New scientific approaches often rise with the availability of new methods, and can stall when those methods do not evolve further. New methods can be particularly influential if they allow a wide range of application without demanding a lot of resources. In the hands of creative graduate students, such methods can quickly turn into productive tools. The field of embodiment, the topic of this special issue, is no difference. In this text, I trace one development that has contributed a lot to the current state of the field: manipulating the body to influence thought. I then outline another one that may take it beyond its current level: measuring how thought influences the body.

Embodiment

Embodiment refers to an idea that has excited many psychologists in the past years. The idea of embodiment is that the way our mind works is deeply rooted in the way our body works. In particular, one of the ideas discussed by researchers in this field is that the ideas we hold about the world – our mental toolbox to understand the world, to categorize it, and to provide it with labels – is based on the way our body interacts with the environment. What do they mean by that?

For some concepts, this is obvious. Take colours as an example. Our colour concepts develop from the interaction of the cones in our retina with light of different wave lengths entering the eye. The three different types of cones respond to three different wave lengths. From these differences, our brain and mind construct the colours red, blue, green, and every other colour. These colours do not actually exist in the world – light consists only of different wave lengths. Colours are entirely the product of how our retina and brain interact with the world. If we had different cones, or a different number of cones, we would see different colours. So, here our brain creates embodied concepts in the first place. It is fun thinking about the consequences (the Radiolab Podcast has a great discussion of this [http://www.radiolab.org/2012/may/21/]).

In other areas the embodiment claim idea is more controversial. For instance, when we judge the importance of a book, we are supposed not to judge it by its cover, but to ponder the knowledge that is written down in it, the beauty of its language, and to compare its wisdom and impact to those of other books. Importance sure sounds abstract and intangible – it is a different kind of concept than colour, right? However, that does not seem to be the way our mind works.

Instead, the embodiment approach argues, even seemingly abstract concepts like importance are rooted in bodily experience. The reason is that in order to understand abstract concepts, we connect them to more concrete experiences. We ground cognition in the body (Barsalou, 2008; Lakoff & Johnson, 1980). Often, metaphors give away the groundings we construct. For importance, one of the crucial sensory dimensions seems to be weight. Embodiment researchers love to scour metaphors to track down those sensory dimensions, and indeed it is easy to find metaphors that connect importance to weigh.

Manipulating the body and measuring thought

But how can psychological research test such ideas in experiments? The main path that has been taken in the last years is to conduct experiments in which the sensory dimension of interest is manipulated in a subtle way. I call this the manipulate-the-body strategy. To show the embodiment of importance, this was done by changing the weight of an object that the participants of these studies held in their hands. For instance, participants filled in a questionnaire holding either a light or a heavy clipboard (Ackerman, Nocera, & Bargh, 2010; Jostmann, Lakens, & Schubert, 2009; Maglio & Trope, 2012). Or, participants held a book that was either light, or made heavier with a concealed weight (Chandler, Reinhard, & Schwarz, 2012). Participants had to perform judgments that involved importance – for instance judging the importance of the book – while holding these objects. And voilà, those who held the heavier object assigned on average more importance than those who held the lighter object. (Note: There is an ongoing and healthy debate about whether this effect is robust. Consult the webpage of Daniël Lakens [https://sites.google.com/site/lakens2/publications] for a list of replication attempts.)

The manipulate-the-body strategy has been used in many studies that investigated the embodiment approach. Let us look at three examples.

Approach and avoidance are embodied in arm movements: We avoid coming close to things we do not like, and we approach things we like. Often we do this by extending our arm to push something away, or flexing our arm to pull something towards us. The idea of valence is thus grounded in approach and avoidance movements. The manipulating-the-body strategy has been applied to study this. For instance, in experiments, participants are instructed to push against a bar, or to pull it towards them. Extending an arm leads to less favourable ratings of objects encountered at the same time than flexing an arm (Cacioppo, Priester, & Berntson, 1993).

Number size is embodied on a spatial dimension from left to right: Because we write from left to right, we come to associate “become more” or “later” or “larger”, and also “impact” and “agency” with the movement towards the right. Among people who learn to write from right to left (e.g., Hebrew, Arabic, Urdu), this is reversed! Again, the manipulate-the-body strategy works: When participants from left-to-right cultures are induced to lean to the right, they estimate buildings to be larger than when they are induced to lean to the left (Eerland, Guadalupe, & Zwaan, 2011).

