IQ and Deaf people APDSIG 11th March 2011 Kevin Baker National Deaf Mental Health Service, Birmingham, & Nottinghamshire Healthcare NHS Trust

Why assess IQ? Subtests of an IQ test (WAIS, WISC, etc) can be used clinically to analyse cognitive processing difficulties in more detail – this helps other people understand a person’s behaviour better. Groups of subtests are grouped together to describe g, or an Intelligence Quotient. These two things are very different!

Adapting for Deaf people Like any person you need to adapt the instructions to make sure you have good engagement and informed consent. Consider how delayed language (spoken and sign) and sign language of the person forces you to adapt description/instructions, and how the test is administered. Not much different to using test materials with people with an intellectual disability?

Adapting for Deaf people Tests drawing on linguistic abilities can be used – but be aware of how to interpret these. Linguistic & cultural isolation: VIQ/VCI subtests are culturally specific – Flynn Effect Are you comparing with the general population or comparing with people who have had similar opportunities? What do you need to say?

ID Classification age of onset in childhood (below 18) a significant impairment of intellectual functioning (IQ 2sd below mean = <70) a significant impairment in two or more areas of adaptive/social functioning.

IQ <70 IQ = PIQ + VIQ IQ ≠ PIQ E.G. : PIQ 72 + VIQ 72 = IQ 70 Don’t rely on PIQ to give you any accuracy about a Deaf person’s IQ You can only compare them with the performance of hearing people of the same age

IQ Do we want to compare a deaf person with their deaf peers – deaf children of hearing parents (90%),or deaf children of deaf parents (<10%)? Do we want to compare a deaf person to the “norm” of the general (hearing) population? Can’t do the first at the moment. We can do the second – but deaf people will have very low IQs because of poor performance on the Verbal subtests. But perhaps this is a good thing?

Adaptive functioning Need significant difficulties in two areas: Community use Communication Functional Academics Home Living Health & Safety Leisure Self care Self direction Social

Adaptive Functioning of Deaf People Do we want to compare with deaf peers or general (hearing) population?

What about other IQ tests? WNV – deaf norms up to 21 Snijders-Ooman Non-verbal But no verbal/cognitive assessment or language assessment. Language assessment is important BEFORE cognitive assessment in order to gauge the understanding of the test!

Other aspects of cognitive functioning that are important? Executive functioning Working memory – visual memory, symbolic memory, narrative memory Ability to use metaphor Theory of mind Social and applied cognitive abilities following on from language development