It may be that global measures of intelligence are not very helpful. Some people with dyslexia have high verbal IQ, others have high performance IQ, others have even verbal and performance (just like the more general population).

I would imagine that the psychometrics being used are those that measure logic and analytical performance rather than IQ to produce a profile that is useful in the selection process. Compensatory skills such as fortitude and being able to persist with soemthing that is difficult would be helpful.

Deficits found in many (but not all) dyslexics such as poor working memory and slow processing speed would not be very helpful unless compensatory skills (such as developing chunking strategies or mnemonic strategies) were developed.

"It may be that global measures of intelligence are not very helpful. Some people with dyslexia have high verbal IQ, others have high performance IQ, others have even verbal and performance (just like the more general population)."

What evidence is there that developmental dyslexics have higher verbal than performance IQs?  (ie, as a group, not in individual cases) 

Dear Anthony,

It is very interesting question. The paradox of Dyslexia is seen in many cases but it is not with all cases. some of them are slow reading but fast thinking and others are different. Reading takes dyslexic people more time than others and it make them frustrated. In this case the IQ test  score would be lower but not real.

People with dyslexia are those whose reading is compromised by an underlying deficit in phonology -- making a mental link between small units of sound and their graphical representation in letters.  Their reading mechanics are poor, but they range in their reading comprehension and verbal reasoning to the same degree, and in the same bell-shaped curve, as the rest of the population. Their auditory working memory may be overwhelmed when they are dealing with text, but many know how to accommodate with screen readers and other technologies.  Some people with dyslexia also have  strong perceptual reasoning, but again, those abilities vary as widely in this group as they do in everyone else.  People with phonological impairments who are nonetheless successful in their chosen fields may be more likely to have good visual-spatial abilities, a good ability to interpret nonverbal communication, awareness of their strengths and weaknesses, and a set of compensatory strategies they have developed over time. .   

btw, the description of "dyslexics" sounds more like people on the autism spectrum than it does people with dyslexia... 

"Their reading mechanics are poor, but they range in their reading comprehension and verbal reasoning to the same degree, and in the same bell-shaped curve, as the rest of the population."

Surely not.  My impression from the literature is that the verbal IQ bell curve for developmental dyslexics is shifted to the left by about 5 IQ points as a result of the underlying phonological defect and consequent disordered auditory input, at the time when the brain linguistic systems were being imprinted.  If reading ability did not mirror V IQ, the driving force for school attainment, then why do we worry so much about dyslexia?

I should have made it clear that I was only considering high-achieving adults, which seemed appropriate given the reference to employment in the question.

In my clinical and research experience, there is no downward shift for adults with dyslexia in reading comprehension, as long as reading tests are untimed (Stothers & Klein, 2010). Untimed reading tests allow adults to compensate for their poor reading mechanics. This is similar for tests of pure verbal reasoning tests -- VCI, not VIQ -- that don't make demands on auditory working memory.  Vocabulary is an exception, yes, but individuals demonstrate positive change with targeted intervention.  Improvement also occurs over time for adults who read using non-traditional methods like Kurzweil screen readers.  Of course five IQ points doesn't begin to explain unexpected underachievement in people with dyslexia.  It's that poor reading mechanics are a huge barrier, given that much of the rest of the curriculum at any level rests so heavily on text.  

IQ measures in themselves are contraversal enough. Also what type of dyslexia are you considering in your study? As a child I was subjected to several of these tests along with my peer group yet dyslexia was not considered when they were implemented. Dyslexics have interesting abilities that are not present in the general population for instance eidatic memory , pattern recognition, lateral thinking, problem sovling and creatiity all qualities GHQ would find extremely useful.  Vocabulary is not always a limitation as listening and verabal  skills can be present especially with the use of audio books. 

Garry Squires,

The label, 'diagnosis etc.' of dyslexia is too broad to be used in this context. The mentally impaired are often labeled dyslexic, however, the subgroup of individuals that the post is referring to is the 'high performing' dyslexics. I would do a k nearest neighbor or a k-means and see if there is a distinct difference between the 'outdated' classification. They used a supervised algorithm when they should have looked at the unsupervised output first.

I would like to see how the different kinds of dyxlexics would group. Development, etc. I will look into M.E. Stothers work and get back to this post at a later date.

Good Answer Anthony G Gordon

Just a single case, but I was diagnosed as dyslexic, by an educational psychologist, with a verbal IQ of 128 and a performance IQ of 106. The information leading to the dyslexia diagnosis seemed to be more from other tests of reading accuracy and text comprehension.

" Just a single case... "

In the 6y this question has been up no one has produced group data of V higher than P IQs.

Which deficits in specific skills or abilities do you or your psychologist think accounts for your dyslexia?

This research reports on a group of dyslexic children with a mean verbal IQ score of 130. They were compared with dyslexic children who had verbal IQ < 100. The groups did not differ on several working memory / executive measures (indicating relatively poor performance by the high verbal IQ dyslexics). Although performance IQ was not specifically reported, it is clear that your statement about dyslexia being defined by low verbal IQ is not correct. In the published group study, the dyslexia is related to working memory problems, independently of verbal IQ.

Article Differences Between Children With Dyslexia Who Are and Are N...

"Although performance IQ was not specifically reported, it is clear that your statement about dyslexia being defined by low verbal IQ is not correct."

I don't think I said dyslexia was defined by absolute low V IQ. It is the discrepancy between V and P IQ that matters. Like autism, there is no upper limit to full scale IQ in dyslexia, as witnessed by the large number of very prominent dyslexic high achievers. My interpretation is that FS and P IQ depend on the state of the brain which I take to be normal (or at least it starts that way), whereas V IQ is very dependent on patterned auditory input in infancy, which I think is abnormal in dyslexia. The congenitally deaf have normal P IQs but quite low V IQs.