I recently listened to an item on ‘All in the Mind’ about Mirror-Touch Synaesthesia a condition which highlights the impact of a particular form of neural mis-functioning on it’s impact on human experience and links neatly to a paper by Decety & Grèzes (2006) on the roots of imagination.
At the heart of this is a relatively simple but profound set of ideas: Whenever we watch someone else do something, or experience something, our brains imagine that happening to us. For the majority of people, our conscious self remains blissfully unaware of this act of imagination. By ‘imagine’ I mean that the part of the brain that is responsible for the experience being viewed activates as if the body were doing it but at a level lower than the threshold for conscious awareness. So, if we watch someone else carrying out an action (e.g. lifting an object) the relevant areas in our motor cortices activate. If someone else is being hurt then the centres responsible for the experience of that pain in our brains activate.
However, the majority of people are able to maintain a strong mental distinction between the self and others. According to the physicians on the programme, this separation is maintained by certain regions of the brain, particularly the anterior insula. Thus, what distinguishes people who suffer from mirror-touch synaesthesia is that their anterior insula does not function as well as ‘normal’ people, it doesn’t suppress the signally from other regions of the brain and therefore they genuinely feel the pain that they see other people experiencing. The paper by Decety & Grèzes suggest other regions of the brain that may play a role in this distinction. Imagine watching ‘Casualty’ whilst experiencing what was going on in the programme!
But the review by Decety & Grèzes puts this act of imagination (or simulation or rehearsal) at the heart of aspects of normal human interaction. So, learning begins because our brains are rehearsing what we see others do before we try to do it ourselves. We see other peoples’ expressions and therefore our brains rehearse those expressions. The link between the act of creating a facial expression and the feeling it expresses is 2-way (i.e. experiencing the feeling can provoke the expression but rehearsing the expression can also evoke the feeling). Seeing people experiencing pain causes us to rehearse that pain. Thus this act of rehearsal potentially lies at the heart of empathy. It should be noted though that for this empathetic mechanism to work, there must be some cross over to conscious awareness.
As ever this links well with ideas of object handling: I once went on a training day about boxes for handling objects where the guy leading day suggested that object handling sessions are like stories and that the story begins with the form of box itself. What the above research suggests is that the second part of the story is contained in the way the session leader retrieves objects from the box and hands it to the participant. Viewers will not only be rehearsing the act of retrieval but this act of rehearsal will then inform their (unconscious) expectations both of the value of the object but also it’s probable physical properties. Those property expectations will then influence the feed-forward motor control mechanisms involved when the participant reaches out for an object. The difference between the expectation and reality of the perceptual properties of the object in the hand shapes not only the on-line, feed-back motor control mechanisms but also creates an expectation of the feel of the object. Again the comparison of expectation and experienced reality shapes the cognitive learning experience of holding.
There is an emotional element to object handling which is influenced by the body language of the session leader. That body language imputes value to the objects. Given a valuable object to a person (by implication) gives value to the person. Case studies show that participants experience increases in self-esteem because they have been given the chance to hold something of value. Moving on from that, the self-esteem is further enhanced by the way that the session leader listens to and responds to the participant. This should come as no great surprise but the review of Decety & Grèzes gives this a firm grounding in our understanding of how the brain works.
Decety, J. & Grèzes, J. (2006) ‘The power of simulation: Imagining one’s own and other’s behavior’, Brain Research, 1079, 4-14