During the TIME100 Summit, Apple CEO Tim Cook said he fears “deeply the loss of privacy” as tracking through digital devices and technology grows, Time reports. Cook questioned whether the constant feeling of user surveillance will lead to behavioral changes. “We begin to do less. We begin to think about things less. We begin to modify how we think,” he said. “In a world like that where we’re restraining ourselves, it changes society in a major way.” Cook also said individuals’ ownership of their own private data is “a large concern of mine.”