What do I call a person who is participating in a survey?

Solution 1:

I suspect participant may be more common, particularly when pluralised, but that may simply be because it's a more common word applicable in many other contexts. For a single individual in this context, respondent seems more precise to me.

It's less common, but I think interviewee is equally suitable in OP's context.

Solution 2:

You would call that person a participant in the survey.

Solution 3:

I have some experience in the surveying industry and we call them respondents.

Solution 4:

For completeness: Google gives some hits for surveyee, e.g. on Wiktionary.

But I do think participant or respondent as suggested in other answers goes better with investigator.

Solution 5:

Most of the answers have decided on participant, which I think is the most appropriate. We can also use respondent, according to the following combase.ca glossary entry:

Respondent: Refers to the selected person in the household who will answer the questionnaire.