If They Move in Sync, They Must Feel in Sync 1

RUNNING HEAD: IF THEY MOVE IN SYNC, THEY MUST FEEL IN SYNC

If They Move in Sync, They Must Feel in Sync: Movement Synchrony Leads to Attributions of Rapport and Entitativity

Daniël Lakens Eindhoven University of Technology Mariëlle Stel Utrecht University

RESEARCH ARTICLE In press, Social Cognition

Correspondence should be addressed to Daniël Lakens, Human Technology Interaction Group, IPO 1.24, PO Box 513, 5600 MB Eindhoven, The Netherlands. E-mail: [email protected].

If They Move in Sync, They Must Feel in Sync 2

Abstract Coordinated behavior patterns are one of the pillars of social interaction. Researchers have recently shown that movement synchrony influences ratings of rapport, and the extent to which groups are judged to be a unit. The current experiments investigated the hypothesis that observers infer a shared psychological state from synchronized movement rhythms, influencing attributions of rapport and entitativity judgments. Movement rhythms of observed individuals are manipulated between participants (Experiment 1) or kept constant while source of the emerging movement synchrony is manipulated (Experiment 2), and both rapport and perceived entitativity are measured. The findings support the assumption that movement synchrony increases attributed rapport and perceived entitativity. Furthermore, mediational analyses reveal that the effects of movement synchrony on perceived unity are not purely perceptual in nature, but caused by psychological inferences. Observers infer the degree to which individuals are a social unit from their movement rhythms.

ABSTRACT: 144 words KEYWORDS: synchrony, entitativity, rapport, entrainment, rhythmic movement

If They Move in Sync, They Must Feel in Sync 3

If They Move in Sync, They Must Feel in Sync: Movement Synchrony Leads to Attributions of Rapport and Entitativity Coordinated behavior patterns are one of the pillars of social interaction. Peoples’ movement rhythms can synchronize unintentionally, for example when walking side by side, or intentionally, as when military units march. The tendency to synchronize movement rhythms has been theorized to play an important role in the formation of a social unit (Condon, 1980; Davis, 1982; Fiske, 2004; Kendon, 1990; LaFrance, 1985; Marsh, Richardson, Baron, & Schmidt, 2006; Newtson, Hairfield, Bloomingdale, & Cutino, 1987; Wiltermuth & Heath, 2009). Movement synchrony is argued to be an indication of shared feelings of rapport, an affective state of mutual attention and positivity (Bernieri, 1988; Tickle-Degnen & Rosenthal, 1990). For the last forty years researchers have been interested in the relationship between synchronous movement rhythms, feelings of rapport, and perceived or experienced social unity (Bernieri, 1988; Cappella, 1996; Condon & Ogsten, 1966; Marsh, Johnston, Richardson, & Schmidt, 2009; Tickle-Degnen & Rosenthal, 1990). Moving in synchrony is argued to influence the degree to which individuals are perceived as a social unit, or their entitativity (Campbell, 1958; Hamilton & Sherman, 1996; Marsh, Richardson, & Schmidt, 2009; Yzerbyt, Corneille, Seron, & Demoulin, 2004). A dynamic interpretation of entitativity (see Brewer, Hong, & Li, 2004) stresses that groups emerge, change and disappear over time. Furthermore, the extent to which groups are seen as a unit depends on both static and temporary properties of the group, as on chronic and temporary beliefs of the perceiver. When people observe synchronized individuals, they are expected to activate certain beliefs about why these individuals move in synchrony. One of these beliefs is that individuals who move in

If They Move in Sync, They Must Feel in Sync 4

synchrony do so because they share a feeling of rapport (Bernieri, 1988; Bernieri, Rosenthal, Davis, & Knee, 1994). LaFrance (1985, 1990) theorizes that movement synchrony is a social gauge by which observers can assess the degree to which individuals are mutually involved with each other. Observers use this “tie-sign” to judge the extent to which individuals are a social unit. The aim of the current studies is to provide empirical support for the theoretical assumption that observers draw psychological inferences from the movement rhythm of synchronized individuals, and use these inferences when judging the extent to which individuals are a social unit. For example, LaFrance (1985) suggests that observers use movement synchrony to assess feelings of rapport between individuals, which subsequently influences entitativity judgments. To examine whether observed movement synchrony activates inferences about a shared psychological state of the synchronized individuals, the current studies measure both attributions of rapport and entitativity judgments. If psychological inferences do not play a role, and movement synchrony influences attributions of rapport and entitativity judgments purely due to the increased perceptual similarity of synchronized movement rhythms, the effect of movement synchrony on entitativity should be independent of attributions of rapport. To test the alternative hypothesis that movement synchrony influences attributions of rapport and entitativity judgments through psychological inferences (Bernieri et al., 1994; LaFrance, 1985), mediational analyses are performed to examine whether the effect of movement synchrony on entitativity is driven by attributions of rapport. Although synchrony researchers primarily seem to favor the pathway where the effect of movement synchrony on entitativity is mediated by attributed rapport (e.g., Bernieri, 1988; Bernieri et al., 1994; Condon, 1980; LaFrance, 1985, 1990; Marsh et al.,

