Fig 10. Relative frequency of visits less than or equal to four presses and of visits longer than four presses for the first nine reinforcers in a component.

Top: First visit to the just-reinforced lever following a series of continuing reinforcers from the same lever (triangles) or following a series of continuing reinforcers ending with a discontinuation (squares). Bottom: Interreinforcer visits beginning with a changeover following a series of continuing reinforcers from the same lever or following a discontinuation. Filled symbols represent visits to the just-reinforced lever. Unfilled symbols represent visits to the not-just-reinforced lever. Triangles represent visits to the rich lever, and the squares represent visits to the lean lever. See text for more details.