Tag Archives: Susan Hespos

Babies have more general physics knowledge than experts realized

A Feb. 10, 2016 news item on ScienceDaily sheds some light on babies and their knowledge of physics,

We are born with a basic grasp of physics, just enough not to be surprised when we interact with objects. Scientists discovered this in the past two decades. What they did not know yet was that, as early as five months of age, this ‘naive’ physics also extends to liquids and materials that do not behave like solids (for example, sand), as demonstrated by a new study.

A Feb. 10, 2016 SISSA (International School of Advanced Studies) press release (also on EurekAlert), which originated the news item, describes the conclusions and the research in more detail,

If we hold a ball and then let go of it and the ball remains suspended in mid-air, even a baby a few months old will be surprised. Just like an adult, the baby expects the ball to fall to the floor. Even at such a young age humans already have some rudimentary knowledge of the behaviour of solids. Now a new study extends this knowledge to add liquids and other non-solids to the “naïve physics” of infants.

“This new study developed out of previous experiments”, explains Alissa Ferry, SISSA research scientist and among the authors of the paper, “in which we observed that infants were surprised when a liquid failed to behave as a liquid (in those experiments we “cheated” by disguising solids as liquids)”. Their surprise, explains Ferry, demonstrates that their expectations for a liquid had not been met. “However, what we couldn’t establish was whether the infants knew how a liquid should behave or whether they just expected it to be different from a solid”.

Ferry and colleagues (the first author is Susan Hespos of Northwestern University in Illinois, USA, where the experiments were conducted) therefore devised a new set of tests with a greater range of materials and “interactions”. In a first “habituation” phase, the infants were shown the contents of a glass by tilting the glass in front of them. The glass either contained a solid (which, when not moving, had identical appearance to water) or some water. When the glass was tilted back and forth, the two materials behaved differently: the solid remained perfectly still whereas the water moved. This phase served to teach the infants whether they were looking at a solid or a liquid.

Next, the infants were shown an identical glass to the one seen in the previous phase (making them believe that it was the same glass) which contained either the material they had already seen or the other material. At this point, the infants watched the experimenter either pour the contents (liquid or solid) of the glass into another glass containing a grid or submerge the grid in the liquid (or rest it on top of the solid) inside the glass.

“In the previous experiments we merely poured the contents of the glass. This time we added a grid to find out whether the infants really understood the loose cohesiveness of liquids, which can pass through a perforated surface and recompose in the vessel unlike solids which, being highly cohesive, cannot pass through a grid” explains Ferry.

In the habituation phase, in fact, the infants could know how liquids change shape with movement, but it was unknown if they could use this knowledge to understand other properties of liquids, like loose cohesiveness. “If infants understand the properties of liquids, then they should be surprised when, what they think is a liquid gets trapped on a grid”.

And the analysis of the infants’ behaviour shows that when they expected a liquid they were surprised to see it blocked by the grid (or see the grid unable to penetrate the material). Conversely, if they thought they were looking at a solid, then they were surprised when they saw it pass through the grid.

The investigators also used other materials like sand and small glass spheres. “Even in these cases the infants showed that they knew the behaviour of substances”, concludes Ferry. “This is especially interesting because, while we can imagine that 5-month-old infants already have had extensive direct experience with liquids and especially water through meals, baths and 9 months in the amniotic liquid, it’s unlikely that they’ve had many encounters with sand or glass balls, suggesting that infants have a naïve understanding of the physics of nonsolid substances”.

Here’s a link to and a citation for the paper,

Five-Month-Old Infants Have General Knowledge of How Nonsolid Substances Behave and Interact by Susan J. Hespos, Alissa L. Ferry, Erin M. Anderson, Emily N. Hollenbeck, anb Lance J. Rips. Psychological Science February 2016 vol. 27 no. 2 244-256 doi: 10.1177/0956797615617897 Published online: January 7, 2016

This paper is behind a paywall.

Babies—natural physicists?

I don’t often get a chance to do cute but here we go,

Are these babies capable of physics?

I came across a Jan. 24, 2012 news item on Medical Xpress about research showing that babies intuitively understand physics (it makes sense when you see the reasoning),

In a review of related scientific literature from the past 30 years, vanMarle [Kristi vanMarle, an assistant professor in the Department of Psychological Sciences at the University of Missouri] and Susan Hespos of Northwestern University found that the evidence for intuitive physics occurs in infants as young as two months – the earliest age at which testing can occur. At that age, infants show an understanding that unsupported objects will fall and that hidden objects do not cease to exist. Scientific testing also has shown that by five months, infants have an expectation that non-cohesive substances like sand or water are not solid. In a previous publication, vanMarle found that children as young as 10 months consistently choose larger amounts when presented with two different amounts of food substance.

For any parents planning to discuss physics with their babies or start them on a physics enhancement programme, vanMarle has a few words of advice,

“Despite the intuitive physics knowledge, a parent probably cannot do much to ‘get their child ahead’ at the infant stage, including exposing him or her to videos marketed to improve math or language skills,” vanMarle said. “Natural interaction with the child, such as talking to him/her, playing peek-a-boo, and allowing him/her to handle safe objects, is the best method for child development. Natural interaction with the parent and objects in the world gives the child all the input that evolution has prepared the child to seek, accept and use to develop intuitive physics.”

For those who want examine the research first hand,

“Physics for infants: characterizing the origins of knowledge about objects, substances and number,” is published in the January issue of WIREs Cognitive Science.

I suppose you could say we are natural physicists.