Most cultures (Falk, 2009) have a special type of language that is used to talk to children: infant-directed-speech (IDL; or informally, motherese, baby talk). For instance, Fernald (1992) argues that motherese is an evolved phenomena that was selected for. This suggests that it has a benefit to child development, hence my questions:

  1. What benefit does IDL provide children?
  2. How do the features of IDL benefit the cognitive development of children?
  3. Are there benefits beyound effects on language-acquisition?


  • The only benefit I am familiar with (shameless self plug) is in helping avoid reversal-errors in pronoun acquisition but Kaznatcheev (2010) is only a theoretical prediction based on a particular computational model of questionable (1, 2) empirical validity.

  • I am interested in the developmental benefit of the very specific language used in IDL, not about the benefit of maternal care in general.


Fernald, A. (1992). "Human maternal vocalizations to infants as biologically relevant signals: An evolutionary perspective." In J. H. Barkow, L. Cosmides, & J. Tooby (Eds.) The adapted mind: Evolutionary psychology and the generation of culture (pp. 391-428).

Falk, D. (2009). Finding our tongues: Mothers, infants and the origins of language. New York: Basic Books.

Kaznatcheev, A. (2010). "A Connectionist Study on the Interplay of Nouns and Pronouns in Personal Pronoun Acquisition." Cognitive Computation 2(4): 280-284.

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    $\begingroup$ Been wanting some answers to your questions for some time now. An aside - given my disposition and previous experience in interacting with infants (not my own), I know I will not baby-talk to my children. In several or so years time I may be able to provide a detailed case study. Hat off to Piaget. $\endgroup$ Jun 3, 2012 at 9:23
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    $\begingroup$ I think that it has not been proven that motherese serves any function at all. People tend to adapt their speech to the cognitive ability expressed in the language of the people they talk to. Academics talking to people they perceive as uneducated speak in simpler terms and in less complex sentences. People talking to foreigners do the same. In fact there is the phenomenon that the pidgin of foreign worker populations influences the host language, because the native speakers adapt to their guests. IMO parents simply speak in a language that they believe may be understood by a toddler. $\endgroup$
    – user3116
    Nov 29, 2013 at 13:48
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    $\begingroup$ What has been shown is that babies prefer a certain pitch. AFIK they don't react to childish vocabulary, but to the way in which you articulate it. This has been confounded in the studies quoted below. $\endgroup$
    – user3116
    Nov 29, 2013 at 13:51
  • $\begingroup$ @what that is very interesting. You should write it up as an answer if you have some time. $\endgroup$ Nov 30, 2013 at 20:37

3 Answers 3


Motherese may play a role in emotional development.

Soken and Pick write:

Concurrent with the exaggerated speech of motherese, there are probably exaggerated facial displays, allowing infants to explore the particular aspects of the face... Child-centered displays may serve as opportunities for learning about affective events.

Walker-Andrews (1997) also suggests that

the presence of the face acts as a setting for attending to the affective quality of the voice.

Yet, according to a recent, extensive review on motherese (Saint-Georges et al., 2013), its role in emotion and cognition is still an open area of research.


  • N. H. Soken and A. D. Pick, “Intermodal Perception of Happy and Angry Expressive Behaviors by Seven‐Month‐Old Infants,” Child development, vol. 63, no. 4, pp. 787–795, 1992.

  • A. S. Walker-Andrews, “Infants' perception of expressive behaviors: differentiation of multimodal information.,” Psychological Bulletin, vol. 121, no. 3, p. 437, 1997.

  • C. Saint-Georges, M. Chetouani, R. Cassel, F. Apicella, A. Mahdhaoui, F. Muratori, M. C. Laznik, and D. Cohen, “Motherese in Interaction: At the Cross-Road of Emotion and Cognition? (A Systematic Review),” PLoS ONE, vol. 8, no. 10, p. e78103, Oct. 2013.


I believe motherese exists to teach the infant to discriminate phonemes in the native language. Kuhl et al. (2005) show that during the first year language critical period, infants gain an increased ability to discriminate between phonemes of the native language, while their ability to discriminate between phonemes of non-native languages declines. Additionally, their ability to discriminate phonemes is initially language-neutral. Kuhl (2003) further shows a strong correlation between mother speech clarity and infant phonetic discrimination ability.

So if clarity is so important, why talk to children in semi-gibberish and not normal speech? One possibility is that motherese emphasizes certain sounds to enhance the perceptual discrimination. Karzon (1983) investigates this idea, with positive results. To us motherese sounds odd, but in reality it is providing a clearer phonetic structure for the infant to learn.