If They Move in Sync, They Must Feel in Sync 5

2006, Marsh, Johnston, et al., 2009), theoretically a case could be made that the effect of movement synchrony on rapport is driven by entitativity judgments (cf., Yzerbyt, Corneille, & Estrada, 2001, Yzerbyt, et al., 2004). Both these pathways most likely account for the influence of movement synchrony on attributions of rapport and perceived entitativity depending on the situation, alternative sources of information about the individuals, and existing beliefs concerning the observed individuals. The goal of the current article is not to differentiate between these two pathways, but to test the underlying assumption they share: Movement synchrony influences attributed rapport and entitativity judgments through psychological inferences. Several studies have shown that observed movement synchrony is significantly correlated with rapport (Bernieri, 1988, Bernieri et al., 1994; LaFrance, 1985). To counteract possible criticisms of correlational data collected in studies where real-life interactions are used as stimulus material (see Cappella, 1990) researchers have recently investigated the relationship between movement synchrony and rapport by manipulating the amount of movement synchrony (Hove & Risen, 2009; Marsh, Johnston, et al., 2009; Miles, Nind, & Macrae, 2009). For example, Miles and colleagues (2009) presented their participants with 24 video animations of two stick figures walking in different rhythms. After each animation was presented, participants were asked to indicate the amount of rapport between the two stick figures on a 9-point scale. As expected, the more similar the movement rhythms of the two stick figures were, the higher the stimuli were rated on rapport. Although these results clearly show that people used the movement rhythms of the stick figures to guide their answer on the rapport judgment, several questions remain. First, it is unclear whether the effects of movement synchrony on rapport

If They Move in Sync, They Must Feel in Sync 6

judgments actually reflect psychological attributions. Since stick figures moving in a similar rhythm are also perceptually more similar, the higher rapport ratings could be the result of the increased perceptual similarity of moving in synchrony. Second, the different movement rhythms in the study by Miles et al. (2009) were manipulated within subjects. Because the 24 stick figures only differed in their movement rhythm, it is less surprising that observers based their rapport judgments on the only aspect the animations differed on, namely the amount of movement synchrony. Manipulating movement synchrony between subjects would provide stronger support for the assumption that synchrony is used as a cue to determine feelings of rapport. Third, rapport is theorized to consist of not only coordination, but also of positivity and mutual attention (Tickle-Degnen & Rosenthal, 1990), and should therefore ideally be assessed by a questionnaire addressing these separate factors. Finally, it might be difficult to attribute a psychological state to stick figures, and using video clips of real individuals might be a better approach to investigate whether observed movement synchrony leads to attributions of a shared psychological state. Overview of the current research The current studies were developed to examine whether the effects of perceived movement synchrony on attributions of rapport and entitativity are caused purely by the perceptual similarity of the stimuli, or reflect underlying psychological attributions. In the first experiment, rapport and entitativity judgments were collected for video clips of two rhythmically waving confederates, who waved either in synchrony or in asynchrony. When individuals in the movie clips synchronized, they coordinated their movement rhythms in-phase (by waving their arms or swinging their legs at the same angle and frequency). Research has shown that in-phase movement synchrony is the

If They Move in Sync, They Must Feel in Sync 7

most stable form of spontaneous movement synchronization and most likely to emerge unintentionally (Kelso, 1995; Neda et al., 2000; Richardson, Marsh, Isenhower, Goodman, & Schmidt, 2007). This method was based on earlier work by Lakens (in press) who showed that movement synchrony influenced entitativity judgments. The first experiment extends this work by investigating both entitativity and rapport, allowing us to draw conclusions about the indirect nature of the relationship between movement synchrony and entitativity. The effect of movement synchrony on entitativity and rapport was predicted to be indirect, following either the pathway from synchrony to attributed rapport to perceived entitativity, or the pathway from synchrony to perceived entitativity to attributed rapport. Importantly, the direct effects of movement synchrony on rapport and entitativity were predicted to disappear when introducing entitativity or rapport in the mediation analysis, respectively. In the second experiment, perceptual differences were controlled for by presenting the same stimulus video to all participants. The critical manipulation in this experiment was whether participants believed that observed individuals synchronized spontaneously, or that observed individuals synchronized because they were instructed to do so. We propose that when individuals synchronize without an external reason to do so, their movement rhythm is a valid source of information which observers can rely on to judge whether individuals feel rapport and are a unit. If individuals synchronize because they are instructed to synchronize their movement rhythms, their movement rhythm is not a useful indication of any shared affective states or feelings of unity among the individuals. Thus, synchronized movement rhythms will lead to attributed feelings of rapport and perceived entitativity when the emerging movement synchrony

