I wanted to make sure to elaborate on one of the most important cognitive leaps that happen at around 8-9 months because it has such clear implications for sleep training. Remember a couple of posts ago, I mentioned that kids this age become obsessed with searching for objects? That's because babies younger than 8 months don't have the working memory capacity (again, think of working memory as similar to the RAM in a computer) to keep any goal in mind, even a simple one like finding and playing with a toy. BEFORE this age, out of sight is really out of mind. By 6 or 7 months, babies will certainly be aware that a toy or a person has disappeared from view, and they may gaze intently at the place where the disappearance occurred. But only for a few moments. Then their gaze wanders about the room, and before long they forget about the vanished object completely (that's why babies that young are so easy to distract and redirect). This is one of the most surprising and counter-intuitive features of mid-infancy. Hide a treasured toy under a mat—right in front of the baby’s eyes—and your 7-month-old will invariably fail to lift the mat to find it. It’s as if the vanished object has disappeared from existence. Do it over and over, showing the baby that you are hiding the toy they want so much under the mat right in front of their face, and they will repeatedly look around, clueless, when the toy is hidden. This was basically the classic experiment by the "father" of cognitive developmental psychology, Jean Piaget. Try it for yourself if you have a baby younger than 8 months...
Of course, Marc and I had to test our kids when we knew they hadn't reached this stage yet. To give you a sense of what it really looks like, here's a quick clip of one of our boys "failing" the task at 7.5 months old:
This “cluelessness” about disappearing objects changes between 8 and 9 months when they become capable of keeping the vanished object in mind while they lift whatever it is that’s covered it. Now they know that a vanished object can be retrieved. And that means that a vanished parent can be retrieved too. Before 8 months, if you walked out the door and didn’t come back, there’s a good chance your baby stopped looking for you in less than a minute. But if you try the same disappearing act a month later, your baby will almost certainly do everything in his power to get you back. He will not forget that you’re out there. If he wants you, he will yell, scream, and cry in frustration, knowing that you are accessible and yet stubbornly refusing to reappear. Now you can see why this is such a potentially tough age to sleep train. Once babies basically get the hang of this stage, by around 11-12 months, they've had lots of experience with mom disappearing and then predictably reappearing and the whole goal of bringing mom back is not as compelling anymore.
Cool, huh?
(BTW, you can find tons of youtube videos of kids going through that "object permanence" task. There are way too many grad students in developmental psychology trying it out on their own kids, I suspect.)
We're just about to hit 11 months. Bub was a preemie, but I almost always go by his birthday instead of my due date. Anyway, we've been getting by with co-sleeping (both next to the bed, and in bed). Our bed's not getting any bigger, and I don't want to be slapped and kicked all summer long, so our transition into the crib in a separate room is not far away. We did consider doing this sooner, but it always seemed like he was in the middle of some event (i.e. teething, a cold, starting daycare), so we procrastinated and kept doing what was "working" for us. I'm glad I trusted my instincts and held off (I'm willing to admit there was a laziness aspect to it as well), we might have tried at an inopportune time. But now that he's entering a more resilient stage, we might just have to suck it up and go for it.
Posted by: Judy B | May 01, 2009 at 02:41 PM
I just ordered your book from Amazon.ca and can't wait to read it. Our daughter is 8.5 months old and she is definitely starting to exhibit signs of this next developmental stage. She is currently "co-sleeping" with us in her side-carred crib. My husband and I were planning on moving her to her own room after I finished my MPH program in 2 weeks, but I get the sense from reading your other blog posts that we may not very successful in getting her to accept this change. I will be going back to medical school rotations in August when she will be 12 months old. I have June and July off from school. When would be the best time to transition her to her own room? Is 10 months ok? Is 11 months better? The problem is, we will be traveling in August so I don't want to "sleep train" her only to have it messed up a few weeks later. Any advice?
Posted by: Catherine C | May 06, 2009 at 11:13 AM