentiated startle amplitude at 9 months.
  • No differences were found in baseline startle responses between the groups.

Conclusions:

  • Early behavioral inhibition may originate from a lower arousal threshold in forebrain limbic areas.
  • Temperament-related differences in fear processing emerge early in infancy.

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