Reading, Dyslexia and the Eyes

One of my patients told me recently that her son had been referred to have some tests on his eye movements because he sometimes makes spelling mistakes. He can read perfectly well, and actually does OK in spelling tests, but just makes mistakes when writing. It struck me that if you referred every child who made spelling mistakes for special tests, you’d probably need to refer 98% of them. So how do these ideas come about, and what’s the story of eyes, reading and dyslexia?

Why reading – especially English – is difficult
Reading is a complicated task that requires the involvement of several different parts of the brain. The image of words falls on the retina and is transferred to the visual cortex of the brain. Here, the image that we see is formed. As part of the processing of that image, shapes are recognised. This information has to link up with the language centres, which recognise sound and meaning.
The written word is, in evolutionary terms, a relatively modern invention. Our brains are really set up to learn language through sound, as we nearly all manage to do easily when we learn to understand and speak our native language at a young age. So when we read, we still have to link the words with how they sound. Even expert readers will say the words in their head when they read.
English is a particularly difficult language to learn to read because there are so many words like “eye” or “cough” whose pronunciation isn’t obvious from the way they’re spelt. These words are generally learned through their meaning, and efficient readers go straight to the meaning when they read, so they don’t have to piece words together from the sounds. Because Italian is a much more phonetic language than English, there are only half as many diagnosed dyslexics in Italy than in England. It seems likely, however, that there are many more Italians whose dyslexia is too mild to be significant.

Reading and the brain
Cutting & Rimrodt (2010) found used a form of MRI scanning called Diffusion Tensor Imaging to study part of a branch of nerves that runs from the visual cortex to the areas at the front of the brain that are responsible for articulation and speech. They found that some of these nerve fibres were less well organised in dyslexics than in controls.
There have been many reports of differences in nerve structure in dyslexics, but these have not been consistent. Differences have been found in the temporal or parietal or occipital parts of the brain, as well as in the cerebellum. It may be that a well organised nerve structure is a sign of proficiency in that particular task, and that, for a mixture of genetic and environmental reasons, this is achieved more easily in some than in others. Italian dyslexics have been found to show the same kind of nerve activation when reading as English and French dyslexics (Paulesu et al 2001). They also had the same difficulty in tests that looked at their ability to recognise the sounds of words. It’s just that in Italian, there’s only one way to represent a sound, whereas in English there are lots, such as “their” or “there”.

Dyslexia and eye movements
Because anomalies have sometimes been found in the nerve pathways that control eye movements, and because dyslexics often have irregular eye movements when reading, it’s been suggested that poor control of eye movements is a cause of dyslexia.
Hutzler et al (2006) investigated this idea by showing dyslexics and controls groups of consonants, such as DSB, LQWB, ZBB and VPLL. The subjects had to say whether each group of consonants had a double letter in them or not. This meant that the subjects had to look at each “word” in a similar manner to reading, but no higher order skills of language and sound recognition were required. No difference in the eye movement patterns between dyslexics and non-dyslexics were found.
The researchers then changed things, so that the subjects had to try and pronounce “words” such as ZIB, VULL and CRUF. Now, the dyslexic subjects showed the same irregular eye movement patterns as had been found in previous research. Patients with diseases such as Parkinson’s and Huntingdon’s often have trouble with reading because of poor control of eye movements. However, they have a lot of other problems for the same reason, and this would not appear to be the case for the vast majority of dyslexics.

