Facial EMG as an indicator of palatability in humans

Two experiments were conducted to observe the sensory hedonic responses and facial EMG activities elicited from different tastes. In Experiment 1, 25 subjects tasted flavors of apple juice, Gatorade, water, soybean milk, and pickle juice. In Experiment 2, 21 subjects tasted a sugar solution, a salt solution, and water. Subjects' sensory hedonic reports and facial EMG activity in the levator labii superioris/ alaeque nasi region were recorded in each experiment. The results from Experiment 1 showed that subjects reported significantly higher ratings of palatability to the apple juice, Gatorade, and water than to the soybean milk and pickle juice. The results from Experiment 2 indicated that the subjects reported significantly higher ratings of palatability to the water and sugar solution than to the salt solution. EMG recordings in both experiments showed that the negative hedonic sensations were associated with higher EMG activity in the levator labii muscle region, and that the positive hedonic sensations were associated with lower EMG activity in the same muscle region. It is concluded that facial EMG activity can be used as an indicator of palatability in humans.