Numerical Cognition: More or Less

Recruit 12-month-old infants. For the purposes of this demonstration, only one child is tested. Larger sample sizes (as in the Feigenson, Carey, and Hauser study¹) are recommended when conducting any experiments.

1. Participants should be healthy, have no history of developmental disorders, and have normal hearing and vision.
2. Because infants of this age can be uncooperative or fussy (e.g., refuse to watch a demonstration or fall asleep during testing), extra participants may need to be recruited in order to obtain sufficient data.

1. Data collection

1. Collect the necessary materials: one empty small bucket, one small bucket filled with square graham crackers, two tall opaque containers too tall for an infant to see inside, and one age-appropriate toy.
2. Warm-up
   1. Sit on the floor facing the infant, approximately 100 cm apart.
   2. While the infant is watching, place the toy into the empty bucket.
   3. Non-verbally encourage the infant to crawl to the bucket and retrieve the toy. Use verbal encouragement if the infant does not immediately crawl to the bucket.
   4. Remove the toy and bucket.
3. Test
   1. Instruct the parents to refrain from providing any feedback to the infant.
   2. Simultaneously introduce the two large containers. Show the infant that they are empty. Place the containers approximately 70 cm in front of the baby and 35 cm apart. This placement ensures that the infant cannot reach both containers at the same time.
   3. Retrieve the small bucket of graham crackers. Hold up individual crackers drawn from the bucket and say, “Look at this.” Only present the crackers and place them into the containers while the infant is watching. The number of graham crackers placed in each container varies by condition.
      1. 1 vs. 2 condition: One container contains 1 cracker and the other contains 2.
      2. 2 vs. 3 condition: One container contains 2 crackers and the other contains 3.
      3. 3 vs. 4 condition: One container contains 3 crackers and the other contains 4.
   4. Counterbalance the order of placement and which side contains which quantity of crackers across infants.
   5. After placing all crackers in the containers, look down to avoid influencing the infant’s response. If the infant does not approach within 10 s, provide verbal encouragement without looking up.
   6. Video tape the infant’s choice.

2. Analysis

1. Exclude from the analysis the infants who do not approach a container within 20 s of the experimenter looking down and infants who looked into one container before approaching the other container.
2. Code the videos of infants who approach a container and reach into it or sit in front of it for at least 8 s without reaching in.
3. Use two independent coders to score videos of infants who made a choice. The coders determine which container the infant approaches, but they do not know how many crackers are in each container.
4. Analyze the proportion of infants selecting the container containing more food to determine if more infants approached it than would be predicted by chance.