GOING INSIDE - the features
Read some of my published features about consciousness issues
Is IQ just a matter of neural conduction speed?
Many IQ theorists feel that the genetic component of intelligence may be nothing more than some raw neural property such as conduction speed, or perhaps reliability. But things can't be quite as simple as some military types, training people in "hyper-time" simulators, seem to believe.
(Copyright, John McCrone, April 1996)
For 20 years, NASA test pilots have been jacking up the speed of their flight simulators to above "real-time" in order to give themselves a mental edge. By cranking up the simulators used in pre-mission training so that events happen at between 1.4 and twice normal pace, pilots say they do not feel so rushed when they drop back into the real world.
Now simulator enthusiasts are claiming that what works for the military may soon be available as a tonic for hard working minds everywhere. A pep-up computer game - or better still, a thorough perceptual work-out in an immersive virtual reality environment - may replace that first cup of coffee to get your head into top gear.
Dutch Guckenberger, a research fellow at the simulator manufacturer, ECC International in Orlando, Florida, believes that humans are surprisingly plastic in their speed of thought. Guckenberger says most of us dawdle along at a lazy ten or 20 "decision cycles" a second. But if trained up by the demands of an artificial reality, this could be boosted to 30 or even 40 cycles a second: "You could take a slow man and turn him into a fast man. From our work with above real-time training (ARTT), the evidence is that a 30 percent performance increase could be a normal gain," says Guckenberger.
The US military take the claims seriously enough to have funded new studies with F-16 pilots learning emergency drills and tank gunners practising shooting down enemy helicopters. Guckenberger says training at an accelerated rate in a simulator left personnel with more time to carry out complex tasks in real-life situations, giving green recruits the battle-hardened reflexes of a veteran soldier.
Computer games to boost your IQ - now there's a twist for worried Donkey Kong addicts. A few years ago it was smart drugs such as hydergine and vasopressin that were going to be the short-cut to a sharper mind. Before that it was subliminal learning tapes and biofeedback machines. How long then before CD-ROM hypertime game trainers are the latest fad in the consciousness expansion industry? The dream of instant braininess - yours for just £99 plus postage - means that there will always be a market for such products. But does science give us reason to believe that we could ever benefit from any quick fix solution? Is IQ based on some simple brain property, such as the level of a vital neurotransmitter, a few key genes, or the tuning of an inner perceptual clock, which would make it susceptible to some gross form of manipulation like gene therapy or virtual reality training?
During the 1970s and 1980s, research into the possible biological foundations of intelligence had a bad name. It did not help that many of the academics working on the "hardware" side of IQ were being sponsored by the Pioneer Fund, a private foundation set up in the 1930s by a group of rich Americans openly sympathetic to eugenic causes. But over the past few years, such research has become rather more acceptable. One reason is that the greying of the population has prompted governments to spend money to find out whether it is possible to preserve the brains we have already got, so keeping us all out of costly institutionalised care. However, the IQ community also feels it is getting somewhere on what actually might be different about the brains of clever people.
Putting the case for a genetic basis to intelligence, Chris Brand, a psychologist at Edinburgh University, argues that comparisons of twins reared apart and other such studies now strongly suggest that about 45 percent of IQ (or, at least, whatever it is that IQ tests measure) is the result of inherited factors. Another 30 percent of the variance in IQ scores is accounted for by complex interactions between nature and nurture, such as the effects of diet and birth difficulties on brain development - or even the way a child's personality might affect the way people treat it, so altering the child's social "microclimate" for better or worse. Of the other 25 percent in variance, Brand allows 10 percent for differences in the home environment, five percent for other environmental influences such as schooling, and 10 percent simply for the vagaries of sitting any test. In pugnacious fashion, Brand argues in a new book (The g Factor, John Wiley) that serious scientists can no longer deny a biological component to intelligence. The next step is to decide what it is about the wiring of brains that might account for the observed differences.
