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Even At 10 Months Old We Understand Good Things Justify More Effort


Stephen Luntz

Stephen has a science degree with a major in physics, an arts degree with majors in English Literature and History and Philosophy of Science and a Graduate Diploma in Science Communication.

Freelance Writer


Even at this age, don't discount babies' capacity to understand core principles of economics and physics. kryzhov/Shutterstock

Infants have an expectation of a relationship between the value of a reward and the effort it takes to achieve it. Not only does it seem that it's never too early for children to start learning economics, but they also intuitively grasp some physics concepts they have yet to experience directly.

Even as babies we have not only a sense that some things are more valuable than others, but a way to work out which ones others value. Ten-month-old babies have been shown to observe when people consistently choose one option over another, and view that choice as more desirable.


These tests, however, have required equal effort for each option – for example when all the chooser has to do is reach left or right. Harvard University's graduate student Shari Liu investigated whether babies can also make more complex assessments.

As Liu notes in Science, such an assessment requires an assumption people act in their best interests – what economists call maximizing utility. It also indicates an ability to distinguish between rewards and costs and to understand that the cost varies with the circumstances – getting something down of a high shelf might require little effort for an adult, but be a major operation for an older sibling.

Liu conducted three experiments and applied them to 80 10-month-old babies. In each case an adult was seen to seek a reward, or refuse to chase it, depending on the costs involved. This created expectations, and the participants showed surprise when these were breached, for example by someone taking a lower value reward when the costs were set equally for each.

In one experiment animated characters where shown jumping over objects to get prizes, but would only tackle the higher obstacles for more valuable prizes. The character would jump low barriers but skip medium ones for one object, but only the tallest obstacles proved an effective deterrent to the chance to gain the greater reward.


A second experiment used ramps of different steepness instead of vertical leaps but the general concept was the same, while a third involved jumping horizontal gaps of differing width.

In each case, the babies apparently concluded that the objects for which the character would put in more effort were more desirable. They showed surprise through longer staring when characters subsequently chose the lower value object when the required effort was equal.

Besides showing the first glimmerings of economic concepts such as opportunity cost, Liu's work demonstrates babies not yet able to walk, let alone jump obstacles, still understand that leaping tall buildings is not done lightly. However, the work raises the question of whether these attributes set children up to expect a fair reward for efforts, something not all will experience.

spaceSpace and Physicsspacephysics
  • tag
  • physics,

  • baby,

  • infant,

  • economics,

  • opportunity cost,

  • effort and reward