Contrasting Experimentally Device-Manipulated and Device-Free Smiles

Area of Science:

• Psychology
• Facial Expression Research
• Nonverbal Communication

Background:

• Experimental psychology often uses mouth-held devices to induce smiles.
• Previous research has not quantitatively compared muscle activation between device-induced and natural smiles.
• The efficacy of the Smile Stick, a novel smile-inducing device, remains unquantified.

Purpose of the Study:

• To compare the magnitude of muscle activation between device-free smiles and smiles induced by chopsticks or the Smile Stick.
• To evaluate participant experience (comfort, fatigue, affect) across different smile induction methods.
• To determine if the Smile Stick is a comparable alternative to traditional methods.

Main Methods:

• Facial electromyography (fEMG) measured orbicularis oculi and zygomaticus major muscle activation.
• 159 participants underwent three 1-minute smile manipulations: Smile Stick, chopsticks, and device-free.
• Post-manipulation ratings assessed comfort, fatigue, affect, and arousal.

Main Results:

• The Smile Stick and chopsticks showed comparable performance in muscle activation and participant ratings.
• Device-free smiles yielded the highest positive affect and lowest negative affect, but were more fatiguing.
• Device-free smiles significantly increased zygomaticus major (∼40%) and orbicularis oculi (∼15%) activation compared to devices.

Conclusions:

• Device-free smiling elicits stronger muscle activation and greater affective changes than device-assisted methods.
• Smile-inducing devices, including the Smile Stick and chopsticks, effectively activate smiling muscles and influence affect to a lesser degree.
• The Smile Stick presents a hygienic and acceptable alternative to disposable chopsticks for smile induction research.