The Influence of Facial Signals on the Automatic Imitation of Hand Actions

Abstract

Imitation and facial signals are fundamental social cues that guide interactions with others, but little is known regarding the relationship between these behaviors. It is clear that during expression detection, we imitate observed expressions by engaging similar facial muscles. It is proposed that a cognitive system, which matches observed and performed actions, controls imitation and contributes to emotion understanding. However, there is little known regarding the consequences of recognizing affective states for other forms of imitation, which are not inherently tied to the observed emotion. The current study investigated the hypothesis that facial cue valence would modulate automatic imitation of hand actions. To test this hypothesis, we paired different types of facial cue with an automatic imitation task. Experiments 1 and 2 demonstrated that a smile prompted greater automatic imitation than angry and neutral expressions. Additionally, a meta-analysis of this and previous studies suggests that both happy and angry expressions increase imitation compared to neutral expressions. By contrast, Experiments 3 and 4 demonstrated that invariant facial cues, which signal trait-levels of agreeableness, had no impact on imitation. Despite readily identifying trait-based facial signals, levels of agreeableness did not differentially modulate automatic imitation. Further, a Bayesian analysis showed that the null effect was between 2 and 5 times more likely than the experimental effect. Therefore, we show that imitation systems are more sensitive to prosocial facial signals that indicate “in the moment” states than enduring traits. These data support the view that a smile primes multiple forms of imitation including the copying actions that are not inherently affective. The influence of expression detection on wider forms of imitation may contribute to facilitating interactions between individuals, such as building rapport and affiliation.

The Emotional Modulation of Facial Mimicry: A Kinematic Study

“…This could be interpreted as the consequence of the tendency of the subjects to accurately reciprocate to a social signal. In support of this hypothesis, our results on RTs are in line with previous studies showing a facilitation effect in performing congruent observed movements in response to emotional facial expressions (Rauchbauer et al, 2015 ; Butler et al, 2016 ); unfortunately, no parameters related to action execution were measured in those studies. However, an increase of accuracy requirements and motor control in response to emotional cues was found in previous experiments that measures kinematic parameters of goal-directed sequences addressed to a social partner (Ferri et al, 2010 ; Stefani et al, 2015 ), and in general during motor interactions in a positive social context (Gianelli et al, 2013 ), for a review see (Krishnan-Barman et al, 2017 ).…”

“…Secondarily, faster movements in response to positive gestures confirmed that positive valence strongly modulates responses of the subjects during social interaction (Butler et al, 2016 ; De Stefani et al, 2016 ) Indeed, the shorter duration of lip-protrusion after observing a positive movement was measured in response to smile but not to anger; moreover, kiss resulted not effective as smile in speeding lip protrusion movements, evidencing a clear interaction between motor features and valence of the gesture. Instead, both negative and positive mouth-closure expressions, respectively kiss and spit, modulated the movement duration of lip stretching.…”

What are reaction time indices of automatic imitation measuring?

“…To this end, several recent studies have shown that social factors can influence SRC measures of imitation (Heyes, 2011;. SRC measures of imitation are increased in situations that promote affiliation through eye contact (Wang et al, 2011), group membership (Gleibs et al, 2016), and facial expressions (Butler et al, 2016), as well as when interacting with more human-like, rather than robotic, agents (Press, 2011;Kilner et al, 2003;Klapper et al, 2014). Other work has shown that when prosocial attitudes are generated (Cook & Bird, 2011;Leighton et al, 2010), or prosocial gestures are signalled , imitation increases.…”

Dynamic emotional expressions do not modulate responses to gestures

“…A number of previous studies have investigated the effect of different emotional expressions on the AI of finger movements ( Butler, Ward, & Ramsey, 2016 ; Crescentini, Mengotti, Grecucci, & Rumiati, 2011 ; Grecucci et al, 2013 ; Rauchbauer et al, 2015 , Rauchbauer et al, 2016 ). However, to date the results of these studies have been somewhat inconclusive.…”