Cognitive Daily

One of Jean Piaget’s most famous observations is the phenomenon of “object permanence”—the idea that babies younger than eight months old have no conception of an object once it’s hidden from view. It’s easy to see how he came to this conclusion. Click on the picture of my daughter Nora at six months of age to see a video of her spectacularly failing the object permanence test. Once the object is hidden under a napkin, she seems to lose all interest in it.


But does she really not understand that the object is still there, or is she simply interested in other things? A team of researchers led by Yuyan Luo developed a different methodology to answer this question (Yuyan Luo, Ren閑 Baillargeon, and Laura Breuckner, University of Illinois; and Yuko Munakata, University of Colorado, “Reasoning about a Hidden Object After a Delay: Evidence for Robust Representations in 5-Month-Old Infants,” Cognition, 2003).

Their procedure involved dividing 5-month-old babies into two groups. The first group was shown a box which was placed behind a screen on a small stage. The experimenter showed the baby that there was no room in the six inches between the screen and the back wall of the stage to fit any objects other than the box. Next, with the screen up, the babies were shown a cylinder that was taller than the screen. The babies were distracted for a few minutes, then presented with the testing phase. In this phase, the cylinder was moved behind the screen—right where the baby had only ever known to be filled with a box. If the baby remembered that the box was there, Luo et al. reasoned, then she would be surprised to see the cylinder move through the space that should have been occupied by the box.

Of course, five-month-olds can’t tell us if they’re surprised, so typically “surprise” is measured by how long the baby looks at the object which is supposed to surprise them. Babies did indeed stare at the cylinder for up to a full 60 seconds after it stopped moving.

The second group was shown the identical procedure, except that the box behind the screen was only a half-inch deep, leaving plenty of room for the cylinder to pass unimpeded. While this group also stared at the cylinder for a long period of time, they tended to lose interest about 20 seconds quicker than the first group. It’s difficult to come up with any explanation for this difference other than that the babies remember that the object behind the screen shouldn’t block the path of the cylinder. The reason they stared at all is simply because they hadn’t seen the cylinder move on its own before.

So apparently babies do remember objects, even several minutes after they are hidden. In the video, Nora may have remembered the rattle after it was placed under the napkin but simply lost interest now that it was no longer moving.


  1. #1 elke's
    August 15, 2005

    rekenen en vrouwen

  2. #2 Valeri
    August 23, 2005

    My now 7 year old daughter has autism. I remember puting a towel over our wine rack to keep her out of it and the look of “shock” on her face at about 8 months that seemed to say; “Where did it go”? My other 2 just pulled the towel right off by that age. There were not many clues to what my autistic daughter was in for at an early age, but this has stuck in my mind as an early sign that something was not quite right.

  3. #3 COG Blog
    September 6, 2005

    infant perception@cognitive daily

    Posted by Deborah Frisch Cognitive Daily is a blog that provides synopses of journal articles in cognitive psychology. It�s nicely done with impressive graphics. Here�s a summary of a 2003 paper in Cognition by Luo, Baillargeon, Brueckner and Munakata …

  4. #4 9rules Network: Weblog
    September 8, 2005

    […] c topics, check out some of my favorite posts: Critiquing the video game violence studies, Do babies known if hidden objects are still there?, and my all-time favorite: Can our understanding of “nor […]

  5. #5 Mengü Gülmen
    December 22, 2005

    The concept of “hidden” things, is a “learned” concept, an “information” in the memory.

    So my idea is, once a baby “learns” that “there are things that can be hidden from view, and come back some time later” (with a method or another), it has learned the concept of “hidden” things and so, starts to learn to “search” for hidden things.

    Before that stage, all the experiments on this subject only helps the baby learn the concept faster 馃檪

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