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Updated: Mar 14, 2026
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Habituation and Prepulse Inhibition of Acoustic Startle in Rodents
Published on: September 1, 2011
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Heritability of startle reactivity and affect modified startle
Devika Dhamija1, Catherine Tuvblad2, Michael E Dawson1
1Department of Psychology, University of Southern California, USA.
Summary
This study found sex differences in startle reflex heritability. While the startle blink reflex is heritable in males, environmental factors influence it in females, with affect-modified startle showing little heritability.
Area of Science:
- Behavioral Genetics
- Psychophysiology
- Developmental Psychology
Background:
- The startle reflex and affect-modified startle reflex are key indicators of defensive reactivity and emotional processing.
- Understanding the genetic and environmental influences on these reflexes is crucial for comprehending individual differences in emotional regulation.
Purpose of the Study:
- To investigate the heritability of the startle blink reflex and affect modification of this reflex.
- To examine sex differences in the genetic and environmental contributions to these reflexes in adolescents.
Main Methods:
- A community sample of 772 adolescent twins (ages 14-15) participated.
- Participants were exposed to affective picture slides (negative, positive, neutral valence; high, low arousal) with and without startling acoustic stimuli.
- The startle blink reflex and its modification by affective stimuli were measured.
Main Results:
- Females exhibited higher mean startle blink amplitudes than males, indicating greater defensive reactivity.
- In males, the startle blink reflex was significantly heritable (49%).
- In females, variance in the startle blink reflex was primarily attributed to shared (53%) and non-shared (41%) environmental factors. Heritability for affect-modified startle was negligible in both sexes.
Conclusions:
- Significant sex differences exist in the etiological factors underlying startle reactivity.
- The startle reflex paradigm may have limited utility for elucidating the genetic basis of emotional processing, particularly affect modification.
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