Approach-avoidance responses and categorical perception of ambiguous facial expressions.

Emotion perception of facial expressions involves two processes: quick approach-avoidance responses and subsequent sorting into emotional categories (i.e., happiness, anger), considering the context. Sorting of morphed ambiguous facial expressions is known to occur categorically, but the occurrence of approach-avoidance responses for morphed facial expressions is yet to be investigated. The present study used morphed angry and fearful facial expressions and measured approach-avoidance responses among Japanese university students (Experiment 1, n = 29). Similar experiments with linguistic load (Experiment 2, n = 28) and visual load (Experiment 3, n = 29) were conducted. The results indicated categorical perception in the sorting of facial expressions but no approach-avoidance response for morphed expressions. Furthermore, linguistic load affected the categorisation of facial expressions, but neither linguistic load nor visual load affected the approach-avoidance response. These results support the idea that the non-linguistic approach-avoidance response and the linguistic categorisation of facial expressions are two different processes. The nature of the emotional perception process is also discussed.