____ in infants was first demonstrated in a classic experiment by Eleanor Gibson and James Walk (1960) with their use of a table called the "visual cliff."

The chances of an infant being born with some type of sex chromosome disorder is which of the following?

1 in 500 1 in 1000 1 in 1500 1 in 5000

Robert Plutchik proposed that human beings have ________ basic emotions

a. five b. ten c. three d. eight