A mechanical encounter or other energy-exchange may cause tissue damage.

(1979). Perceiving Acting and Knowing: Toward an Ecological Psychology. ).

In his classic work The Perception of the Visual World (1950) he rejected the then fashionable theory of behaviorism for a view based on his own experimental work which pioneered the idea that animals 'sampled' information from the 'ambient' outside world. They are all prosperous.