Dr Lasana Harris, Experimental Psychology, explains the bystander effect on BBC iWonder

Dr Lasana Harris, Experimental Psychology, speaks with Brooke Kinsella, actor and campaigner, about the bystander effect as part of a BBC iWonder article on whether we would help a stranger in distress.

In a staged a demonstration to show how people in a crowd can be influenced by the bystander effect, in which an actor plays a man in distress on a street, Lasana shows Brooke that if no one walking past stops, then other people will also fail to stop. The busier it is, the less likely people will stop. In the demonstration, some people ignore the man in distress, whilst others see him but take no action.
However, when one person stops to help, others are more likely to also take action, and this is because we get our information from those around us.

• Watch the demonstration and read the full article on the BBC iWonder website