Power is embodied in certain postures and gestures: When participants are put into a typical “power pose” (think Superman), or to make a gesture associated with winning (e.g. raising a fist), they feel more powerful (Carney, Cuddy, & Yap, 2010; Schubert & Koole, 2009). (Watch the TED talk by Amy Cuddy [http://on.ted.com/Cuddy] for more details.).

Experiments of this style are often easy to conduct – they require single participant experimentation, but no complicated equipment or measures (the study from Eerland et al., 2011 cited above is an exception, it used a Wii balance board to trick participants into leaning to the side). Indeed, the simplicity of combining an embodied manipulation with a questionnaire is part of the charm of these experiments. Consequently, many more such studies exist (see Barsalou, 2008; Glenberg, 2010; Landau, Meier, & Keefer, 2010; Landau, Robinson, & Meier, 2013).

Despite their elegance, these studies also have a problem: They tend to be open for alternative explanations. In particular, even when experimenters make the manipulation unobtrusive, it might happen that the participants spontaneously and consciously judge the sensations they experience, such as “wow, this book is really heavy”. The experimenters typically debrief carefully to check for such spontaneous judgments, but it is possible that we sometimes miss them. It might not sound like a big deal, but if participants do explicitly think about the manipulated sensation, this creates a problem for the interpretation of the studies. The problem is that they can then be explained by other processes than embodied concepts – for instance by judgments based on general knowledge about the world. As a result, the embodiment research has a problem: It has an easy way to come up with elegant studies, but their interpretation is sometimes difficult.

Manipulating thought and measuring the body

What can be done about this? It seems that one way out of this dilemma is to reverse the experiments. Instead of manipulating the body and measuring thought, researchers could manipulate what participants are thinking and feeling, and measure their bodily behaviour. If the mind is truly embodied, the effects should go both ways: Thinking and feeling should influence the body, even if no specific behavioural intention is executed.

Indeed that is what some researchers have been doing. Several properties of the living, breathing, moving human body have been measured in such studies.

Think back to the studies showing that inducing approach to objects results in liking them more. The obvious reversal would be to test whether we indeed spontaneously and quite unconsciously approach positive objects and avoid negative ones, even if we do not have to actually move around. Eerland and colleagues tested this by asking their participants to stand on a WII balance board – a component of the computer game platform that measures where you place your centre of gravity. Participants viewed strongly positive and negative pictures on a computer screen while standing on this platform. In the first second of just viewing, participants indeed swayed slightly forward towards positive pictures, but did not move much when seeing negative pictures (Eerland, Guadalupe, Franken, & Zwaan, 2012). Watch out how you sway the next time you see something (or somebody) really attractive.

Experimenters have also observed how our bodies react to words. For instance, Suzanne Oosterwijk and colleagues asked the participants in their study to generate words related to disappointment or pride (and also neutral words) (Oosterwijk, Rotteveel, Fischer, & Hess, 2009). Unbeknown to the participants, the researchers tracked their head postures. Participants wore head phones that were marked with a yellow patch, and they were filmed by a hidden camera. The researchers later painstakingly analysed the clips frame by frame tracking the position of the yellow patch. They found that while participants generated words of disappointment, their heads literally sank into despair, while they staid levelled and even initially rose a little when generating words of pride.

In a similar study, participants were asked to think about what their life had been like four years earlier, or to think about what their life would be like in four years (Miles, Nind, & Macrae, 2010). They were doing that while standing upright, blindfolded to facilitate vivid imagery, and with a motion tracking sensor attached to their leg above the knee. When thinking about the past, participants slightly leaned backward, but when thinking about the future, they slightly leaned forward. Presumably, the way we think about time is not completely abstract – we mentally represent it on a path through space, with the past behind us and the future in front. When we mentally travel in time, we physically try to move there as well.

In these three studies, participants had no real reason to move their bodies, but they did, and this movement was tracked by the researchers. In another type of experiments, participants get an instruction to move in a specific way, and it is studied how quickly and accurately they can do that. The trick is here that the correct movements are made easy or hard by other ideas that again come from embodied representations.

Here is an example experiment following this strategy (Zwaan & Taylor, 2006): Participants were presented with complete sentences and asked to judge whether these  made sense (some did not). In order to indicate their judgment, participants had to turn a rotating knob either to the left in one condition or to the right in another condition. Some sentences implied movement, for instance “He turned down the volume”, typically a counter-clockwise movement on many devices. By now you will probably guess what happened: Judging the correctness of this sentence was easier (and thus faster) when having to perform a counter-clockwise movement to do so, and the opposite occured for sentences implying clockwise movements. (This type of experiment has a long tradition, going back to the 90s, when Solarz (1960) built a system with mechanical levers participants had to push and pull.)

