Exposure to violent erotica may contribute to

If schizophrenia depended solely on genetic make-up, then compared to rates of schizophrenia in siblings in general, "fraternal" twins should have:

A) four times the concordance rate for schizophrenia. B) twice the concordance rate for schizophrenia. C) the same concordance rate for schizophrenia. D) half the concordance rate for schizophrenia.

One puzzle is why infants do not search for hidden objects until 8-12 months if indeed they understand object permanence by age 4-5 months. All of these are possible explanations except

a. infants have no awareness that objects continue to exist behind a barrier until 8-12 months. b. infants’ working memory skills improve enough by 8-12 months to help them keep track of hidden objects. c. infants become better able to plan and execute responses such as searching by 8-12 months. d. infants may have improved perceptual skills that allow them to perceive object persistence under a wider range of conditions by 8-12 months.