If They Move in Sync, They Must Feel in Sync 8

can be attributed to the group members, but not when movement synchrony emerges due to an external instruction to synchronize. Moreover, as in Experiment 1, we expected mediational analyses to reveal that the effect of movement synchrony on rapport and entitativity is indirect, indicating that movement synchrony leads to psychological attributions which influence rapport and entitativity judgments. Experiment 1 Method Participants. A total of 104 volunteers (65 females, mean age 20.7) from a Dutch university participated in the study, and were randomly assigned to the synchrony vs. asynchrony condition of the between subject design. Procedure. All participants were told they would watch a movie clip, and would be asked some questions about what they had seen. In the movie clip, two women faced the camera and waved their left hand (cf. Lakens, in press). Depending on the condition, the waving movements were performed in perfect in-phase synchrony (both individuals waved their hands once every 833 milliseconds, and reached the most leftward point of the waving motion at the exact same frame in the movie clip) or in asynchrony (one woman waved her hand once every 833 milliseconds, while the other waved her hand once every 500 milliseconds). After watching the movie, participants received a four item entitativity questionnaire (Postmes, Brooke, & Jetten, 2008, see Appendix). In addition, they completed the rapport questionnaire adapted from Puccinelli and TickleDegnen (2004), consisting of six items (see Appendix). All items were rated on a 7point scale. Subsequently, several control questions were asked. People were asked to indicate to what extent the behavior of the individuals was spontaneous. In addition, general similarity questions were asked, concerning the extent to which the individuals

If They Move in Sync, They Must Feel in Sync 9

had the same habits and goals (cf. Ip, Chiu, & Wan, 2006) to make sure movement synchrony did not influence overall similarity. Finally, participants answered a manipulation check about how similar the movement rhythms of the individuals were, filled out demographic questions, and were thanked and debriefed. Results A factor analysis (principle component analysis) with a varimax rotation was conducted on the 10 items of the entitativity and rapport questionnaires. A Scree test suggested the extraction of two factors. The first factor consisted of the four items of the entitativity questionnaire (Cronbach’s α = .84). The second factor consisted of the remaining items of the rapport scale (Cronbach’s α = .81). This factor analysis supports the theoretical distinction made in the literature between the psychological constructs of rapport and entitativity (e.g., Bernieri, 1988; Campbell, 1958; LaFrance, 1985; TickleDegnen & Rosenthal, 1990; Yzerbyt et al., 2004). A manipulation check confirmed that the confederates waving in synchrony were judged to move in a more similar rhythm (M = 6.19, SD = 1.21) than confederates waving in asynchrony (M = 2.34, SD = 1.71), t(102) = 13.45, p < .001. Rapport and entitativity. The average of the six rapport items was calculated. An univariate ANOVA revealed that individuals waving in synchrony were judged higher on rapport (M = 4.99, SD = 1.01) than individuals waving in asynchrony (M = 4.32, SD = 0.95), F(1, 102) = 8.51, p = .004, ηp2 = .08. The four items of the entitativity scale were averaged, and an univariate ANOVA confirmed the hypothesis that confederates waving in synchrony were rated higher on entitativity (M = 4.05, SD = 1.12) than confederates waving in asynchrony (M = 3.25, SD = 1.22), F(1, 102) = 12.01, p = .001, ηp2 = .08. Observers did not rate the two individuals differently as a function of their

If They Move in Sync, They Must Feel in Sync 10

movement synchrony on the control questions asked after the entitativity and rapport scales, such as to what extent the individuals had similar habits or goals (cf. Ip et al., 2006), or how spontaneous their behavior was (all p > .10). Mediational analysis. We subsequently tested whether the effect of movement synchrony on rapport and entitativity were two direct effects, or whether the results were best described by one of the two indirect pathways described in the literature. In addition to the effects of movement synchrony on rapport and entitativity described above, attributed rapport significantly predicted perceived entitativity, β = .60, t = 7.50, p < .001. Adding rapport to the regression of synchrony on perceived entitativity significantly reduced the effect of synchrony on entitativity, β = .17, t = 2.12, p = .037, SOBEL test z = 2.72, p = .001. Similarly, adding entitativity to the regression of synchrony on rapport significantly reduced the effect of synchrony on rapport, β = .09, t = 1.19, p = .266, SOBEL test z = 3.15, p < .001. These two analyses suggest that the effect of movement synchrony on rapport and entitativity is indirect in nature. Discussion The results reveal that movement synchrony influences perceived entitativity and attributed feelings of rapport. Confederates waving in the same rhythm were seen as more entitative and were rated higher on rapport compared to confederates waving in asynchrony (Miles et al., 2009; Lakens, in press). The two mediational analyses supported the assumption that direct effects of movement synchrony on rapport and entitativity were not independent of each other, providing a first indication that psychological attributions, and not purely perceptual similarity, played a role. That these results speak against a purely perceptual effect of movement synchrony on

