When Will My Baby Understand....?

Concerned parents (and what other kind is there, really?) pore over lists of developmental milestones, checking out the average age for the first independent step, first word, and so on. Even more important-- but much harder to establish-- would be developmental milestones for ways of understanding and communicating with other people.

As it happens, an American developmental psychologist who has contributed much to our understanding of infant understanding, Michael Tomasello, has just received the 2011 Wiley-Blackwell/British Academy prize for contributions to psychology. I’ve been going through some of his research articles (kindly posted for free by Wiley-Blackwell), and I put together some “milestones” that I think will be of interest to parents. Some of these developmental achievements may seem pretty ordinary at a casual glance, but if you think it over you’ll see that they’re very significant steps in understanding other people.

12-month-olds:

How do 12-month-olds understand pointing? Do they just look where you point, as they look where you look, or do they understand that a pointing person means to communicate some information? When an adult pointed at a hidden toy, 12-month-olds could usually find the toy. Those who had understood the pointing could also point correctly themselves when an adult asked them where a toy was. This suggests that 12-month-olds know that a gesture like pointing means that another person knows something and wants them to know it too.
[Behne, T., Liszkowski, U., Carpenter, M., & Tomasello, M. (2011). Twelve-month-olds’ comprehension and production of pointin. British Journal of Developmental Psychology, 29, 1-17.]

Do 12-month-olds point just because they are interested in a toy or an entertaining sight? No, they point for various reasons. One is to call a person’s attention to something she does not know about or isn’t looking at; one is to share a positive or negative attitude about things they are both looking at; and one is in reference to things that are mentioned but are not there--- for example, a puppet that is no longer in a window the baby can see. These different purposes seem to be related to the 12-month-old’s developing understanding of other people’s mental states.
[Liszowski, U., Carpenter, M., & Tomasello, M. (2007). Pointing out new news, old news, and absent referents at 12 months of age. Developmental Science, 10, F1-F7.]

14-month-olds:

Do 14-month-olds just remember things like toys, or do they pay attention to the toy experiences they have shared with other people? In this study an adult and a baby played with three toys. The adult acted excited and encouraged the baby to be excited about one toy but was bland about the others. Later, the baby was shown all three toys on a tray, and the adult excitedly said “give it to me!” (leaving it unclear which toy was meant). 14-month-olds most often chose the toy they had been excited about--- but they did not make the same choice if they had only watched the adult acting excited without being involved. The babies could use the past history of playing together to figure out which toy the adult meant.
[Moll, H., Richter, N., Carpenter, M., & Tomasello,M. (2008). Fourteen-month-olds know what “we” have shared in a special way. Infancy, 13, 90-101.)

Do 14-month-olds understand when someone else is having trouble, and do they want to help? In one study, an adult pretended not to be able to reach a dropped clothespin. 14-month-olds spontaneously tried to help. When the adult was struggling with a more complicated task like opening a box, though, 14-month-olds did not always try to help. The toddlers could understand that the adult had a problem, and wanted to help, but they could apparently also figure out whether they could do the task or not.
[Warneken, F., & Tomasello, M. (2009). The roots of human altruism. British Journal of Psychology, 100, 455-471.]

18-month-olds:

Will 18-month-olds work hard to give help when they see it’s needed? When older toddlers saw an adult “struggling” to reach a dropped object, 18-month-olds would walk around obstacles to help, and they did this without being rewarded. They not only understood what another person might want, but they were eager to help and would do something difficult for them to manage while they were still amateur walkers.
[Warneken & Tomasello, above]

Do 18-month-olds understand that different people can know and mean different things, even if they say or do the same things? In one study, when 18-month-olds played with a toy one way with the first adult and another way with a second adult, they started the first activity when the first adult pointed at the toy, and the second activity when the second adult pointed at the toy.
[Liebal, K., Behne, T., Carpenter, M., & Tomasello,M. (2009). Infants use shared experience to interpret pointing gestures. Developmental Science, 12, 264-271.]

20-month-0lds:

Will 20-month-olds put helping someone above their immediate play interests? In one study, 20-month-olds would stop playing and leave an attractive group of toys to help someone who seemed to be having trouble. They would not only do this without reward-- if they were rewarded they became less likely to help on another occasion! Their understanding of the need for help and their motivation to help were both apparently very high.
[Warneken & Tomasello, above.]

