What kind of curiosity does Frankl write that the prisoners had?

Frankl writes that a "cold curiosity" developed among the prisoners who would use this to detach their minds from their surroundings. They grew curious about how long they could survive "standing in the open air, in the chill of late autumn, stark naked, and still wet from the showers." They were curious about their own survival at the same time that they were surprised to learn they could survive what they never imagined they could.