How we change what others think, feel, believe and do
When we are have tasks which we find relatively easy, we find the presence of other people a positive stimulus such that we perform even better. However, when the tasks are difficult, we find the audience unnerving and we are more likely to put in a worse performance.
When the task being performed is relatively easy, we are likely to do it more quickly. When the task is difficult, then we are likely to take more time to ensure we get it right (it is more embarrassing to be seen to be wrong than be seen to be slow).
This is because first, the presence of others increases physiological arousal such that our bodies become more energized, and secondly because when we are aroused it is more difficult to perform new or difficult tasks. The dominant response is that under arousal it is easier to do things we can easily perform.
The presence of others makes us suspect evaluation. Depending on how we forecast that evaluation, we may look forward to either adulation or criticism and rejection.
Zajonc, Heingartner and Herman (1969) got cockroaches to run down a clear tube towards a light. They ran faster when watched by other cockroaches. When put in a simple maze, it took them longer when they were being watched. (But did the watching humans have an effect? Who knows? :).
Michaels (1982) and three colleagues overtly watched students play pool. The better players got better. The novices got worse.
Top sports people are often lifted by the crowd to give their best ever performances at big events. Lower down the order, less confident sports people can find the crowds unnerving and consequently make mistakes.
When you want someone to feel good, give them an audience for an easy task. If you want to destabilize them, give them an audience for a difficult task. This will give you an opportunity to rescue them, building trust.
When an audience suddenly appears when you are uncertain about an important task, ask them to go away. Refuse to continue until they do and you have subsequently calmed down.