1) In a fixed-ratio schedule of reinforcement a fixed number of performances (counted from the preceding reinforcement) are required for reinforcement. Thus on an FR 50 schedule, the fiftieth performance after the preceding reinforcement produces the next reinforcement. The term ratio refers to the ratio of performances required for each reinforcement.

2) upon completion of a fixed number of responses counted from the preceding reinforcement. ("Ratio" refers to the ratio. responses/reinforcement.) A given ratio schedule is designated by adding a number to the letters FR to indicate the ratio. (E.g.,FR100is a schedule of reinforcement in which the 100th response after the preceding reinforcement is reinforced.) food magazine, see magazine.

3) A schedule of intermittent reinforcement in which a response is reinforced