Lights! Action! Kids!

This is a guest post by Laura Younger, one of Greta's top student writers for Spring 2007.

Take a look at these static images from a video clip.

Can you tell what the person is doing? It might be hard to make it out from these still pictures, but when you see the same thing in motion it becomes quite clear. Visit the Biomotion Lab and you'll quickly understand.

What you see is called a point-light display. Lights are attached to joints on the body and filmed while a person is performing an action. The animated display makes it surprisingly clear that this person is walking. But, could a young child, who has just learned verbs, recognize that this person is walking?

Once children learn verbs they must be able to generalize them to different people and situations. By showing children point-light displays, it might be possible to understand the process children use to extend verbs. Because point-light displays give no specific hints about a verb such as an associated location or object, the verb is represented only by the manner and path that define it. For example, a picture of a person using a shovel on the beach could give away the verb if a child recognizes the shovel, whereas showing the action of bending over, pushing towards the ground, and then standing up again shows the manner and path of shoveling.

A research team led by Roberta Golinkoff had 3-year-old children look at point light displays in an attempt to discover if children can label verbs presented in this format.

Success with this task would possibly indicate that children learn to extend verbs because they understand the specific motion that makes up an action and then form a word-action association. For example, when you tell a child 'Look, Dad's running,' the movement of the arms, the bend of the knee, and the forward, fast motion is then represented by the new word, running, which is later generalized if the same motion is observed in an animal or another person. But, for children to be able to label point-light displays as specific verbs, they must have first been introduced to those verbs, especially since children might have a hard time comprehending that a group of lights is actually a person. Because of this, the researchers chose children who already knew the names of at least 7 out of 8 specific verbs. Point-light displays were created by filming people walking, dancing, shoveling, picking flowers, running, rolling, hopping, and skipping with lights attached to their ankles, knees, hips, wrists, elbows, and shoulders. In experiment 1, children were presented with 2 simultaneous films of point-light displays on separate screens. As they watched, an experimenter said things such as "Do you see dancing?" or "Find dancing! Look at dancing!" The expectation was that if children look more to the screen depicting the named verb, then they are able to make a distinction between the 2 actions. All children were held facing the screens by their parents, but parents were told not to help the children in any way.

The following diagram shows the setup of the testing room.

Children were first presented with a point-light display of a cat; the cat and action were verbally labeled to familiarize the children with the concept of point-light displays. Then children saw 2 simultaneous videos, this time depicting people. The experimenter verbalized both actions so the children would understand what the displays were showing. However, the experimenter did not tell them which screen displayed which action. For example, "Hey, one is walking and one is dancing!" Next, children were given the test trials. Pairs of verbs were presented while the experimenter named 1 of the 2 verbs. A red light between the 2 screens helped to attract children's attention before the start of a new trial. Observers who could not see the screens indicated which screen children looked at and how long they looked.

The results show that 29 out of the 32 three-year-olds looked at the point-light display that matched the spoken verb! The average time that children looked at the screen depicting the match was 3.36 seconds compared with only 2.29 seconds spent looking at the screen that did not match. These data suggest that children can extend verbs to something they have never seen before.

Children could successfully look at the screen depicting the matching verb, but would they be able to name the verb? Perhaps children only recognized the action once they were given the label, which then helped them understand what they were seeing. In order to gather more evidence that children can recognize point-light action without suggestion, the researchers brought in a new group of children and asked them to say the verb that they saw.

In experiment 2, children once again sat on their parent's laps but saw the point-light displays one at a time. The experimenter then prompted the children, asking "Can you tell me that was?" Often the children would label the object, and in this case, the experimenter would then prompt again, saying something such as "What was the lady doing?" If a child still did not say a verb, he or she was prompted with the actual label, "Was the lady walking?" Most children successfully answered with some kind of action after the first question. The experimenters accepted a few different descriptions for specific actions based on adults' ratings of the appropriateness of each response. For instance, walking, jogging, and marching were all considered appropriate responses for running. The following chart shows the number of children who gave appropriate responses for each action over the total number of children who gave responses.

As you can see, skipping and shoveling had only a few appropriate responses but children were still able to say some type of motion verb even if it was not appropriate. These results are quite impressive considering that 3-year-olds actually produced a verb for a strange group of moving lights

Although there are no point-light displays in the real world, this research shows us that children most likely recognize motions by summarizing the components that make up a specific motion and then storing those components in memory. If children can extend familiar verbs to point-light displays, could they learn verbs from point-light displays? Since autistic children struggle to develop language, point-light displays might be incorporated into autism treatment programs as a way to teach motion verbs. Research about how children acquire, categorize, and label information from their surroundings is particularly applicable to this group. As Golinkoff and colleagues point out, verbs are the building blocks of sentences, so understanding how children learn to use them may hint at how children learn to label their surroundings with words.

Golinkoff, R. M., Chung, H. L., Hirsh-Pasek, K., Liu, J., Bertenthal, B. I., Brand, R., Maguire, M..J., & Hennon, E. (2002). Young children can extend motion verbs to point-light displays. Developmental Psychology, 38, 604-614.