Head Motion Elicited by Viewing Affective Pictures as Measured by a New LED-Based Technique

Area of Science:

• Psychology
• Neuroscience
• Biomechanics

Background:

• Motor reactions are integral to emotional responses, influenced by motivational systems like the appetitive and defensive systems.
• While emotions involve action tendencies, few studies have used kinematic methods to analyze motor responses to emotional stimuli.
• Head motion analysis offers a novel approach to understanding how affective visual stimuli impact emotional responses.

Purpose of the Study:

• To investigate the impact of viewing affective pictures on head posture and movement using kinematic analysis.
• To explore the relationship between emotional valence (pleasant, neutral, unpleasant) and motor responses.
• To examine gender differences in motor reactions to emotional visual stimuli.

Main Methods:

• Participants viewed unpleasant, neutral, and pleasant affective pictures while instructed to remain still.
• Head movements were tracked using light-emitting diodes (LEDs) attached to the forehead and a motion-sensing device.
• Kinematic data, specifically medial-lateral and anterior-posterior sway, were analyzed in response to different picture types.

Main Results:

• Participants exhibited significantly more body sway when viewing unpleasant pictures compared to neutral or pleasant ones.
• Unpleasant pictures elicited faster head movements than both neutral and pleasant stimuli.
• Men demonstrated faster movement responses than women, consistent with previous research on gender differences in emotional reactivity.

Conclusions:

• Head motion analysis can effectively quantify motor responses to emotional visual stimuli.
• The observed increase in sway and movement speed for unpleasant pictures may indicate a readiness to act, linked to the defensive system.
• Findings highlight the role of motor responses in emotional processing and reveal gender-specific patterns in reacting to affective content.