Barry has pioneered studies of how instinctive behaviours are genetically programmed into an animal's nervous system, focussing as a model on the reproductive instincts of the fruit fly Drosophila. He has also developed powerful genetic tools for probing the functions of individual genes and neurons in Drosophila.

Barry is a member of the European Molecular Biology Organisation, a Fellow of the American Association for the Advancement of Science, and a recipient of the Wittgenstein Prize from the Austrian Science Fund.