cold reading

cold reading (countable and uncountable, plural cold readings)

1. The technique, or an instance, of using likely guesses and assumptions, then narrowing in on any positive responses, in order to give the impression of having information about a person or event.

   The self-described psychic was merely using cold reading.

2. Used other than figuratively or idiomatically: see cold,‎ reading.

   Acting auditions often include cold reading.

•   cold reading on Wikipedia.Wikipedia