You are sitting in a laboratory watching a monkey and a row of peanuts. The monkey is specially wired for sounds that denote brain activity. Each time the monkey pinches a peanut, its brain crackles loudly. No surprise there. But then a lab assistant enters the room and removes a peanut. And a strange thing happens. The monkey’s brain crackles with activity although the monkey is doing nothing but watching. It looks as though watching an activity causes the same brain response as is caused by performing the act itself. Strange – but important.
Important, because that accidental experiment was a clue to a central characteristic of human nature. Scientists call it “theory of mind”. All that can actually pass between human beings are the signals carried by the five senses, yet we have no difficulty in recognising the other as a person, and attributing to that person his own mind with its own intentions. And triggered by different clues we are able to make a good guess about what is going on in his mind. Sometimes we do this out of experience and sometimes we do this by assuming that the other person has feelings and reactions similar to our own. The capacity is present in the first year of infant life and becomes more sophisticated with time.
We can see immediately that this faculty is essential to our identity as human beings. Aristotle styled us as social animals, and you cannot be social without communicating as persons. Nor can you participate in a culture, or learn from tradition. You cannot love your fellows as human persons, or find any meaning in altruistic morality.
Before the lab assistant set the monkey’s brain a-ticking, we knew that we were affected by the emotions of others. It was not just that we recognised, say, a smile as an expression of happiness, we found ourselves inclined to be happier. Our sympathy for someone being struck by a fast tennis ball was extended by wincing as if we ourselves were hit. If someone in our proximity screwed their face up in disgust, we immediately became wary and our expression changed even before we knew what was disgusting. And when the funeral procession went by we sadly looked at the sad mourners and, for a moment at least, participated in their sorrow. While facial expressions vary across cultures to some degree, they are for the most part recognised universally.
The monkey’s brain crackle suggested to Giacomo Rizzolatti at the University of Parma, over 20 years ago, that there was a group of specialist brain cells which recognised the feelings of others and reproduced them in the onlooker. So the idea of mirror neurons was born – and has been studied for the last two decades. In 2010 they were first directly recorded in action, where it appeared that, in addition to mirror neurons, brain regions involved in vision and action were activated.
In fact the mirror system is in two related parts of the brain, and it reacts under two conditions: when you perform an action and when you watch another performing an action. Even hearing the word “run” can trigger the appropriate brain response.
The idea is intriguing. All at once we have a plausible mechanism through which we know the feelings of others, not as just so much information, but as feelings we ourselves experience. Before we love our neighbour we first experience our neighbour by mirroring his feelings in the most intimate of exchanges. We are truly members one of another.
As you would expect, the scientists disagree about many details. At this early stage in our knowledge the only point of general agreement is that mirror neurons are an exceedingly important clue to understanding our human characteristics, and that we are no more than on the threshold of understanding: the most important work is yet to come.
So here I am, shamelessly cribbing from a summary report published in Perspectives on Psychological Science, in August last year. I only add that, having followed this issue over the last few years, the summary appears to reflect well the work which has been done.
Mirror neurons play a lesser part in interpreting speech than was once thought, and the idea that they were a route to learning speech seems unlikely. But they would play a part, say, in a noisy room where we need visual clues to help us understand.
They certainly help us to understand actions, but they are at their best with unfamiliar actions – such as watching the Tiger Woods golf swing. Familiar actions are no doubt interpreted through memory. One of the most powerful roles suggested is the ability, as I have noted, to understand not only actions but minds and intentions. Whether mirror neurons help solve the problem of autism – where a central symptom is a reduced understanding of others’ feelings – is as yet disputed. But a recent study suggests that the problems may be elsewhere in the neural system.
An interesting study, earlier this year, provides some evidence that our capacity to experience the feelings of others through our mirror responses is related to our degree of empathy. That is scarcely surprising since we know that the ability to see things through the eyes of others is at the heart of empathy. It is marvellous to me that God not only gave us the gift of brotherly love, he also gave us brains well fitted to the task.