If They Move in Sync, They Must Feel in Sync 11

entitativity, is further corroborated by the fact that movement synchrony did not influence general similarity questions regarding the habits or goals of the participants. Experiment 2 The first experiment revealed that the individuals who waved in synchrony were rated higher on entitativity compared to individuals waving in asynchrony, and that this increase in entitativity was related to higher attributions of rapport. Although this study reveals that movement synchrony influences attributions of rapport and entitativity, the two video clips used in Experiment 1 differed in how perceptually similar the individuals were. After all, individuals who moved in synchrony in the movie clip in Experiment 1 shared the same body posture throughout their movements, whereas the individuals waving in asynchrony adopted different body postures at different times throughout the movie clip. To directly manipulate the inferences participants draw when observing individuals moving in synchrony, in the current experiment the same stimulus video was presented to all participants, and we directly manipulated whether the emerging movement synchrony could be attributed to an external source or not. When individuals are explicitly instructed to synchronize, movement synchrony should no longer be an informative cue to judge the extent to which individuals are a social unit, or to infer shared feelings of rapport. On the other hand, when individuals synchronize without being instructed to do so, observers are assumed to interpret the emergence of movement synchrony as a useful source of information regarding the presence of shared feelings of rapport, and rate synchronized individuals higher on entitativity. The current experiment provided a more stringent test of our hypothesis by manipulating whether participants believed that individuals synchronized spontaneously, or that individuals were instructed to synchronize. Participants all

If They Move in Sync, They Must Feel in Sync 12

watched the same movie clip (taken from the movie Dead Poet Society) where three boys walked around a courtyard and synchronized their walking rhythms. Importantly, whereas participants received perceptually different movie clips in Experiment 1, there were no perceptual differences in the movie clip the participants received in the current experiment. Before watching the movie clip, participants in the walk instruction condition were told that the boys were instructed to walk, whereas participants in the synchronize instruction condition were told that the boys were instructed to walk and synchronize their movement rhythm. When individuals are instructed to synchronize, their movement rhythms should no longer be attributed to shared feelings of rapport. Therefore, observers were expected to ignore the movement rhythms of the individuals as an informative cue regarding the degree to which they were a social unit. After the video, we measured participants’ attributions of rapport between the three boys and entitativity judgments. Both judgments of rapport and entitativity were expected to be higher when the individuals were instructed to walk, compared to when the individuals were instructed to synchronize. In addition, we expected a similar indirect effect of movement synchrony on rapport and entitativity as observed in Experiment 1. Method Participants. Thirty-eight students (24 female, mean age 20.3) at a Dutch university participated in this study in return for monetary compensation. Participants were randomly assigned to the walk vs. synchronize instruction condition of the between participants design. Procedure. The experiment was introduced as a memory study. Instructions on the computer screen explained to participants that they would watch a short movie clip

If They Move in Sync, They Must Feel in Sync 13

and would be asked some questions about what they saw and how they felt. Participants were told several movie clips were used in the experiment, and the one they would watch was about a group of American boys attending a private school (in reality, all participants watched the same movie clip). Three of the boys walked around in a courtyard while their teacher and fellow students were present. Participants were told the teacher had given the three boys an instruction. On the next screen, participants in the walk instruction condition read: The teacher has given the three boys the following instruction: Walk around the courtyard. In the synchronize instruction condition, participants instead read: The teacher has given the three boys the following instruction: Walk around the courtyard, and establish a shared walking rhythm. After reading this instruction, participants watched the movie clip. The movie clip was taken from the movie Dead Poet Society, starting from 63 minutes and 37 seconds in the movie, with an 11 second duration. In the actual movie, the three boys did not receive any instruction from their teacher before they started to walk. Because the movie clip lasted only 11 seconds, the participants watched the movie clip three times. Before participants watched the movie clip for the final time, they received the instruction to direct their attention to the three walking boys in the movie clip, since the following questions would mainly concern the three boys. This instruction was added to ensure all participants would pay attention to the three boys, and would not focus on the background or other people in the movie clip. The three boys in the movie clip walked around the courtyard in counterclockwise direction. The last 4 seconds of the clip consisted of a close-up, showing the three boys legs in perfect in-phase synchrony. Their feet touched and left the ground at the same moment in time,

If They Move in Sync, They Must Feel in Sync 14

such that when one boy lifted his right foot, the other two boys lifted their right feet in the exact same frame of the movie clip. After watching the movie clip for the third time, participants received the same rapport and entitativity questionnaires used in Experiment 1. Subsequently, the participants indicated if they had seen the movie clip before and if so, if they could write down the name of the movie the clip was taken from. After answering questions regarding the obedience of the three boys, and the extent to which the three boys started to walk in the same rhythm, participants filled out demographic questions, were thanked, and debriefed. Results Two students indicated they had seen the movie clip used in this experiment before and both could specify the name of the movie it came from (Dead Poet Society). Since these participants most likely knew that real context of the movie clip was about peoples’ automatic tendency to conform, they were excluded from the analysis. A factor analysis (principle component analysis) with a varimax rotation was conducted with the 10 dependent variables of the entitativity and rapport questionnaires. A Scree test suggested the extraction of three factors. The first factor consisted of the four items of the entitativity questionnaire. The second and third factors consisted of the remaining items of the rapport scale, and divided this scale in a positivity component (mutual feelings of liking, comfortable feeling and feeling the same) and a mutual attention component (mutual agreement, mutual understanding and being aware of each other). Given that the rapport questionnaire consisted of a single factor in Experiment 1, and that the instruction manipulation influenced the two components in the same way, we followed the same procedure as in Experiment 1 and combined all six items into a

