June 1, 2011
Inside the Infant Mind
(Ivanhoe Newswire) -- Over the past two decades, scientists have shown that babies only a few months old have a solid grasp on basic rules of the physical world. They understand that objects can't wink in and out of existence, and that objects can't "teleport" from one spot to another.
Now, an international team of researchers co-led by MIT's Josh Tenenbaum has found that infants can use that knowledge to form surprisingly sophisticated expectations of how novel situations will unfold. The scientists developed a computational model of infant cognition that accurately predicts infants' surprise at events that violate their conception of the physical world.
The model, which simulates a type of intelligence known as pure reasoning, calculates the probability of a particular event, given what it knows about how objects behave. The close correlation between the model's predictions and the infants' actual responses to such events suggests that infants reason in a similar way, says Tenenbaum, associate professor of cognitive science and computation at MIT.
"Real intelligence is about finding yourself in situations that you've never been in before but that have some abstract principles in common with your experience, and using that abstract knowledge to reason productively in the new situation," Tenenbaum said.
Tenenbaum and Edward Vul, a former MIT student who worked with Tenenbaum and is now at the University of California at San Diego, developed a computational model, known as an "ideal-observer model," to predict how long infants would look at animated scenarios that were more or less consistent with their knowledge of objects' behavior. The model starts with abstract principles of how objects can behave in general (the same principles that Spelke showed infants have), then runs multiple simulations of how objects could behave in a given situation.
In one example, 12-month-olds were shown four objects "” three blue, one red "” bouncing around a container. After some time, the scene would be covered, and during that time, one of the objects would exit the container through an opening.
If the scene was blocked very briefly (0.04 seconds), infants would be surprised if one of the objects farthest from the exit had left the container. If the scene was obscured longer (2 seconds), the distance from exit became less important and they were surprised only if the rare (red) object exited first. At intermediate times, both distance to the exit and number of objects mattered.
"We don't yet have a unified theory of how cognition works, but we're starting to make progress on describing core aspects of cognition that previously were only described intuitively. Now we're describing them mathematically," Tenenbaum said.
He is also developing similar models for infants' "intuitive psychology," or understanding of how other people act. Such models of normal infant cognition could help researchers figure out what goes wrong in disorders such as autism. "We have to understand more precisely what the normal case is like in order to understand how it breaks," Tenenbaum said.
SOURCE: MIT press release May 26, 2011