ANSWER: LIE SCALE
EXPLANATION:
LIE SCALE refers to a set of items (scales) within a psychological instrument or inventories used to indicate whether a respondent has been truthful in answering varied questions.
Hence, Lie scale is used to detect lie and can be expressed as "truthfulness indicators".
Thus, the psychologist (Calvin) make use of redundant questions which elicits the same information but expressed in different question formats to determine the consistency of answers presented by his clients.