The diagram presents the cycle of human interaction with the computer as a circle divided into six equal pie wedges. There is a bold line splitting the left half of this pie from the right half and the left is labeled "human" and the right half "computer" to say that the three phases running down the left half of the circle, sensation, cognition, and actuation, are things done by the human; while the three phases running up the right half of the circle, input, computation, and display, are done by the computer. An arrow wrapped around the axle of this wheel indicates a couter-clockwise rotation, imparting the direction of flow: up the right side and down the left; from computer display to human sensation and from human actuation to computer input.
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