Language Discrimination by Human Newborns and by Cotton-Top Tamarin Monkeys

Abstract

Humans, but no other animal, make meaningful use of spoken language. What is unclear, however, is whether this capacity depends on a unique constellation of perceptual and neurobiological mechanisms, or whether a subset of such mechanisms are shared with other organisms. To explore this problem, we conducted parallel experiments on human newborns and cotton-top tamarin monkeys to assess their ability to discriminate unfamiliar languages. Using a habituation-dishabituation procedure, we show that human newborns and tamarins can discriminate sentences from Dutch and Japanese, but not if the sentences are played backwards. Moreover, the cues for discrimination are not present in backward speech. This suggests that the human newborns' tuning to certain properties of speech relies on general processes of the primate auditory system.A fundamental question in the study of language evolution and acquisition is the extent to which humans are innately endowed with specialized capacities to comprehend and produce speech. Theoretical arguments have been used to argue that language acquisition must be based on an innately specified language faculty (1, 2), but the precise nature and extent of this "language organ" is mainly an empirical matter, which notably requires studies of human newborns as well as non-human animals (3-5). With respect to studies of humans, we already know that newborns as young as four days old have the capacity to discriminate phonemes categorically (6) and perceive well-formed syllables as units (7-9); they are sensitive to the rhythm of speech, as shown in experiments where newborns distinguish sentences from languages that have different rhythmic properties, but not from languages that share the same rhythmic structure (10, 11); however newborns don't discriminate languages when speech is played backwards (10), and neurophysiological studies suggest that both infants and adults process natural speech differently from backwards speech (12, 13). All of these studies indicate that humans are born with capacities that facilitate language acquisition, and that seem well attuned to the properties of speech. Studies of non-human animals, however, show that some of these capacities may predate our hominid origins. For example, insects, birds, non-primate mammals, and primates process their own, species-typical Correspondence should be addressed to Franck Ramus. E-mail: f.ramus@ucl.ac.uk. Present address: Institute of Cognitive Neuroscience, 17 Queen Square, London WC1N 3AR, GB. sounds in a categorical manner, and some of these species perceive speech categorically (14-18).Our aim in this paper is to extend the comparative study of speech perception in three directions. First, we have conducted joint experiments on human newborns and on monkeys using the same design and the same material. Second, whereas most studies of non-human animal speech perception involve extensive training prior to testing on a generalization task, our experimental approach -the habituationdishabituation paradigm -involves no traini...

Voice processing in human and non-human primates

“…However, the pairs with which the monkeys had most difficulties were also the ones that led to the longest reaction times in humans, suggesting comparable analysis mechanisms (Sinnott 1989). Ramus et al (2000) found that both cotton-top tamarins as well as human babies were able to discriminate speech sentences in two different languages, but not if the sentences were played backwards (Ramus et al 2000). Conversely, Hopp et al (1992) found that Japanese macaques were less accurate than human listeners in a discrimination task along a continuum of synthetic 'coos' varying on the temporal position of the f0 peak-although humans also generally perform better at discrimination tasks involving lower-level acoustic cues .…”

Prosody guides the rapid mapping of auditory word forms onto visual objects in 6-mo-old infants

“…Evidence for such innate constraints is quite strong. In the first month of life, infants prefer intonated speech to syllable lists, show a right ear and left-hemisphere brain advantage for processing speech-like stimuli, and can discriminate nonnative languages across, but not within, prosodically defined linguistic families (25)(26)(27)(28).…”

Cognitive gains in 7-month-old bilingual infants

“…Indeed, neonates can discriminate utterances from 2 languages of different rhythmic classes (6)(7)(8). Two-to four-month-olds learn to distinguish languages belonging to the same rhythmic class (4,9).…”