bernstein ( 1967 ) identified the degrees of freedom problem  the notion that the large number of independently controllable movement system df poses a computational burden to the cns ( turvey et al . bernstein 's solution ( see also gelfand and tsetlin , 1966 ; turvey et al . , 1978 ; tuller et al . , 1982 ) was that rather than controlling each df separately , the df are coupled to form a synergy , enabling the df to regulate each other . this reduces the need to control each df , and allows compensation for variability in one component of the synergy by another . is expressed in figure 1 ( kay , 1988 ; riley and turvey , 2002 ) . df that potentially are independent are coupled so that the synergy has fewer df ( possesses a lower dimensionality ) than the set of components from which it arises . the behavior of the synergy has even fewer df , a second level of dimensional compression as one moves from structural components to the behavior enacted by the interactions among the df . dimensional compression at both stages results from imposing constraints , which couple components so they change together rather than independently . dynamical systems approaches have emphasized dimensional compression ( kugler et al . , 1980 ; kugler and turvey , 1987 ; kay , 1988 ; turvey , 1990 ; turvey and carello , 1996 ) . dimensional compression occurs in self - organization ( nicolis and prigogine , 1977 ) and features prominently in synergetics ( haken , 1983 ) , a theory of self - organization that describes how systems of many non - linearly interacting , micro - scale components exhibit low - dimensional spatio - temporal patterns . interactions among micro - components give rise to the macroscopic pattern , which then constrains the behavior of the micro - components to sustain the pattern . coordination dynamics ( kelso , 1995 ) applies synergetics to describe how micro - scale neuromuscular processes give rise to macroscopic movement patterns . in interlimb rhythmic coordination ( synchronized oscillations of body segments , such as the rhythmic patterns of walking legs ) , the order parameter relative phase ( the difference in the segments oscillation phases ) captures the low - dimensional behavior that arises from the high - dimensional neuromuscular system . relative phase describes the spatiotemporal pattern of rhythmic coordination and the changes in coordination that occur in response to manipulations of control parameters ( e.g. , movement frequency ) . the dynamics of relative phase are understood to reflect the behavior of a synergy ( kelso , 1994 ; turvey and carello , 1996 ) . dimensional compression is a necessary but insufficient condition for the existence of a synergy ( latash , 2008 ) . the second and more critical characteristic of synergies , reciprocal compensation , refers to the ability of one component of a synergy to react to changes in others . a classic example occurs when one effector is perturbed during speech ( kelso et al . , 1984 ) . when the lower jaw was tugged downward , it was quickly compensated by a reciprocal change ( the lower lip extended upward ) that enabled the speaker to complete pronunciation of the sound . reciprocal compensation is central to the uncontrolled manifold ( ucm ) approach ( scholz and schner , 1999 ; latash et al . , 2002 ) . this approach assumes that coordinated movement is achieved by stabilizing the value of a performance variable ( such as a value of relative phase corresponding to an interlimb coordination pattern ) . in doing so , a subspace ( i.e. , manifold ) is created within a state space of task - relevant elements ( the df that participate in the task , for example the angular positions and velocities of two oscillating limbs ) , such that within the subspace the value of the performance variable remains constant . component values that do not lead to desired values of the performance variable ( values outside the ucm ) are restricted , whereas values that do not affect the performance variable ( those within the ucm ) are allowed . . , 2002 ) is using two fingers to produce a total force of , for example , 10  n. this target can be achieved by producing 5  n of force with each finger , or by pressing unequally hard with the fingers but so that the total force is 10  n ( e.g. , one finger produces 9  n and the other produces 1  n , or one produces 7  n while the other produces 3  n , etc . ) . if the force produced by each finger is plotted on orthogonal axes , the ucm is a subspace of the resulting plane , a line corresponding to forcefinger 1  +  forcefinger 2  =  10  n. as long as performance falls along the ucm , the target force is achieved as one finger compensates for the other . in the ucm analysis the hypothesized stabilization of a performance variable is evaluated by computing two quantities . the first , variance along the ucm , measures the extent to which variability among the df is compensated to preserve the performance variable . variance perpendicular to the ucm measures uncompensated variability that causes the performance variable to deviate from the target . while the individual variance components are often informative , their ratio provides a compact measure of the existence and strength of a synergy . if compensated variance is greater than uncompensated variance ( ratio  >  1 ) , the hypothesized performance variable is stabilized by compensation among the df the higher the ratio , the greater the amount of compensated variance , suggesting a stronger synergy ( depending on the magnitude of uncompensated variance ) . 