The temporal organization of human perception and cognition is apparently of discontinuous nature. Stimulus processing appears to be temporally segmented by sequential processing units of 30 to 40 (more conservative: 20–50) ms duration. Such time quanta may reflect 'system states' brought about by neuronal oscillations. These oscillations are stimulus dependent and, thus, can be described as relaxation oscillators. Successive system states can be linked together by an integration mechanism. Such temporal integration has an upper limit of a few (approximately 3) seconds. This integration can be conceived of as one of the fundamental mechanisms of mental activity because it provides discrete temporal segments within which unique chunks of percepts or cognitions are represented.