In this chapter I want to explore the extent to which our bodies are involved in what we tend to think of as strictly cerebral operations, such as problem-solving or perception.
Esther Thelen performed a series of experiments with babies to investigate bodily influence on problem-solving.* She began with a twist on a classic experiment done by the twentieth-century Swiss psychologist Jean Piaget, the ‘A not B’ test.
* Esther Thelen and Linda B. Smith, A Dynamic Systems Approach to the Development of Cognition and Action, 1994.
Jean Piaget would always introduce himself at parties as a ‘genetic epistemologist’. He would then stand there expectantly, with a mischievous smile playing about his lips, waiting for someone to ask him, ‘What’s that?’ But sadly no-one ever did. And so, when Jean Piaget died in 1980, he took the secret with him to the grave. From that day to this, no-one has ever found out what ‘genetic epistemology’ could possibly mean. It’s thought to have something to do with not shouting at your children in supermarkets, but beyond that all is guesswork.
One of the things he did leave us however, is the A not B test, which goes like this. Once you teach a baby to reach out and take a toy from Box A, if the toy is then placed in Box B, the baby will keep reaching for Box A even if they see the experimenter place the toy in Box B. Only after they are eight months old, said Piaget, will babies start investigating whether the toy might in fact be in Box B.
But Esther Thelen discovered that babies can pass the A not B test if you attach weights to their arms or make them stand up. Her results show that babies as young as seven months old can, if weighted down enough, successfully find the toy in Box B.
The baby’s memory, she concludes, is in the sensorimotor circuit that is involved in reaching for the toy. By strapping weights to the baby’s arms she interrupts this sensorimotor circuitry. A change in the reaching dynamic orchestrates a change the brainwaves. Freed from repeating the same gesture as before, the baby can try a different way of searching, one which activates neural pathways outside the runnels of the old, failed action.
Esther Thelen also looked at babies’ spontaneous stepping activity. Newborn babies when held upright have a stepping reflex that vanishes at two months when their legs become too chubby and unwieldy. Once gone, the stepping reflex usually won’t return until the baby is at least nine or ten months old, and gearing up to start walking. Here again, Thelen was able to tweak the standard developmental chronology by strapping weights to babies and putting them on a treadmill. She placed seven-month-old pre-walking babies on a treadmill, strapped weights to their legs and found that the stepping reflex returns very quickly indeed once the machine is turned on. It even does so, she found, when babies have one foot on each of two parallel treadmills that are going at different speeds.
I was intrigued by Esther Thelen’s findings and so I decided to visit her in prison.
I wanted to know whether the ability of seven-month-olds to successfully reach for the toy in Box B, might be explained by other factors than sensorimotor circuitry. An alternative explanation might have to do with what neurologists call the ‘stickiness’ of left-hemisphere processes. The left hemisphere is given to ‘punding’, meaninglessly or automatically repeating a task, going round and round in ever-decreasing circles unable to escape the gravitational pull of pointless repetitive activity. As everybody knows, the way to snap out of the left hemisphere’s punding tendency is to go for a wander and come back at the task afresh. Whenever we are stuck at a problem we get up, potter about and often return to find that our unconscious has solved it for us. Perhaps Esther Thelen’s experiments show that memory is stored in patterns of movement. Anyone who has ever learnt a tune by heart on the piano, will know about muscle memory, the way your hands remember how the tune goes better than your head, and you find your fingers on the right piano keys before you have sent them there. Her work also suggests perhaps that by bringing the body back into the equation, we escape left hemisphere’s tendency to fall into an attractor basin of ever-decreasing circles.
Where a lot of neuroscience seeks to dash the brains from the body, to brain us, Esther Thelen’s valuable work helps put brain back in the body, and shows the body to be an integral part of problem-solving. The same is true of Edoardo Bisiach and Claudio Luzatti’s work with hemineglect patients.*
* E. Bisiach & C. Luzzatti, ‘Unilateral Neglect of Representational Space’, Cortex, 1978.
In Milan in 1978, Bisiach and Luzatti were examining two patients, a man and a woman, both with left-sided hemineglect as a result of strokes injuring the right parietal lobe. Even though there’s no damage to the eyes, left hemineglect patients lose the left side of their visual field. The added wrinkle is that they are not aware that there is anything missing from their picture of the world. They take the right half for the whole picture.
Typically there are three tests which neurologists give to patients. If they fail at all three they have what is called chronic hemineglect. When asked to draw a clock-face, patients with left hemineglect draw all the numerals from one to six, but leave seven to twelve completely blank. They don’t think anything is missing. As far as they’re concerned, they’ve drawn the whole clock. Ask them to draw a cat, they will draw the right half of the cat and not notice that everything from the left is missing. Asked them listen to the Today program, they will find it to be perfectly balanced broadcasting.
