Bouncing babies can become junior scientists by taking part in a fun experiment at the University of Essex.

Ten-month old babies are required by Dr Claudia Uller of the Department of Psychology as she seeks to discover if babies can differentiate between number and size.

In a quick series of experiments babies will be invited to choose between a selection of cookies, some will be spaced out to clearly indicate how many there are, while others will be close together to resemble one big cookie.

Dr Uller said: 'It has already been shown that at ten months babies have a rudimentary idea of numbers, if you show them two jars of cookies, one with three in and one with two in, most of the babies will head for the jar with the most cookies.

'However when you get to four to six cookies they find it more difficult to tell the difference, so we are devising an experiment to see if they make their decisions based on mass or density.'

The babies need to be aged ten months between June and November and each child taking part receives a child scientist certificate and a special Graduate of the University of Essex Infant Cognitive Laboratory tee-shirt.

The Infant Cognitive Laboratory is always looking for babies under 12 months for their research and anyone interested can find out more on their website www.essex.ac.uk/psychology/ICL or e-mail iclab@essex.ac.uk.