A common view is that the brain is such a complex system that any variations in its performance must be due to some incredibly subtle details of its design. But hard-bitten hereditarians take the opposite view. They reason that the brain is grown from a relatively limited number of genes, therefore some very simple factors will have to dictate its final level of performance. Something about the basic speed or efficiency of a person's neurons will have to account for much of the observed variation.
The idea that IQ might be linked to raw conduction speed or perceptual efficiency dates back to the work of Sir Francis Galton, the Victorian gentleman-scientist. Galton compared the reaction times and sensory acuity of labourers and middle-class subjects. However, when he failed to find any correlations, psychologists moved on to develop the pencil and paper tests of reasoning that are familiar as IQ tests today. A few isolated figures - such as Arthur Jensen at the University of California, Berkeley - kept looking for evidence that perceptual speed might play role in intelligence, but most psychologists became convinced that IQ was solely a matter of high level skills such as logic and abstract thinking.
Neuroscience certainly gave ample reason to doubt that nerve conduction speeds would count. After all, the brain does not use just one kind of nerve. The conduction speed of a nerve fibre depends on its size and also the thickness of its fatty insulation. On the kind of heavy-duty trunk cabling used to connect the eye to the brain or send a muscle command down to the hand, impulses zip along at over 200 miles per hour. But inside the brain, the wiring is generally much slower and also more varied. Impulses tend to crawl along at between two and 20 miles per hour. The fact that the brain uses such a mix of nerves would seem immediately to blow any speed hypothesis out of the water. It appears to be more a case of horses for courses. Yet over the past few years, a number of labs have claimed to find positive correlations between IQ test scores and various measures of neural speed.
Perhaps the most radical are studies by Philip Vernon at the University of Western Ontario in Canada who has matched IQ to the speed of impulses in the median nerve of the arm. Using electrodes at the elbow and armpit to time the reaction to a small electric shock to the wrist, Vernon claims that variations in conduction velocity show a modest, yet significant, correlation of about .45 with IQ score. Unfortunately, even those sympathetic to conduction time theories of IQ, such as Arthur Jensen and Hans Eysenck at London's Institute of Psychiatry, have been unable to replicate these particular findings. Given that an arm nerve is fairly remote from what might be happening in the brain, a more plausible approach has been to measure mental processing speeds using evoked response potential (ERP) techniques.
An ERP is a scalp electrode recording of the electrical snap of activity produced in the brain by a simple stimulus, such as a flash of light or the reversal of a chequer-board pattern. Nothing can be seen in a single trial because the brain produces too much background noise. But by averaging hundreds of trials, the background activity cancels itself out, leaving just the rises and falls in neural activity associated with the processing of the stimulus. With a visual sensation such as a reversing chequer-board, the first big ERP peak comes after about a tenth of a second. This rise in polarity is taken to be the building of a primary sensory representation in the visual cortex. Other peaks follow in different parts of the brain and these are believed to be related to thoughts about the meaning or significance of the sensory information.
The conventional wisdom is that ERP timings are much the same from person to person. Mike Rugg of the University of St Andrews in Fife says that on a common measure, such as the P100 spike which occurs 100 milliseconds after the sharp visual jolt of a chequer-board reversal, the standard deviation is only about 4 milliseconds. "In fact, the variation in times are so small that the P100 is used clinically to test for medical conditions like multiple sclerosis," says Rugg. Furthermore, only a few milliseconds are actually taken up by the transmission of impulses down the optic nerve from eye to brain. The rest of the 100 milliseconds is spent first in the transduction of light by retinal pigments and then by the visual cortex taking time to organise its reaction.
However a standard deviation of 4 milliseconds still means that a few percent of people will have ERP's stretching out past 116 milliseconds, or running under 84 milliseconds. Arthur Jensen, working with Ed Reed at the University of Toronto in Canada, believes this leaves plenty of room for speed differences to count. Reporting a small, but constant, correlation between P100 times and IQ scores, Jensen argues that if ERP differences over the first leg of the sensory processing journey reflect a general efficiency of wiring in the brain, then raw conduction advantages could well account for as much as 25 percent of the variance in IQ scores.