Dyslexia and the cerebellum
Similarly, because scans have sometimes shown anomalies in the cerebellum of dyslexics, it’s been suggested that the cerebellum holds the key to dyslexia. The cerebellum is in control of the things we do without thinking, such as brushing our teeth, and it also plays a crucial role in maintaining our balance. And it’s certainly true that dyspraxia (a disability affecting movement and coordination) and attention deficit hyperactivity disorder (ADHD) are more frequently found in dyslexics than non-dyslexics. On this basis, it’s suggested that specific exercises aimed at improving balance and coordination will improve reading.
One of the many problems with his idea is that there are plenty of elite sportsmen and sportswomen, who would appear to have excellent balance and coordination, but who have suffered from dyslexia. Another problem, and one shared with several other “miracle cures”, is that the statistics used to promote it are unreliable. One of the main reasons for this is a statistical phenomenon called “regression to the mean”.
Imagine 100 people took a multiple choice test in a subject about which they knew absolutely nothing, so had to guess every time. If each question had 2 choices, you’d expect the overall mark to be around 50%. Some people, however, would do rather better, and some worse. If you got the top 10% do another similar guessing test, their mean score would be about 50%, so on average, will have done worse on the second test than on the first. Similarly, a repeat test on the bottom 10% would see their average score improve. This is regression to the mean, and it’s why it’s easy to show that people who weren’t very good at something when you first tested them, can show a dramatic improvement when you test them again after their “treatment” compared with those who did well first time round. The only way round this is to have a genuine control group, who are as similar as possible to the treated group, and who have the same tests at the same time. So you would need to compare dyslexics of the same level of disability, with and without the treatment, to make a valid comparison. This seems to be rarely done.

Dyslexia and eye dominance
I recently read the claim by an optometrist offering diplomas in “Schoolvision” that the “predominant visual skill in reading is aiming”, and that this can be undermined by unstable eye dominance. The role of aiming in reading has been largely neglected up until now (for good reason, you might think), although the importance of eye dominance in aiming sports is widely accepted, including by myself.
But the idea that eye dominance is relevant to dyslexia is not a new one. Stein & Fowler (1982) claimed that more than half of the dyslexic population had an unfixed reference eye on a binocular vision test, compared with 1% of controls. The test used was the Dunlop Test, in which the eyes diverge until double vision occurs, and the child has to say in which direction an object has moved. The test is repeated ten times, and if they give inconsistent answers they’re said to have an unstable response. This doesn’t seem to bear much relation to reading, and, anyway, others (Newman et al 1985; Bishop et al 1979) found that excellent readers did just as badly as poor readers on this test.
Stein & Fowler went on to suggest that some dyslexic children might be helped by the occlusion of one eye. But when Bishop (1989) re-analysed the data, she found no evidence that occluding one eye improved reading scores, and described the original findings as “methodologically flawed”. And whilst some have claimed that cross-dominance (e.g. right eye dominant + left handedness) is especially prevalent in dyslexia, many studies of large numbers of dyslexics have failed to find this link.



What’s the answer?
Most dyslexics clearly don’t have something fundamentally wrong with them, otherwise they’d have a lot more problems than being slower than others in learning to read. Also, we wouldn’t see the differences between languages if vision were really at the heart of dyslexia.
Having said that, there are quite a lot of children who have difficulty when reading because of their vision, and some of them will be dyslexic. Their difficulty often arises because they have either a weakness of accommodation (ability to focus on near objects) or convergence (ability to bring the eyes together for near objects), or both. After a while, they find words go blurred and/or double.
These children generally respond very well to simple exercises, and rarely need glasses. So if your child is having reading difficulties, it’s worth getting their eyes examined to rule out this kind of problem.
Whatever the cause of dyslexia, the answer seems to be one-to-one tuition in reading. Whether this should be phonics or something else, I leave to others to debate.

David Donner

A Look At Shooting

If you’re shooting inaccurately, it could be due to poor alignment with the target, or it could be due to body movement or hand/arm tremors as you fire. There are now pistols equipped with lasers to help distinguish between these errors. The laser isn’t turned on until the shooter has aimed. If the laser centres on the target, then the problem is with body movement and not with aiming.

Because of the distance between the gun’s sight and the target, both cannot be seen clearly. So should one focus on the sight or the target? The general consensus is that you should focus on the sight. This makes sense, as it intuitively seems easier to put a clear object in the centre of a blurred ring, than trying to put a clear ring equidistant around a blurred object. It also explains why some short-sighted people have been excellent marksmen. But it does cause problems for older shooters.

Unless one is short-sighted, one’s ability to focus close objects, such as a gun sight, goes down as one gets older. It’s possible, however, to have a correcting lens for this, and there are special shooting spectacles which can be adjusted to ensure that the lens is perfectly positioned.

