Wednesday, February 18, 2015

Stories from the mind of a toddler

Right around the holidays, M started doing something new and charming. Although she had been speaking individual words all throughout the fall, she began to use single word utterances and gestures together to tell stories about events that had happened to her. Even young infants have long-lasting memories that seem tied to individual events, but there's something different about being able to share your memories using language. For us, it meant the first opportunity to have multi-turn conversations with M. She can now share something she's thinking about and we can reminisce about it together.

The first narrative I saw was very simple. Perhaps it was less clearly evocative of a particular event than a class of events, but still different from what came before. M would say "meow" (or her equivalent, which has a lengthened second syllable only, so /aw/) and then make the gesture/sign for come here, palm upright with fingers pulling towards her. This was how she recalled our nightly walks, which tended to go to a street near our house where a friendly cat could occasionally be seen. We'd say "Are you thinking about the kitty cats? ["yah!" replies M] Did you see a kitty last night? [M - /aw/] What did you say to it? [M makes "come here" gesture] That's right - come here, kitty kitty."

So you can see how this little narrative becomes a linguistic routine, something that reinforces the memory it refers to. But this is example is also a little weak; our scaffolding of the memory was probably critical to making it more than just generalized, undirected longing for cats (something that M has quite a bit of).

The second example – the one that really convinced me – came a few weeks later when we took M to a local farm. She had been reading animal books with us for many months, so we thought she'd enjoy the experience. We were right. She was totally transfixed by watching a cow be milked and fed. After we got home, she wanted to talk about the cow a lot. Every fifteen minutes or so, out of nowhere she would moo, but we were confused by what she was trying to express. After mooing, she'd say "uh oh" and point to her tongue.

It took us several repetitions to figure out what M was telling us. Here's the story (in all its toddler glory): when the cow was eating, a lot of its feed fell out of its mouth (hence "uh oh"). But then once we figured out the story, the gesture of food coming out of the mouth got conventionalized into something like the reverse of an "eat, eat" gesture – fingers pressed together, pulling from the mouth. And then we had to do the whole routine over and over again. M: "moo" - parent: "are you thinking about the cow?" M - "uh oh!" and then [falling food gesture]. Ad nauseam. Two months later, she will still tell this story.

When M was very tiny and I had some free nap times, I read a fair amount about baby sign – we never made a decision not to teach signs to M, but life seemed too short. But the most interesting thing I learned was that there was a whole literature on children's spontaneous signs (one paper by the baby sign folks; another by an independent group). The baby sign folks in particular had documented idiosyncratic signs that got built up in structured conversations between parents and kids.

This is exactly the kind of thing M has been doing – she now has a repertoire of such signs that she uses in her narratives, including the "come here," the "falling food" gesture, as well as signs for rain, traffic, and getting splashed in the face by water. Several of them seem quite bound to particular stories, but she has also generalized. For example, her "traffic" sign is pointing and then rapidly swinging her arm back and forth. She spontaneously used this to tell a story about a horse that she had seen, who had both done some messy eating and also run around: "neigh" - [food falling sign] - [running sign]. So these signs do seem at least somewhat flexible and word-like.

Children famously suffer from "childhood amnesia" – the relative inability to recall specific episodic memories from childhood. There are many explanations for this puzzling phenomenon, but one I'm especially fond of (without too much support) is that language plays a role. Episodic memories are not always stored in language, but language provides a medium for encoding and rehearsal. Of course, if language is changing dramatically from the time of encoding to retrieval, that could cause problems for retrieval – hence possible "amnesia."

So I think M's narratives might be a first attempt to express and re-encode episodic memories. The degree to which she retains them will be variable. The relative distinctiveness of the memories will play a role, but the way she encodes them may also matter. The use of signs – which will probably vanish from her vocabulary once she can produce the appropriate words – may help in telling the stories now. But maybe – as the signs fade – she'll also forget the stories more easily?

Monday, February 9, 2015

Could conference submission be preregistration?

If we care about the answer to a particular question, preregistration – registering hypotheses and analyses ahead of time so that they are not data-dependent – is an important strategy for improving the strength of the evidence from studies bearing on that question. Of course, preregistration has some pros and cons. In my mind, the most notable these is that prereg is more appropriate for large, expensive, confirmatory studies than small, cheap, exploratory studies that are easily replicated (see my post about this topic).

In brief: My worry about pre-registered journal papers is that they can be very expensive in terms of research effort. If no one really cares about a hypothesis, then it's not a big deal not to publish on it. But if you preregister your crazy, speculative claim, then you may be stuck writing a paper telling everyone something they already expected: that your crazy idea, which would have been cool if true, is actually false. And writing papers is hard work: it takes a long time, and has severe opportunity costs. You could be doing new research during the time you are writing a careful, clear, and comprehensive paper on a thing that no one cares about because it wasn't likely to be true and indeed isn't.*

Nevertheless, there's no denying that it's good to be able to see an unbiased sample of experimental hypotheses. So here's a thought.

Something I always tell students NOT to do is to submit to conferences before they are done collecting data. This practice means that you have to impose your own biases on your preliminary data, and it can put you in an awkward position if you write a strongly hypothesis-driven abstract about data that don't end up supporting your spin on them.

But what about if we exploited this issue? We could create a track at conferences where you would submit an abstract on what you were going to do but hadn't yet done – essentially a prereg track. Then we'd have a particular poster session for seeing the results. All we'd need to do is to make sure that the conference abstracts themselves were indexed appropriately, and perhaps require an updated, post data-collection addendum. The upsides would be A) a chance for folks (especially undergrad and early grad students) to get an opportunity to present their work, and B) a low-cost preregistration mechanism.

The Cognitive Science Society already has a track for lightly-reviewed "member abstracts" – essentially posters on work that isn't done enough to merit a six-page paper. Why not "pre data-collection abstracts" too?

* Let me emphasize here that I'm not talking about hypotheses where a null result is important and informative, e.g. as in intervention work, or tests of theoretically-central claims. I'm talking about the kind of exploratory work – trying to play around with novel theoretical ideas – that characterizes a lot of research in cognitive science.