One cause of severe intellectual disability responsible for phenylketonuria (PKU) is ____

You are watching a video of a man in a developing country performing a task intended to determine if he is in the formal operations state of development. The person performing the task is 28 and he is performing quite poorly. What explanation would late 20th-century researchers have given to account for his poor performance?

a. He was cognitively incapable of formal operations. b. He did not have formal education that included the scientific method. c. He had previously experienced brain damage. d. He was not interested in "proving" his abilities.

Through play, preschoolers learn to make plans and carry out tasks during which of Erikson's psychosocial stages?

a. trust versus mistrust b. autonomy versus shame and doubt c. initiative versus guilt d. industry versus inferiority