Scientists have found that clapping is contagious, and applause length is influenced by the behaviour of members of the crowd.
Lead author Dr Richard Mann, from the University of Uppsala, told the BBC that a person can get different applause length - even if the quality of the performance is same.
Scientists carried out the research by studying video footage of groups of undergraduates as they watched a presentation.
They found that it took just one or two people to clap together to build a ripple of applause.
Mann said that the pressure comes from the volume of clapping in the whole room rather than what their neighbour was doing.
They also found that the performance that was witnessed - no matter how good - had little effect on the duration of the applause.
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Dr Mann said that all this comes from the social pressure that a person has to start clapping, but once they have started there is an equally strong pressure not to stop, until someone initiates that stopping.
The researchers believe that clapping is a form of social contagion, which can give a insight on how ideas and actions gain and lose momentum.
The Swedish study has been published in the Journal of the Royal Society Interface.