Complex sentence: A different triad is chsoen, a further construct elicited, and all elements rated on this new construct; and so on, until the interviewee indicates that s/he can think of no other constructs.
Split into simpler sentences: A different triad is chosen, a further construct elicited, and all elements rated on this new construct. And so on, until the interviewee indicates that s/he can think of no other constructs.