I suppose one way to answer this is a tad sarcastic – it depends if the psychologist is working across more than one sport or not! Truth be told the correct term is ‘sports psychologist’ using the plural version of the word ‘sport’. If the psychologist only worked with clients of a single sport it would make much more sense to refer to yourself as a ‘golf psychologist’ or ‘tennis psychologist’ (for example).
The reason why the singular version – sport psychologist – still gets used a fair bit (hence the confusion) is down to something called ‘word blending’. Word blending occurs when the end of one word in a phrase or sentence has the same sound as the start of the next word and therefore the words gets ‘blended’ and it’s not actually possible to hear where that common sounds belongs. Examples in English are ‘apple lover’ and ‘circus stars’.
Due to word blending the terms ‘sports psychologist’ and ‘sport psychologist’ sound exactly the same when spoken and this has caused some confusion regarding the correct spelling.
Note: this article was written before we stumbled across a very informative blog post on the same topic by Canadian sports psychologist Kate F. Hays where she correctly points out that the original correct spelling was actually without the s – so sport psychology and a