1. Animal vision, particularly the optics of eyes and visual control of behaviour.
2. Human eye movements during everyday actions such as driving, playing ball games, preparing food and reading music.
3. The maintenance of a stable world in spite of movements of the eyes, head and body.

I am still active in the field of animal vision, but much of my work in that field was consolidated in a book 'Animal Eyes' with Dan-Eric Nilsson from Lund in Sweden. The book was first published in 2002 by Oxford University Press, and in a new edition in 2012. The book is written for a general readership, but particularly students of biology and vision science.

From about 1990 I became interested in human eye movements. Although there had been a century of work on eye movements, very little had been done on the eye movements strategies people use in everyday life. I built a highly portable eye-movement camera, and studied where people look during everyday activities. Much of this work, and a review of the field, is contained in a book I wrote with my former student Ben Tatler (now a Reader in Psychology at Dundee University). Its title is 'Looking and Acting: Vision and Eye Movements in Natural Behaviour', published by Oxford University Press in 2009.

In the last few years I have become interested in the ancient problem of why the subjective world stays still in spite of the more or less continual shifts of our position and viewpoint within it. My thoughts are summarised in an article 'The Operation of the Visual System in Relation to Action' in Current Biology 22, R811-817 (2012).  

I am also writing a short book 'The Eye. A Very Short Introduction' for Oxford University Press.

I have written about 180 papers on various topics on vision in animals and men.

I continue to teach in various biology courses at the University of Sussex, where I have been based since 1971.