These were all examples involving movements, but measuring the body does not end there. Psychologists have studied various physiological processes for a long time: changes in heartbeat, breathing, sweating, hormonal changes, and movements of facial muscles, such as smiling and frowning (see Blascovich, 2014, for an overview). For instance, it is known that the temperature of the body and fingers change in certain patterns when emotions are experienced (Ekman, Levenson, & Friesen, 1983). Similarly, IJzerman and colleagues (2012) have recently found that when a person is excluded socially from a group, their finger temperature drops somewhat. They used a very precise industrial thermometer hooked up to a computer to measure finger temperature. Following an embodiment reasoning, the idea is that such physiological processes feed back into our feeling and thinking.

How to measure the body, or tinkering in the name of Psychology

It is noteworthy that all these efforts involve technology of some kind. Some of the examples use general recording technology combined with a lot of laborious coding. Other experiments creatively adapt consumer hardware such as joysticks, WII balance boards or keyboards for their purposes, often adding special computer programs. Still others use expensive and specialized technology, such as expensive professional motion trackers.

There is a long tradition of psychologists tinkering with technology to measure behaviour. It actually goes back all the way to the founding fathers of modern psychology, such as Galton, Wundt, Helmholtz, and others, who all built wondrous devices to measure behaviour, including its speed (see Figure 1). Obviously, technology and tinkering with it is needed to come up with ways to fuel a new wave of embodiment research that measures the living body. What can that be?

It just so happens that this need for measurement technology coincides with a renaissance of tinkerers and makers in general. The availability of open source software and hardware that is cheap and flexible has led to an increase of people who dare to build hardware themselves, and program it themselves. In computer science departments and elsewhere, so-called maker spaces are opening, inviting people to experiment with building their own gadgets.

One cornerstone of this movement is a family of small microcontroller boards called Arduino – essentially tiny computers that have only the fraction of the power of a PC, but also cost only the fraction of a PC (see a TED video at [http://on.ted.com/Arduino], and find out more at their website [http://arduino.cc/]). These microcontroller boards can be hooked up to a PC, and become themselves the hub for a range of sensors. For instance, you can get sensors that measure acceleration, position in space, temperature, or distance to the nearest object, typically for just a few euros. It is easily conceivable that all kinds of measurement instruments for embodiment studies can be built with this hardware, measuring movements and positions of body parts, or skin temperature, to name just a few.

Of course, this will not reach the precision of professional hardware. However, what may be more important than excellent precision is that a community has sprung up around these Arduino boards and hardware in general, where know-how and computer code is shared openly. Measuring the body becomes affordable and workable.

In our own lab, we are already using Arduino hardware to build up experimental devices. Here are three examples: We started by hooking up an Arduino to a computer, connecting it to two buttons, and programming the Arduino in such a way that it could interface with one of the standard software packages used by psychologists. We tested the performance, and results were excellent: Our device was able to measure reaction time as well as professional hardware, with millisecond precision (to learn more, read Schubert, D’Ausilio, & Canto, 2013). We also tested whether an Arduino combined with a device measuring its own angle, a gyroscope, can replace the laborious frame-by-frame coding of head movements by tracking movements, and this works as well (see a short description and videos on our blog). Finally, we were also able to hook up a temperature sensor, giving us a cheap way to measure finger temperature. We also realized that we could not only connect sensors, but also components that do something – lights, small vibrators to apply tactile stimulation to the body, and more. With this interface in place, all the building blocks are there so that experimental psychologists curious enough to measure bodily behaviour can start experimenting.

Conclusion

One implication of the embodiment approach, the topic of this special issue, is that even when we think about abstract concepts, we use representations arising from bodily experiences. Many experiments supporting this idea have been manipulating the body and showing effects on thought. Such experiments are easy to do and often impressive, but they have some weaknesses. Researchers will of course not stop conducting such studies and neither should they – often they provide excellent illustrations of a particular embodiment. However, the reverse experimental direction, namely manipulating thinking and measuring the body, will probably become crucial in future research.

What researchers need are measurement tools. I encourage experimental psychologists to start tinkering with open source hardware, and connect to the maker movement. It is a lot of fun. And I hope the makers and hackers out there who are interested in psychology will welcome them with open arms.

Embodiment research started with a fascinating idea. Its theoretical development has now somewhat stalled. Sometimes, technology does not just follow theoretical developments and needs, but drives it. Maybe this is one of those times.

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Author Note

I thank Janis Zickfeld for help with this manuscript.