The Scientific Method: Learn It 2—Theories and Hypotheses

Two key concepts in the scientific approach are theory and hypothesis.

Theories and Hypotheses

A theory is a well-developed set of ideas that propose an explanation for observed phenomena that can be used to make predictions about future observations. For example, the theory of evolution by natural selection in biology is a well-developed explanation for how genetic characteristics change through generations. In psychology, there are theories about child development, about how people act in social situations, about why we experience certain emotions, and more.

 

A hypothesis is a testable prediction that is arrived at logically from an observation. It is often inspired by a theory. The results that come from testing the hypothesis may lead to theories being adjusted or modified. A hypothesis is often worded as an if-then statement (e.g., if I study all night, I will get a passing grade on the test).

A diagram has seven labeled boxes with arrows to show the progression in the flow chart. The chart starts at “Theory” and moves to “Generate hypothesis,” “Collect data,” “Analyze data,” and “Summarize data and report findings.” There are two arrows coming from “Summarize data and report findings” to show two options. The first arrow points to “Confirm theory.” The second arrow points to “Modify theory,” which has an arrow that points back to “Generate hypothesis.”
Figure 1. The scientific method involves deriving hypotheses from theories and then testing those hypotheses. If the results are consistent with the theory, then the theory is supported. If the results are not consistent, then the theory should be modified and new hypotheses will be generated.

 

To see how this process works, let’s consider a specific theory and a hypothesis that might be generated from that theory. As you’ll learn in a later section, the James-Lange theory of emotion asserts that emotional experience relies on the physiological arousal associated with the emotional state, or in other words, your body gets alerted, and then you experience an emotion.

- James lange theory of emotion flowchart showing that arousal (like from a snake) leads to the heart pounding and sweating, which leads to the emotion of fear.
Figure 2. The James-Lange Theory proposes that emotional responses come after the physical experience.

If you walked out of your home and discovered a very aggressive snake waiting on your doorstep, your heart would begin to race and your stomach churn.

Northern copperhead snake
Figure 3. According to the James Lange theory of emotion, a person who is unable to experience the physical symptoms of being started by a snake, like a racing heartbeat, would not experience the emotion of fear.

According to the James-Lange theory, these physiological changes would result in your feeling of fear. A hypothesis derived from this theory might be that a person unaware of the physiological arousal that the sight of the snake elicits will not feel fear.

Some individuals who suffer significant injuries to their spinal columns are unable to feel the bodily changes that accompany emotional experiences. Therefore, we could test the hypothesis by determining how emotional experiences differ between people who have the ability to detect these changes in their body and those who do not. In fact, this research was conducted—it turns out that while the emotional experiences of people who are unaware of their physiological arousal may be less intense, they still experience emotion (Chwalisz, Diener, & Gallagher, 1988). This particular research study did not support the hypothesis—even without being physiologically aroused, people still experienced fear.