Chapter 1.

Introduction

Princeton University

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1.1 Experimental Design in Action

This video shows an experiment with human subjects whose findings suggest that the effectiveness of placebo drugs is partly a result of the patients' release of endorphins, their natural opioids. The implication is that, for some people, the expectation that a given treatment will soon be helpful causes them, without awareness, to release endorphins throughout their brain and body. In turn, the endorphins reduce their pain or help them to feel better in other ways.

1.2 Check Your Understanding

1.3 Activity Completed!