"Let's have lunch at that café — you know the one . . . Aquamarine," said my friend. And realized immediately, before even getting to the end of the word, that the café was not called anything like that. There is no Aquamarine café in Edinburgh. The one I rapidly guessed my friend was alluding to is a very nice Turkish place on Nicolson Street, and it's called Turquaz (their sign says "TurQuaz"). What the hell was going on with that crazy error? A random brainslip?
No. It wasn't so crazy. It had a rationale.
The key is that of the hundreds of words in English containing the sequence -qua- in an internal position, only one is the name of a shade of the color blue: aquamarine. And of course Turquaz, which also has an orthographic -qua-, is a phonetic rendering of the word turquoise, which is also the name of a shade of blue—almost exactly the same shade of blue, in fact (the RGB values according to Wikipedia are turquoise = <64, 224, 208> and aquamarine = <127, 255, 212>, and very few people could reliably distinguish them).
Assuming that when you're trying to activate your recollection of a proper name you may have aspects of the word's orthographic shape and aspects of its meaning in mind at the same time, the mystery largely dissolves.
Aquamarine wasn't a whacked-out inexplicable error. My friend needed to solve a pair of simultaneous equations, in a fraction of a second (you generally need to retrieve lexical items in a few hundredths of a second to keep talking at a normal pace):
- spelling(X) = …qua…
- meaning(X) = light greenish shade of blue
There is just one solution for X in the English lexicon, so it wasn't at all strange to retrieve that, instead of the non-word that was the actual target. And I think it should reminds us that people probably do their lexical access in a way that involves orthography, phonology, morphology, syntax, semantics, and pragmatics simultaneously. My friend didn't just link the spelling TurQuaz to a specific business on Nicolson Street without any reference to what turquoise means; there was a lot more going on than that.
[Thanks to Eric P. Smith for relevant information.]