Ripoll et al (1985) compared the gaze strategies of international elite pistol shooters with national near-elite shooters. They found that the near-elite looked at their hand and weapon as they brought it up towards the target, whereas the elite shooters fixated the target, and then brought the pistol into line with their gaze before aiming and pulling the trigger. Compared with the near-elite, the elite shooters were quick to bring the pistol into line, but then took longer to aim and complete the shot.

Although this might appear to contradict the advice to focus on the sight, and not the target, it’s likely that the elite shooters did their final aiming adjustment fixated on the sight, but because the sight and target were in alignment, no difference in gaze would be found by the cameras monitoring them.

The gaze strategy of elite shooters goes beyond sport. For some, it’s been a matter of life and death.

Joan Vickers (of “Quiet Eye” fame) and Bill Lewinski (Force Science Research Centre) studied members of Britain’s Emergency Response Team. 11 were highly experienced, and 13 were younger rookies who’d just completed their training.

They set up a scenario in which the subjects were to provide security at an Embassy. A man gets into an argument with the receptionist, and at some point turns around, taking an object from his coat pocket, which is either a gun or a mobile phone.

In more than 60% of trials, the trainees fired when the assailant brandished a mobile phone, compared with only 18% of elite trials. When the assailant pulled out a gun, elite officers shot first 92.5% of the time, compared with 42% for the trainees. The elite officers were also more accurate in their shooting, with the trainees more likely to miss the target completely.

In the last half-second before aiming, in 82% of their tests the trainees took their eyes off the assailant and attempted to look at their own gun, trying to find or confirm the sight alignment as they aimed. Although 30% of the elite also looked at their gun, these fixations were before they aimed (and fired).

When most officers learn to shoot a handgun, they are taught to focus first on the rear sight, then on the front sight, and finally on the target, aligning all three before pulling the trigger. It seems that through experience, the elite officers had learned to keep most of their attention on the assailant’s weapon. Like Ripoll’s elite shooters, they kept their gaze on the assailant’s weapon and brought their gun up into their line of sight.

This research by Vickers & Lewinski is likely to result in changes to the way that officers learn to shoot. If this had been done before, might Jean Charles de Menezes still be alive today? DD

If you’re shooting inaccurately, it could be due to poor alignment with the target, or it could be due to body movement or hand/arm tremors as you fire. There are now pistols equipped with lasers to help distinguish between these errors. The laser isn’t turned on until the shooter has aimed. If the laser centres on the target, then the problem is with body movement and not with aiming.

Because of the distance between the gun’s sight and the target, both cannot be seen clearly. So should one focus on the sight or the target? The general consensus is that you should focus on the sight. This makes sense, as it intuitively seems easier to put a clear object in the centre of a blurred ring, than trying to put a clear ring equidistant around a blurred object. It also explains why some short-sighted people have been excellent marksmen. But it does cause problems for older shooters.

Unless one is short-sighted, one’s ability to focus close objects, such as a gun sight, goes down as one gets older. It’s possible, however, to have a correcting lens for this, and there are special shooting spectacles which can be adjusted to ensure that the lens is perfectly positioned.

Ripoll et al (1985) compared the gaze strategies of international elite pistol shooters with national near-elite shooters. They found that the near-elite looked at their hand and weapon as they brought it up towards the target, whereas the elite shooters fixated the target, and then brought the pistol into line with their gaze before aiming and pulling the trigger. Compared with the near-elite, the elite shooters were quick to bring the pistol into line, but then took longer to aim and complete the shot.

Although this might appear to contradict the advice to focus on the sight, and not the target, it’s likely that the elite shooters did their final aiming adjustment fixated on the sight, but because the sight and target were in alignment, no difference in gaze would be found by the cameras monitoring them.

The gaze strategy of elite shooters goes beyond sport. For some, it’s been a matter of life and death.

Joan Vickers (of “Quiet Eye” fame) and Bill Lewinski (Force Science Research Centre) studied members of Britain’s Emergency Response Team. 11 were highly experienced, and 13 were younger rookies who’d just completed their training.

They set up a scenario in which the subjects were to provide security at an Embassy. A man gets into an argument with the receptionist, and at some point turns around, taking an object from his coat pocket, which is either a gun or a mobile phone.

