Dynamic concordance between subjective and facial EMG hedonic responses during the consumption of gel-type food.

The concordance between subjective and facial hedonic responses while eating is informative, both practically and theoretically. Recent psychophysiological studies reported that hedonic ratings during the consumption of gel-type food were negatively associated with facial electromyography (EMG) signals recorded from the corrugator supercilii and positively associated with those from chewing-related muscles. However, the relationships were tested in a static manner, and the dynamic subjective-facial concordance remains untested. Therefore, we investigated this by assessing participants' dynamic valence ratings and recording their facial EMG from the corrugator supercilii, zygomatic major, masseter, and suprahyoid muscles while they chewed and swallowed gel-type food stimuli of various flavors. Cross-correlations with dynamic valence ratings were negative for corrugator supercilii EMG signals and positive for zygomatic major, masseter, and suprahyoid EMG signals during both chewing and swallowing. These findings indicate that subjective hedonic experiences and facial EMG signals are dynamically coupled during the consumption of food.