1987 ) is expressed in figure 1 ( kay , 1988 ; riley and turvey , 2002 ) . df that potentially are independent are coupled so that the synergy has fewer df ( possesses a lower dimensionality ) than the set of components from which it arises . the behavior of the synergy has even fewer df , a second level of dimensional compression as one moves from structural components to the behavior enacted by the interactions among the df . dimensional compression at both stages results from imposing constraints , which couple components so they change together rather than independently . , 1980 ; kugler and turvey , 1987 ; kay , 1988 ; turvey , 1990 ; turvey and carello , 1996 ) . dimensional compression occurs in self - organization ( nicolis and prigogine , 1977 ) and features prominently in synergetics ( haken , 1983 ) , a theory of self - organization that describes how systems of many non - linearly interacting , micro - scale components exhibit low - dimensional spatio - temporal patterns . interactions among micro - components give rise to the macroscopic pattern , which then constrains the behavior of the micro - components to sustain the pattern . coordination dynamics ( kelso , 1995 ) applies synergetics to describe how micro - scale neuromuscular processes give rise to macroscopic movement patterns . in interlimb rhythmic coordination ( synchronized oscillations of body segments , such as the rhythmic patterns of walking legs ) , the order parameter relative phase ( the difference in the segments oscillation phases ) captures the low - dimensional behavior that arises from the high - dimensional neuromuscular system . relative phase describes the spatiotemporal pattern of rhythmic coordination and the changes in coordination that occur in response to manipulations of control parameters ( e.g. , movement frequency ) . the dynamics of relative phase are understood to reflect the behavior of a synergy ( kelso , 1994 ; turvey and carello , 1996 ) . dimensional compression is a necessary but insufficient condition for the existence of a synergy ( latash , 2008 ) . the second and more critical characteristic of synergies , reciprocal compensation , refers to the ability of one component of a synergy to react to changes in others . a classic example occurs when one effector is perturbed during speech ( kelso et al . , 1984 ) . when the lower jaw was tugged downward , it was quickly compensated by a reciprocal change ( the lower lip extended upward ) that enabled the speaker to complete pronunciation of the sound . reciprocal compensation is central to the uncontrolled manifold ( ucm ) approach ( scholz and schner , 1999 ; latash et al . , 2002 ) . this approach assumes that coordinated movement is achieved by stabilizing the value of a performance variable ( such as a value of relative phase corresponding to an interlimb coordination pattern ) . in doing so , a subspace ( i.e. , manifold ) is created within a state space of task - relevant elements ( the df that participate in the task , for example the angular positions and velocities of two oscillating limbs ) , such that within the subspace the value of the performance variable remains constant . component values that do not lead to desired values of the performance variable ( values outside the ucm ) are restricted , whereas values that do not affect the performance variable ( those within the ucm ) are allowed . 2002 ) is using two fingers to produce a total force of , for example , 10  n. this target can be achieved by producing 5  n of force with each finger , or by pressing unequally hard with the fingers but so that the total force is 10  n ( e.g. , one finger produces 9  n and the other produces 1  n , or one produces 7  n while the other produces 3  n , etc . ) . if the force produced by each finger is plotted on orthogonal axes , the ucm is a subspace of the resulting plane , a line corresponding to forcefinger 1  +  forcefinger 2  =  10  n. as long as performance falls along the ucm , the target force is achieved as one finger compensates for the other . in the ucm analysis the hypothesized stabilization of a performance variable is evaluated by computing two quantities . the first , variance along the ucm , measures the extent to which variability among the df is compensated to preserve the performance variable . variance perpendicular to the ucm measures uncompensated variability that causes the performance variable to deviate from the target . while the individual variance components are often informative , their ratio provides a compact measure of the existence and strength of a synergy . if compensated variance is greater than uncompensated variance ( ratio  >  1 ) , the hypothesized performance variable is stabilized by compensation among the df the higher the ratio , the greater the amount of compensated variance , suggesting a stronger synergy ( depending on the magnitude of uncompensated variance ) . apparent interpersonal coordination could be merely incidental ( figure 2a )  rather than reflecting true coordination , with the signatures of dimensional compression and reciprocal compensation , people may appear to coordinate their movements because they simultaneously execute similar motor programs , mediated by shared motor representations ( garrod and pickering , 2004 , 2009 ; sebanz et al . , 2006 ) . the studies described below contradict this alternative hypothesis and instead support the interpersonal synergy hypothesis ( see figure 2b ) . one study applied the ucm analysis to interpersonal rhythmic