Role of Surprise in the Discrimination of the Facial Expression of Fear.

The facilitating role of the facial expression of surprise in the discrimination of the facial expression of fear was analyzed. The sample consisted of 202 subjects that undertook a forced-choice test in which they had to decide as quickly as possible whether the facial expression displayed on-screen was one of fear, anger or happiness. Variations were made to the prime expression (neutral expression, or one of surprise); the target expression (facial expression of fear, anger or happiness), and the prime duration (50 ms, 150 ms or 250 ms). The results revealed shorter reaction times in the response to the expression of fear when the prime expression was one of surprise, with a prime duration of 50 ms (p = .009) and 150 ms (p = .001), compared to when the prime expression was a neutral one. By contrast, the reaction times were longer in the discrimination of an expression of fear when the prime expression was one of surprise with a prime duration of 250 ms (p < .0001), compared to when the prime expression was a neutral one. This pattern of results was obtained solely in the discrimination of the expression of fear. The discussion focuses on these findings and the possible functional continuity between surprise and fear.