Video: Researchers from Yale University showed babies puppet shows involving helping and hindering blocks to see if the infants could judge character.

Babies are good judges of character long before they learn to speak, according to a new study. Infants as young as six months preferred characters which helped rather than hindered others in a simple puppet show.

Researchers say the findings reveal that humans begin making social evaluations far earlier than previously thought.

“This is the very first experiment in anywhere near this age that shows babies develop preferences for individuals based on their actions,” says Karen Wynn at Yale University in New Haven, Connecticut, US, who led the study.


Wynn and her colleagues studied the reactions of infants to a sketch in which a brightly coloured wooden block with goggly eyes attempts to climb up a hill. Much like in a puppet show, the infant could not see the person behind a curtain who controlled the character’s movement with a wooden stick.

Understood intent

Along with the wooden character attempting to climb the hill in tiny increments, a helper block was also involved at the bottom of the slope, which pushed the main character up the track from time to time.

Additionally, another wooden block positioned at the top of the hill occasionally came down to hinder the upward movement of the first block.

The blocks had different shapes and colours to help the babies distinguish one piece from another. But the scientists controlled for these attributes by varying them from trial to trial.

After the show, the researchers brought out the helper block and the hinderer block on a platter and placed it in front of the infants. A colleague who did not see the skit, and did not know the role of each block in the performance, recorded how the babies interacted with the objects.

Wynn says that the infants are very willing to reach out for one of the blocks, an action that indicated their preference: “They’re very cooperative in grabbing things.” She says that all 12 of the six-month-olds preferred the helper block. Similarly, 14 out of the 16 infants aged 10 months reached for the helper block.

The researchers believe that the babies understand the intent of the middle block to climb the mountain because of its small incremental movements in that direction. Wynn adds, though, that it is not clear how the babies pick up on this. “We don’t know exactly which micro-cues the babies pick up on,” she explains.

Early preference

Her team conducted a control experiment in which the main character – a small ball – was pushed up and down by the helper and hinderer blocks, but did not move independently. In this case the babies showed no preference for the helpful character that provided an uphill push.

Wynn notes that earlier studies have shown that babies have shown a preference for beautiful faces.

She believes the results from her study indicate that babies have a preference for helpful individuals about a year earlier than previously thought. “They are an unbiased third party and they are not at all shy about rendering a judgement on social actions,” she says, adding that this tendency appears early in development because it is a strongly advantageous trait later in life.

Maria Legerstee, a child development expert at York University in Toronto, Canada, says the results of the study are “very interesting” but is not certain whether babies evaluate the actions of people the same way they judge the actions of wooden blocks.

She notes that infants interact differently with people compared with objects such as dolls: “The babies will always respond more to a person with smiles and vocalisations than to the doll.”

Legerstee hopes the experiment will be repeated using another skit involving human actors rather than wooden blocks. By altering the people who play the role of helpers and hinderers the scientists can control for confounding factors, such as babies preferences for attractive people.

Journal reference: Nature (DOI: 10.1038/nature06288)