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Sensitization and aversive conditioning: effects on the startle reflex and electrodermal responding
Summary
Shock exposure sensitizes human startle reflexes, enhancing protective responses before aversive learning. This potentiation of the acoustic startle reflex indicates an avoidance disposition, distinct from skin conductance changes.
Area of Science:
- Psychology
- Neuroscience
- Human experimental psychology
Background:
- Animal studies indicate shock sensitization and aversive learning enhance the acoustic startle reflex.
- Previous research shows startle response magnitude correlates with induced affective valence.
Purpose of the Study:
- To investigate shock sensitization of the startle reflex in humans.
- To determine if shock sensitization precedes aversive conditioning.
- To compare startle reflex and skin conductance responses during sensitization and conditioning.
Main Methods:
- Sixty human subjects viewed emotional slides before and during conditioning.
- Shock electrodes were attached, and subjects received unpredictable shocks during acquisition trials.
- Acoustic startle probes were administered during preconditioning, acquisition, and extinction phases.
Main Results:
- Shock exposure significantly potentiated the startle reflex magnitude in human subjects.
- Shock sensitization was observed for the startle reflex but not for the skin conductance response.
- Startle reflex potentiation preceded the learning observed in skin conductance, which was modulated by cognitive processes.
Conclusions:
- Startle reflex potentiation may index the acquisition of an avoidance disposition in humans.
- General sensitization of protective reflexes precedes aversive learning.
- Distinct learning trajectories exist for the startle reflex and skin conductance response, influenced by different factors.