Single-step initiation supports the interplay between fear expression perception and approach motivation

The perception of emotional faces plays a critical role in shaping human motor responses. However, the relationship between perceived facial expressions, particularly fear, and approach-related movement remains unclear as prior research often employed ambiguous approach behaviour and task requiring emotion identification before action planning, potentially introducing biases from differences in recognition accuracy across emotions. To address these limitations, we examined the effect of emotional faces (fear, angry, happiness) on unambiguous approach-related movement, i.e., forward single-step initiation by using a go/no-go paradigm. Moreover, two conditions were conducted: in the explicit condition, motor responses depended on whether the face was emotional or neutral, while in the implicit condition, they depended on the face’s gender. Results showed that the perception of emotional faces impacted forward single-step initiation in the explicit condition only. More precisely, the motor response was stronger (higher anticipatory postural adjustments amplitude) in front of fear and happy faces than angry faces, and faster (shorter anticipatory postural adjustments duration) to fear than to angry faces. Altogether, these results highlighted a movement improvement in front of a face which expressed fear compared to anger and, in a slightly more contrasting way, compared to happiness. These results supported the idea that fearful faces, although signalling threat, are associated with approach, whereas angry faces appear to be perceived as threatening and linked to avoidance movements.