When I'm talking I can hear my own voice. And with that feedback I can tell almost immediately when I’ve made an error. Like I just did. An error.

Adults have this skill and so do older children. But we are not born with this ability. It develops between ages two and four. So finds a study in the journal Current Biology.

Researchers had adults, four-year-olds, and two-year-olds say “bed” repeatedly. But scientists filtered the sound so that the subjects heard themselves through headphones pronouncing it as “bad.” Adults spontaneously compensated, and changed so that the word sounded correct to their own ears. They wound up saying “bid.”

Four-year olds also adjusted their speech.

But the two-year olds kept saying “bed” even though they kept hearing “bad.”

So if two-year olds ignore their own vocal feedback, how do they learn to say words correctly?

It’s not clear. But this study suggests that toddlers must have an alternative source of auditory feedback. Researchers think it might simply be that they rely on parents to monitor and correct their speech.

Then again, with sentences like... (sound clip of a toddler), it's no surprise they aren’t paying attention to what they are hearing.

—Christie Nicholson

[The above text is a transcript of this podcast.]