It's likely that the mother's desire to talk to her baby in motherese, and the babies appreciation of it are traits that co-evolved. Perhaps, like Falk suggests, motherese is an exapted remnant of some early hominid proto-language.

This type of interaction might also have a role in the larger structure of mother/child bonding. But I feel it's unlikely that it evolved for that particular reason. What's more likely is that it was simply co-opted into that mechanism.


Karzon, R.G. (1985) Discrimination of polysyllabic sequences by one- to four-month-old infants Journal of Experimental Child Psychology 39(2): 326-342.

Kuhl, P.K., Conboy, B.T., Padden, D., Nelson, T., & Pruitt, J. (2005) Early Speech Perception and Later Language Development: Implications for the "Critical Period" Language Learning and Development 1(3-4): 237-264.

Liu, H-M., Kuhl, P.K., Tsao, F-M. (2003) An association between mothers’ speech clarity and infants’ speech discrimination skills Developmental Science 6(3): F1-F10.

  • $\begingroup$ Thanks, this explains the phonetic and high-pitched/weirdly-articulated nature of motherese. It doesn't capture why they would use simplified grammar, etc... maybe someone else will pitch in on if those have well understood developmental roles. $\endgroup$ Aug 15, 2012 at 2:27

Fonagy and Target, although they do not specifically cite the term 'Motherese', believe that what they call 'Marking'- signalling an unreality or playfulness in mirrored displays of affect can play a crucial role in the development of a faculty they call 'Mentalization'.

According to their model, newborns experience affect as all-pervading, and do not see it as limited to a self. By internalising mirrored affect displays by the primary caregiver they are able to conceptualise their own affect on a second order (symbolic) level, are able to 'play' with their own feelings as the mother brings affect into the realm of the pretend. Thus they implicate improper marking in later development of borderline personality disorders.

Here's a paper of theirs on the subject, although I recommend their book, which is considerably more expansive.

Edit: Sorry, off the internets for a month. Here are some useful quotes:

Take the case of pretend play: here markedness is conveyed by a series of salient perceptual features that distinguish a pretend action or pretend emotion expression from a real one. Knowing looks, slightly tilted head, high pitch and slowed down down, exaggerated intonation and contour, schematic, abbreviated or only partial execution of action schemes... ...all mark for the child that the pretend expression is categorically different from its realistic equivalent- that it is "not for real". We have argued... ...that in the case of adaptive parental affect-mirroring interactions, the affect-reflective emotion display is also modified by the same kinds of transformations... (Fonagy, Gergley, Jurist and Target, "Affect regulation, Mentalization and Development of the Self" p296 , Other Press 2002- linked above)

Frustratingly, this was the most explicit exposition of marking behaviours I could find in the book, which is mainly theoretical. You will immediately observe that what is described is not all motherese, nor only motherese- but you will agree, I hope, that there is a not-inconsiderable overlap between the two- and that the wedding of IDL to such concepts is not, so to speak, of shotgun ilk. To say that the function of motherese was precisely the above would certainly be wrong- but I would hope you would concurr that as an adaptation it would confer advantage in part for this reason, were Fonagy et al's hypothesis

...[T]hat the perception of markedness activates the yound child's metarepresentational system (Leslie 1987) which allows for "decoupling" of the expression from its referents in actual reality. (Ibid, p296)


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    $\begingroup$ their theory (as presented in the paper you link) is about early social interaction and attachment's effects on development. Not the effects of the form and peculiarities of child-directed speech. As far as I can tell, their whole paper remains unchanged even if I talk to the child with normal (or simple) adult speech as long as I still provide comfort, joking, etc. Thus, it unfortunately does not address my question. However the Smith (1996) that they cite "Language and the evolution of mind reading" does seem relevant. Do you know more about that article and if it deals with IDL? $\endgroup$ Jun 11, 2012 at 22:29
  • $\begingroup$ Apologies, I should have made it clear that the role of motherese represesnts a small (if crucial) part of a large theory (the relevant portion is at the beginning of page 686). My mistake also linking to a paper I haven't read through the whole way (I'm just aware it is the canonical reference for their model): it certainly doesn't bring out the role of motherese to the extent the book does: rather referring to marking as incorporating "a display incompatible with the childs affect". In their book, though, their descriptions of marking from observations match closely with.... $\endgroup$ Jun 12, 2012 at 12:04
  • $\begingroup$ ...(at least the spirit of) motherese. Will try and find a quote this evening. As for the Smith paper, I have to admit to never having read it. In fact my only experience of it is as a reference in Fonagy and Target... $\endgroup$ Jun 12, 2012 at 12:06

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