There are numerous studies, behavioural and objective (electro-physiological; functional brain imaging, pupil dilation etc.) that show that hearing impaired adults and children expend more effort in hearing. There are more brain connections involved in understand speech.

My own group has shown this in children using cochlear implants.

the more brain activity, the more metabolic energy used, more fatigie etc. This is a well researched area.

You can use reflective thinking methods to assess the thinking prowess of a person who is hearing impaired.

Administer the same battery of standardized IQ and cognitive tests as used for the normal hearing.

A multi-modal approach can be used to assess the thinking processes of any person--deaf or hearing. They include: systematic observation using a set of criteria related to cognitive processes; standardized tests of reasoning such as the Raven's Matrices; analysis of the person's written products for evidence of such criteria as depth, sequence, logic, comprehensiveness, and understanding;standarized individual methods such as certain subtests of the Woodcock-Johnson test; and individual interactive interviews in which the interviewer uses probes to get at the same criteria as named above for analysis of written products.

---David S. Martin,[email protected]

"standardized tests of reasoning such as the Raven's Matrices"

What is the evidence that this, unlike the unbiased Wechsler P IQ, is a valid measure of g in the Deaf? In other words, that they do not score below the normal mean, as standardised on the hearing, because of some contribution of verbal ability to the Ravens IQ?

Excellent question, which I would not be able to answer directly. However, in my own research with deaf learners, as well as others who have used the Matrices with deaf learners, the test was selected specifically because

(a) the Matrices have shown in prior research with learners of different types of populations that they are sensitive to the effects of a visually-based cognitive education program (Instrumental Enrichment), which in this case was the experimental condition , and (b) because the Matrices have the advantage of being non-verbal, of course, and are visual---requiring the application of reasoning processes--which makes it ideal for assessing deaf learners. During the administration there is no discussion during the testing, oral or signed, because they are individualized. In the case of the research that we did, we expressly selected experimental and control groups with severe to profound hearing loss, and in their upbringing there had been no possibility of input with auditory language; of course, since they used American Sign Language, there would be some verbal ability derived from mastering the grammar and syntax of that Language, but none due to experiences with auditory language and that effect would have been constant across experimentals and controls. With deaf learners, the only interactive input is that we used sign language to explain the process,and to work through one sample page; then students were left on their own at their own pace within a particular time frame (pre and post)--15 minutes. I am , I realize, only answering your question indirectly, but it is all that can be said with certainty. I hope it helps at least somewhat. Thank you for the question.

"the Matrices have the advantage of being non-verbal, of course, and are visual---requiring the application of reasoning processes"

Face validity is not the same as Construct validity. What is the factorial evidence for the absence of a loading on Verbal Ability (exclusive of g)? It would be quite surprising if compensatory verbal strategies were not developed.

You raise a valid question. The manual for the Matrices tells that the test is a measurement of fluid intelligence--reasoning and problem-solving ability; fluid intelligence is a core component of g; it further notes that the simplicity of the test's use and interpretation is coupled with its "independence of language and reading and writing skills"--that was and is the rationale for the selection of that test as one of the measures related to the effects of the cognitive-education program. However, I don't find anything explicit regarding the absence of loading on Verbal Ability, exclusive of g. I appreciate your points because they can assist in the any discussion of the possible limitations of studies using the test with deaf individuals. If you should locate anything related to the factorial evidence, I would be very pleased to know of it. Thanks again for your ideas.--David

See sentence below I have highlighted. I have not reviewed subsequent data, but on this basis Raven's test are dubious in the congenitally deaf

"MH’s book review of Deafness, Deprivation, and IQ (Braden 1994)

SEPTEMBER 21, 2014 / MENG HU / 0 COMMENTS

Jeffery P. Braden. (1994). Deafness, deprivation, and IQ. Springer.

The book is a compilation of studies on deaf people, which concludes that cultural deprivation due to deafness lowers verbal IQ but not nonverbal IQ. Braden sought to prove Arthur Jensen wrong about his conclusions on the genetic component in racial differences in IQ. At the end, his research culminated in a trauma well known to scientific history, namely, his perfectly good theory was ruined by his data. Being born deaf does not affect g. And genetic theories are the most powerful arguments to account for the pattern of the data...

The state of research is that deaf and normal-hearing people perform similarly when the language demands, but not the intellectual demands, of the tasks are reduced. Verbal language is therefore not a mediating factor (p. 9). The language barrier is so serious that Binet & Simon (1914), the inventors of modern intelligence tests, have declared long ago that verbal IQ was absolutely impracticable for deaf people (pp. 35, 77)...

After this description, Braden examines closely the magnitude of the group difference in IQ scores. He has collected a large amount of studies and graphed all the data points. The samples range from 4 to 21,307 with a median of 60.5.

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Given the normality of distribution in scores depicted in the above graph, we have no doubt that the performance IQ of deaf children tends to be near 100. This is the central value on which the data points tend to converge, and was derived from a total of 193 studies...

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A closer inspection of the 195 reports (i.e., distinct samples) shows the IQ of deaf by type of test, as depicted in the above graph. The mean verbal IQ of 85.54 (SD=9.54) from 32 distinct samples is close to the IQ estimates usually given to blacks (Rushton & Jensen, 2010). The standard deviation of VIQ (MSD=12.84, SDSD=3.26) is also lower than among the normal population. The mean of performance IQ is 99.95 (SD=10.52). The average standard deviation derived from 119 studies of PIQ is also strikingly similar to that of the normal population (MSD=15.36, SDSD=3.11). With regard to motor-free nonverbal IQ, the mean (77 studies, M=94.57, SD=7.97) is lower but not the standard deviation (51 distinct samples, MSD=15.95, SDSD=3.64).

We first examine the different nonverbal IQ tests. Braden (pp. 81-82) suggests 4 explanations for the lower motor-free nonverbal IQ. First, the processes required for motor-free tests of intelligence are not easily demonstrated. Second, manual manipulation and dexterity skills boost the performance on this kind of test. Third, the solution of motor-free items is facilitated with verbal mediation. This is suggest by a study of Conrad (1979) in which the performance of deaf with internal language skills on this test is higher than the deaf without internal language skills. Fourth, performance IQ tests yield greater feedback than motor-free tasks, and consequently provide impulsive individuals with cues to let them know when their problem-solving strategies are unsuccessful. This in turn gives them the opportunity to correct their responses."

This exchange and chain has truly been most informative, and Jeff Braden is certainly a highly respected scholar in this field--in fact, he accepted an invitation to present at a Symposium on Cognition and Deafness and wrote a chapter for the subsequent book, that I had organized during the 1990's. I would hope that future researchers would keep these points clearly in mind;I am retired at this point and no longer conducting any active research. Thank you to everyone.