movement coordination ( black et al . , 2007 ) and another applied principal component analysis ( pca ) to performance of an interpersonal precision task ( ramenzoni , 2008 ) . each actor assembles a synergy that achieves the movement pattern required by the actor 's role in the task . because actors share similar representations of the task they are able to execute similar but independent movement patterns without demonstrating the reciprocal compensation that characterizes synergies . ( b ) hypothetical mechanism for interpersonal coordination that involves the formation of a joint or interpersonal synergy , composed of elements of each actor 's movement system . ( 2007 ) and ramenzoni ( 2008 ) because they directly address dimensional compression and reciprocal compensation . for example , condon and ogston ( 1971 ) hand - scored videotapes of interpersonal interactions to determine when conversants spoke relative to one another . cohn and tronick ( 1988 ) evaluated when similar affect was exhibited by interacting mothers and children . ( 1977 , 1987 ) quantified interpersonal coordination by hand - scoring joint - angle changes in videos of interacting participants . the degree of overall joint - angle change over time was submitted to spectral analysis to capture movement periodicity , and the spectral profiles were compared using coherence analysis to evaluate how similar two the methodology of these studies does not allow for direct evaluation of the interpersonal synergy hypothesis , although the processes of interpersonal coordination they documented is consistent with that hypothesis . programmatic studies on interpersonal rhythmic coordination ( reviewed by schmidt and richardson , 2008 ) have also produced evidence for interpersonal synergies . coordination of rhythmically moving limbs between two individuals exhibits the same phenomena observed within individuals and predicted by the hkb model of interlimb rhythmic coordination ( haken et al . , 1985 )  the existence of two spontaneously stable coordination patterns ( in - phase and anti - phase ) , transitions from anti - phase to in - phase at a critical movement frequency , critical fluctuations ( increases in movement variability ) preceding the transition , and a shift in the phase relation between oscillating segments when coordinating segments with different intrinsic frequencies ( schmidt et al . , 1990 ; these findings are important because according to the dynamical systems perspective , intrapersonal interlimb rhythmic coordination is a paradigmatic synergy ( e.g. , kugler and turvey , 1987 ; turvey , 1990 ; kelso , 1995 ; turvey and carello , 1996 ) . this raises the possibility that interpersonal coordination likewise reflects the activity of a synergy supported by visual coupling of the actors df ( schmidt and richardson , 2008 ; marsh et al . the first study we discuss ( ramenzoni , 2008 ) involved pairs of participants performing an interpersonal precision task . one participant held a target ( a circle ) , while another held a pointer through the circle without touching its sides ( figure 3a ) . preliminary results showed that with greater task difficulty participants hand and torso movements became increasingly coordinated ( as quantified by cross - recurrence quantification analysis crqa ; webber and zbilut , 1994 ; shockley et al . , 2002 ; shockley , 2005 ; richardson et al . , 2007 ) . crqa quantifies the degree of shared activity between two time series by evaluating how they unfold similarly over time in a multi - dimensional ( embedding ) space . the proportion of body configurations shared between the time series ( an overall measure of coordination ) and how long they maintain similar patterns ( how stable the coordination is ) are among the crqa measures ( see webber and zbilut , 1994 ) . ( a ) depiction of the individual- ( left ) and interpersonal- ( right ) task conditions from ramenzoni ( 2008 ) . ( b ) time series of the data projected onto the intrapersonal principle components from the individual ( left ) and interpersonal - task ( right ) conditions . the striking coordination in the interpersonal - task condition was confirmed by cross - recurrence quantification analysis , which revealed a greater degree and higher stability of coupling in that condition . displacements of participants hands , forearms , arms , and torsos were tracked in 3-d as they performed the interpersonal task or performed the subtasks ( pointing , holding the target ) without interacting with each other in an individual - task condition . pca identifies relations within high - dimensional datasets and maps the original data into a space whose axes ( principal components ) represent the dataset 's primary dimensions of variation ( daffertshofer et al . , 2004 ; those dimensions can be abstract and need not map directly onto the original dataset 's dimensions . fewer dimensions are required to account for most of the variation in the dataset ( a criterion of 90% of the variance was employed in this study ) than the number of original variables . vectors consisting of 12 displacement time series ( 4 body segments    3 spatial dimensions ) were submitted to pca to identify the principal dimensions or modes of variation for each participant . for both individual- and interpersonal - task conditions six components were required to account for 90% of the variance in the original dataset  a two - fold dimensional reduction . we then projected each participant 's movements onto the participant 's first principal component , creating