Shape Bias Overview

The shape bias is the tendency of infants and children (as well as adults) to generalize information about objects by their shapes.

I have been giving talks to parents on the topic of early learning for more than 20 years. Rarely have any of the parents ever heard of the shape bias, yet it is a concept that can have a large impact on how efficiently your baby learns words. Since early vocabulary is a predictor of later vocabulary, learning the shape bias earlier could help increase the size of your child’s vocabulary. Not only does learning the shape bias increase the baby’s rate of word learning, a newer study from Stanford University indicates that knowing more words at 18 months of age could also lead to faster brain processing speeds than knowing fewer words. This means that teaching your child the shape bias earlier could have important long-term positive benefits for your child’s language and brain development.

Note: You can teach the shape bias without purchasing any of our products. The studies mentioned above did not test the babies for the shape bias and were not done on our products.

What is the shape bias?

The shape bias is the tendency of infants and children (as well as adults) to generalize information about objects by their shapes, rather than their colors, materials, sizes, or textures when learning nouns.

Infants initially categorize objects inefficiently. However, a baby who has learned the shape bias is more likely to categorize objects according to their shapes instead of using color, material, size, or other less important attributes.

Three different chairs, three different books, and three different hats.

Do you want your baby to categorize these objects by shape or by color?

The above objects categorized by color would likely be in five different categories: red, blue, purple, black, and green.

The above objects categorized by shape would likely be in three different categories: chairs, hats, and books.

What happens if babies categorize objects more by their shapes than by their colors?

Look at the image above. If you sort by shapes, then you have three groups: chairs, books, and hats. If you sort by color, then you have five groups: red, blue, green, black, and purple. The shapes of the chairs, books, and hats give more information about their functions than their colors, materials, textures, or sizes. Acquiring the shape bias helps children organize their world in a more logical manner and it is associated with more rapid word learning1,2,3. Imagine you are an 18-month-old infant who organizes the world based primarily on color. Babies who would be doing this would be sorting the above blue objects together, and according to research they learn new words at slower speeds.

If your baby sees novel objects and hears the word associated with the object, in most cases the baby will learn the function of the category that the object is a member of when the baby focuses more on the object’s shape compared to the object’s color, texture, size, or material.

Why does knowing the shape bias matter?

Learning the shape bias can result in an increase in the vocabularies of infants and children (Smith, 2000; Landau, Smith, & Jones, 1988). Infants or children who have learned the shape bias tend to learn words at a faster rate than infants and children who have not learned the shape bias1,2,3.

Can the shape bias be taught?

In a laboratory setting, 17-month-old babies learned it within four fifteen-minute sessions. As soon as they were taught, then their rate of word learning increased1,2,3. The shape bias is displayed when a child consistently organizes objects more by their shapes than by their colors or other often-trivial features of the objects.

My daughter Keelin was a pilot baby for some shape bias studies at Indiana University in 1995. Keelin already knew the shape bias long before she was 17 months of age, so she was more likely to sort the novel objects in the experiments by their shapes. I knew that she had already acquired the shape bias because she could recognize written words from their shapes instead of using color, size, texture, or material. By definition, babies who can recognize the written words clap, waving, and mouth from the word cards shown here are using the shapes of the words instead of the colors, background colors, fonts, or other features.

Shape Bias Language Cards, Teaching Cards, and Milestone Cards
How do I teach the shape bias?

Do many sorting activities where you organize objects or words based on their shapes.

For example, put many different cups, plates, and spoons in a large opaque (non-transparent) container out of your baby’s view. The cups should vary in color, size, material, and design. The plates and spoons should also vary greatly in many ways, but the spoons, plates, and cups should have similar shapes. Quickly take one object at a time out of the large container and name it. For example, say “This is a metal spoon. We will put all of the spoons in this area. This is a black cup. The cups will go here. This is blue plastic spoon. It goes here with the metal spoon. We can put food on a spoon and use the spoon to eat. This is a red plate. We will put the plates here. This is a little blue plate. It goes with the first plate. This is a metal spoon. It goes with the spoons. This is a white plastic spoon. It goes with the spoons. This is a white plastic plate. It goes with the plates.” Continue sorting these objects. I recommend using color, size, and material adjectives so your baby sees these factors are less important for sorting. The next time you could use socks, t-shirts, and jeans, or other objects.

Babies who have memorized many written words using our program have done so by learning that the shape was more important than the color, background color, specific font, size, or other factor. Our Your Baby Can Learn videos intentionally vary the fonts, font colors, and background colors and while keeping the generalizable shapes of the words the same. Just as cups, chairs, or other objects do not only have one specific shape, words also have slightly different shapes. We vary the fonts so the children can learn the generalizable shapes, which should also make it easier for them to recognize the same words in new fonts or new contexts.

Learning and strengthening the shape bias is very important. Babies who have a stronger shape bias learn words faster than babies who have a weaker shape bias. Parents often categorize objects by their colors or sizes, which can slow down the learning of the shape bias if parents don’t also focus on sorting by shape. Until your baby’s shape bias is relatively strong, it is better to sort objects by their shapes more than you sort objects by their colors. This does not mean not to sort by color, texture, size, or material. Instead, I am recommending to sort objects by their shapes more than you sort them by more trivial object features.

Sort images by shape rather than color or other features to help teach the shape bias.


  1. Gershkoff-Stowe, L. & Smith, L.B. (2004). Shape and the first hundred nouns. Child Development, 75(4), 1098–1114.
  2. Landau, B., Smith, L.B., & Jones, S.S. (1988). The importance of shape in early lexical learning. Cognitive Development, 3, 299–321.
  3. Smith, L.B. (2000). Learning how to learn words: An associative crane. In R.M. Golinkoff, et al.  (Eds.), Becoming a Word Learner: A Debate on Lexical Acquisition. New York: Oxford University Press.


Share this information with friends!