The ERP approach to measuring brain speed has proved more robust than Vernon's work on peripheral nerves and has been replicated by a number of laboratories over the past few years. However many now feel that pure neural speed is probably, after all, a little too simple a property for explaining advantages in intelligence. The belief that the quick movement of nerve traffic must be a good thing is based on a rather old-fashioned, computational view of the brain.
In the classic serial processing computer, information is chopped up and passed through a sequence of calculating steps. The faster each step is completed, the sooner a computer reaches the end of its program. But modern neuroscience sees the brain as a dynamic connectionist network. A state of information has to grow organically, evolving through the pressures of positive and negative feedback until it reaches a state of balanced tension. In such a network, it is not the speed of traffic along individual strands of wiring that counts but the smoothness and precision with which the entire network settles into its solution state. So what ERP studies might really be measuring is reliability rather than speed.
Pat Rabbitt of the University of Manchester, a former sceptic about simple biological explanations of IQ now persuaded by his own work on perception timing tasks, reminds that each person's ERP score is the average of hundreds of trials. A close analysis of these averages suggests that what actually happens with better performers is that rather than being markedly quicker, they instead exhibit less overall variation. Their means are lower because fewer trials are skewed by the occasional lagging response. "When you look at the development of reaction times in kids, what you get is fewer slow responses occurring as they get older, rather than more fast ones," says Rabbitt. He adds that the same phenomenon shows on other mental tasks such as judging short spans of time: "If we ask people to estimate time periods of under a second, clever and less clever subjects have similar averages, but the variance of one is smaller than the other."
This picture fits with recent findings by Peter Caryl, a colleague of Chris Brand at Edinburgh University. Caryl says he looked at the ERPs of subjects who had to judge which of a pair of lines were longer when the lines were flashed up on a screen for just 30 milliseconds or so. The ERPs of high IQ scorers tended to show a steeper, more pronounced rise, as if there were a sharper synchrony in the response of their brains. The bunching of ERP times would fit the idea that some brains form mental representations which are somehow crisper, more precise.
Yet both Caryl and Rabbitt warn against an over- interpretation of these findings. As Rabbitt points out, if it turns out to be network performance rather than plain neural conduction speed which is basic to the biology of intelligence, then that is really quite a complex "simple factor". At the moment, researchers can only guess what it might take to tune a brain network to optimum pitch. All sorts of variables, from the branchiness of neurons to the replenishment rates of neurotransmitters, could play a part in producing a crisp response. Caryl adds that as soon as you take a dynamic network view of the brain, it also becomes difficult to separate "upstream" from "downstream" processes.
The old cognitive science model saw sensory information being dumped in visual cortex then being analysed for meaning and content by a succession of filters. Like an assembly line, processing would occur in a series of stages. But in a neural network, feedback from high level brain areas will be flooding down to affect the primary mapping even as it forms. Indeed, there is now plenty of evidence that the brain runs ahead of itself, making guesses about what it expects to happen in the next few moments so as to guide its sensory processing. When we reach for a door handle, our brains will already have anticipated how the handle should feel, setting up a shadowy image to steer our somatosensory cortex towards its sensory reaction. We only notice this ever-present habit of anticipation when something goes wrong - such as finding someone has pulled the door open from the other side just as we were about to close our hand on the handle. The unexpected causes a moment's sensory confusion and we find ourselves briefly flummoxed.
Neuroscientists like Jeffrey Gray of London's Institute of Psychiatry are working on elaborate models for how consciousness is the product of marrying a flow of priming expectations to confirming - or disconfirming - sensory information. However the point for IQ researcher says Caryl is that if feedback connects high level processes intimately to basic sensory processes, then high IQ people might have their advantages elsewhere. The crispness of an ERP might merely reflect the efficiency of priming and attention directing processes further up the brain. In that case, even a strong correlation between some apparently basic neural property and IQ would not mean that one was causing the other. A fast brain could be just one that anticipates better.
