Acta Psychologica 46 (1980) 95-102 0 North-Holland Publishing Company PERCEPTUAL CENTRES FOR DUTCH DIGITS * Paul A. ELING and John C. MARSHALL Interfakultaire Werkgroep Taal- erl Spraakgedrag, The Netherlands Gerard P. VAN GALEN Dept. of Experimental Psychology, Utliversity of Nijmegen, The Netherlands Accepted January 1980 In two experiments, analogous to those reported by Marcus (1976) with English words and sub- jects, we determined the psychological moment of occurrence @-centre) of Dutch digit names. In the first experiment we determined the p-centres for the digits 1 through 10 and compared the empirical results with values calculated from the formula that Marcus defines over the acoustic characteristics of stimulus words. We found good agreement between empirical and predicted values. In a second experiment we studied the effect of cycle time and repeated mea- surement on perceptual centres. The results confirm the independence of the p-centre phenom- enon from practice and periodicity. A comparison of ‘identical’ and ‘non-identical’ stimulus pairs shows that larger variances are associated with the former condition. Introduction When Morton et al. (1976) tried to prepare tapes with a computer with items (words) at ‘regular intervals’ they noted that perceptual regularity was not simply a question of physical regularity. From a series of experi- ments (Marcus 1976) they discovered that subjects made temporal adjustments and that the amount of adjustment was dependent on the acoustic waveform of the particular stimulus. Morton et al. (1976) define the ‘p-centre’ of a word as the psychological moment of occur- rence of that word. By definition, then, in an adjusted list (one which sounded regular) it was the p-centres of the words which were at regular intervals. It is not totally clear what the ‘moment of occurrence’ of a word means. Nonetheless, “it was apparent that producing items at * Request for reprints may be sent to Gerard P. van Galen, Dept. of Experimental Psychology, University of Nijmegen, Erasmuslaan 16,650O HE Nijmegen, The Netherlands. 95