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Perception of linguistic rhythm by newborn infants
Franck Ramus
Laboratoire de Sciences Cognitives et Psycholinguistique (EHESS/CNRS), Paris, France
Previous studies have shown that newborn infants are able to discriminate between certain lan-
guages, and it has been suggested that they do so by categorizing varieties of speech rhythm.
However, in order to confirm this hypothesis, it is necessary to show that language discrimina-
tion is still performed by newborns when all speech cues other than rhythm are removed. Here,
we conducted a series of experiments assessing discrimination between Dutch and Japanese by
newborn infants, using a speech resynthesis technique to progressively degrade non-rhythmical
properties of the sentences. When the stimuli are resynthesized using identical phonemes and
artificial intonation contours for the two languages, thereby preserving only their rhythmic
structure, newborns are still able to discriminate the languages. We conclude that new-borns
are able to classify languages according to their type of rhythm, and that this ability may help
them bootstrap other phonological properties of their native language.
Key-words: newborn speech perception language discrimination rhythm prosody bootstrap-
ping.
Human newborns, as young as a few days old, have in-
triguing speech perception capacities. For instance, they
perceive phonetic contrasts categorically (Eimas, Siqueland,
Jusczyk, & Vigorito, 1971), and they perceive well-formed
syllables as units (Bertoncini & Mehler, 1981; Bijeljac-
Babic, Bertoncini, & Mehler, 1993; Bertoncini, Floccia,
Nazzi, & Mehler, 1995; van Ooyen, Bertoncini, Sansavini, &
Mehler, 1997). In addition, it has been repeatedly suggested
that they process linguistic rhythm, as revealed by their ca-
pacity to discriminate between different languages (Mehler
et al., 1988; Nazzi, Bertoncini, & Mehler, 1998; Ramus
et al., 2000). Linguistic rhythm may be viewed as a param-
eter that shows variation across the languages of the world.
Three types of linguistic rhythm have been identified, lead-
ing to a classification of languages into three classes (Pike,
1945; Abercrombie, 1967; Ladefoged, 1975): stress-timed
languages, including most Germanic languages as well as
Russian, Arabic or Thai, syllable-timed languages, includ-
ing most Romance languages as well as Turkish or Yoruba,
and mora-timed languages, including Japanese. It has also
I thank Jacques Mehler, Marc Hauser, Anne Christophe,
Christophe Pallier, Emmanuel Dupoux and Ghislaine Dehaene-
Lambertz for useful discussions, Sylvie Margules and Renate Zangl
for help testing the subjects, Jacques Mehler, Anne Christophe and
Sarah Griffiths for comments on a previous version of this paper,
Xavier Jeannin and Michel Dutat for technical assistance, and the
Delegation Generale pour l’Armement for financial support.
Experiments 1 and 2 have already been partially reported in Ra-
mus, Hauser, Miller, Morris, and Mehler (2000), to compare the
perceptual abilities of newborns with those of monkeys.
Correspondence to: Franck Ramus, now at Institute of Cogni-
tive Neuroscience, 17 Queen Square, London WC1N 3AR, GB. E-
mail: [email protected].
been proposed that an early setting of this parameter might
act as a bootstrap in the acquisition of phonology (Mehler,
Dupoux, Nazzi, & Dehaene-Lambertz, 1996; Ramus, Nes-
por, & Mehler, 1999). However, the evidence that newborns
are sensitive to linguistic rhythm does not seem to be entirely
conclusive.
Some researchers have directly studied rhythm percep-
tion by infants. Demany, McKenzie, and Vurpillot (1977)
showed that 2-3 month-old infants are able to discrimi-
nate sequences of tones differing in temporal organization.
Fowler, Smith, and Tassinary (1986) moreover showed that
3-4 month-olds where able to discriminate sequences of syl-
lables whose P-centers (Morton, Marcus, & Frankish, 1976)
were isochronous or not. However, it is not clear at all
whether the notion of rhythm investigated in those studies
has anything to do with that of linguistic rhythm, as de-
fined above. There are nevertheless two lines of evidence
suggesting that newborns may classify languages accord-
ing to their rhythm. The first one comes from the pattern
of successes and failures accumulated across the different
studies: newborns have been shown to discriminate between
stress-timed and syllable-timed languages (French-Russian
and English-Italian: Mehler et al., 1988; English-Spanish:
Moon, Cooper, & Fifer, 1993) and between stress-timed and
mora-timed languages (English-Japanese: Nazzi et al., 1998;
Dutch-Japanese: Ramus et al., 2000). However, the only
attempt to assess within-class discrimination has yielded a
negative result (English-Dutch: Nazzi et al., 1998). More-
over, newborns also discriminated between a set of English
and Dutch (stress-timed) sentences and a set of Spanish and
Italian (syllable-timed) sentences, but failed when the two
sets (English and Italian versus Dutch and Spanish) did not
reflect two types of rhythm (Nazzi et al., 1998). Thus, they
seem to be able to discriminate between sets of languages,
if and only if these sets are congruent with different rhythm
classes. As impressive as this result may be, the small num-