So intelligence researchers are far from having the answers - just some firmer correlations and a few ideas about possible neural networks properties. Quite properly, therefore, most are reluctant to speculate about whether intelligence could be boosted by some mind-drug or perceptual training technique. Nevertheless, the main argument against mind-drugs, gene therapies and other physical interventions is that if peak mental performance depends on delicately tuned neural networks, then pumping in a psycho-active substance would be like jamming a screwdriver into the front of your hi-fi. The accepted view on mental training has been that while the brain is very plastic in its performance, any benefit is normally strictly limited to the skill being practiced. Rabbitt says the evidence is that playing a lot of chess, doing crosswords - or even filling in IQ questionnaires - makes you better at those activities, but there is no general boost to the system.
So where does this leave Dutch Guckenberger and his dreams of using "hypertime" training to quicken a person's thinking? Firstly, his attempts to explain a training effect in terms of an increase in decision cycles owes too much to an out-dated, serial computer, model of the way the brain works. Perhaps rather than fast and slow man, Guckenberger should be taking about the difference between precise and blurred man.
But more importantly, a consultant who looked into accelerated simulator training for NASA back in the 1970s came up with a relatively straight-forward explanation of how the effect might work. NASA's Dryden testing ground in Edwards, California, first stumbled upon above real-time training in the early 1970s while working on the F-15 jet fighter project. The prototype of the F-15 was actually a remotely piloted scale model glider designed to test out the controls and flight surfaces. The pilot sat in a cockpit simulator on the ground and flew the model via radio signals. After preparing for many hours in the simulator, pilots still complained of feeling rushed when it came to flying the real model, so NASA engineers tinkered with the simulator to let pilots adjust its speed to what seemed a psychologically realistic level. This turned out to be about 1.4 times real-time. Ever since, NASA Dryden has routinely used speeded up simulators for the final stages of flight training.
Simulator consultant, Robert Hoey, was called in to investigate the basis of the effect. Hooking the pilots up to a heart rate monitor, Hoey found that they were much more relaxed in a simulator than when flying a real plane. Even just knowing the simulator was driving a radio controlled glider was enough to produce an extra adrenaline rush. Such physical arousal is a normal response, preparing a person to take violent action in potentially dangerous situations. Arousal also has a psychological effect, altering the balance of certain neurotransmitters and lowering sensory thresholds, so making us feel more "jumpy". In neural network terms, the weights of connections are adjusted so the network is more likely to respond to partial information, allowing the brain to trade off urgency against a greater probability of errors.
Hoey argued that under these conditions, the brains of test pilots would have more trouble dealing with the kind of detached, intellectual skills needed to check out a new plane. Test pilots, unlike normal pilots, have to follow a tight plan of manoeuvres while keeping an eye on possible problems. Training under accelerated conditions in a simulator appeared to be a good way of mimicking the effects of added psychological stress, so making the eventual flight seem less rushed.
Guckenberger's own more recent studies bear this explanation out. In his work with F-16 pilots, the area where they benefited most was in dealing with an enemy avoidance drill which involved a complicated sequence of manoeuvres and decoy releases - the pilots had to deal with a lengthy mental checklist while under severe stress. Guckenberger found much less evidence of an advantage in above real-time training for learning ordinary flight skills. Likewise, the tank gunnery exercise was peculiarly dependent on making complex calculations under pressure, whereas most combat skills, such as firing a rifle, are more like driving a car - something that needs to become an almost unthinking motor habit.
This suggests that time pressured training may only help in situations that mix high arousal with a need to preserve a measure of analytical detachment. A speeded up virtual reality environment might well prove valuable for training city traders, surgeons, or people who suffer exam nerves - any skill where it might be important to allow for the extra effects of stress - but it is unlikely to deliver the general IQ boost talked about by Guckenberger.
Still, Guckenberger is not downhearted. He admits that he has no hard evidence for believing above real-time training could be harnessed as other than a way of simulating the effects of psychological stress. But he can still dream. Right at the moment he is toying with a computer display that takes you down a road of columns, with the columns zipping by faster and faster. "Staring at the screen might pick up the brain rate. It's worth a try," says Guckenberger.
(This is a version of an article that appeared in New Scientist, 20 April 1996)
