Three-month-olds’ Surprisingly Sophisticated Social Judgments

I’ve spent three weeks showing you how infants perceive the world very differently from adults – in how they listen to language, process sensory information, and experience emotions. It only seems fair to turn the tables and take a look at the way very young infants may have surprisingly adult-like awareness of what’s going on in the world.

What do you think the average three-month-old knows about the social interactions of the people around them? Watching a video featuring many three-month-olds, you can see that babies are working on very rudimentary social interactions: they smile, and want you to smile at them, and are working on facial expressions and other ways of getting your attention. But they’re also stuck in a mostly prone position, waving arms and legs about and even rolling over but not yet sitting up or even deliberately reaching out to grab things. So it should be very surprising that these babies demonstrate some sophisticated understanding of social interactions.

Researcher J. Kiley Hamlin and her colleagues already knew that older infants, at six and ten months old, prefer people who help others to people who hinder others from achieving goals.  Of course, I’m using “people” very broadly, because the characters involved were actually simple colored shapes, carved out of wood and painted with large “googly eyes” stuck on. These characters engaged in a carefully timed and orchestrated play, as described by second author Karen Wynn below:

Photos from Hamlin, Wynn & Bloom (2007).

Given a choice between two painted wooden characters, both six- and ten-month-olds prefer the one that helped our red circle friend reach the top of the hill, not the one that pushed him back down to the bottom (top picture). This is not a simple matter of thinking that getting up the hill is better than getting down the hill: Take away the googly eyes and the previous failed attempts to get to the top of the hill (bottom picture), and infants are equally happy with characters that pushed a ball up a hill or down a hill. (It’s also nothing against yellow triangles – sometimes the yellow triangle was the good guy, and the blue square was the bad guy. Helping and hindering were what mattered, not the appearance of the characters.

But was this something even younger infants would be aware of? Most researchers who go the trouble of studying babies are interested in the origins of knowledge, or how much of what we know comes from our experiences. Six-month-olds might recognize the value of helpers from their own experience of having parents help them achieve their goals – not climbing up hills, just yet, but certainly in being given things that are out of reach or being supported so they can try standing. Three-month-olds, on the other hand, will have fewer and more simple experiences, as well as less-developed brains. Can they also distinguish helpers and hinderers?

The trick to finding out anything about infants so young is that they have very few ways to show us what they know. Unlike six-month-olds, they can’t just reach out to touch an object deliberately, clearly signaling “I like this one best”. When researchers try to figure out what’s going on in a three-month-old’s mind, all we can go on is what they look at. Often researchers will use “preferential looking”, which usually means showing two pictures or objects side-by-side and seeing how long infants spend looking at each one.

In this case, a researcher put the two wooden characters on a tray and brought them to the infant, just like in the video with the older infants – but this time they just held them in view, about 2 feet in front of the infant, and used a video camera to record where the infant looked. Once the infant’s eyes were on one character or the other, coders carefully tracked how long the infant spent looking at each of the two characters.

On average, the three-month-olds preferred to look at the “helper” than the “hinderer”: They spent roughly 13 seconds gazing at the character that helped the circle, and only six looking at the character that pushed it back down the hill. This preference seems to be based on disliking the hinderer: Given a choice between the hinderer and a neutral character (who zoomed past the red circle to head up the hill), infants spent 12 seconds looking at the neutral character and only three looking at the hinderer. On the other hand, when infants were given a choice between the helper and a neutral character, they spent the same amount of time – about 8 seconds – on each of them.

It looks like three-month-olds have managed some pretty sophisticated social thinking here. They realized that the red circle had a goal to get up the hill – no mean feat in itself, when many people believe such “theory of mind” doesn’t emerge until preschool – that the hinderer prevented the circle from reaching that goal, and that the hinderer should therefore be avoided. They might not yet have realized that characters who help should be preferred over bystanders, but on the whole it’s still a very impressive skill set for infants still working out the best way of sucking on their fists.

However, we do have to be careful about what skills we’re willing to grant babies based on how long they look at things. Scientist Marshall Haith warns against “rich interpretation” of these kinds of studies: We can say with certainty that infants looked at one character longer, but we can’t be certain why. I’ve already told you how infants see the world differently than we do, so they could have very different reasons than we imagine for looking at one character more than another. The researchers tried to make sure that it wouldn’t be a color or shape preference, by changing who was the helper and who was the hinderer for different infants, or even a side preference, by swapping who was on the right and who was on the left for different infants, but it’s impossible to consider everything.

Hamlin and her colleagues did at least make the effort of trying to show that infants looked at the things they preferred. Going back to the videos from the study in the video, they looked at how long six-month-olds looked at the helper and hinderer before they reached for one of them. Most of these infants looked longer at the helper, by about 3 seconds, before they reached. This isn’t perfect, of course: These six-month-olds are planning a reach, and those brief seconds of looking longer at the helper could just be the time it takes for the infant to make a decision and work out how to get that reach started. When younger infants are just looking, at objects that are beyond their reach even if they could work out the mechanics to do it, “looking longer” might mean something completely different.

The setup of this “preferential looking” also shows how designing research with infants can be as much art as science. The researchers recorded where infants looked for 30 seconds – but why half a minute? Why not a full minute, or only 10 seconds? Well, the infants are going to need some amount of time to see that both characters are present and identify them, so if the researchers only looked for 10 seconds there might not have been enough time for a preference to show up. And there’s only so long an infant can gaze at a wooden puppet with googly eyes, even a helpful one, before they get bored and start looking elsewhere. There’s no hard and fast science that says what the best time is – 30 seconds probably just sounded like a good number.

Obviously, understanding what’s going on in an infant’s mind can be very tricky science. Still, I’m inclined to give infants the benefit of the doubt. I doubt they’re mentally calling the hinderer a “meanie”, or even consciously aware of any kind of logic like “he hurts people, I should avoid him”. But it seems very reasonable that at such a young age, infants would be attuned to the simplest actions of other people, and have a kind of mental reflex to avoid the ones who can be unhelpful. Making sense of social interactions and other people’s intentions is key to our everyday function and eventual survival, and it’s a puzzle we might have to start working out very soon after we’re born.
Hamlin, J.K., Wynn, K., & Bloom, P. (2010). Three-month-olds show a negativity bias in their social evaluations. Developmental Science, 13, 923-929 DOI: 10.1111/j.1467-7687.2010.00951.x


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