In recent years, technological advances in electronics have been applied for designing flexible and inexpensive interfaces for recording and controlling events in operant research. One example, tested for accuracy and reliability, uses the popular Arduino microcontroller boards in combination with Visual Basic Express Edition programming. This paper describes one of the applications of the Arduino-Visual Basic interface to record movement using photocells. Each photocell uses a phototransistor, and an infrared LED, and allows recording the interruption of the light emitted by the infrared LED. Such interruptions are detected as responses, and are used to schedule experimental events in Visual Basic programs. These photocells can be used in diverse experimental settings under varied conditions of illumination