Just Seconds of Laughter Reveals Relationship Status: Laughter with Friends Sounds More Authentic and Less Vulnerable than Laughter with Romantic Partners. Sally D. Farley, Deborah Carson & Susan M. Hughes. Journal of Nonverbal Behavior, Jul 1 2022. https://rd.springer.com/article/10.1007/s10919-022-00406-5
Abstract: The dual pathway model posits that spontaneous and volitional laughter are voiced using distinct production systems, and perceivers rely upon these system-related cues to make accurate judgments about relationship status. Yet, to our knowledge, no empirical work has examined whether raters can differentiate laughter directed at friends and romantic partners and the cues driving this accuracy. In Study 1, raters (N = 50), who listened to 52 segments of laughter, identified conversational partner (friend versus romantic partner) with greater than chance accuracy (M = 0.57) and rated laughs directed at friends to be more pleasant-sounding than laughs directed at romantic partners. Study 2, which involved 58 raters, revealed that prototypical friendship laughter sounded more spontaneous (e.g., natural) and less “vulnerable” (e.g., submissive) than prototypical romantic laughter. Study 3 replicated the findings of the first two studies using a large cross-cultural sample (N = 252). Implications for the importance of laughter as a subtle relational signal of affiliation are discussed.
General Discussion
In these studies, we demonstrated that raters exceeded chance in determining relationship status (friend versus romantic) based on brief vocal samples of laughter, that friendship laughter sounds more authentic (louder, more relaxed, more natural, and more variable/”changing”) than romantic laughter, and that these judgments were consistent across five unique cultures. In addition, we found support for the vulnerable love hypothesis—romantic laughter sounded warmer, more feminine and more submissive than friendship laughter.
The ability of raters to identify the conversational partner (friend versus romantic) with greater than chance accuracy complements previous work on laughter’s ability to signal important information about the relationship between co-laughers (Bryant & Aktipis, 2014; Bryant et al., 2018; Lavan et al., 2016). But this research goes beyond previous work by revealing that raters can differentiate between laughter directed at two types of dyads that are both high in affiliation—friends and romantic partners. For a variety of reasons (motivational and emotional), we maintained that laughter directed at friends was more authentic than laughter directed at romantic partners, and the tendency for friendship laughter to be more accurately identified than romantic laughter implicates it as more authentic (Bryant & Aktipis, 2014). In addition, raters’ judgments of relationship status (friend versus romantic) were reliably linked to subjective characteristics of laughter authenticity. Laughter between friends was perceived as louder, more natural-sounding, more changing/variable (in Studies 2 and 3), breathier (in Study 2), and more relaxed (in Study 3).
Vulnerable Love Hypothesis
In Studies 2 and 3, we found support for the notion that laughter cues reveal the vulnerable relationship status of early-stage romantic love. Other work has shown that raters can differentiate friends and romantic partners via 20 s of content-masked clips and short content-controlled clips such as “How are you?” (Farley et al., 2013), but it is impressive that this skill extends to brief segments of laughter. The intimate voice associated with romantic love is softer, higher in pitch, and more submissive-sounding (Montepare & Vega, 1988), and these vulnerability-type cues were effective at differentiating romantic laughter from friendship laughter in our work. Specifically, in Studies 2 and 3, romantic laughter was perceived to be quieter, more feminine-sounding, and more submissive, and in Study 2, when the measure was used, more baby-like. From an evolutionary standpoint, vocal cues such as these serve to communicate “I mean you no harm” (Bryant, 2020; Gervais & Wilson, 2005). Moreover, romantic laughter was perceived as less pleasant-sounding than friend laughter, which dovetails with other research finding that masked clips of vocal cues from romantic partners are evaluated less favorably than clips from friends (Farley et al., 2013; Montepare & Vega, 1988). Early-stage romantic love is marked by a great deal of tumultuous physiological arousal and uncertainty, and romantic love renders individuals to be highly dependent on their relationships (Hatfield & Rapson, 1993a, 1993b). This might translate into a vocal style lacking in confidence and attractiveness.
