038-23 – Seeing the unseen: exploring the effects of subliminal facial expressions on human mood, behaviour, and physiology.

Introduction: Processing images of facial expressions subliminally (below consciousness level) can affect behavioural responses, including our opinions and decision making. Subliminally presented emotional faces can also increase our electrical skin conductivity and facial muscle activity. However, it has not been tested whether this type of stimuli can influence the way we feel. Therefore, the current study tests whether subliminal presentation of happy faces affects mood and physiological responses in contrast to neutral faces, particularly if facial images present highly familiar people. It is hypothesized that processing subliminal happy faces improves participants’ mood and intensifies physiological responses, especially for familiar faces. Understanding how facial expressions influence emotional states may have further implications for approaching mood disorders.
Methods: Twenty neurotypical participants perform an object recognition task during which images of unfamiliar happy (Session 1) or neutral (Session 2) faces are presented subliminally on each trial. Immediately before and after the task, participants complete a mood questionnaire while during the task, skin conductivity and facial electromyography are measured. Additional measures of task performance and empathy are taken. 10 of the participants also complete the study with subliminal presentation of closely related to them individuals displaying either happy (Session 3) or neutral (Session 4) expressions.
Statistical analysis: The main analysis will be done on the mood questionnaire, each physiological measure and task performance using repeated measures tools. They will be done for all 20 participants without the familiarity factor. An additional analysis with the familiarity factor will be performed for 10 of those participants. Tests of difference will be used to investigate main effects and interactions. Correlation will be used to test links between empathy and other measures.