<p>Hi, neuropsychologist here!</p>
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<p>First of all, a pp was right that one or two subtest (and only 2 make up the Processing Speed Index) should not really be interpreted in isolation. That said, a slower coding speed can be "caused" by many,many things... starting with something as basic as distraction during that particular subtest. Was it given when he was hungry? Had to use the bathroom? Getting tired? A lower score there can also point to (relative) fine motor, attention, or other motor skills. However, your son's Processing Speed Index, while certainly a weakness for HIM in relation to his other Index scores is still, at 37th percentile well within the average range. So, although he may percieve this (accurately) as an area that is not as strong as his others, compared to the world (and to his classroom) he is still working at a speed that is well within the expected range (so he is not likely to be finishing last, for example).</p>
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<p>I've tested and worked with some very gifted children who end up displaying behavior and academic problems in school partly because they are SO used to things coming extremely easily to them (and always finishing first, always understanding right away, etc.) that when there is an area of RELATIVE difficulty (i.e. something in the average range like your son, or maybe difficulty with an algebra unit) they really struggle with how to cope with this challenge on an emotional level. (Not saying, obviously, that this is anything that is happening for your DS, just something that I've seen). In addition, even the most gifted of people are really unlikely to be equally excellent at everything.. and the higher your son's many strengths are, the more likely it is that something will be significantly below them... since almost any score is way below them. Does that make sense?</p>
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<p>So, unless the Processing Speed Index (which, again, is solidly average) score exists in the presence of other issues (i.e. ADHD, behavior problems in school, difficulty completing work in expected time frames, fine motor skills issues, etc.) I wouldn't worry much about it. The coding subtest, which requires both processing speed skills, fine motor skills, and even some memory skills doesn't always relate well to board copying, which also requires far more concentration and visual skills.</p>
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<p>Also, just wanted to comment briefly on the question of non-verbal learning disorder. Your son's IQ scores are definately not consistent with that diagnosis... especially if there isn't a history of math learning disablity, social skills deficits, anxiety, motor skills deficits, visual spatial deficits, etc. Though not all of those symptoms are found in every kid with NLD, having gifted-range visual processing skills on an IQ test and above grade level math skills would make it extremely unlikely. (although, off topic, there is some discussion in the field about there being a sort of variety of NLD which does not include math type deficits, but is more of a social learning disability.</p>
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<p>Hope some of that helps!</p>