infants can know your intentions… by the tone of your voice

Los bebés pueden conocer tus intenciones… por el tono de tu vozI confess that I love the experiments with infants (always respect the ethical standards of experimentation, of course). And that for two reasons:

In the first place, are evidence for the ingenuity of the experimenters, since they must design experimental procedures for individuals with the that the chances of a direct communication are very limited; in the second place, these experiments say a lot about our nature and about the degree in which we possess innate abilities (or learned).

So I’m delighted to review a recent study that concluded that infants can infer the intentions of other people from the tone of your voice when you perform certain actions.

The study has been carried out by Elena Sakkalou and Merideth Gattis, who wanted to check to see if the infants could determine whether an adult intended to do intentionally an action, or if on the contrary the action of the adult was an error, from the words that the adult says to perform the action.

It consists of two parts:

In the first place, Sakkalou and Gattis replicated a previous experiment that seemed to show that babies could use certain preferences to infer whether the action of an adult was intentional or not. In this way, 28 infants of 14 to 18 months observed an experimenter perform two actions with a toy: one of them had been accompanied by the word “There”, giving to understand that the action was intentional; the other had been accompanied by the onomatopoeia “Whoops”, giving to understand that the action had been a mistake.

When babies are given the opportunity to manage by themselves the toy, Sakkalou and Gattis noted that they performed more often the action that the experimenter was accompanied with the word “There”. Just as if they knew that that action had been done deliberately by the experimenter, thus ruling out the option that seemed to have been a mistake not intentional. And what is more important:

Additional analyses demonstrate that this effect was due neither to face nor action cues, nor to learning during the study.

In the second place, Sakkalou and Gattis analyzed the prior preferences of “There” and “Whoops” to find their differentiating characteristics (pitch, jitter in the time, etc.), which is known as prosody: the proferencia “There” was characterized by a higher amplitude, a higher duration, and a tone decreasing; “Whoops” is characterized by a contour tone rising.

The initial experiment was replicated with 56 more babies, but this time the proferencias “There” and “Whoops” are exchanged by the Greek words “Nato” and “Ochi”, and vice versa, but keeping their same prosodic features. Thus, the specific words changed, but thanks to the conservation of their prosodic features could still be associated to actions, intentional or accidental (it is noteworthy that the infants had been reared in families of English-speaking, so that they had never before heard of the Greek words).

Well: lI * older babies 16-month-old imitated the actions that were accompanied by the word that denoted intention thanks to its prosody. Therefore, it seems that the infants could use the way in which were uttered the words to infer what actions were intentional and which accidental.

It is important that you lI infants under the age of 16 months did not show this trend. Thus, the ability to infer intentions through prosody could be acquired in a gradual way. As they say the authors:

Our age-related results are consistent with recent findings demonstrating a developmental progression in infants’ ability to differentiate between purposeful and non-purposeful mental states. Infants first begin to show an understanding of mental states, such as simple goals and intentions, and the spell check is made according to this understanding from approximately 12 months of age, but it is not until later in the second year that they demonstrate an understanding of the distinction between accidental and purposeful behavior, as measured by imitation

A beautiful study, that is important because it shows us how infants are introduced progressively in the world of communication and because, as we say Sakkalou and Gattis in the introduction:

Recent advances in nonverbal methods have yielded evidence for some aspects of mental state understanding in infants as young as 9 months […]. However, we still understand little about how infants begin to attribute mental states, such as intentions, desires, and beliefs, to others.


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