TEMPORAL CONSTRAINTS IN PROCESSING OF NONVERBAL RHYTHMIC PATTERNS

This study investigates the effect of a mental content of presented st imuli, normal aging and individual differences in cognitive abilities on temporal Limits of an integration mechanism. Younger and older subj ects grouped together the beats generated by a metronome. Subjects wer e asked to listen to the beats of a metronome and to accentuate mental ly every second, third, fourth...etc. beat, to create a subjective rhy thm. This rhythm exists, in fact, only in subjects' mind and not objec tively. Subjects reported verbally how many clicks they were able to i ntegrate into a perceptual unit. On this basis, the time interval duri ng which subjects were able to integrate temporally separated stimuli was calculated (number of beats reported as being integrated x time di stance between beats) for different metronome frequencies. The results show, firstly, that the length of integration periods significantly d epends on the frequency of presented metronome beats. When the frequen cy of metronome beats is high, the time interval during which the subj ects integrate beats into a single perceptual unit is shorter. Secondl y, older adults integrate information during a longer time interval th an younger ones. Thirdly, the length of an integration period is relat ed to a subjects' level of cognitive ability. These results suggest th at the length of an integration period is not a constant, stable featu re, but varies across the life span depending on the mental content of the information presented and individual factors.