He has been investigating the perceptual and neural bases of synesthesia for nearly 20 years, and has more than 30 publications on synesthesia. His work has appeared in specialist journals such as The Journal of Consciousness Studies, Neuron. Nature Reviews Neuroscience, and Science and popular journals such as Scientific American. He is a founding member of the American Synesthesia Association and co-hosted the ASA meetings in 2001 at UCSD and 2010 at Vanderbilt. In 2011, he was the keynote speaker for both the American Synesthesia Association and the UK Synaesthesia Assocation meetings. He is the co-editor, with Julia Simner, of the Oxford Handbook of Synesthesia, published in December 2013, which was recognized as a “highly commended” book by the British Medical Association in 2014.