1036 entrainment to some extent; speakers can entrain to one another in conversational turn-taking (Wilson & Wilson, 2005), adjust their speech rate with that of another speaker (Cummins, 2009; Jungers, Palmer, & Speer, 2002), and synchronize their speech with regular nonlin- guistic auditory cues (Cummins & Port, 1998). We examine here whether listeners can entrain their motor responses to the rhythms present in speech. The rhythmic structure of language has been categorized in terms of stress-timed and syllable-timed distinctions (Abercrombie, 1967; Pike, 1945). Stress-timed languages, such as English, are thought to contain an alternation of stressed and unstressed syllables, with approximately equal time elapsed between stressed syllables. Syllable-timed languages, such as French, exhibit roughly equal stress on each syllable and, thus, display less systematic alternation of stressed and unstressed syllables. Sensitivity to stress- timed and syllable-timed distinctions appears early in life (Nazzi, Bertoncini, & Mehler, 1998) and is thought to facilitate the segmentation of speech into lexical units (Cutler, Mehler, Norris, & Segui, 1986; Mersad, Goyet, & Nazzi, 2010). Although there is little empirical support for a strict dichotomy of these rhythmic classes (Cooper & Eady, 1986; Kelly & Bock, 1988; Roach, 1982), distinctions between stress-timed and syllable-timed languages are supported by other acoustic parameters. These include the durational contrast between successive vocalic intervals (normalized pairwise variability, or nPVI; Grabe & Low, 2002), the proportion of vocalic intervals (Ramus, Nespor, & Mehler, 1999), and the coefficient of variation of intervocalic intervals (White & Mattys, 2007). Stress- timed languages show a lower proportion of vocalic intervals, higher variability in the duration of these vocalic intervals, and higher vocalic nPVI than do syllable-timed languages. The higher vocalic nPVI of stress-timed languages is consistent with an alternation of long and short vowels (Dauer, 1983), which can lead to the perception of an alternation of strong and weak beats that form hierarchical rhythmic structures (Liberman & Prince, 1977). Stress-timed languages should, therefore, be perceived as more rhythmic and, thus, more regular than syllable-timed languages (Cutler, 1991). This difference in perceived regularity may translate into greater entrainment with the rhythms of stress-timed languages; we test this hypothesis here. We measured listeners’ entrainment to speech rhythms with a tapping task, an open-ended nonverbal task commonly used in studies of timekeeping mechanisms. Participants tapped along with the beat they perceived in English and French utterances. If stress-timed languages are perceived as more regular than syllable-timed languages, participants’ taps should be more regular for English utterances than for French utterances. The coefficient of Psychon Bull Rev (2011) 18:1035–1041 variation of intertap intervals (ITIs; SD/mean ITI), a common index of tapping variability (Repp, 2005), was expected to be smaller for tapping to English than for tapping to French utterances. In addition, we examined the influence of linguistic experience on tapping behavior by comparing native monolingual speakers of French, native monolingual speakers of English, and French–English balanced bilinguals. Native language experience can influence the perception of speech rhythm in nonnative languages (Cutler, 2001), and listeners’ cultural/linguistic familiarity can influence the hierarchical level at which they tap to song (Drake & Ben El Heni, 2003). Comparison of native and nonnative responses to speech rhythm allowed us to investigate whether experience with a stress-timed language increases perceived regularity and preferred hierarchical levels. Method Participants Twenty-four monolingual native French speakers (mean age = 24 years, range = 19–45), 24 monolingual native English speakers (mean age = 23.6 years, range = 18– 43), and 24 French–English balanced bilinguals (mean age = 24 years, range = 18–43) were recruited from the Montreal area. Monolinguals were defined as individuals who had been exposed to only one language at home, at school, and at work, from birth. Balanced bilinguals were defined as individuals who rated themselves as highly proficient in both French and English and who either had been raised in a French–English bilingual environment or were native speakers of one of these languages and had been schooled in the other language. Balanced bilinguals were screened with the Bilingual Dominance Scale (BDS; Dunn & Fox Tree, 2009), adapted to French, which determines whether partici- pants are dominant in one language: A score of 0 would indicate a perfectly balanced bilingual (possible range of the BDS : −30 to +30). The bilingual participants had to score in a narrow range between +6 (French dominant) and -6 (English dominant) to ensure fluency with both languages; the mean score was −0.66 (range = +6 to −5). Stimuli and equipment Twelve sentences, each containing 13 monosyllabic words, were created in each language. French and English sentences were matched in terms of syntactic structure and word frequency. Sentences were constructed to present an alternation of content and function words,