If They Move in Sync, They Must Feel in Sync 15

rapport scale. Importantly, this factor analysis again confirms that entitativity and rapport are two distinct psychological constructs. To control for differences in perceived obedience between the conditions, participants were asked to indicate how obedient they thought the boys were, but no differences were observed (p > .10). In addition, when asked to what extend the three boys in the movie clip started to walk in the same rhythm, participants in the two conditions did not differ in their judgments (p > .10), indicating that participants all agreed upon how similar the movement rhythm of the two boys had been. Rapport and entitativity. The average of the six items of the rapport scale (Cronbach’s α = .65) were calculated, and subjected to an univariate ANOVA with the instruction manipulation as between participants factor. Participants inferred the three boys felt more rapport when synchronizing spontaneously (M = 5.37, SD = 0.50), than when instructed to synchronize (M = 4.89, SD = 0.87), F(1, 34) = 4.33, p < .05, ηp2 = .11. The average of the four items of the entitativity scale (Cronbach’s α = .88) were calculated, and subjected to an univariate ANOVA with the instruction manipulation as between participants factor. The predicted effect of instruction emerged: Participants perceived the group of three boys to be more entitative if they were instructed to walk (M = 5.34, SD = 0.90), compared to when the teacher instructed them to synchronize (M = 4.38, SD = 1.44), F(1, 34) = 6.02, p = .02, ηp2 = .15. Mediational analysis. To test for the predicted mediation of the effect of the manipulated source of the movement rhythm on entitativity by attributed rapport, a regression analysis with instruction as predictor was run on both perceived entitativity, β = .39, t = 2.43, p < .05, as perceived rapport, β = .34, t = 2.08, p < .05. In addition,

If They Move in Sync, They Must Feel in Sync 16

attributed rapport significantly predicted perceived entitativity, β = .60, t = 4.42, p < .001. Finally, adding rapport to the regression of instruction on perceived entitativity caused the effect of instruction on entitativity to disappear, β = .20, t = 1.44, p = .16, SOBEL test z = 2.13, p = .03. Similarly, adding perceived entitativity to the regression of instruction on rapport, caused the effect of instruction on rapport to disappear, β = .12, t = 0.81, p = .42, SOBEL test z = 1.88, p = .06. These mediational analyses again support the two pathways described in the introduction, providing further support that the psychological effects of movement synchrony are not purely perceptual in nature. Additional analyses were performed to test the relationship between the subjectively perceived similarity of movement rhythms of the boys in the movie clip and judgments of rapport and entitativity. For participants who thought the three boys were instructed to synchronize, mediational analyses revealed that perceived similarity of the movement rhythms predicted entitativity judgments, β = .54, t = 2.40, p = .03, but not perceived rapport, β = .32, t = 1.25, p = .23. On the other hand, for participants who believed the boys synchronized their movement rhythms without the explicit instruction to do so, perceived similarity of the movement rhythms predicted entitativity judgments, β = .42, t = 1.98, p = .06, and judgments of perceived rapport, β = .49, t = 2.35, p = .03. In addition, perceived rapport predicted perceived entitativity, β = .59, t = 3.06, p = .007. Finally, after adding perceived rapport to the equation, the effect of subjective similarity of movement rhythms on perceived entitativity disappeared, β = .29, t = 1.41, p = .18, Sobel z = 1.89, p = .03, one-sided. A mediation model where the effect of perceived similarity of movement rhythms on rapport was reduced by adding entitativity judgments to the model also reached significance, β = .18, t = 0.82, p = .42, Sobel z = 1.86, p = .03. These two

If They Move in Sync, They Must Feel in Sync 17

pathways again support the indirect effect described in the introduction. These analyses reveal that the perceived similarity of movement rhythms predicted entitativity judgments (but not attributions of rapport) when participants believed the boys in the movie clip were instructed to synchronize. However, when observers believed the three boys synchronized spontaneously, the perceived similarity of movement rhythms predicted both attributions of rapport as perceived entitativity, and the direct effect of movement similarity on entitativity (or rapport) was mediated by attributions of rapport (or entitativity). General Discussion When individuals wave in synchrony, observers attribute feelings of rapport to the individuals, and rate them higher on entitativity, compared to when they wave in asynchrony. Furthermore, individuals walking in synchrony were rated higher on rapport and entitativity by observers who believed the individuals simply synchronized their walking rhythm, compared to observers who believed the individuals synchronized because they were instructed to do so. These results show that when the emergence of movement synchrony can be attributed to an external source (i.e., the explicit instruction to synchronize), it is used as a source of information regarding shared feelings of rapport among group members to a lesser extent. Individuals who are thought to move in synchrony without being instructed to do so are judged to share a feeling of positivity and mutual attention, and are rated higher on entitativity. Furthermore, both experiments reveal that the effect of movement synchrony on entitativity (or rapport) is driven by psychological attributions of rapport (or entitativity). These results speak against a perceptual similarity explanation of the effect of movement synchrony on perceived entitativity.

