Moving together in time with others (social entrainment) has been shown to increase co-operation  between entrainers, but its effects don’t end there. A wide variety of ‘affiliative effects’ have been reported to be produced by entraining with others.

Social Entrainment has been reported to Increase co-operation, helping behaviour and trust between people, even when interpersonal elements are removed and even if such co-operation comes at a personal sacrifice. It fosters emotional connection, compassion, rapport, empathy and feelings of similarity to those we entrain with (and conversely the more rapport you already have with someone the more you will synchronise with them).

Moving in time with others improves our ability to engage in joint action, increases our attention to co-actors and facilitates better memories for them. It has also been shown to diminish the self-other memory advantage and there is evidence that it may form an agentic (we) identity in entrainers.

It can also Increase pain and fatigue thresholds and foster compliance to aggressive requests and obedience to questionable orders.
Those with a pro-social Social Value Orientation co-ordinate their movements with others to a greater extent, as do those primed with pro-social as opposed to pro-self goals. More movement co-ordination with people is also seen when co-actors are of a different minimal group as opposed to the same minimal group (but only if groups are based on meaningful preferences).

Synchrony combined with shared intentionality fosters more co-operation than just synchrony alone. Synchrony can foster co-operation and helping even in very young children  and young children can sync to a beat outside of their normal range if its presented in a social context.

But you don’t even have to get involved in co-ordinated movement to see the effects of entrainment. People rate others higher in  rapport and entiativity if they are seen moving in sync compared to async and these effects are larger if the individuals being observed are believed to have synchronised of their own accord.  Finally despite actual levels of co-ordinated movement, same race dyads are judged as making more co-ordinated movements than mixed dyads.


Seeing a small congregation of  50 or so birds flying together in time as a flock can be a pretty spectacular sight,  in fact just watching a group of  3 or 4 synchronously  soaring through the skies, each individual consistently changing its place in the formation all the while keeping the same basic formation is a fascinating sight.

A 1.5 billon strong flock  (which would take over 5 hours to fly overhead) of red billed quelea flying in formation just seems incomphrendable. Flocking truly is spectacular, even today watching these masses navigate through the skies in unison, moving so well as a whole,  so perfectly that they can look like a single colossal beast flying through the skies,  its hard to imagine how this would have been perceived by our prehistoric relatives.

So how do birds manage to fly in such fascinating formations without a leader, without a flight plan without any shared information being communicated, all the while moving in unity, avoiding obstacles, heading in one direction.

The answer was discovered in the 1980’s with the aid of computer simulations,  the secret lies in 3 or 4 simple rules that each individual follows with reference only to its local (direct) neighbours, “Boids” 3(or 4) laws.

In order of importance “Boids” laws are.

Collision avoidance – avoid collision with nearby flock mates

Velocity matching – attempt to match velocity with nearby flock mates

Flock centering –  attempt to stay in the centre of nearby flock mates.

And a 4th that has since been suggested

avoidance – move out of the way of predators / obstacles.

The following  simulation shows how realistic flocking behaviour (minus the aerodynamics and physics of flight) can emerge from “Boids” rules.  How these complex behaviour can emerge without any leader or information sharing, by multiple individuals each separately following a few simple rules.

But why do birds flock?
The answer is no ones sure yet,  but flocking would seem to have multiple advantages over solo flight, such as predators perceiving the flock as a single large organism or finding it hard to target individuals in the flock, or for aiding individuals  in the flock’s ability catch there own prey through cooperative hunting.

This kind of emergent synchronous group behaviour isn’t just seen in the skies though, it can be seen all around us, birds flock, fish school and mammals herd.

And “Boids” laws does a pretty good job of explaining all of this behaviour.

At least we have more individual control of our own movements,

complex crowd behaviour cant be realistically modelled using simple rules,


Although I’m not going to pretend I understand biology or physics well enough to write a detailed or wholly accurate blog on this subject, it’s so fascinating that I couldn’t not mention what I’ve learned from Steven Strogatz’s book ‘Sync’, (which does a fantastic job of making this quite a tough and, at times, a dense subject not only followable but thoroughly enjoyable).

