What is the fine-grained topic of the following text: They created a pair of earrings that function as recording devices, a prototype for a visor with a dichroic reflective surface that allows its wearers to see but not be seen, headgear made to reflect threatening gazes back at the watcher, and a scarf equipped with patterns specifically designed to overwhelm facial recognition software. Only return the topic.
Prototype wearable technology for privacy protection