1) A commonly used laboratory instrument that records the frequency of operant behaviour in real time. For example, paper is drawn across a roller at a constant speed, and each time a lever press occurs a pen steps up one increment. When reinforcement occurs, this same pen makes a downward deflection. Once the pen reaches the top of the paper, it resets to the bottom and starts to step up again. See also cumulative record.

2) A device that represents each response in real time in a standard cumulative graphic display format.

3) A device for obtaining a cumulative record of the responses of an organism.