Experiments conducted by researchers at the University of Toronto suggest that very young children make judgments about people based on their tone of voice.

Infants are known to prefer positive over negative voices, but it wasn’t known if this information affects their social preferences, the researchers said. The ability to evaluate people’s actions and intentions is an important skill, they added.

The study involved 20 children from 10.5 to 11.5 months old. In one experiment, they watched four puppets take turns uttering neutral statements such as “Let me tie your shoe” in male and female voices with a happy or irritated tone. After several repetitions of the exercise, the children could choose a puppet for themselves. They selected the happy or nice puppet an average of 67 percent of the time, the analysis showed.

The second experiment was identical to the first, using happy or irritated voices, but this time the objects were drinking cups that lacked facial features. The children selected the cup associated with the nice voice nearly half the time, indicating tone of voice had no effect on their preference for an inanimate object, the study suggests.

In a final experiment, the children heard the same voices from the first two experiments, but this time speaking in a neutral tone. Still, 69 percent of the children preferred the formerly positive voice over the formerly negative one. This suggests they retained information about the speaker’s tone and could possibly use it to guide future encounters with that person, the researchers said.

The children showed no preference for male or female speakers in the experiments.

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