After he moved to Paris, he socialized mostly with his family and, since he was a suspicious man who suffered from a mild but persistent persecution complex, with a small circle of trusted associates.
The time-sensitive pattern created by that pinch-circle motion, along with the motion involved in rotating the dial, are complex enough that Memon says a study of about 100 users has shown it can identify users with about 2% false positives and 2% false negatives.