A discrepancy as large as the one you describe between processing and the other scores is an indication of a learning disability.
Really?
Maybe, maybe not. "Profile analysis" (i.e. determining diagnoses from an IQ profile or scatter alone) can be inexact and is controversial. I've seen slow processing speed on IQ be an artifact due primarily to factors like perfectionism, age of the tester contributing to immaturity and misunderstanding the need to do that part as fast as possible or unwillingness to do so, or a variety of other non pathological factors. I've also seen it occur when there is a problem such as dysgraphia, dyspraxia, ADD (where the speed may not be truly slow but so many mistakes are made on the types of visual scanning and rote tests that IQ processing speed tests entail that the score comes out low)...
My general approach is to only assume a LD or other problem if issues are seen IRL. Do you notice your dc taking longer to complete tasks that are at the appropriate level of instruction? For instance, my one kiddo with true low processing speed can perform extremely highly at tasks that are well above grade level (they are the appropriate level of instruction for her), but she is slow at it. We've always called her "deep, not fast."
