The Biggest Lie I was Told about Becoming a Parent

The biggest lie I was told about becoming a parent is that baby's poop doesn't really smell for the first few months. Seriously. I can't imagine anything further from the truth. Paulina's poop smells, well, like poop. She obviously eats a lot (she was 99th percentile for weight at her 2 month checkup), but I didn't think that would cause anything out of the ordinary (in all honesty, though, I have no idea - I'm happy to hear thoughts on this - well, not exactly happy, but I always welcome dialogue).

I was thinking about this when I saw a trailer for a movie coming out in October called "The Invention of Lying." Here's a quote, describing it from Yahoo Movie's Coming Attractions:

"In an alternate reality, lying -- even the concept of a lie -- does not even exist. Everyone -- from politicians to advertisers to the man and woman on the street -- speaks the truth and nothing but the truth with no thought of the consequences. But when a down-on-his-luck loser named Mark suddenly develops the ability to lie, he finds that dishonesty has its rewards."

Link to Yahoo Movies on The Invention of Lying

What this reminded me of what it must be like to be a child, and develop a concept of lying.

How might this work? Answering this question would take a while - there's a lot of research on how children deceive and understand deception. One of my favorite papers on this topic is work by Beate Sodian and her colleagues from 1991. They found that 4-year-olds recognize when to deceive another person (in a competitive situation) and when not to deceive (in a cooperative one). Three-year-olds, in contrast, deceived indiscriminately.

Link to Sodian et al. (1991) in Child Development

This finding makes sense. In order to deceive another person, you have to represent what they are thinking, and how your actions will give them a false belief. Children's understanding of false belief typically develops between the ages of 3 and 4.

But there is some recent research that challenges this assumption. In 2005, Kristine Onishi and Renée Baillargeon published an article in Science suggesting that much younger children understood when another person had a false belief. In their experiment, 15-month-olds watched an actor place a desirable object in one location. Then, unbeknownst to the actor, the object moved to another location (both of the locations were containers, so you couldn't tell where the object was just by looking at it). Some infants then observed the actor return and look in the original location; others saw the actor look where the object really was. Infants stared at the display longer when the actor looked where the object actually was, as opposed to where the actor thought the object was; that is, they showed surprise when the actor didn't act according to his false belief.
Importantly, they didn't do this when the actor had a true belief about the world - when she witnessed the object move

Link to Onishi and Bailargeon (2005) in Science

There's an aside here - I don't really think the longer looking time has anything to do with surprise, but that's an easy way to think about this paradigm.

Onishi and Baillargeon's paper has now inspired a whole field of researchers to examine infants' understanding of others' mental states (and notably infants' understanding of belief). At the 2009 meeting of the Society for Research in Child Development, I saw numerous talks and posters dedicated to examining infants' early comprehension of mental states using Onishi and Baillargeon's techniques (as another aside, I'll mention that two of my students got really interested in this, and are starting data collection on their own experiment soon - if things go well, I'll mention their findings sometime in the future). There is genuine interest in this topic in the field right now.

But there's also a big question: Why do 15-month-olds behave as if they understand others' mental states in these experiments, but 3-year-olds do not when asked to deceive (or for that matter, when asked to recognize that someone has a false belief using any task that involves simply asking them). It could be that the linguistic aspect of these tasks adds cognitive demands for the older children, which causes them to fail. On this view, children have the cognitive wherewithal to understand others' mental states, but fail because of the way experimenters ask the question. A similar possibility is that the tasks used on older children all require the child to inhibit some kind of prepotent response, and such inhibitory control develops around the same time (and indeed, researchers like Stephanie Carlson and her colleagues have found that success on measures of inhibitory control that have nothing to do with mental states predict children's understanding of others' false beliefs). Again, on this view, there's nothing about mental states that develops between ages 3-4; these findings are about children developing the capacity to demonstrate success - they have the underlying cognitive abilities.

I'm a little skeptical of these explanations. In 1991, Alison Gopnik and Virginia Slaughter found that when the inhibitory demands were equated, children appeared to understand another's desires earlier than their beliefs. Some of my own work has looked at the role of inhibition in pretending, and while there is a benefit to reducing inhibitory demands or other demand characteristics within an experiment, it's not the whole story.

Link to Gopnik and Slaughter (1991) in Child Development

So what is the story about children's developing understanding of belief? Ian Apperly and Stephen Butterfill recently argued in a paper in Psychological Review that there are two systems for understanding belief - one that is innate (or acquired very early) and that is potentially shared with non-human animals - and one that develops from this system. Put simply, Onishi and Baillargeon's findings indicate the presence first system, while the development observed by Sodian and others indicates the latter.

Link to Apperly and Butterfill (in press) in Psychological Review

This is a good explanation. But, I want to speculate on another. Consider the phenomenon of infant amnesia. It's somewhat reassuring to know that when Paulina has bouts of gas (that occasionally are a precursor to the aforementioned poop), she's not going to remember how traumatized she was as a preschooler or an adult. Why not? Why are our first memories as children usually from the preschool (or rarely, the toddler) years? There are a lot of theories, but the one that I like the best is that our memories go through a reorganization that is related to learning language. Language gives us a narrative structure, which helps us to remember what happened to us. Why can't the same be true of our semantic memory - our understanding of rules and concepts, such as when another has a false belief? It might be that Onishi and Baillargeon's data shows early competence, but sometime afterwards, we lose that understanding, only to reacquire it as part of learning various aspects of language and linguistic structure.

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I've got no evidence for this - it's not exactly clear how this would function or what aspects of language truly affect this cognitive system. But, this does explain a nagging finding in the literature. Right at the third birthday (before children show any understanding of others' false beliefs on standard tasks, or on tasks of deception like Sodian's), they generate contrastives about belief in their linguistic utterances. Three-year-olds say things like "I thought it was a car, but it was really a truck." Karen Bartsch and Henry Wellman's 1995 book, Children Talk about the Mind dedicates a chapter to this phenomenon. If children have the cognitive capacity to understand others' false belief as infants, but must relearn it when they learn language wouldn't it make sense that this understanding should first appear in their own linguistic utterances?

Renée Baillargeon is coming to my department to give a talk at the beginning of November. I'm excited to hear what she has to say. Stay tuned.