Touch is fundamental to how we perceive our own bodies and connect with others. A gentle brush stroke on our body can feel soothing, while a pinch or cut can be painful. We often think of being touched as something we feel through our skin, but our eyes also play an important role in shaping what we experience.
One famous example is the rubber hand illusion. When people see a rubber hand being stroked while their own hidden hand is touched in the same way, they can start to feel as if the rubber hand is part of their body. This illusion shows how what we see can change what we feel.
But how does the brain actually do this? In our latest study, we measured brain activity to see how quickly the brain interprets what the eyes see when someone is touched.
We wanted to know how and when the brain works out whether the touch is pleasant or painful, threatening or safe, or whether it’s happening to our own body or someone else’s.
What happens in the brain when we see someone touched
We used electroencephalography (EEG) to record brain activity from the scalp with millisecond precision while participants watched hundreds of short videos showing different types of touch to a hand. These included soft strokes with a brush, presses with a finger, or sharp contact with a knife.
We then used machine learning to see whether patterns of activity in viewers’ brains could reveal what kind of touch they were seeing.
Within just 60 milliseconds of seeing a touch, the brain distinguished who and what was being touched. For example, it could tell whether the scene showed a hand from a first-person perspective (likely one’s own) or a third-person perspective (likely another’s), and whether it was a left or right hand.
By around 110 milliseconds, sensory information was being processed, such as how the touch might feel on the skin — soft and tingly from a brush stroke or sharp and painful from the tip of a knife.
A little later, around 260 milliseconds, the brain began to register emotional dimensions, such as whether the touch looked soothing, painful, or threatening. These findings show that, in just a fraction of a second, our brain transforms a simple image of touch into a rich sense of who is involved, what it might feel like, and whether it’s comforting or painful.
Why this matters for empathy and social connection
Our findings show that when we see someone being touched, our brains quickly interpret what that touch might feel like. This fits with the idea that the brain briefly “mirrors” what it sees in others, simulating their experience as if it were our own. This rapid, embodied response may form the basis of empathy, a process that helps us to recognize danger and connect socially.
Some people actually feel sensations such as tingling, pressure, or pain when they watch others being touched — a phenomenon known as “vicarious touch.” Understanding how the brain instantly decodes observed touch may help explain why seeing an image of injury or pain can make some people physically cringe while others remain unaffected.
Our next step is to explore how these rapid brain responses differ between people who experience vicarious touch and those who do not, which could help explain individual differences in empathy.
In the long run, understanding how the brain sees and interprets touch could help explain problems with empathy, improve therapies that use touch or body awareness, and enhance immersion and social connection in digital environments such as virtual reality.
It reminds us that even seeing touch can help us feel closer to others.
Sophie Smit, Postdoctoral Research Associate in Cognitive Neuroscience, University of Sydney, and Tijl Grootswagers, ARC DECRA Senior Research Fellow in Cognitive Neuroscience, Western Sydney University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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