If They Move in Sync, They Must Feel in Sync 18

The analyses in Experiment 2 seem to indicate that in addition to the absolute increase in perceived rapport and entitativity when individuals synchronize spontaneously (compared to when they synchronize because they are instructed to do so), the indirect effect of subjective movement similarity on perceived social unity through psychological attributions is only present when synchrony occurs spontaneously. When individuals are explicitly instructed to synchronize, movement rhythms are no longer predictive of attributions of rapport, but show a direct relation to perceived entitativity. These results suggest that movement synchrony can influence perceived entitativity directly, but that individuals will attribute a shared psychological state to synchronized individuals, and rate them higher on entitativity, when the situation allows for such attributions. The nature of relation between movement synchrony and perceived entitativity when attributions of a shared psychological state does not mediate the effect of movement synchrony on entitativity awaits further research, but might be the result of a Gestalt-like similarity based perceptual organization. These findings conceptually replicate and extend previous work on movement synchrony and rapport (e.g., Miles et al., 2009) by showing movement synchrony influences attributed rapport of real individuals, using a multiple item rapport questionnaire in a between participants design. In addition, we provide empirical support for the theorized interplay between movement synchrony, attributions of rapport, and entitativity by manipulating movement rhythms in Experiment 1 and by manipulating the attributions of the observer in Experiment 2, providing further insights into the processes underlying the effect of movement synchrony on rapport (Miles et al., 2009) and entitativity (Lakens, in press). Together, these studies provide converging

If They Move in Sync, They Must Feel in Sync 19

evidence that movement synchrony is used as a cue to draw psychological inferences about the extent to which individuals are a social unit. Two regression models fitted the data. In the first model the effect of movement synchrony (Experiment 1) or the instruction manipulation (Experiment 2) on perceived entitativity is mediated by attributed rapport. In the second model the effect of movement synchrony or the instruction manipulation on attributed rapport is mediated by perceived entitativity. The rationale of both models and a complete overview of studies supporting either the pathway in which inferred shared characteristics influence entitativity judgments or the pathway in which perceived entitativity influences the inferred shared characteristics has been reviewed elsewhere (Yzerbyt et al., 2001, 2004). Based on the current results, we cannot differentiate between these two pathways. However, the model where the effect of movement synchrony on entitativity is mediated by attributions of rapport is most in line with synchrony researchers’ theoretical assumptions about the relationship between movement synchrony, rapport and entitativity (e.g., Bernieri, 1988; LaFrance, 1990; Marsh, Richardson, & Schmidt, 2009; Tickle-Degnen & Rosenthal, 1990; Yzerbyt et al., 2001). Even though no univocal causal relation between rapport and entitativity could be determined in the experiments, the most important finding of these studies is that movement synchrony does not influence perceived entitativity purely due to the increased perceptual similarity of synchronized movement rhythms, but is caused by psychological attributions. Support for this assumption is twofold. First, mediation analyses revealed that in both studies the direct effect of movement synchrony on entitativity (or rapport) disappeared when rapport (or entitativity) was added to the regression model. Importantly, both pathways are in line with the hypothesis under

If They Move in Sync, They Must Feel in Sync 20

investigation that movement synchrony activates psychological inferences about the social unity of the observed individuals. Second, even when the perceptual information was the same for all participants in Experiment 2, entitativity judgments differed based on whether the movement synchrony simply emerged, or was the result of an explicit instruction to synchronize. Furthermore, the relation between perceived similarity of the movement rhythms and entitativity ratings were mediated by attributions of rapport, but only for participants who believed movement synchrony emerged spontaneously. Together, these results reveal that when people see individuals move in synchrony, they draw inferences about the shared psychological state of the synchronized individuals. In addition to the theoretical contribution of the present research to our understanding of the relationship between movement synchrony, rapport and entitativity, the attribution paradigm used on the second experiment might provide a useful approach to investigate the psychological consequences of experienced or observed movement synchrony. By manipulating whether the synchronized movement rhythm can be attributed to an external source or not, researchers can investigate the psychological consequences of movement synchrony, without manipulating movement rhythms. This could be one way to circumvent the problems associated with the manipulation of movement rhythms (which some researchers equate with manipulating the socialness of the interaction, e.g., Cappella, 1990) while still enabling researchers to go beyond correlational support for the relationship between synchrony and rapport (e.g., Bernieri, 1988; Bernieri et al., 1994; LaFrance, 1985). Given that people synchronize their movement rhythms unintentionally (e.g., Richardson et al., 2007; Ulzen et al., 2009), people have to automatically process similarities or subtle differences in movement rhythms. Attribution research suggests

