On the physiology of interruption after unexpectedness

Area of Science:

• Psychology
• Neuroscience
• Physiology

Background:

• Surprise involves interruption and attention, potentially triggering physiological changes similar to threat responses.
• The unexpectedness of an event is a primary driver of surprise, suggesting initial responses may be valence-independent.

Purpose of the Study:

• To investigate the physiological changes associated with surprise.
• To compare physiological responses to positive, neutral, and negative surprising stimuli.
• To examine how repeated exposure to unexpected stimuli affects physiological responses.

Main Methods:

• Repetition-change studies were conducted across multiple experiments.
• Physiological measures included heart rate, blood pressure, body movement, and finger temperature.
• Stimuli varied in valence (positive, neutral, negative) and unexpectedness.

Main Results:

• Surprise led to a decrease in heart rate and an increase in blood pressure.
• No significant effects were observed on body movement or finger temperature.
• Heart rate returned to baseline with repeated exposure, but blood pressure remained elevated.
• Initial responses were not influenced by stimulus valence, though a trend suggested higher systolic blood pressure increase for negative surprises.

Conclusions:

• Surprise elicits specific physiological changes, including heart rate deceleration and blood pressure elevation.
• These physiological effects are primarily driven by unexpectedness rather than emotional valence.
• Sustained elevation in blood pressure suggests a lasting physiological impact of unexpected events.