So what do inanimate objects, quantum particles, electricity, the planets, our own heart and brain cells have to do with synchrony? Well synchrony is present throughout the universe or as Strogats puts it “At the heart of the universe is a steady, insistent beat: the sound of cycles in sync …. The tendency to synchronise is one of the most pervasive drives in the universe, extending from atoms to animals from people to planets”.

Time for a few examples … … …

Our bodies display synchrony within themselves and with the outside world. It is well known that our pace maker cells fire synchronously to a rhythm, and that a disruption in the time keeping between these cells can cause a whole host of cardiovascular problems. But each and every  organ is composed of  distinct cellular oscillations, with chemical and electrical rhythms moving in lockstep, every organ period matching with each other to the 24 hour cycle on which most of us spend our lives. Our bodies are entrained to this 24 hour cycle, sleeping at given times and awaking at others. All throughout the day our bodies go through periodic cycles of awake and alertness, sleep and drowsiness driven by the time keeping of the sun and the peaks and troughs of our internal temperatures. It seems that even when we are deep in sleep, our bodies don’t stop synchronising.

But synchrony isn’t just apparent in the living world; it is present in inanimate object too. Without synchrony we wouldn’t have CD players, barcode scanners or laser surgery. The way masses of atoms can multiply and form into a single laser beam is through their ability to synchronously emit light waves of the same phase and colour. In fact it seems there’s as many examples of entrainment in inanimate objects as there are in the living realm. As it happens, without synchrony we wouldn’t even have the power grids that pump electricity to all of our homes since a necessary condition of a functioning power grid is that the generators remain synchronous, and when they desynchronize, the power goes out.

Entrainment exists outside of our own little part of the universe too, in the way two planets orbit round their stars in step, so that as one orbits exactly once, the other has orbited exactly twice.  Or the way our moon turns own its own axis at precisely the same rate it orbits earth.  Strogatz even proposes that this kind of astronomical synchrony may even explain how we acquired our life giving oceans and maybe even extinction of the dinosaurs

But to learn how, you’ll just have to read his book

Just why is it that soldiers still spend so much of their time training engaging  in synchronised  drill when modern warfare no longer favours tactics involving units moving in perfect formation? This is one of the question historian William McNeil addressed in his 1995 book “Keeping Together in Time” but their were very few scientific studies documenting the effects of moving together in time then. So what did McNeil advocate was the purpose of formation drill and  how does the psychological evidence available today sit with these ideas.

European Armies have been engaging in muscular bonding (making matched movements in unison) since the time of Maurice the Orange  (1500’s) and has likely been present for thousands of years previously.  One can easily imagine how having an army practised in moving together as one entity would have been a direct advantage in an old fashioned battle. Not only would they be more practised at working as a whole, but they would likely appear as a force to be reckoned with. As highlighted in south park when Eric Cartman begins to fear the military power of the Chinese after seeing their mass synchronised drumming displays. Research has shown that seeing groups act in sync, leads us to see them as more of a unified group, with shared goals and a heightened ability to act together. Witnessing an enemy army marching towards you in perfect unison is surely a more terrifying experience then an approaching bunch of seemingly disparate and disorganised individuals.

But 21st century war hasn’t isnt waged by 2 armies meeting in the middle of a field in a battle of strength and numbers and it hasn’t been for some time now, its fought with technology, machinery, and tactics. So why is it many armies still spend much of their time engaging in synchronised drill.

In his book McNeil recalls his own drill experience and how it invoked “a sense of pervasive well being  … [and} …  personal enlargement” it is for these reasons he suggest some soldiers still spend up to 40% of their time in training engaging in synchronised drill. To develop group cohesion, to knit the soldiers together helping them not only work better as a unit but also to experience less personal fear. There is certainly some evidence for this, research has found increased group cohesion between people after engaging in synchrony and that making synchronised movements with people can facilitate their ability to perform unrelated joint action.

