用你的头: 测量婴儿的理性模仿的行动

Imitation is a form of social learning that goes beyond simply copying others’ actions and involves understanding the goals and intentions behind behaviors.

For example, think of an infant watching their father drink from a water bottle. If the father accidentally drops the bottle while the lid is closed before taking a drink, the infant must then decode this complex set of events to decide which steps are necessary, and which can be ignored, to simply drink water.

Ultimately, once infants assume that others are rational, they can understand which goal-oriented actions to imitate exactly and which incidental actions to ignore, such as drinking from the water bottle without first dropping it on the floor.

This video demonstrates how to design and conduct an imitation experiment in infants based on the seminal methods of Andrew Meltzoff, György Gergely, and colleagues, as well as how to analyze and interpret results across rational and irrational conditions.

In this 2-group experiment, 14-month-old infants are assigned to one of two conditions—one in which an adult’s hands are occupied or one where they are free.

In the hands-occupied condition, infants evaluate a rational scenario, where an adult pretends to be cold, wraps a blanket around themselves, and keeps both hands holding the blanket. They are logically unable to touch a lamp with their hands and must do so with their head.

Alternatively, in the hands-free condition, infants observe an irrational situation. In this case, the adult again pretends to be cold and uses the blanket, but then rests both hands flat on the table, clearly making their hands available to use. However, the experimenter still touches the lamp with their head.

In a follow-up session one week later, the infant is simply placed near the same touch lamp and briefly observed over a short, 20-s period.

During this observation period, the dependent variable is recorded as the percentage of infants who mimic the adult by touching the lamp with their head or respond by using their hands.

It is hypothesized that young infants imitate selectively. That is, when they infer that there is a reason for the unusual behavior they are observing—as in the hands-free condition—they mimic exact actions rather than responding simply by using their hands.

Prior to the experimental sessions, gather the necessary materials, which include a touch-sensitive lamp at least 6 in. in diameter, a platform to rest the lamp on, a few small toys, and a blanket.

For session one, place the touch sensitive lamp on the platform at a height where you can reach it with your forehead.

Then, set up a rectangular table with two chairs on one side—one for you and one for the parent. Move the lamp out of sight but within reach, and place some toys on the table.

To begin the session, invite the parent and infant into the room. Direct them to sit on the chair to the left with the infant on their lap, while you sit on the chair to the right.

Help the infant become comfortable with the environment by providing some toys for them to play with for 1-3 min.

While the infant is playing, inform the parent that you will be demonstrating an action for the infant, and that they must avoid interacting with their child during this time.

Following the explanation, put away the toys, and place the touch lamp on the platform.

Start the experiment by getting the infant’s attention. After randomly dividing them into one of two conditions, pretend to be cold and wrap a blanket around you. Continue to hold the blanket with both hands for the hands-occupied group versus visibly resting both hands flat on the table in the other hands-free condition.

Next, lean forward, touch the lamp with your forehead, and then straighten back to an upright position; repeat this procedure 3x in a 20-s period. Note that the same action is performed for both groups, only the hand positions are different.

Following the demonstration, escort the parent and infant from the testing room and inform the parent not to discuss or model the actions shown to their child.

Seven days later, prepare for session two by setting up a video camera to record the infant’s torso, head, and the tabletop. Also, verify that the lamp is turned off to prevent it from accidentally illuminating.

After starting the video recording, escort the parent and infant into the testing room and have them sit at the table as they previously did during the first session.

Once again, provide toys for the infant to play with for 1-3 min to acclimate them to the environment.

Then, remove the toys and place the touch lamp on the table directly in front of the infant. Allow them to interact with the lamp, and after 20 s from the initial contact, stop the recording.

When the study is finished, have two independent raters, who are blind to the conditions, code the 20-s interaction period for each infant by writing a yes response if the infant made head contact or leaned very close to the lamp, or no if they did not.

To analyze the responses, compare the percentage of infants that used their hands only, or their head, to touch the lamp.

Note that 69% of infants in the hands-free condition re-enacted the head action during session two. In contrast, only 21% of infants in the hands-occupied condition did so. These data support the claim that 14-month-olds are able to evaluate the reasons for an adult’s behavior well after they first observed the behavior.

Now that you are familiar with how infants are already thinking about the reasons for a person’s behavior and using them to guide their own behaviors, you can apply how such rational imitation is critical in a number of situations.

Understanding rational behavior underlies many slapstick comedy routines. For instance, seeing an actor slip on a banana peel because it was their goal to do so is not funny. However, the same actor accidentally slipping on a banana peel in a way not aligned with their goals is hysterical.

Rational imitation can also be applied to understanding the development of creativity and flexibility in problem solving.

Performing tasks the way that individuals have seen them done before, like standing on a wobbly chair to reach a fan switch, is not always the most efficient—or safest—solution. Rather, with a little ingenuity, a new solution can be developed.

You’ve just watched JoVE’s introduction to studying rational imitation in infants. Now you should have a good understanding of how to design and conduct the experiment, and finally how to analyze and interpret the results.

Thanks for watching!