1) A discontinuous observation procedure in which the observational period is divided into intervals but the observer only notes the status of the target behaviour during a "moment" following the end of each interval.

2) A time-sampling procedure in which a response is recorded only if it is occurring at the point in time at which the interval terminates. For example, a timer goes off at the end of a 10-minute interval, and the observer cheques to see whether the youngster has his thumb in his mouth at that moment.