McNeil highlighted how engaging in drill may make one feel larger then themselves, a real part of a real group, becoming part of something larger than oneself that will live on after ones own death, therefore feeling less angst or fear of personal injury or death as ones spirit lives on with your comrades in arm.

While no research to date has directly addressed this claim, research has shown  that engaging in synchrony makes people feel more entitative (part of a unified group) and that engaging in synchronised exercise with people may have the psychological effect of reducing susceptibility to fatigue and pain.

Despite it no longer being a direct advantage armies still spend significant amounts of training performing muscular bonding, the mere fact this still occurs means it must be serving some purpose. There is clearly some indirect support from the social entrainment literature for McNeil’s ideas, but it has also shed light on some other possible functions of entrainment that ensure it is still employed as a crucial part of military training

The recent surge in the study of synchrony’s social effects are starting to show that the effects of drill may not just serve to tighten the relations and bond between those engaging in it, but may serve a whole host of effects beneficial in military situations. But the most relevant and the most shocking social entrainment findings of the past 20 years has to be that after engaging in synchrony with someone we are more likely to comply with aggressive requests or obey destructive orders. Its not hard to imagine how these findings relate to why some armies still spend significant amounts of time marching round the drill field in unison when this skill would be of no direct practical use in today’s machinery and technology dominated battlefields.

Flasing Fireflies

Posted: July 23, 2013 in Introduction

Synchronous displays of male fireflies found in southeast Asia (as well as parts of America and Africa) have proved an awe inspiring phenomenon to observe for hundreds of years. Great masses of fireflies stretching out for miles all flashing light in perfect unison.

Until recently no one was able to explain how such vast numbers of these tiny insects were able to coordinate their displays in perfect synchrony without a conductor of any sort. In fact some prominent scientists of the early 1900’s insisted such a thing was ‘contrary to all laws of nature’, numerous articles were published in academic journals dismissing the phenomenon as nothing more than coincidence or illusion.

Until around 50 years ago when the pieces were put together by biologist John Buck who through observations and experiments showed that these fireflies not only flash in unison with each other but they do so to a constant tempo (of about 1 flash per second). Each insect is flashing to a beat using some form of internal clock and does so even when isolated. But when they congregate in groups these disparate underlining rhythms get pulled in to tune with those of its neighbours, each insects internal metronome is reset, rewound or advanced depending on where in its cycle it is when it observes another’s flash.

As this computer simulation shows, in the beginning each individual flashes along happily at its own pace, but as individuals perceive g the flashes of others , its own cycle is reset in time with it, either advanced or delayed, as time goes on, with vast numbers of rhythms all tugging on and being tugged by each other, slowly,  pockets of synchrony start to emerge, order from chaos, until eventually almost all individuals are lighting up in perfect time.


Its believed that they do this as a selective adaption to aid mating (makes males more visible to females, makes small groups appear larger and makes the females easier to spot in-between the flashes by reducing noise)

I’m a PhD student in the psychology department at Leeds Metropolitan University. My research involves looking at the effects that moving in time with other people can have on our social lives and how it is that this coordinated movement fosters these social effects. What is it about synchronous movements that can facilitate changes in our social behaviour?

That might not sound very interesting or relevant to anyone who isn’t spending the next 3 years getting people to move in unison and measuring what happens next, but you may be surprised to know just how much the answer to these questions could already be playing a part in all of our lives.

Synchrony is present, in some form or other, throughout the universe and probably always has been. From the less observable pulls of the planets that keeps things just as we like them and the firings of our pacemaker cells, to the more observable firefly flashing, bird flocking and fish schooling. Just how is it that fireflies synchronise their light displays without any centralised control; how do birds navigate the skies in unison changing direction, avoiding obstacles all the while moving in such organised formations without a leader or chorographer?

