She joined the Department of Psychological Science at La Trobe University in 1996 where she established her autism research lab.
In addition to detailed behavioural observation studies, she investigated the physiological correlates of behaviour including the cardiac and attentional responses of Autistic children to social and emotional stimuli and undertaking studies of biological markers.
[6] More recently, Dissanayake has engaged in studies of Autistic adolescents and adults focused on employment and mental health.
[7] In 2018, Dissanayake was elected Fellow of the International Society of Autism Research[8] in its inaugural round, and served as vice-president between 2019–2021.
In 2021, she was awarded a Lifetime Membership by the Australasian Society for Autism Research,[9] which she helped co-found in 2011, and where she served as vice president for 10 years.