a new variable that expressed change over time along the dimension of primary variation ( figure 3b ) . crqa revealed a significantly greater degree of coordination as well as significantly more stable coordination between the principal components for the interpersonal- than individual - task condition . data from both participants  a 24-dimensional vector ( 2 participants    4 body segments    3 spatial dimensions )  were submitted to a second pca . for the individual - task condition six components accounted for 90% of the variance , but for the interpersonal - task condition additionally , the first component accounted for significantly more variance in the interpersonal- than the individual - task condition . . however , pca can not provide unequivocal evidence for the existence of synergies , because it does not directly measure reciprocal compensation ( latash , 2008 ) . 2007 ) used the ucm approach to determine whether interpersonal coordination involves dimensional compression and reciprocal compensation . they had participants oscillate a hand - held pendulum ( kugler and turvey , 1987 ) in each hand ( intrapersonal coordination ) at a metronome - specified frequency to produce relative phase patterns corresponding to in - phase (     0 ) or anti - phase (     180 ) , and had two participants , each holding a pendulum in one hand ( interpersonal coordination ) , produce the same patterns . 2007 ) treated  as the performance variable ( with desired values of 0 or 180 for in - phase and anti - phase , respectively ) , and the position and velocity of each hand as component  df . those variables determine each hand 's phase angle  the point of the oscillating hand in its ever - repeating movement cycle  and  is the difference between the two hands phase angles . the ucm analysis thus quantified how variation in the position and velocity of each hand was structured ( or not ) to preserve the goal  value . in all cases the ratio of compensated to uncompensated variance was > 1 , indicating the presence of synergies for intrapersonal and interpersonal coordination . dimensional compression occurred because a lower dimensional variable ,  , was selectively stabilized via reciprocal compensation among the components . ratios were higher for intrapersonal ( mean  =  2.71 ) than interpersonal ( mean  =  1.995 ) coordination , paralleling findings of greater coupling strength for intrapersonal coordination ( schmidt et al . , 1998 ; the similitude between interpersonal and intrapersonal coordination was further reinforced because other manipulations , such as whether subjects were instructed to produce in - phase or anti - phase movement patterns , produced the same effects for interpersonal as for intrapersonal coordination [ ratio was higher for in - phase ( intrapersonal : 3.78 ; interpersonal : 2.31 ) than antiphase ( intrapersonal : 1.64 ; interpersonal : 1.68 ) ] . it could be argued that the existence of stable relative phase modes already provided evidence for synergies in interpersonal rhythmic coordination , at least insofar as this evidences dimensional compression . however , an observed stable value of  is mute regarding whether  is selectively stabilized through synergistic compensations . no specific value of  identifies the existence of a synergy , and neither a change in the mean nor the standard deviation of  indicates a change in synergy strength . the black et al . ( 2007 ) results provide direct evidence for interpersonal synergies . they were weaker than intrapersonal synergies , but nonetheless exhibited reciprocal compensation and dimensional compression . the findings suggest synergies are not hard - wired features of an actor 's neuromuscular system , but instead they are emergent properties of perception  action systems that are linked together informationally ( in the case of interpersonal coordination , the informational linkage was visual ) . the first study we discuss ( ramenzoni , 2008 ) involved pairs of participants performing an interpersonal precision task . one participant held a target ( a circle ) , while another held a pointer through the circle without touching its sides ( figure 3a ) . preliminary results showed that with greater task difficulty participants hand and torso movements became increasingly coordinated ( as quantified by cross - recurrence quantification analysis crqa ; webber and zbilut , 1994 ; shockley et al . , 2002 ; shockley , 2005 ; richardson et al . , 2007 ) . crqa quantifies the degree of shared activity between two time series by evaluating how they unfold similarly over time in a multi - dimensional ( embedding ) space . the proportion of body configurations shared between the time series ( an overall measure of coordination ) and how long they maintain similar patterns ( how stable the coordination is ) are among the crqa measures ( see webber and zbilut , 1994 ) . ( a ) depiction of the individual- ( left ) and interpersonal- ( right ) task conditions from ramenzoni ( 2008 ) . ( b ) time series of the data projected onto the intrapersonal principle components from the individual ( left ) and interpersonal - task ( right ) conditions . the striking coordination in the interpersonal - task condition was confirmed by cross - recurrence quantification analysis , which revealed a greater degree and higher stability of coupling in that condition . displacements of participants hands , forearms , arms , and torsos were tracked in 3-d as they performed the interpersonal task or performed the subtasks ( pointing , holding the target ) without interacting with each other in an individual - task condition . pca identifies relations within high - dimensional datasets and maps the original data into a space whose axes ( principal components ) represent the dataset 's primary dimensions of variation ( daffertshofer et al . , 2004 ; forner - cordero et al . , those dimensions can be abstract and need not map directly onto the original dataset 's dimensions . fewer dimensions are required to account for most of the variation in the dataset ( a criterion of 90% of the variance was employed in this study ) than the number of original variables . vectors consisting of 12 displacement time series ( 4 body segments    3 spatial dimensions ) were submitted to pca to identify the principal dimensions or modes of variation for each participant . for both individual- and interpersonal - task conditions six components were required to account for 90% of the variance in the original dataset  a two - fold dimensional reduction . we then projected each participant 's movements onto the participant 's first principal component , creating a new variable that expressed change over time along the dimension of primary variation ( figure 3b ) . crqa revealed a significantly greater degree of coordination as well as significantly more stable coordination between the principal components for the interpersonal- than individual - task condition . data from both participants  a 24-dimensional vector ( 2 participants    4 body segments    3 spatial dimensions )  were submitted to a second pca . for the individual - task condition six components accounted for 90% of the variance , but for the interpersonal - task condition there was greater dimensional reduction and just four components were required . additionally , the first component accounted for significantly more variance in the interpersonal- than the individual - task condition . however , pca can not provide unequivocal evidence for the existence of synergies , because it does not directly measure reciprocal compensation ( latash , 2008 ) . black et al . ( 2007 ) used the ucm approach to determine whether interpersonal coordination involves dimensional compression and reciprocal compensation . they had participants oscillate a hand - held pendulum ( kugler and turvey , 1987 ) in each hand ( intrapersonal coordination ) at a metronome - specified frequency to produce relative phase patterns corresponding to in - phase (     0 ) or anti - phase (     180 ) , and had two participants , each holding a pendulum in one hand ( interpersonal coordination ) , produce the same patterns . black et al . ( 2007 ) treated  as the performance variable ( with desired values of 0 or 180 for in - phase and anti - phase , respectively ) , and the position and velocity of each hand as component  df . those variables determine each hand 's phase angle  the point of the oscillating hand in its ever - repeating movement cycle  and  is the difference between the two hands phase angles . the ucm analysis thus quantified how variation in the position and velocity of each hand was structured ( or not ) to preserve the goal  value . in all cases the ratio of compensated to uncompensated variance was > 1 , indicating the presence of synergies for intrapersonal and interpersonal coordination . dimensional compression occurred because a lower dimensional variable ,  , was selectively stabilized via reciprocal compensation among the components . ratios were higher for intrapersonal ( mean  =  2.71 ) than interpersonal ( mean  =  1.995 ) coordination , paralleling findings of greater coupling strength for intrapersonal coordination ( schmidt et al . , 1998 ; the similitude between interpersonal and intrapersonal coordination was further reinforced because other manipulations , such as whether subjects were instructed to produce in - phase or anti - phase movement patterns , produced the same effects for interpersonal as for intrapersonal coordination [ ratio was higher for in - phase ( intrapersonal : 3.78 ; interpersonal : 2.31 ) than antiphase ( intrapersonal : 1.64 ; interpersonal : 1.68 ) ] . it could be argued that the existence of stable relative phase modes already provided evidence for synergies in interpersonal rhythmic coordination , at least insofar as this evidences dimensional compression . however , an observed stable value of  is mute regarding whether  is selectively stabilized through synergistic compensations . no specific value of  identifies the existence of a synergy , and neither a change in the mean nor the standard deviation of  indicates a change in synergy strength . the black et al . ( 2007 ) results provide direct evidence for interpersonal synergies . they were weaker than intrapersonal synergies , but nonetheless exhibited reciprocal compensation and dimensional compression . the findings suggest synergies are not hard - wired features of an actor 's neuromuscular system , but instead they are emergent properties of perception  action systems that are linked together informationally ( in the case of interpersonal coordination , the informational linkage was visual ) . the evidence reviewed here is consistent with claims that movement system df residing in different actors are coupled to form low - dimensional , reciprocally compensating synergies . this may be controversial , because interpersonal synergies span organisms and extend beyond boundaries of skin , with the coupling among movement system df achieved ( in these studies ) visually . might reside beyond the boundaries of an organism , or more specifically beyond a particular , singular component of an individual 's brain . the control evident during interpersonal coordination may be an emergent property of a social perception , 2008a , 2010 ; schmidt and richardson , 2008 ; marsh et al . , 2009 ; shockley et al . , 2009 ) . a key point to consider with regard to situating this approach scientifically and philosophically this echoes the distinction between interaction - dominant dynamics and component - dominant dynamics described by van orden et al . component - dominant dynamics is assumed by classical cognitivism , with its emphasis on static modules that perform their functions in relative isolation of the activity of other modules . interaction - dominant dynamics emphasizes interactions between components rather than their structure , entailing a functional , dynamical approach to understanding coordinated action . instead of focusing on component structures , this question raises another key point : the interpersonal synergy approach , with its roots in self - organizing complex systems , entails notions of  mechanism  and  causality  that are broader than the usual ( newtonian ) sense of the terms as involving only efficient causes , the kinds of forceful interactions produced by colliding cogs or billiard balls ( rosen , 1991 ; juarrero , 1999 ; van orden et al . , 2005 ) . complex systems exhibit circular causality ; bottom - up processes give rise to macroscopic patterns that simultaneously constrain the components from the top down . constraints play the role of causal mechanisms in complex systems insomuch as constraints allow or deny certain states . constraints limit the df of a system , but do not cause the system to take on particular states by virtue of forceful  pushes  ( local , efficient causes ) . control ( manipulation of the movement system ) first entails coordination ( organization of the movement system ) , as anticipated by bernstein ( 1967 ) . control parameters are constraints that guide the movement system through sequences of stable states ( identified by values of order parameters ) . in rhythmic movement coordination ,  is the order parameter and movement frequency is a control parameter that , when varied , results in transitions between coordination patterns . movement frequency has been identified as a control parameter for interpersonal rhythmic coordination ( schmidt et al . , 1990 ) , but the identification of control parameters for other interpersonal synergies remains an important avenue for future research . possibilities include attention to movement information ( richardson et al . , 2007 ; schmidt et al . , 2007 ) , individual or social intentions or goals , perceived social differences , or rapport and liking ( e.g. , chartrand and bargh , 1999 ; hove and risen , 2009 ; marsh et al . , 2009 ; miles et al . , 2010 ) , to name a few . the alternative hypothesis to interpersonal synergies is that coordination observed between agents results because they execute similar but independent motor programs anchored in shared representations neurons in the pre - motor cortex that are activated when observing others performing actions  suggest a common neural basis for motor control and action understanding . watching someone engage in an action is hypothesized to activate the actor 's own motor representation of that action , resulting in a shared motor representations . it is claimed that shared representations facilitate understanding others actions ( e.g. , blakemore and decety , 2001 ; richardson and dale , 2005 ; sebanz et al . , 2006 ) , which may explain why motor coordination occurs spontaneously in social contexts . this would not predict the synergistic nature of interpersonal coordination that we have described , however . although this approach might predict dimensional compression ( pca would be sensitive to any correlations between the two actors movements ) , it would not predict reciprocal compensation . reciprocal compensation means that the actors movements are not independent , directly contradicting this hypothesis . interpersonal coordination is a fundamental means of forming social units ( marsh et al . , 2009 ) . , 1996 ; chartrand and bargh , 1999 ; hove and risen , 2009 ; marsh et al . , 2009 ) . being psychologically distanced from another individual can inhibit the emergence of interpersonal synergies ( miles et al . , 2010 ) . interpersonal synergies facilitate memory for those with whom we interact ( miles et al . , 2010 ) and can more generally facilitate performance of social cognitive or linguistic tasks ( richardson and dale , 2005 ; shockley et al . , 2009 ) . synergies might also be a mechanism for interpersonal coordination in team sports ( e.g. , passos et al . , 2009 ) . for example , highly effective teams might exhibit a greater degree of reciprocal compensation than poorly effective ones . developing a detailed understanding of interpersonal synergies may have broad and significant implications for understanding social perception the interpersonal synergy hypothesis can be subjected to additional tests , using a range of paradigms and complementary methods such as the ucm analysis and pca . if the hypothesis is supported movement science will be charged with the important task of broadening its conceptions of fundamental processes of coordination and control , and areas such as social psychology or sports psychology might benefit from the development of new tools and paradigms . the authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest .