The Edie Neurolearning Blog has an interesting post on how memory changes with age.
“Item memory is pretty similar at all ages, except for a little drop off by age 72, but look how kids age 7-10 have such an excellent sensitivity to color memory, but comparatively poor memory for location in space.“
Memory Strengths Differ at Different Ages
According to a one study it does. In comparing 14 children with ADHD to 13 children without ADHD the researchers noted that the ADHD children were worse at distinguishing colors and the at Stroop test. Oddly this effects the blue-yellow part of the spectrum worse than the red-green.
“Children with ADHD committed more errors on the [Farnsworth–Munsell 100 Hue Test], particularly on discrimination of colors along the blue–yellow axis, and were slower on Stroop subtests involving colour naming. However, the latter deficit was accounted for similarly by blue–yellow and red–green discrimination abilities. Blue–yellow colour perception problems in ADHD contribute to but do not fully explain the observed slowed colour naming.”
Colour perception in ADHD
Visual problems are heavily linked to learning difficulties such as dyslexia or ADHD. The problems are not with visual acuity, the traditional 20/20 eye tests, but with issues such as tracking or co-ordinating both eyes to look at the same point. Children with learning problems often have poor motor control so it is reasonable that a child who lacks control over the rest of their body will struggle to master the micro movements of their eyes. The eyes, just like every other part of the body is moved by muscles that are controlled by the cerebellum.
There have been several methods promoted over the years for improving eye sight without glasses. The most famous is the Bates Method first published in 1920. Though rejected by mainstream ophthalmology as ineffective, many people claim to have been helped by the method. Now there is a new method of training and improving the visual system that is suitable for the 21st Century.
Exercise Your Eyes is gym equipment for your eyes. Its design is simple and elegant. A wide arm about a metre in length contains a row of red and blue LED lights. Using the controls on the device you set the pattern in which the lights will blink and their speed. Once the program starts you track the blinking lights with your eye, exercising the muscles and the cerebellum that controls them.
This simple approach has two very clever twists. Firstly the device is designed in such a way the that wide arm can be turned to different angles, stretching the eyes in different dirrections, Additionally it can be configured so that you look down the length of the device, much like looking down the length of a rifle barrel.
The second clever twist is the inclusion of reversible sun-glasses with one red and one blue lens. They are reversible so that the red lens can be over the left eye with the blue lens over the right and vice versa. Because the LED lights are red and blue only one eye will be able see the light because the red or blue lens will filter out light of the same colour. This allows the eyes to be exercised independently.
I’ve been trying out a unit sent by Exercise Your Eyes for almost two weeks but its too early to say whether it working or not. However there has been research carried out by Exercise Your Eyes on its effectiveness. I was sent three studies, one on police recruits, one on children playing Little League Baseball and one on college students. Only the Little League study has been published in a peer-reviewed journal (unfortunately its not yet available online) and so the other two studies have to be regarded with caution. Two of the three studies lacked a control group and in the study on police recruits this is a serious short-coming as the subjects where under going intensive police training. Thus making it impossible to say whether any improvements where due to the visual training or the general police training. That said, all three studies where well conducted and the presented data showed clear improvements in the subjects.
I will be continuing my training for the next few weeks and post an update on the results.
“A wide array of visual perceptual difficulties have been found in subjects diagnosed with autism, and it’s clear, we’re only at the beginning of our understanding how visual information is being conveyed differently“.
Tip of the Iceberg: Visual Perception and Autism
In October 2004 I visited the Sound Learning Centre (in London, UK for an assessment and subsequently underwent Lightwave Stimulation or light therapy. This significantly improved my field of vision and that has had all sorts of beneficial effects but I never had the chance to go back to be retested until last week.
Normally the retest procedure takes place shortly after the treatment Pauline Allen and the rest of the staff were interested to see what changes would be evident after 15 months. The good news is that the test confirmed my field of vision had improved. Pre-Treatment my scores were 1 to 11 degrees for my right eye and 3 to 12 for my left eye. Post treatment it is 7 to 17 degrees and 5 to 13 degrees. A ‘normal’ range is about 25 to 30 degrees so my visual field has increased but is still short of normal levels.
The field of vision is measured by a Perimetry test. With one eye covered you stare at the centre point of a target. Slowly the coloured tip of a narrow wand is moved from the outside of the target to the centre and you let the examiner know when you can tell the wands colour. The position is marked then the process is repeated with a variety of different colours and different angles of approach. This builds up a map of where each colour can and cannot be seen. The colour aspect of this test is important as it is testing the visual range of the cone cells. These are clustered towards the centre of the eye and used to detect colour, fine details and fast changes. Peripheral vision is a function of the rod cells. These cells are sensitive to changes in light levels not colour and are found towards the edges of the retina.
You can try a simple version of this test right now. Pick up a brightly coloured object and hold it at arms length out to one side. Stare straight ahead and whilst keeping the object at arms length, bring it around slowly in an arc so that it is in front of you. What you will notice is that when the object first enters your peripheral vision you can see its shape but not its colour. As you bring it around further there will be a point where you can see its colour. This is the edge of your colour visual field.
The exact role a poor colour visual field has in learning difficulties is unknown as there has been too little research in this area. It is probable that it is related to some of the visual effects dyslexics have when trying to read, e.g. the letters jumping around. It may also be related to Meares-Irlen (also known as Scotopic sensitivity syndrome and ASFEDIA).
Further Reading: International Perimetric Society (IPS)
There are several devices and approaches on the market for tackling Learning Difficulties such as ADD / ADHD that aim to effect the patterns of electrical activity in the brain. This goes back to the discovery of EEG in the 1930’s. It was noticed that when people are relaxed they have a regular, more synchronised brain wave patterns where as agitated people tend to have more chaotic patterns. Since then, various bio or neuro-feedback devices have been marketed on the assumption that calmer, more synchronised brain wave patterns are better.
In a new experiment using monkeys researchers looked at how attention and reaction times were effected by gamma-band synchronisation in the visual areas of the brain.
“Our capacity to process and respond behaviourally to multiple incoming stimuli is very limited. To optimize the use of this limited capacity, attentional mechanisms give priority to behaviourally relevant stimuli at the expense of irrelevant distractors. In visual areas, attended stimuli induce enhanced responses and an improved synchronization of rhythmic neuronal activity in the gamma frequency band (40–70 Hz). Both effects probably improve the neuronal signaling of attended stimuli within and among brain areas. Attention also results in improved behavioral performance and shortened reaction times. However, it is not known how reaction times are related to either response strength or gamma-band synchronization in visual areas. Here we show that behavioural response times to a stimulus change can be predicted specifically by the degree of gamma-band synchronization among those neurons in monkey visual area V4 that are activated by the behaviourally relevant stimulus“.
What this study demonstrates is that attention and reaction times are effected by synchronisation, in monkeys anyway. It does not demonstrate that products such as light therapy or neuro-feedback work but it does support their arguments.
Previously on Myomancy: History of Audio Visual Entrainment, SharperBrain Claims a Breakthrough in ADHD Treatment, Play Attention: Biofeedback Treatment for ADHD
See Also: Gamma Synchrony on Developing Intelligence.
Sensory Integration is often used with autistic children or childern with severe learning problems but its is not a specific technique. Its an approach that tries to normalise a child’s reactions to sensory input. The School Psychology blog has identified a publication by the National Association of School Psychologists on Sensory Integration in 2002. They weren’t impressed.
“There is no study that uses a quality research design (e.g., random assignment of subjects, matched control groups, consideration of the effects of maturation, evaluators blind to treatment condition) that finds SI therapy to be effective in reducing any problem behaviors or increasing any desired behaviors. There is plenty of evidence from which a verdict can be drawn. And the verdict is that, despite the intuitive appeal and glowing testimonials, SI therapy is not an effective treatment ….
Despite this harsh criticism, SI theorists and practitioners may be close to something important. I strongly encourage continued research in this area. However, the general public should not be Guinea pigs. Nor should resources be taken from effective treatments to go towards an unproved treatment. I hope that when new and improved SI models are proven safe and effective, they will dramatically improve the lives of children and their families. When there is evidence of SI as a safe and effective treatment, I promise to publicize such positive findings as vigorously as I have pointed out its current shortcomings.“.
A School Psychologist Investigates Sensory Integration Therapies: Promise, Possibility, and the Art of Placebo
Previously on Myomancy: The Senses of Autism, Sense Round-Up, Integrated Senses, Sensory Integration and ADHD, Sensory Integration, Sensory Integration Research
The Neurology department at Wake Forest University have been researching how the ability or lack of ability to integrate multiple senses together can play a part in dyslexia. In Altered temporal profile of visual-auditory multisensory interactions in dyslexia :
“[W]e studied the effects of task-irrelevant auditory information on the performance of a visual temporal-order-judgment (TOJ) task. Dyslexic subjects’ performance differed significantly from that of control subjects, specifically in that they integrated the auditory and visual information over longer temporal intervals. Such a result suggests an extended temporal “window” for binding visual and auditory cues in dyslexic individuals“.
On the Wake Forest website is another article Early Experience May Shape our Sensory Perceptions, New Research Shows looking at the neurology of cats to understand how humans combine different sensory information.
“The researchers studied individual neurons in the neocortex of cats to see how they respond to sight, sound and touch. Surprisingly, they found that many of the neurons could respond to stimuli in several of these senses.
‘The neurons responses to combinations of sensory stimuli were often much greater than we predicted,’ said Wallace. ‘This suggests that these neurons have the capacity to greatly amplify their signals when confronted with stimuli from multiple senses.’
He said this finding may explain how multisensory stimuli can lead to improvements in our perceptions – such as how seeing a friend speaking across a crowded and noisy room can help us better ‘hear’ what he or she is saying.
In addition to studying these neurons in adult cats, the researchers also examined how multisensory neurons mature in the developing brain. They found that immediately after birth, multisensory neurons were not present in the neocortex. Only after several months of development did these neurons first appear, and they were strikingly immature, lacking the ability to amplify their signals. Several weeks later, these neurons began to acquire this multisensory capability“.
Sensory integration training is often used in treating autism and learning difficulties like dyslexia or ADHD and this research gives some theoretical basis to that approach. However I can’t find any published work on this research so treat the information with a pinch of salt.
Did you know the size of your pupils is a good indicator of your cognitive workload (i.e. how hard your brain is working)? This titbit of knowledge comes from the newish but very interesting Developing Intelligence blog. A quick search for pupil dilation and dyslexia or ADHD revealed nothing of interest. This is a shame because I suspect dyslexics would be shown to be working harder than normal children on most academic test.
On the research blog for the British Psychological Society there is a curious study that demonstrated that five year olds scored 18% better on a test when instructed to look away whilst thinking about the answer.
“The children were tested individually, with all questions posed by the same researcher who sat 1.5 feet in front of them. During a practice session and before the test proper, half the children were instructed to look away from the researcher while they thought of answers to the questions; the remaining children received no such instruction and acted as controls.
The researchers found that the children encouraged to look away while they were thinking, did indeed look away more than the controls (52.5 per cent of the time on average vs. 34.7 per cent). The difference was particularly noticeable for harder questions, whereas it was absent for the easy maths questions. Crucially, the children trained to look away also answered more questions correctly than the control children (72.5 per cent vs. 55.9 per cent)“.
If you have any theories, neurological or psychological, why looking away helps then please post a comment.
A good resource for parents concerned about their child’s vision is the Children’s Vision Information Network. As well as information on normal visual development in children it has information on the sort of problems that often go undetected and visions role in dyslexia and ADHD.