Synchrony has long amazed and intrigued us. We now know that fireflies synchronise their flashes utilising internal clocks whose rhythms are pulled in accordance with their local neighbours. Boids 3(or 4) laws govern flock behaviour whereby each individual bird follows 3(or 4) simple rules with reference to only its direct neighbours: steer so as to avoid collision with neighbours, steer towards the general direction of those neighbours and move towards the centre of those neighbours (and get out of the path of obstacles / predators).

But what does any of this have to do with psychology? How does any of this directly affect our day-to-day lives?

It’s quite well known that seeing masses of Nazi soldiers goose stepping in perfect unison can stir quite a chilling effect in some people , but after just watching stick figures or strangers walk or wave in synchrony, people have rated them as more similar, higher in rapport and entitivaity (seeing them as a unified group) and this synchrony information may be more important for this than other perceptual information such as size or colour.

As it turns out synchrony isn’t just spectacular to observe, actually engaging in synchrony may have some pretty spectacular effects on us too.

A plethora of research has now shown that after moving in time with others, we may see each other as more likeable and more similar, we may improve our performance in unrelated joint action (e.g., 2 player labyrinths games, moving large objects). People may even move to cooperative strategies earlier after synchronising, but probably the most well known effect is that people could become more cooperative with each other (even if such co-operation comes at a real financial cost). Synchronising with other people while exercising could even help reduce pain and fatigue.

But it’s not all good news; synchrony also has a dark side. It has been shown that more people may comply with an aggressive request to crush bugs or expose a 3rd party to a noise blast after moving in time with the requester.

Synchrony has an array of social effects that could help explain well-known phenomenon such as why armies marching together in time may commit atrocities, why individuals can lose their sense of individuality identity and responsibility in mobs, and why people report feelings of elated joy and togetherness after raves and rock concerts.

But why?

Why does moving in synchrony with someone else seem to facilitate such a vast array of effects? And what is it about making these coordinated rhythmic movements that underpins these effects?    The answer is, no one knows yet.

Some people think that it diffuses the barrier between self and other, that it causes a shift from a salient individual identity to a salient group identity, that it strengthens group cohesion. Some people think that the same capacities supporting synchronisation also support joint action, that it engages the MNS which facilitates feelings of empathy for those we move in time with.

It has been suggested that synchronous displays were an evolutionary precursor to language, allowing us to model our strength, coordination and shared goals as a group before we could use language to verbalise these. Synchronisation  in turn led to a strengthening of affiliation to the group and the effects we see today are an evolutionary throw back from this.

But no one really knows yet, why synchrony has the wide array of social effects it seems to have.

Synchrony occurs every day of our lives, whether it’s the internal coupled oscillations of our own cells, the matching of breathing paces with interlocutors, or the synchronising of menstrual cycles of women living in close quarters.  All of this happens often without us ever being aware of it and normally without us asserting any conscious control over it.

It’s most commonly observed in the way people’s strides can synchronise when walking side by side. This might sound some small feat. But, if you stop to think about it, each person has their own preferred rhythm, speed, pace, stride length etc., which could be affected by any number of things such as limb length, agility, fitness  even the weather and their clothing.  It’s pretty amazing that two people can, and often do, start to walk together in perfect synchrony. Without either of them ever planning, discussing or even noticing it, it just happens, with no conscious control from either party or any other agent.

This entrainment is more likely to occur between people you share some bond or connection with and, what’s more, it seems this synchronised walking may have a number of effects on us from making us feel more similar, building rapport, even facilitating joint action and  co-operation, perhaps even allowing us to become more likely to trample insects at each other’s bequests.

It is clear that we, like much else in our universe, have a fundamental pull to synchronise in some fashion or another. What’s not clear is how and where synchrony is pulling us?

That is exactly what this blog will be about. The social effects of moving in time with other people, what they are, and how/why they occur. There will be pages detailing the research findings related to social entrainment and its effects, the explanations of why these effects are fostered, summaries of the key publications, an introduction to my own research, and other interesting things about synchrony in nature – plus some cool videos.