Tara and Keagan were identical twins. A school psychologist tested both of their IQs. When the IQ scores of identical twins differ, behavior genetics researchers attribute this primarily to differences in

The modal model explains primacy and recency in free recall as follows:

A. Primacy occurs because of rehearsal and recency occurs because of interference. B. Primacy occurs because of rehearsal and recency occurs because of delay. C. Primacy occurs because people retrieve from short term store and recency occurs because of rehearsal. D. Primacy occurs because of rehearsal and recency occurs because subjects retrieve from short term store.

When you are beginning to train your dog to "sit," it is most effective to put him on

a. partial reinforcement. c. a variable-interval schedule. b. continuous reinforcement. d. a variable-ratio schedule.