Bisiach and Luzatti asked each patient to draw the Piazza del Duomo, Milan’s famous cathedral square. Sure enough, only the right half of the cathedral was there but not the left. Slap bang in the middle of the square stands the huge bronze statue of King Vittorio Emanuele II on horseback. The statue faces right. When asked to sketch the statue, everything from the left visual field was missing, such as the back legs of the horse. Instead of leading his troops into the Battle of San Martino, King Vittorio
Emanuele now appeared to be arguing with the front half of a pantomime horse. Once again, the patients saw nothing wrong, but this time they did betray a sense that things were a little odd. When questioned about the statue, they responded that it commemorated how Vittorio Emanuele managed to hold together a troubled production of Aladdin.
What Bisiach and Luzatti did next was something that no-one had ever thought of doing before. They poured icy cold water into each patient’s right ear. Why? Maybe they were bored. Maybe the patients had been annoying them. We will never know. What we do know are the spectacular results. It was a beautiful, magical Oliver Sacks moment. As if they had never suffered right parietal brain damage, the left side of the Piazza del Duomo swam into view. On the clock tower the numbers seven to twelve suddenly appeared, the king’s horse sprouted back legs and a tail, and both patients demanded to know why John Humphrys describes oil-industry lobbyists as ‘independent think-tanks’.
Remission of the Milanese patients’ hemineglect proved only temporary, alas. As soon as Bisiach and Luzatti stopped sluicing the inner ear the left side of the picture dropped out again. Since the restoration of vision lasts only seconds, it cannot be called a cure, but Bisiach and Luzatti’s experiment seemed to show that neuroscience had only been seeing half the picture. What else were they missing?
How can the inner ear possibly influence what we see? How can cold water do what brain surgery cannot and restore sight, albeit temporarily?
One possible solution to the puzzle of why sluicing the inner ear with cold water results in temporary remission of hemineglect might be because the inner ear is involved in the onset of all movement, all action. Its semicircular canals, each set at right angles to the other, are involved in the initiation of all activity. Every physical response has to be run past the ear before it gets the nod. If the brain evolved primarily to serve movement, then it may perhaps help our understanding of the brain to reverse the usual hierarchy. Instead of seeing the sensorimotor system as subordinate to perception, sensation might be better understood as part of doing: ‘two eyes serve a movement.’
Inside the cranium, the sensory and motor areas lie side by side, two adjacent vertical strips like Togo and Benin. Taken together, these neighbouring West African states make up the sensory-motor cortex. Sensory business is supposed to go on in Togo, while motor activity is coordinated in Benin. But the Milan experiment questions this picture of discrete functions in separate cortical locations. In Pain: The Science of Suffering, Patrick Wall speculates whether the Milan experiment shows that ‘we can sense only those events to which we can make an appropriate motor-sensory response’:
Could it be that we in fact sense objects in terms of what we might do about them? Could it be that we have erected an artificial frontier between a sensory brain and a motor-planning brain which does not in fact exist?
Could it be that there is no real border between Togo and Benin. This idea of a circuit matches Wall’s own conclusion, drawn from a lifetime of studying pain, that pain is not the simple receipt of a stimulus but the stage at which the body has got to in reacting to the stimulus.
Over a hundred years earlier, the same thought struck the American philosopher John Dewey. In his paper ‘The Reflexive Arc Concept in Psychology’ (1896) he takes issue with ‘pre-formulated ideas of rigid distinctions between sensations, thoughts and acts’. He argues that the standard concept of reflex arcs – sensation-followed-by-idea-followed-by-movement – is not a true description of how humans and other animals behave. The status of our attention before the stimulus is an important factor in how we respond to the external event. We are primed to hear a sound in a particular way depending on what we are doing at the time: ‘If we are reading, if we are hunting, if we are watching in a dark place on a lonely night, if one is performing a chemical experiment’. After a blazing row our hearing is sensitised to each micro-fluctuation in the decibels with which a cup is put on a table. We are finely attuned to the fractional increase in decibels, because the argument has primed nerve cells to assemble in a particular formation and chemical composition. If a cup is set down even a tiny bit louder than usual then it may mean that the other person is still angry and the row may flare up again.
Instead of an arc, says Dewey, we have a sensorimotor coordination. This helps explain why water in the ear brings the Piazza del Duomo back to the eye. Vision is restored because the broken circuit has been temporarily completed. A relay of Christmas tree lights stops working if just one bulb goes. But tap the dead bulb’s socket with an electrically conducting pair of pliers, and the Christmas tree lights up again. (Or catches fire. I’m not 100 per cent sure about the details of this experiment.) Anyway, Dewey is saying, I think, that the sensorimotor coordination is like an electrical circuit.
