1. Gibson, J. J. The Ecological Approach to Visual Perception (Houghton Mifflin, Boston, 1979).
2. Lee, D. N. Phil. Trans. R. Soc. B290, 169–179 (1980).
3. Fitch, H. L. & Turvey, M. T. in Psychology of Motor Behavior and Sport–1977 (eds Landers, D. M. & Christina, R. W.) 3–35 (Human Kinetics Publishers, Champaign, Illinois, 1977).
4. Lee, D. N. in Tutorials in Motor Behavior (eds Stelmach, G. E. & Requin, J.) 281–295 (North Holland, Amsterdam, 1980).
5. Schiff, W. & Detwiler, M. L. Perception 8, 647–658 (1979).