The female advantage in nonverbal sensitivity (Knapp et al., 2014) was generally unsupported in this research. However, in Study 3, gender interacted with partner type. For arguably more “authentic” friendship samples, which may be easier to identify (Bryant & Aktipis, 2014), men and women performed similarly well. But for the potentially less “authentic” romantic samples, which were more challenging for raters, women’s accuracy was significantly higher than men’s. This is a unique finding given that sex differences in accuracy have not emerged in previous research (Bryant & Aktipis, 2014; Bryant et al., 2018). This female advantage to accurately decipher romantic intent via laughter may be explained by the Error Management Theory which predicts that women have an evolved bias to be skeptical of men’s commitment (Haselton & Buss, 2000), and therefore may be more in tune to discriminating signals of men’s romantic intent through a variety of means. Further, the cross-cultural ability of individuals to do this provides support for the evolutionary significance of laughter as a signal of relational import.
The research presented here augments an impressive body of work on the accuracy of thin slices of behavior (Ambady & Rosenthal, 1992). Not only can individuals make accurate inferences about important social dimensions such as sexual orientation (Rule, 2017), status (Bjornsdottir & Rule, 2017), and leadership emergence in organizations (Re & Rule, 2017) based on photographs, individuals discern critical relational information based on vocal cues (Farley et al., 2013; Hughes & Harrison, 2017; Montepare & Vega, 1998). Laughter is potentially unique because it not only reflects or signals affiliation (Brown et al., 2018), but it is also capable of enhancing relationship quality (Kurtz & Algoe, 2015, 2017). The role of laughter in signaling relational information internally within the dyad and externally to observers also supports social functional accounts of emotion, such as the emotions as social information model (EASI) (Van Kleef, 2009).
Limitations and Future Directions
The current investigations were not without some limitations. The first two studies had relatively smaller samples sizes and the second study did not include comprehensive demographics of the sample. Study 3 addressed these limitations by demonstrating ubiquity in our findings through the use of a large cross-cultural sample diverse on Hofstede’s (2011) six cultural values. Interestingly, the sample from the United States in Bryant et al. (2018) was least accurate at making forced-choice decisions from the sample of laughs from their own culture, which converges with our results from Study 3. Examination of this curious finding would be a fruitful area of future investigation.
Using the laugh samples that were the most identifiable in terms of discerning whether they were directed toward a friend or a romantic partner (Study 2) allowed us to better comprehend what specific subjective perceptions may have contributed to the success of discriminating between samples. However, whereas these samples served as good prototypes for investigation, it limits the generalizability of the findings. We attempted to account for this limitation in Study 3 by selecting different laughter samples that were not prototypical representations, and this method yielded similar findings. Study 3 also redressed a limitation from Study 2 in which we had to account for an experimental error where we had to omit some of the ratings for a set of participants as described above.
Although a unique constellation of acoustic features contributes to the perception of vocalizations (Babel et al., 2014), pitch appears to be one of the most salient features in vocal discrimination (for review see Puts et al., 2014) and is an indicator of arousal (Bryant & Aktipis, 2014; Ruch & Ekman, 2001). Examining how detailed acoustic parameters impacts perception was beyond the scope of this study as our focus was to explore subjective assessments made by listeners. However, future studies should consider the variety of acoustic features of laughter such as pitch, perhaps even through artificial manipulation, to see how they affect different percepts of laughter within romantic and non-romantic contexts. In addition, this research expanded the work of previous investigations, which have only examined female laughers (e.g., Bryant & Aktipis, 2014; Bryant et al., 2018; Lavan et al., 2016), but more studies are needed to understand sex differences in both the expression and perception of laughter across different contexts.
Our investigation examined the laughter between couples who were at the advent of their romantic relationships. It would be prudent to examine laughter obtained from couples during the early versus later stages of their relationships. Laughter appears to be an important factor throughout a couple’s exchange; it frequently occurs during courtship (with men being more likely to use women’s responsive laughter to gauge their interest; Hall, 2015), and mutual laughter has also been linked to long-term relationship satisfaction (Hall, 2013). Yet, romantic relationships often trade the early novelty and volatility of romantic love for security and commitment over time, potentially rendering the laughter of long-term romantic partners to sound similar to that of friends. This avenue could also benefit from examining how self-reported feelings for one’s romantic partner correlate with the sound of one’s laughter.