Recruit 4- to 6-year-old children who have normal vision and hearing. For the purposes of this demonstration, only two children are tested (one for each condition). Larger sample sizes are recommended when conducting any experiments.

1. Gather the necessary materials.

1. Obtain two sets of four small tokens. For this experiment, use four red checkers and four blue checkers.
2. Obtain two 10 in (25.4 cm) pieces of string or yarn of different colors. For this experiment, use blue and white yarn.
3. Acquire a stuffed animal that fits in a box. For this experiment, use a teddy bear.

2. Data collection

1. Introduction
   1. Place the teddy bear in the box on the table before the child enters the room.
   2. Seat the child at the table across from the experimenter.
   3. Remove the teddy bear from the box, show it to the child, and say: “This is a very naughty bear. Sometimes he escapes from his box and messes up the game. He likes to spoil the game.”
2. Initial judgment of number
   1. Set up the tokens so they are in two rows of equal length, where the tokens are evenly spaced and there is a one-to-one correspondence between the rows. Make sure each row contains the same color tokens.
   2. Point to each row and ask the child: “Is there more here or more here, or do they both have the same number?” Record the child’s response.
   3. Alternate the location of the red and blue rows of tokens (closer or farther from the child) between subjects.
3. Transformation
   1. At this point, randomly assign children to one of two conditions.
      1. In the intentional condition, direct the child’s attention to the tokens by saying, “Now, watch me,” and move the row of tokens that is further away from the child into a cluster closer together, so they touch.
      2. In the accidental condition, act surprised and say: “Oh, no, it’s the naughty bear. Look out! He is going to spoil the game!” Remove the bear from the box and use his hands to rearrange the row of tokens furthest from the child into a cluster closer together, so they touch. Then ask the child to return the bear to his box.
   2. Post-transformation judgment of number
      1. Point to each row of tokens and ask the child: “Is there more here or more here, or do they both have the same number?”
      2. Put away the tokens.
   3. Judgments of length
      1. Repeat the exact procedure just described for judgments of length.
      2. In these trials, initially place both strings on the table so they are straight and parallel to each other. The transformation involves pulling on the middle of one string so it is curved.
      3. Assign the children to the same condition for the judgment of length trials as they were for the judgment of number trials.

3. Analysis

1. Exclude any children who answered the initial judgment questions incorrectly, as this suggests the children could not accurately judge number or length equivalence before the objects were transformed.
2. Calculate a score of 0-2 for the number of times children in each condition judged the number or length of the objects stayed the same.
3. Compare children’s scores across conditions using an independent samples t-test.