Professor Johnston joined the University in Canberra after three years as Pro Vice-Chancellor (Research & Innovation) at Murdoch University. Previously she was Dean of Graduate Research at the University of Newcastle and Dean of Postgraduate Research at the University of Canterbury, New Zealand. In 2004, she was a Distinguished Visiting Professor at the University of Connecticut. 

Professor Johnston completed her BA (Hons) in Experimental Psychology at the University of Oxford and her PhD in Social Psychology at the University of Bristol and is a qualified sport psychologist. She is an internationally recognised experimental social psychologist, whose research focuses on the non-verbal behaviour of individuals in social interactions. She has also undertaken research on various aspects of tertiary education.  

Professor Johnston was a member of the inaugural management team of the New Zealand Institute of Language, Brain and Behaviour, and following the Christchurch earthquakes in 2011, was appointed to the Psychosocial Recovery Advisory Group for the Joint Centre for Disaster Research. She was the Chair of the New Zealand Deans and Directors of Graduate Studies and a member of the Australian Council of Graduate Research (ACGR) and was involved in the development of the Australian Best Practice Guidelines for Higher Degrees by Research. She was Convenor of the Universities New Zealand Scholarship Committee. 

Awarded Oxford Blues and Colours at the University of Bristol for basketball she also played for the British Universities. She rowed for her Oxford College and the City of Bristol and played soccer for the University of Bristol. She has now retired from over 10 seasons completing in road cycling, ocean swimming and triathlons.