Translated from the French1 by Bruno H. Repp The difficulty of producing syncopation in music - that is, of playing a strong note off the beat established by other notes - is a well-known fact. It is explained by the difficulty we have in breaking an ongoing periodicity that arises from the movement of another limb or the playing of another instrument. We have indeed a tendency to synchronize our movements with musical accents, as is shown by our reactions to marching tunes or dance music. Within the framework of our previous research (Fraisse, 1955), we have set ourselves the task of finding out how the impulse to synchronize and, conversely, the possibility of syncopating might change as a function of the rate of succession of sounds. The principle of our experiment was very simple. The subject hears a regular sequence of sounds, similar to that produced by a metronome, and we ask him to tap at the same rate but to interleave the taps with the sounds. The task is difficult, and [often]2 the subject spontaneously synchronizes with the sounds he hears. In a musical schema the sounds would represent the beats and the interleaved taps, the off-beats. METHOD The sequences were produced by the rubbing of a brush against the insulating surface covering a metal timing cylinder. (For details, see Fraisse, 1950.) The subjects sat in a sound-attenuated booth and listened to the sounds over a loudspeaker. They tapped on a telegraph key. The sound sequence and the sequence of taps produced by the subject were recorded simultaneously by a polygraph. The [interonset] intervals [of the sounds] were 275, 375, 518, 750, 1025, 1360, or 2050 ms. We tested 30 students, both male and female. The first 15 received only five sequence rates, the fastest (275 ms) and the slowest (2050 ms) rate being omitted. The procedure was as follows: The subject practiced first for 1 min with a slow (1360 ms) sequence. For the last 15 subjects we added another practice period of the same duration using a sequence [with intervals] of 680 ms. The sequences were then presented in a random order that varied from subject to subject, so as to neutralize any effects of order or learning. For each sequence the subject was first given a trial period of 1 min, followed by a brief rest after which the same sequence was presented again, and responses during 25 intervals were recorded. All subsequent analyses were based on these 25 responses. RESULTS The results obtained can be divided into three categories: (a) Syncopation: The subject succeeds in inserting a tap, more or less regularly, between every two sound stimuli. (b) Synchronization: The subject cannot resist synchronizing the taps with the sounds. (c) Phase drift: The subject tries to syncopate but does not succeed, either because he adopts a tapping tempo that does not correspond to that of the presented sequence or because in trying to syncopate he succeeds only in producing an irregular sequence of taps. Table 1 shows the number of cases in each category as a function of sequence tempo. Because the results of the last 15 subjects were very similar to those of the first 15, we combined the two groups, and multiplied the results obtained for the slowest and fastest sequences by two, to facilitate comparison with the other sequences. Table 1 shows immediately that some subjects are capable of syncopating with all sequences, but that the group as a whole becomes successful only with a sequence interval of about 1 s. The coercive tendency to synchronize manifests itself only in the very fast sequences. These results become more precise through a quantitative analysis, performed only on those subjects who were able to syncopate. We examined their results in the following way: (1) We calculated the intervals between successive taps for those subjects who syncopated with every sequence. …