Patrick Wall’s idea that ‘we sense objects in terms of what we might do about them’ links to Edward Tolman’s findings that animals are not passive responders to stimuli. In 1948, Edward Tolman’s ‘On Cognitive Maps in Rats and Men’ showed the ‘largely active selective character in the rat’s building up of his cognitive map’. If a rat receives a mild shock while running a maze, he stops and looks around for its source. What hit me? Where did that shock come from? Rats are seeking to plot meaning on the map they are making. Immediately after receiving a mild electric shock out of the blue, they look up, down and all around for what hit them.
It’s like the gag the old silent film stars used to do when sent sprawling by an inanimate object. Knocked down by, say, a loose roof slate, Buster Keaton puts up his dukes on the lookout for who hit him. The gag is funny for lots of reasons. Taking a pugilistic stance towards the inanimate world is funny. And so is Keaton’s readiness to believe he is under attack. But perhaps his reaction is also funny because we recognise ourselves in his shadow-boxing. We laugh because we recognise our complete if momentary bewilderment when we have no idea what hit us, the perfect ignorance with which we hunt for meaning and significance in all accidents great and small. Keaton is mimicking how we all react by doing something, anything before we know what to do.
Are there things here that may help us understand why the Piazza del Duomo returned to those two Milanese patients? Does the sudden shock of cold water in the middle ear activate the search for a stimulus? Does vision come back for a moment like an instinctual inner Keaton putting his dukes?
Our brain’s activity patterns, argues Louise Barrett in Beyond The Brain, are responsive to the significance of a sensation, rather than to the sensation itself. We are guided by meaning. Our senses probe the world for meaning. But what happens down at level of cells and tissue and dendrites and axons to give something significance? A clue as to how this may work was suggested by Walter J. Freeman’s concept of a nerve cell assembly.
In his paper ‘The Physiology of Perception’, Freeman shows how he measured the activity in rats’ olfactory bulbs as rats sniffed different smells, and concluded that ‘the neurons in the bulb must first be primed to respond strongly to the input’.
This priming comes by way of the rats’ personal history with different smells, a history that has lead them to attach significance to the stimulus, by giving it privileged attention.
We tend to think attaching meaning to something is a high-end, conscious, cerebral deliberate act – and it can be that of course. But allocating significance can also happen unconsciously. The senses, said J. J. Gibson, ‘can obtain information about objects without the intervention of an intellectual process’. In 1971, John O’Keefe and Jonathan Dostrovsky discovered ‘place cells’ in the mammalian brain that fire in response to the significance of a particular location, rather than in response to this place or that.* As rats build internal maps they look to allocate meaning to objects and places in their environment.
* John O’Keefe & Jonathan Dostrovsky, ‘The hippocampus as a spatial map. Preliminary evidence from unit activity in the freely-moving rat’, Brain Research, 1971.
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Some of the experimental work touched on in this chapter has served to put body and mind back together again, and to remind us that, in the words of Mary Midgley, we are not two things but one thing.
But how did we ever get to thinking otherwise? Why are we so chary of including the sensorimotor system in our picture of how the mind works? When did we first start thinking of body and mind as being separate?
Dewey blames this tendency on slave-owning Greek aristocrats who downplayed the work-related aspects of things. The Greeks put Contemplation on a pedestal – or rather they got someone else to do the heavy lifting. (Too much like hard work.) Their patrician habits of thought, argues Dewey, have led us to downplay the significance of work-related aspects of the brain such as the sensorimotor system. Under their influence, we have made the brain a detached consciousness module, an executive, as an overseer. If the brain has to deal with the dirty world, let it do so only as some sort of perception and integration module. That this is a dead end can been seen in the way that most brain books quickly degenerate into playing Edwardian parlour games based around optical illusions. Is this a picture of a duck’s bill or a rabbit’s ears? Two black noses or one white candlestick? And here they will stay until they grasp the nettle that perception is part of doing, that the sensorimotor system is a dynamic circuit, and that the ‘primary relation between the mind and the world is interaction not representation’. *
* Andrew Wells, Rethinking Cognitive Computation, 2006.
And perhaps this last idea – which Wells calls ‘ecological functionalism’ – takes us a few steps further towards understanding why the Piazza del Duomo floats into view on a tide of cold water. For a few seconds, the dormant right parietal snaps into life when we think we are interacting, on receipt of a signal from our ear. Instead of the stillness of sleep the brain is frozen in a moment of action, like the statue of the king on his horse.