Psychon Bull Rev (2011) 18:1035–1041 1039 Fig. 2 Mean correlation of coefficients of variation for intertap intervals and stimulus intervocalic interval by participant group and stimulus language. Error bars represent the standard error of the mean analysis on the number of individuals by stimulus language and participant group indicated a main effect of participant group, χ²(4, 72) = 18.03, p < . 01; French participants were more likely to tap at low hierarchical levels (every word), whereas English participants were more likely to tap at higher hierarchical levels. Bilinguals were equally distributed in both categories. There was no effect of stimulus language and no interaction, p > .10; listeners within each participant group responded the same way to both languages. Furthermore, the participant groups did not differ a priori in their metronomic tapping [mean ITI = 499 ms for each group, F < 1; French monolinguals, CV(ITI) = .047, English monolinguals, CV(ITI) = .057; bilinguals, CV(ITI) = .047; F(2, 69) = 1.94, p > .10]. They also did not differ in their spontaneous tapping rate (French monolinguals, mean ITI = 766 ms; English monolinguals, mean ITI = 695 ms; bilin- guals, mean ITI = 760 ms, F < 1) or their spontaneous tapping variability [French monolinguals, CV(ITI) = .077; English monolinguals, CV(ITI) = .079; bilinguals, CV(ITI) = Fig. 3 Frequency of participants who tapped with every word or every two or four words by participant group and stimulus language .060, F < 1], indicating that the group differences were specific to speech rhythms. Discussion Monolingual and bilingual speakers of English and French tapped more regularly to English than to French utterances, indicating that the stress-timed rhythms facilitated entrain- ment for all listeners. Even balanced bilinguals (highly proficient in both languages) showed increased tapping regularity for English utterances, as compared with French utterances; thus, the perceived rhythmic differences cannot be due to differential access to semantic information between the native and nonnative speakers. The utterances used in the present study were carefully controlled to allow the perception of alternating strong and weak stresses in both languages. This manipulation may have weakened natural rhythmic differ- ences between French and English by artificially increasing the perceived regularity of the utterances. In spite of this, robust differences in listeners’ tapping regularity to French and English speech were found. Overall, these findings support the stress-timed/syllable-timed rhythmic distinction and suggest that speech rhythm differentially entrains listeners at acoustic levels prior to lexical comprehension. Listeners’ tapping regularity increased for the more regular utterances within each language, suggesting that the acoustic stimulus regularity was sufficient to entrain tapping. Increased tapping variability was correlated with the variability of stimulus intervocalic intervals [CV(IVI)], an acoustic measure of temporal variability between vowel onsets (incorporating silent periods) that controls for speech rate. Tapping variability was not related to previous measures of vocalic durational variability that distinguish stress-timed from syllable-timed languages (%V and ΔV, Ramus et al., 1999; V-nPVI, Grabe & Low, 2002). Linguistic experience influenced the correlation between tapping vari- ability and stimulus variability; French monolinguals showed less correspondence in tapping variability and stimulus variability for English, perhaps because they were less sensitive to the regularities present in English utterances. Long-term experience with a stress-timed language seems to have heightened English speakers’ entrainment to stress regularities, as observed in their tendencies to tap regularly to both languages and to entrain to speech rhythms at higher hierarchical levels (tapping every two or four words). This finding challenges the idea that periodicity is specific to music and absent in speech (Patel, 2008). Speech entrainment might be driven by a perceived temporal regularity that depends in part on one’s familiarity with stress-timed languages. Native speakers of a stress-timed language may have greater expect- ations for rhythmic regularity in speech and may synchronize at higher levels with the “beat” of speech. These expectations