[gzer0]

This is commonly referred to as Yerkes-Dodson Law [1]. This is typically where one's performance, whilst performing a task and being watched while doing said task, will result in decreased output compared to if the individual was not being watched at all.

[1] https://en.wikipedia.org/wiki/Yerkes%E2%80%93Dodson_law

[MonkeyClub]

Thanks for the formal name, I always knew it just as the "I can't go while you're watching" syndrome.