Human (and robot) touch has health benefits

Of all our senses, perhaps the least well understood is touch. The importance of which became apparent when many of us were no longer able to hug or be hugged by loved ones during the pandemic. Now, a growing body of scientific evidence suggests that regular, physical contact with other people can confer a whole raft of health benefits: from reducing physical pain and stress, to feelings of depression and anxiety.

This led Julian Packhesier from The Ruhr University Bochum and colleagues to conduct a meta-analysis of research from this flourishing field. They sought to describe the factors most responsible for the effectiveness of touch. James Tytko started by discussing how at no stage of our lives is this dependence on touch more keenly felt than when we are first born…

Julian - We do not have fully developed senses, for example, for vision when we are born and the vision is very blurry. So the way that the word is interacted with is often through touch. What is the first thing we experience after we are born? We are being cradled usually in our mother's arms, and that is something that is a crucial experience for our bonding to our parents and this continues throughout our whole lifespan, essentially. We make emotional bonds and we deepen them through touch and we sometimes forget how important it is. When you think about, 'Which sense do I not want to lose?' most people would say, of course, I never want to lose my eyesight. But if you couldn't sense anything anymore through your skin, that would be extremely detrimental for our wellbeing and it would even be hard to conceive.

James - That's a good way of putting it. I suppose it's the most intuitive way we can communicate.

Julian - Exactly. After we have learned how to communicate through language, of course, it becomes less critical to also communicate intentions through touch. But communicating emotions through touch, that is something we keep throughout our lifetime. Our intimate relationships are usually critically built on exchanging touch both to deepen affection but also to just express how you feel, right?

James - So we're talking now here in terms of the health benefits of a life filled with plenty of touch. Let's talk about another one, I'm thinking mainly of the way it helps us manage stress. I wonder if you could unpick the mechanism by which touch helps us deal with that particular affliction.

Julian - So the mechanisms are still under investigation, but what we know for sure is that touch releases the hormone oxytocin. Oxytocin is quite well known as a hormone. Many people have deemed it the so-called 'love' hormone. Of course this is a simplification. Oxytocin has a wide variety of functions and the functions are not yet completely understood. But what we do know is that intimate and affectionate touch releases this hormone and if this hormone is released in the body, it has both analgesic properties - so it can reduce pain - and it has the property of reducing anxiety and stress. The way it reduces stress, so the mechanism behind it, is that it actually blocks the building of the stress hormone cortisol in the body. This is how, on the hormonal level, we know that touch can ultimately reduce stress and can relieve pain through the release of this hormone.

James - One of the other things that your study pays particular attention to is the impact of who is doing the touching and whether that has an impact on these health benefits. What were your key findings there?

Julian - Yeah, the findings in that regard were particularly interesting to us because our intuitive understanding initially was, if it is someone who we feel more connected to, someone we know, that should probably increase the benefits of touch compared to someone where you just receive, for example, a massage at a professional physiotherapist or something like that. In adults, we actually found that it did not make a difference. So if you are seeking touch, obviously always with consent, the effects were on average the same. Why that is is still a little bit unclear to us. We thought of some potential mechanisms that could underlie it. It could be, for example, that someone who applies a professional massage, someone who really knows, 'Okay, this is the area I need to touch in order to make people feel better' if they are, for example, having pain in a certain region, they just have more expertise in doing it. But this can be then counteracted by people who you have more of an emotional bond with. So even if they do not know exactly how to touch in a professional sense, there the emotional bond might actually be enough to then even out the lack of expertise of that person doing the massage.

James - There's another factor at play here which I wonder if your results reflect that when it comes to not being touched, you don't suffer these poorer mental health outcomes or health outcomes because you don't have relationships necessarily whereby someone might touch you. You don't have the same connection with friends or loved ones. Is that another factor here kind of complicating the picture?

Julian - That could very well be right. So people who are seeking our professional massages because they do not have access to touch in their everyday life because they are not, for example, part of an intimate social network, yes, they might then have a stronger longing for touch even by someone whom they do not personally know and then that might actually make it also more effective. That's a perfectly reasonable answer to this mystery that we are still facing in our study. We can just say, this is what we found and now more research is actually needed to understand why that is the case.

James - And then you also took this one step further and asked, does it even matter whether it's a person that's touching us or not? Tell me about that.

Julian - Yeah, that was also something that we were really interested in, especially since this field of touch research has developed more recently also in the non-human domain. So many studies in the recent past have actually looked at novel social robots and also touch interactions which, for example, a body pillow, a weighted blanket, hugging devices that you can really embrace and that feel more natural, more human. We were really interested in it. Can we actually substitute human touch? And the results were also extremely surprising to us because our intuition before was probably that it would not reach the level of human touch but, actually, for physical health at least, when it came to reductions in stress hormones, reduction of pain and blood pressure, we actually found effects that were on par with that of human touch. Where robots and also these objects were not as effective was when it came to the improvement of mental health conditions: so feelings of anxiety and depression, negative mood. There, using something that substitutes human touch probably is not as advisable at the current moment.

James - Yeah, I'm not sure how to feel about that. The fact that they were able to confer the same physical health benefits but, is it just a matter of time as society becomes more comfortable with the prospect of having a relationship with a robot that perhaps will reach parity on those fronts? Fascinating finding nonetheless.

Julian - And we really want to understand why that is and there are reasonably good explanations, right? So one thing that is missing when you touch a robot is skin-to-skin contact. And our study has also shown that in humans, if the skin-to-skin contact is missing, the mental health benefit seems to be lacklustre. So something seems to be important to us to touch other people's skin, feel their warmth, feel their humanness in a sense. And another factor is that if you are engaging in touch with a social robot, even though they become more human-like as technology develops, if you do not have an emotional connection to these robots, they might still seem strange to you. Let's see how society develops in that regard, but that could also be a critical factor as to why mental health benefits in particular were not as improved if you used a non-human agent, essentially.