How does the presence of others affect individual behaviour?

How does the presence of others affect individual behaviour? In social facilitation, it enhances performance on easy tasks and inhibits performance on difficult tasks. It appears that others affect our performance by just being there, as evaluators, and by distracting us. In social loafing, the presence of co-performers reduces individual output. The key to understand this effect is that group performance allows task outcome responsibility to be diffused among fellow co-actors. Finally, in certain circumstances, people’s normal inhibitions diminish due to a loss of individual identity, and they experience what has come to be called deindividuation. By inducing anonymity and reducing self-awareness, deindividuation can unleash both prosocial and antisocial tendencies. (Franzoi, 2000)