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Infants Possess a Physics Engine

January 27, 2012

One feature that separates humans from animals is instinct. An instinct is an unlearned, automatic, unmodifiable, irresistible behavior of every member of a species, occurring at a specific point in an organism's development, that's triggered by a specific stimulus.

People may have urges, but the human species demonstrates nothing corresponding to instinct. Our intellect rules the roost, but a consequence of this is that everything we do must be learned.

How much can an infant learn about its environment in just a few months? Quite a lot of physics, as demonstrated in a review article recently published in Wiley Interdisciplinary Reviews: Cognitive Science by two psychologists, Kristy vanMarle of the University of Missouri and Susan J. Hespos of Northwestern University.[1-2]

Infant holding a wrench Adults have a great knowledge of their physical environment, an innate physics engine. We understand simple concepts, such as "what goes up must come down," and the complex projectile mechanics of catching a tossed ball.

Infants are apparently able to understand from a very early age the physical concepts of
solidity, continuity, cohesion, and change. This understanding is apparent in infants as young as two months, which is the earliest age at which meaningful psychological testing is possible. At first, these concepts are primitive, but they are developed through learning and experience.[2]

It's conjectured that this
intuitive knowledge of physics is present at birth. In normal development at two months, infants realize that unsupported objects will fall (Wile E. Coyote notwithstanding), and that objects that are hidden do not cease to exist. At five months, the physics palette is increased to include the idea that sand, water and other non-cohesive substances are not solid. At ten months, quantitative reasoning kicks in, and children will prefer a larger portion of food.[1]

Review author, Kristy vanMarle, offers the following advice to parents who wish to nurture their young physicist.
"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."[1]

These results seem to overlap with the instinct concept, possibly adding to the debate about human instinct. Infants appear to be born with an expectation of how the physical world operates. This knowledge is, at first, primitive, but it's refined by experience so the point at which people will try to catch a falling cup, but never think about trying to catch the spilling milk it contained.[1]

In related research, the British Economic and Social Research Council (ESRC) has developed physics training software for elementary school students.[3-4] The software was written in response to a study of children, aged 6-11, that identified the following problem areas: [3]
• Children have just a limited knowledge of horizontal motion and fall, and their knowledge does not seem to improve throughout the course of their elementary education, despite efforts to teach these topics.

• The concept of acceleration during fall is not learned.

• The traditional teaching methods for object motion are not working.

The software, developed to address these shortfalls, was tested on about 150 children, aged 8-12, who used the software under adult supervision, or with classmates. This software, which is unfortunately available for Windows, only, can be downloaded at no charge from www.educ.cam.ac.uk/research/projects/objectmotion.

Now that tablet computers are making inroads into schools, an Android tablet version would be nice.

PLATO V CAI terminal (1981)

Computer-aided instruction (CAI) has been with us for a long time.

The PLATO Computer System (Programmed Logic for Automated Teaching Operations) was developed in the 1960s.

This PLATO V terminal, with an orange
plasma display, is dated 1981.

(Via Wikimedia Commons).


  1. Steven Adams, "Babies Are Born With “Intuitive Physics” Knowledge, Says MU Researcher," University of Missouri Press Release, January 24, 2012.
  2. Susan J. Hespos and Kristy vanMarle, "Physics for infants: characterizing the origins of knowledge about objects, substances, and number," WIREs Cognitive Science, vol. 3, no. 1 (February 20120, pp. 19-27.
  3. Danielle Moore and Jeanine Woolley, "Supporting primary children's understanding of physics," Economic and Social Research Council Press Release, January 24, 2011.
  4. Object Fall, Economic and Social Research Council Web Site.

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