London, Oct 20 (IANS): Scientists from Queen Mary University of London have developed an app to understand why some rhythms are more difficult to perform than others.

The team collected and analysed a huge dataset of more than 100,000 people and found that changing rhythm is more difficult than playing a complex individual rhythm.

"It is quite rare in music psychology to study the performance of rhythms that change, especially when played in ensemble with another player, and yet these are very common in actual music," said Dr Sam Duffy from Queen Mary's School of Electronic Engineering and Computer Science.

The app challenges users to play Clapping Music -- a ground-breaking piece of music written by contemporary classical composer Steve Reich which is performed entirely by clapping.

In the original piece, two people clap the same short rhythmic pattern while one shifts the pattern gradually until the patterns align again.

In the app, developed with the London Sinfonietta and Touchpress, the device takes the part of the performer playing the static pattern and the user takes the part of the performer making the pattern transitions.

Rather than clapping, players tap in a performance area in the lower part of the screen.

Users from more than 100 countries have downloaded the app more than 250,000 times since the launch in July 2015.

The research focused on the first 12 months, including 109,303 players and a total of 46 million rows of gameplay data.

The results, published in the journal PLOS ONE, provide a new understanding of the musical factors that determine how easy or difficult it is to play a rhythm.

The findings showed show that performance accuracy varied not with the complexity of the individual rhythms in the piece but with the complexity of transitioning between rhythms, which is not something that has been investigated in traditional lab-based music psychology.

"In spite of the apparent simplicity of Clapping Music, it is a challenging piece to perform and the app generated a very large and complex set of data to analyse," said Dr Duffy.

The researchers hope the findings could lead to similar large-scale game-based approaches to investigating other aspects of music psychology than rhythm and even the psychology of other artistic areas such as music and dance.