Professor Halligan gained qualifications in psychology, philosophy and education at University College Dublin. In 1985, he moved from Ireland to work at a specialist NHS neuro-rehabilitation Centre in Oxford as a research psychologist while also pursuing a PhD in neuropsychology. In 1987, he joined the Neuropsychology Unit at the Department of Clinical Neurology in Oxford University and in 1997 following a MRC Senior Research Fellowship award, joined the Department of Experimental Psychology in Oxford. 

In 2000, he moved to Cardiff’s School of Psychology as a Distinguished Research Professor and in 2003, he played a central role in establishing Cardiff University’s Brain Research Imaging Centre (CUBRIC), becoming the founding Director.

From 2010-2014, he was Chair and Academic lead of the Welsh Crucible, the all -Wales staff leadership programme for early career researchers. In 2012, he joined Universities Wales as Head of Strategic Futures as part of a 2 year secondment.

In March 2018, he moved from the role of Chief Executive at the Learned Society of Wales to become the third Chief Scientific Adviser for Wales, working in the Welsh Government. 

Prof Halligan is a research psychologist and neuroscientist by background. He has worked in neuropsychology, neuropsychiatry and neuro-rehabilitation and has published over 200 papers including papers in Nature, BMJ, Lancet, Nature Reviews Neuroscience, Trends in Cognitive Science and also edited 10 books.