Spelling ability is a significant predictor of an individuals global IQ?
Not spelling. My brother is incredibly smart, but dyslexic. My son is incredibly smart, but six. I'm incredibly smart, but have autocorrect. ;)
Hell, I'm a professional writer and I STILL f**k up it's vs. its on a regular basis. I'd say probably vocabulary is a much better predictor -- but I think the best such predictor is the ability to "play" with language in a way that other people grok.
Like if I said "We were all gawkward at a few enshambled hice in the midst of some Old-White-Man-sions we passed," the fact that you can read that and understand what it means and understand that it's pungrammatical means I'm fulls geniusy. :)
Vocabulary is. I'd assume spelling to show some indication but less usefully than vocab.
Probably. It's an indication of education and thinking of the variables that predict education, most of them would be good predictors of IQ (or the ability to score well on IQ tests).
It's weird because vocabulary comprehension, especially with regards to the WAIS-IV test, is a predictor of IQ, but spelling apparently isn't. I'm sure spelling helps in academic situations though.
Hmm. Maybe the lower-level cognitive stuff is just an indirect effect, while the higher-level stuff is a direct correlation.
Though vocabulary comprehension is an excellent predictor of IQ, spelling itself is not.