Can 20-month-olds use other information to figure out the meaning of words they don’t know? In one study, 20-22-month-olds were shown pictures of puppets doing odd things that were described with nonsense words like “tamming”. If they were shown a picture and just told “this is tamming”, they did not seem to learn the meaning of the word. But if they were helped to practice by seeing pictures and hearing about one thing doing something to another thing, they were later able to use that kind of information to choose the right meaning for a word. If they saw a picture of a frog “tamming” a monkey, and heard it described with a complete transitive sentence, they would later look toward the correct picture -- for example, they would look at a frog doing something to a monkey, not at a picture of a monkey doing something to a frog. They used the relationship between the two animals to help decide what the unknown word probably meant; they did not need to be “taught” every word.
[Dittmar, M., Abbot-Smith, K., Lieven, E., & Tomasello, M. (2008). Young German children's early syntactic competence: A preferential looking study. Developmental Science, 11, 575-582.]

24-month-olds:

Children of 24 months know that if someone leaves the room before an event occurs, that person does not know about the event. But in one study, when an adult stayed in the room but could not see a new object because of a barrier that was above her eye level, 24-month-olds did not act as if the adult knew more about the hidden object than about two other objects she had seen. Just being together when the child saw the object was a factor that confused the children about what the adult might know—suggesting that for all the social and cognitive skills described here, there was still a lot of development ahead.

[Moll, H., Carpenter, M., & Tomasello, M. (2011). Social engagement leads 2-year-olds to overestimate others’ knowledge. Infancy, 16, 248-265.]

36-month-olds:

Do three-year-olds understand enough about what others can see or hear to be able to be “sneaky” in disobedience? Even though this might be something we don’t want them to do, we have to give credit for understanding to anyone who is able to manage this task. In one study, 3-year-olds were told not to peek in a box that had a very nice toy in it, and told they could play with it when the adult said it was all right. They were more likely to peek when they could tell that the adult could not see what they were doing. Given a box with two doors, one decorated with bells and one that would not make noise, they chose the silent door to peek through. To manage this “sneakiness”, they had to be able to think about what the adult could see or hear and whether they could do what they wanted to without being “caught”. (This is one of many cases in child development where being “bad” is evidence of good development.)

[Melis, A.P., Call, J., & Tomasello, M. (2010). 36-month-olds conceal visual and auditory information from others. Developmental Science, 13, 479-489.]

Can 3-year-olds really pretend, by playing that an object is one thing at one time, another thing at another time? In one study, they were able to switch back and forth from one pretend identity of an object to another and could talk about whether a wooden block “was a car” or “was an apple” at different times. This advance in pretend play may be associated with the earlier understanding that different people may mean the same thing by different gestures.
[Wyman, E., Rakoczy, H., & Tomasello, M. (2009). Young children understand multiple pretend identities in their object play. British Journal of Developmental Psychology, 27, 385-404.]

Do 3-year-olds mind if bad things are done to other people? Does their earlier “helping” tendency extend to social problems? In one study, each child and each of two hand puppets made a picture or a paper sculpture. One hand puppet “left”. For half of the children, the remaining hand puppet then destroyed the other one’s work; for the other half, the puppet destroyed some extra materials that had not been used. The children seeing the departed puppet’s work destroyed were more likely to protest, tell the puppet not to do that, and tattle on the destructive puppet; they also comforted or helped the second puppet on its return. The children’s concern extended to situations where another person was hurt, even though the child had no problems of his or her own. “Tattling” in this situation seemed to be a natural part of the child’s attempt to help.
[Vaish, A., Missana, M., & Tomasello, M. (2011). Three-year-old children intervene in third-party moral transgressions. British Journal of Developmental Psychology, 29, 124-130.]

Tomasello’s work shows that young children already know a lot about how to learn from other people and how to communicate with and act toward them. But what if your child can’t do all these things at the “right age”? Should you be worried? Parents usually ARE worried, but there are a lot of reasons not to panic here. One is that even in these studies there were some children of a given age who did not manage to do the task. They may have been having a bad day, or maybe the successful children were having good days. (Some of the children didn’t complete the tasks at all.) Also, the researchers did not just march up to each child and try to get him or her to do a task. They spent a long time with “warm-up” tasks and with getting the child ready. In addition, they were in a specially-designed lab, without a lot of familiar objects and people to distract the child from the job at hand. You may try this at home-- but results will vary!