In more than 60% of trials, the trainees fired when the assailant brandished a mobile phone, compared with only 18% of elite trials. When the assailant pulled out a gun, elite officers shot first 92.5% of the time, compared with 42% for the trainees. The elite officers were also more accurate in their shooting, with the trainees more likely to miss the target completely.

In the last half-second before aiming, in 82% of their tests the trainees took their eyes off the assailant and attempted to look at their own gun, trying to find or confirm the sight alignment as they aimed. Although 30% of the elite also looked at their gun, these fixations were before they aimed (and fired).

When most officers learn to shoot a handgun, they are taught to focus first on the rear sight, then on the front sight, and finally on the target, aligning all three before pulling the trigger. It seems that through experience, the elite officers had learned to keep most of their attention on the assailant’s weapon. Like Ripoll’s elite shooters, they kept their gaze on the assailant’s weapon and brought their gun up into their line of sight.

This research by Vickers & Lewinski is likely to result in changes to the way that officers learn to shoot. If this had been done before, might Jean Charles de Menezes still be alive today?

"http://www.donneroptometrists.co.uk/sports-vision.htm"

Brain Waves

Does the study of brain waves help us distinguish experts from novices, and can brain waves be altered to improve performance?
Four types of brain wave have been identified. Alpha waves (8 – 14 Hz) are seen when we are relaxed, daydreaming or visualising. Increases in alpha waves are often associated with reduced overall activity of the brain. Beta waves (15 – 38 Hz) are associated with conscious thought, with higher frequency beta being associated with anxiety or stress. Gamma and delta waves are mostly seen in different stages of sleep.
Neurofeedback, also known as EEG biofeedback, is a strategy to enable people to alter their own brainwaves. It has been used in the treatment of ADHD (Attention-deficit hyperactivity disorder). Often the patient is using a videogame that’s linked to their EEG, and the aim is usually to increase beta waves and reduce theta waves. When the desired effect is taking place, they get some kind of encouragement in the game, such as beep or a character moving in the desired direction.
Neurofeedback has also been used to improve the balance of patients who have suffered brain injury or stroke. Significant improvements have been found after just 8 – 10 sessions, whereas ADHD treatments usually take 40 – 50 sessions.
Before trying neurofeedback to improve sporting ability, one would need to know if experts demonstrate different brainwave activity compared with lesser players. And there is actually some evidence for that. It’s hard to play rugby or football when attached to the electrodes of EEG equipment, so most of the evidence comes from aiming sports, such as archery, shooting and golf putting.
Haufler et al (2000) found that during aiming, when marksmen were compared with novice shooters, marksmen exhibited less activation (increased alpha with less beta and gamma activity) at all electrode sites on the head, but especially in the left hemisphere. Kerick et al (2001) looked at skilled marksmen during shooting. Over an 8-second period preceding the pull of the trigger, they exhibited greater alpha activity in the left temporal area compared with when they were doing a control activity. Hatfield et al (1984) also found a progressive increase in alpha power in the left temporal area during the last 7.5 seconds of aiming, with no change in the right temporal area.
These results could fit in with the idea that the left hemisphere dominates in language, and that a lot of verbal thoughts could inhibit efficient sporting performance.
Landers et al (1991) used neurofeedback to try and improve the performance of pre-elite archers. On the basis that reduced cortical activity in the left hemisphere (associated with increased alpha waves and reduced beta waves) would increase accuracy, the archers were randomly assigned to one of three groups. One group was given “correct” feedback (reduced left hemisphere activity), another “incorrect” feedback (reduced right hemisphere activity), and a control with no feedback.
They found that those trained to have reduced left temporal activity showed a significant improvement in performance, whilst those trained to have reduced right temporal activity showed a significantly worse performance. The control group showed no change.
However, there’s a problem. Examination of the participants’ EEG spectra failed to show a clear pattern of change after the test compared with beforehand. It’s as if the feedback changed something, but not what it was supposed to.
Also, the link between brain waves and sport performance turns out not to be as simple as first thought. For instance, Del Percio et al (2007) found a correlation between a reduction in alpha output in part of the right hemisphere and skilled karate performance. In contrast, Collins et al (1990) found that skilled karate performance was linked to a bilateral increase in alpha output.
Crews & Landers (1994) found that in the last second before a golf putt, increased alpha waves in the right hemisphere were associated with increased putting accuracy. This is in contrast with the increase in the left hemisphere that had been found in shooting and archery. Looking at putting novices, however, Shelley-Trembley et al (2006) found that lower beta levels in the right hemisphere correlated with accuracy.
So it seems that we need to understand brain waves rather better before we can be sure that trying to change them will improve performance. Oh well, back to practise then.

David

www.donneroptometrists.co.uk

Sprinting

With the European Championships in full swing in Barcelona, I turned my Sports Vision to Athletics...

When sprinters start from the blocks, in order to keep aligned their head needs to be down so that they’re in the most aerodynamic position.

Watching Asafa Powell compete at Gateshead recently, he seemed to keep his head down longer than all the other competitors in the race, and it helped him at the start of the race even if he wasn’t the quickest to react to the gun. Sadly for him, he was overtaken towards the end of the race by Tyson Gay, and the same thing happened a week later when he lost to Usain Bolt in Paris.

Fixating a point a few metres ahead can help to keep the head in the correct position. As the athlete comes to a more erect position, fixation needs to move to a point above the track, past the finishing point.

When running indoors, some athletes change their head posture in response to the wall in front of them in anticipation of having to stop rapidly (www.runningmechanics.com). To avoid this, they should be encouraged either to fixate a point on the wall that’s about head height above the ground, or to adopt a soft focus, as if they’re able to look through the wall.

When I go jogging around the park, I find that focusing on one point in the distance helps me to run better. If I imagine that I’m attached by a rope to that point, and that I’m being winched in, I can keep going for longer even if I’m feeling tired. As I approach the “winch”, I refocus on another distant point and start again.

David

www.donneroptometrists.co.uk

Dealing With Errors – Oosthuizen’s Red Spot

A few weeks ago I was umpiring a junior cricket match when a young leg spinner came on to bowl. His first ball pitched in line with middle stump and turned so much that I had to think about whether I should call it a wide. At last, I thought, an English Shane Warne in the making.

Unfortunately, although he continued to turn the ball, whenever he bowled a bad ball, or even if the batsman managed to hit away quite a good ball, the bowler got increasingly down on himself. Although he wasn’t intended to be taken literally, by towards the end of his spell he was making comments such as “I think I should go home” and “I should give up cricket”. Whereas the best spin bowlers, like Warne, are able to put pressure on the batsman, luring him into a mistake even if the pitch isn’t helping him too much, this bowler was putting all the pressure on himself.

Although it’s easy to be critical, many of us do similar things when we perform badly at sport, getting increasingly cross with ourselves with each mistake. Golfers, in particular, are prone to letting one momentary lapse of concentration, or even an unlucky bounce, ruin an excellent round as their game collapses because their brain is constantly reliving the past, and they get more and more tense.

Even Shane Warne would occasionally bowl a bad ball, but the best sportsmen are able to put a previous mistake out of their mind and concentrate on what they’re doing next. Some sportsmen actively “park” the past by wiping it away; for instance, wiping their hand on their clothing or on the ground.

In a sport where you have time to prepare yourself, such as golf, or bowling in cricket, or serving in tennis, a pre-shot routine is really useful; focus on the visual target(s), visualise what you want to achieve, and carry it out, giving no thought to what happened before, or the pressure of the situation. Some golfers make a clear beginning to the pre-shot routine, for instance saying “Now” or “Start” to themselves when they take their club out of the bag, or just before they start their practice swing.

And this is where I think Louis Oosthuizen’s red spot comes in. The open champion didn’t used to have a set routine in his build-up to playing shots, and had problems keeping his mind focused in major tournaments. Golf psychologist Karl Morris suggested that Oosthuizen mark a red dot on the thumb of his glove. He could then look down at the spot as a way of re-focusing on the next task. The result – maintaining his lead over the last two rounds and winning by seven strokes - was mightily impressive. Let’s hope our young leg spinner finds a way of doing something similar.

Cycling and Running Tactics

There seemed to have been quite a lot of crashes in the early stages of the Tour de France this year. I suppose that shouldn’t be surprising when you have a pack of cyclists jostling for position at 45mph, and if the guy in front of you hits a problem, you don’t have much chance of avoiding them.

In middle distance athletics, some athletes seem better at keeping themselves out of trouble than others, and I wondered if this also might apply to cycling, and how one might train to improve ones tactical awareness when in a pack.

In cycling there does seem to be an answer – rollers. Rollers can be placed in several positions, such as line abreast or one behind the other, so that the riders can practice the different situations that they’re likely to experience in a race, including bumping and jostling.

I don’t see any reason why a similar idea couldn’t be used in athletics, either with several treadmills side by side or with one large one. Runners could even be attached to harnesses so they aren’t hurt if they trip up.

It’s about time we produced another Steve Ovett, who was the master of forcing his way out of a blocked position on the track. Get onto it now, Sir Clive.

David

www.donneroptometrists.co.uk

World Cup

World Cup

The FA has a goalkeeper development website showing a woman goalkeeper in position to collect a low shot. She has clearly watched the path of the ball carefully, because everything is in alignment to intercept the ball. He hands are well forward, preparing to draw the ball in, “little fingers touching”, and her head is right over her hands, so will imminently be right over the ball. Because her body is square on, even if she fails to catch the ball, it could only bounce straight out. And because her head is so far forward, she could probably drop on to the ball easily if it did pop out.

As Robert Green tries to save a 25-yard shot from Clint Dempsey in England’s World cup match against USA, there are a number of differences from the textbook picture above. His head is not quite aligned with his hands, and neither is aligned with the ball. His hands are at uneven heights, and crossed. The ball appears to miss his left hand completely, hitting his right wrist. His body is twisted in the direction that the ball rebounds, into the net. It would appear that he did not track the ball accurately along its path, so did not align himself correctly.

And he is not the only one. You could see the same thing when Algerian goalkeeper Fawzi Chaouchi let in a goal against Slovenia. And a similar thing happened to Scott Carson playing for England against Croatia in 2007. The neural pathways in their brains must be established to enable them to make a textbook save; otherwise they wouldn’t be international goalkeepers. So why didn’t it happen in these cases?

One answer could be that they weren’t concentrating on the game adequately, so were simply late in seeing the shot coming towards them, and so didn’t have sufficient time to get into the correct position. This seems improbable for players at this level.

A more likely explanation is the effect of nerves. When you are nervous, the conscious, thinking part of the brain tries to take over, with the result that movements become a lot less smooth and efficient. Before the USA goal, Green made a clearance which he didn’t appear to hit with perfect timing, with the result that the ball fell to a group of USA players rather than to the intended target. But there could be another factor, which could be described as “falling into bad habits”.

You’re on a motorway, about to overtake the car in front. You check your mirrors, indicate and pull out to overtake, nearly hitting a car outside you that you hadn’t noticed. Although you looked, you didn’t look as carefully as you would have done if you’d been taking your test, for instance. You’ve actually been doing this for a while, but because on other occasions a car hadn’t been there, you had believed that what you had done was adequate, and it had become your routine in these situations.

For professional goalkeepers, a low shot from distance represents a relatively easy save. They can detect its path at an early stage, so might set themselves up on that basis, rather than following the path of the ball all the way. A less than perfect body position may also not matter on most occasions. But if the keeper’s made an early misjudgement, or nerves mean that his body has not moved as smoothly as normal, he can be found out.

Coaches need to watch out for a player who’s getting into bad habits, even if they seem to be getting away with it. Marking the ball with numbers or letters which the keeper has to call out as he catches it can ensure that he carefully follows the path of the ball. Players can sometimes give themselves a verbal reminder to ensure their technique remains solid.

I was umpiring a cricket match recently. It was near the end of the game, with the batting side about to win comfortably. I saw the batsman pull another ball to the boundary for four. It was only sometime later that the fielding side pointed out that the wicket had been broken. After seeing the player make the shot, I’d followed the ball, and hadn’t noticed that the batsman had hit his own wicket.

My mistake was a bit embarrassing, but some are rather more important. However, there, but for the grace of God, go all of us.

David