Johansson (1975) attached lights to an actor's joints. While the actor stood still in a darkened room, observers could not make sense of the arrangement of lights. However, as soon as he started to move around, they were able to perceive the lights as defining a human figure.

ratio. Tau on its own would be insufficient to estimate time to contact, because the two objects would always be at different distances from the observer throughout their flight.

Tresilian (1995) argued that the tau hypothesis may be of most relevance when the moving target is viewed briefly, when a response needs to be made rapidly, and when the perceiver is well practised. When these conditions do not apply, then perceivers may use various cognitive processes to determine time to contact instead of, or in addition, to tau.

In sum, several sources of visual information can be used to facilitate the task of catching a moving ball or other object. Tau may be the most important variable, but familiar size, binocular disparity, angular position, and velocity of the object relative to the participant are other important variables.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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