If They Move in Sync, They Must Feel in Sync 21

that people initially explain a person’s actions in terms of dispositional traits, and subsequently adjust for situational factors (Gilbert & Malone, 1995). When observers listen to a speech by a fellow student who was assigned a topic, observers under cognitive load make more dispositional attributions (and fail to correct for the situation) than participants not under cognitive load. Future research could provide support for the automaticity of the inferences observers draw from movement synchrony by showing that the difference between spontaneous and instructed movement synchrony on attributions of rapport and entitativity disappears under cognitive load. An important question for the psychological consequences of movement synchrony is whether the difference between spontaneous movement synchrony and instructed movement synchrony observed in the second experiment will extend to situations where people directly experience movement synchronization. Would marching soldiers see themselves as a stronger unit if they create their own movement rhythm, compared to when they march in the rhythm their superior dictates? If being instructed to tap in synchrony with a metronome increases affiliation with someone else who is tapping in the same rhythm (Hove & Risen, 2009), will spontaneously synchronization with an interaction partner create an even stronger bond? Future research could focus on these questions to determine the circumstances under which movement synchrony functions best to facilitate the formation of a group. Another possible role for future research could be to investigate how sensitive people are to synchronized movement rhythms. Previous studies that have revealed effects of movement synchrony on cognition, such as enhanced memory for interaction partners (Macrae, Duffy, Miles, & Lawrence, 2008) and interpersonal cooperation (Valdesolo, Ouyang, & DeSteno, 2010), as well as the Experiment 1, rely on explicit

If They Move in Sync, They Must Feel in Sync 22

manipulations of movement synchrony. Previous research has shown that observers can reliably rate subtle amount of naturally occurring movement synchrony in real-life interactions (Bernieri et al., 1994). Given that people are sensitive to different degrees of movement synchrony, and the pervasive tendency of individuals to synchronize their movement rhythms in social interactions (e.g., Fiske, 2004; Haidt, Seder, & Kesebir, 2008), further investigation is warranted of how salient movement synchrony needs be in real-life interactions to influence person perception and other cognitive processes. From our results, we can conclude that the source of non-verbal movement synchrony influences the extent to which perceivers attribute feelings of rapport to synchronized individuals. When people synchronize spontaneously, their movement rhythm is seen as a useful source of information to determine whether the individuals feel rapport. Observers rate synchronized individuals higher on entitativity, and this effect is not purely due to the perceptual similarity of synchronized movement rhythms, but the result of psychological attributions. These results enhance our knowledge of the relationship between movement synchrony, rapport and entitativity, and underline that people intuitively draw inferences from non-verbal behavior to determine whether individuals are a social unit.

If They Move in Sync, They Must Feel in Sync 23

References Bernieri, F. J. (1988). Coordinated movement and rapport in teacher student interactions. Journal of Nonverbal Behavior, 12, 120-138. Bernieri, F. J., Davis, J. M., Rosenthal, R., & Knee, C. R. (1994). Interactional synchrony and rapport: Measuring synchrony in displays devoid of sound and facial affect. Personality and Social Psychology Bulletin, 20, 303–311. Brewer, M. B., Hong, Y-y., & Li, Q. (2004). Dynamic entitativity: Perceiving groups as actors. In V. Yzerbyt, C. Judd, & O. Corneille (Eds.), The psychology of group perception: Perceived variability, entitativity, and essentialism (pp. 25–38). Philadelphia: Psychology Press. Campbell, D. T. (1958). Common fate, similarity, and other indices of the status of aggregates of persons as social entities. Behavioral Science, 3, 14–24. Cappella, J. N. (1990). On defining conversational coordination and rapport. Psychological Inquiry, 1, 303-305. Cappella, J. N. (1996). Dynamic coordination of vocal and kinesic behavior in dyadic interaction: Methods, problems, and interpersonal outcomes. In J. Watt, & C. Van Lear (Eds.), Dynamic patterns in communication processes (pp. 353-386). Thousand Oaks, CA: Sage. Condon, W. S. (1980). The relation of interactional synchrony to cognitive and emotional processes. In M. R. Key (Ed.), The relation of verbal and nonverbal behavior (pp. 49–65). The Hague, Mouton. Davis, M. E. (Ed.). (1982). Interaction rhythms: Periodicity in communicative behavior. New York: Human Sciences Press.

