Andrew, a 4-year-old, received a firetruck Lego set for his…

Andrew, a 4-year-old, received a firetruck Lego set for his birthday. The Lego set says that it is designed for 6-8 year olds. However, under the guidance and direction of his father, Andrew is able to put together the majority of the Lego set. This task is considered within Andrew’s __________.

Injection of an animal with amphetamine leads to heart rate…

Injection of an animal with amphetamine leads to heart rate acceleration. With repeated injections, however, the injection procedure alone (i.e., when an inert substance is injected) can elicit heart rate acceleration. In this situation, which of the following is true?