​Which term does NOT belong in this group?

​Classical conditioning focuses on the relation between the consequences of behavior and the likelihood that the behavior will recur.

​Kathleen and Alphonse are expecting their first child, and are having a pleasant conversation about the sex of the baby. Kathleen says, “Well, as long as all of the chromosomes are X, we’ll be having a girl!” How can Alphonse best respond?

Most one-year-old children have already developed a theory of mind.

​The primary pioneer in the study of behaviorism was Erik Erikson.

Through the first 12 months of life, infants have a very general prototype for a face that is fine tuned to be more consistent with familiar faces between 12 and 24 months of age.

​An embryo rests in a sac called the placenta, which is filled with amniotic fluid that cushions the embryo and maintains a constant temperature.

​The reliability of a research measure refers to the extent to which that measure provides consistent evaluations of a given characteristic.

At around 18 months of age, children will learn approximately 10 or more new words and labels each week.

By the age of 24 months, most children can climb steps, walk backward, and kick a ball.