If They Move in Sync, They Must Feel in Sync 24

Gilbert, D. T., & Malone, P. S. (1995). The correspondence bias. Psychological Bulletin, 117, 21–38. Haidt, J., Seder, J., & Kesebir, S. (2008). Hive psychology, happiness, and public policy. Journal of Legal Studies, 37, 133–156. Hamilton, D. L., & Sherman, S. J. (1996). Perceiving persons and groups. Psychological Review, 103, 336-355. Hove, M. J., & Risen, J. L. (2009). It’s all in the timing: Interpersonal synchrony increases affiliation. Social Cognition, 27, 949-960. Ip, G. W-m., Chiu, C-y., & Wan, C. (2006). Birds of a feather and birds flocking together: Physical versus behavioral cues may lead to trait- versus goal-based group perception. Journal of Personality and Social Psychology, 90, 368 – 381. Kelso, J. A. S. (1995). Dynamic patterns. Cambridge, MA: MIT Press. Kendon, A. (1990). Conducting interaction: patterns of behavior in focused encounters. Cambridge; New York: Cambridge University Press. LaFrance, M. (1985). Posture mirroring and intergroup orientation. Personality and Social Psychology Bulletin, 11, 207-218. LaFrance, M. (1990). The trouble with rapport. Psychological Inquiry, 1, 318-320. Lakens, D. (in press). Movement synchrony and perceived entitativity. Journal of Experimental Social Psychology. doi:10.1016/j.jesp.2010.03.015 Macrae, C. N., Duffy, O. K., Miles, L. K., & Lawrence, J. (2008). A case of handwaving: Action synchrony and person perception. Cognition, 109, 152–156. Marsh, K. L., Johnston, L., Richardson, M. J., & Schmidt, R. C. (2009). Toward a radically embodied, embedded social psychology. European Journal of Social Psychology, 320 – 339.

If They Move in Sync, They Must Feel in Sync 25

Marsh, K. L., Richardson, M. J., Baron, R. M. & Schmidt, R. C. (2006). Contrasting approaches to perceiving and acting with others. Ecological Psychology, 18, 138. Marsh, K. L., Richardson, M. J., & Schmidt, R. C. (2009). Social connection through joint action and interpersonal coordination. Topics in Cognitive Science, 1, 320 – 339. Miles, L. K., Nind, L. K., & Macrae, C. N. (2009). The rhythm of rapport: Interpersonal synchrony and social perception. Journal of Experimental Social Psychology, 45, 585 – 589. Neda, Z., Ravasz, E., Brechet, Y., Vicsek, T., & Barabasi, A. L. (2000). The sound of many hands clapping - Tumultuous applause can transform itself into waves of synchronized clapping. Nature, 403, 849-850. Newtson, D., Hairfield, J., Bloomingdale, J., & Cutino, S. (1987). The structure of action and interaction. Social Cognition, 5, 191–237. Postmes, T., Brooke, D., & Jetten, J. (2008). Social identity formation and team performance. Unpublished manuscript, University of Groningen. Puccinelli, N. M., & Tickle-Degnen, L. (2004). Knowing too much about others: Moderators of the relationship between eavesdropping and rapport in social interaction. Journal of Nonverbal Behavior, 28, 223-243. Richardson, M. J., Marsh, K. L., Isenhower, R., Goodman, J., & Schmidt, R. C. (2007). Rocking together: Dynamics of intentional and unintentional interpersonal coordination. Human Movement Science, 26, 867 – 891. Tickle-Degnen, L., & Rosenthal, R. (1990). The nature of rapport and its nonverbal correlates. Psychological Inquiry, 1, 285-293.

If They Move in Sync, They Must Feel in Sync 26

Ulzen, N. R., Lamoth, C. J. C., Daffertshofer, A., Semin, G. R., & Beek, P. J. (2008) Characteristics of instructed and uninstructed interpersonal coordination while walking side-by-side. Neuroscience Letters 432, 88–93. Valdesolo, P., Ouyang, J., & DeSteno, D. A. (2010) The rhythm of joint action: Synchrony promotes cooperative ability. Journal of Experimental Social Psychology, 46, 693 – 695. Wilmermuth, S. S., & Heath, C. (2009). Synchrony and Cooperation. Psychological Science, 20, 1-5. Yzerbyt, V., Corneille, O., & Estrada, C. (2001). The interplay of subjective essentialism and entitativity in the formation of stereotypes. Personality and Social Psychology Review, 5, 141–155. Yzerbyt, V., Corneille, O., Seron, E., & Demoulin, S. (2004). Subjective essentialism in action: Self-anchoring and social control as consequences of fundamental social divides. In V. Yzerbyt, C. M. Judd, & O. Corneille (Eds.), The psychology of group perception: Perceived variability, entitativity, and essentialism (pp. 101– 124). New York: Psychology Press.

If They Move in Sync, They Must Feel in Sync 27

Appendix Entitativity items: I feel the people in this movie are a unit; I think the people in this movie can act in unison; I experience a feeling of togetherness between the individuals in this movie; I feel the people in this movie are as one. Rapport items: To what extent do you think the individuals liked each other; To what extent do you think the individuals were aware of each other; To what extent do you think the individuals felt coordinated with each other; To what extent do you think the individuals felt the same; To what extent do you think the individuals understood each other; To what extent do you think the individuals had a feeling of mutual agreement.

If They Move in Sync, They Must Feel in Sync 28

Author Note The authors would like to thank the Cratylus research group, the Utrecht NERDs, Luigi Castelli and two anonymous reviewers for helpful suggestions and comments on this research. Special thanks go to Martijn van Zomeren, Henk Aarts, and Marina Kouzakova for helpful comments on an earlier version of this manuscript and to Kaska Kubacka for her never-ending knowledge of pop-culture.