Prior to the development of Schachter and Singer’s two-factor theory, two of the main theories of emotion were the James-Lange theory and the Cannon-Bard theory. The James-Lange theory states that emotions are the result of physiological responses in the body, while the Cannon-Bard theory states that physiological responses and emotional responses occur at the same time.

Both the Schachter-Singer and James-Lange theories suggest that bodily responses are an integral part of our experience of an emotion. However, unlike the James-Lange theory, and like the Cannon-Bard theory, the Schachter-Singer theory states that different emotions can share similar patterns of physiological responses. According to Schachter and Singer, we look to our environment to try to figure out what is causing these physiological responses—and different emotions can result depending on the context.

Schachter and Singer’s Study

In a famous 1962 study, Stanley Schachter and Jerome Singer tested whether the same type of physiological activation (receiving a shot of adrenaline) could have different effects on people depending on the situational context.

In the study, participants (all of whom were male college students) were given either a shot of epinephrine (which they were told was merely a vitamin injection) or a placebo injection. Some of the participants who received the epinephrine shot were informed of its effects (e.g. shaking, pounding heart, feeling flushed), others were told they would have no side effects, and others were told incorrect information about its effects (e.g. that it would make them feel itchy or cause a headache). For participants who knew what to expect from the epinephrine, they had a straightforward explanation for any effects they felt from the drug. However, Schachter and Singer believed that participants who were uninformed of epinephrine’s effects (or who were told incorrect information) would look for something in their environment to explain why they were suddenly feeling different.

After receiving the injection, participants were put into one of two environments. In one version of the study (designed to induce feelings of euphoria), the participants interacted with a confederate (someone who appears to be a real participant, but is actually part of the research staff) who acted in a happy, joyful way. The confederate flew a paper airplane, crumpled up balls of paper to play a mock “basketball” game, made a slingshot out of rubber bands, and played with a hula hoop. In the other version of the study (designed to induce feelings of anger), the participant and confederate were asked to fill out questionnaires, which contained increasingly personal questions. The confederate became more and more irritated by the invasiveness of the questions, and eventually tore up the questionnaire and stormed out.

According to the Schachter-Singer theory, emotions are a result of two factors:

1.     Physical processes in the body (such as activation of the sympathetic nervous system, for example), which researchers refer to as “physiological arousal.” These changes can include things like having your heart start beating faster, sweating, or trembling.

2.     A cognitive process, in which people try to interpret this physiological response by looking at their surrounding environment to see what could be causing them to feel this way.

For example, if you notice your heart beating faster, you might look around your environment to see what is causing it. If you’re at a party with friends, you’d be more likely to interpret this feeling as happiness—but if you were just insulted by someone, you’d be more likely to interpret this feeling as anger. Of course, many times this process occurs quickly (outside of our conscious awareness), but it can become conscious—especially if there’s not an immediately obvious situational factor to account for how we’re feeling.

Schachter and Singer’s Results

The Schachter-Singer theory would predict that participants would feel happier (or angrier) if they did not know to expect the effects of the drug. Since they had no other explanation for the symptoms they felt, they would assume that it was the social environment making them feel this way.

In the version of the study where participants were made to feel euphoric, Schachter and Singer’s hypothesis was supported: participants who were not told about the actual effects of the drug reported higher levels of euphoria (i.e. higher levels of happiness and lower levels of anger) than participants who knew what to expect from the drug. In the version of the study where participants were made to feel angry, the results were less conclusive (regardless of how the confederate acted, participants didn’t feel very angry), but the researchers found that participants who did not know to expect the drug’s side effects were more likely to match the behavior of the angry confederate (for example, by agreeing with his comments that the questionnaire was annoying and frustrating). In other words, feeling unexplained bodily sensations (e.g. a pounding heart and trembling) caused participants to look to the confederate’s behavior to figure out how they felt.

A diagram shows a photograph of a snake on the left and a photograph of a frightened person on the right, with an arrow labeled “time.” Beneath the photos are flow diagrams of four theories of emotion: James-Lange Theory, Cannon-Bard Theory, Schachter-Singer Two-Factory Theory, and Lazarus’ Cognitive-mediational Theory. For James-Lange Theory arousal (seeing the snake) leads to the heart pounding and sweating, which leads to fear (emotion). For Cannon-Bard theory arousal (seeing the snake) leads to both heart pounding and sweating and fear (emotion) simultaneously. For the Schachter-Singer Two-Factor Theory arousal (seeing the snake) leads to both heart pounding and sweating, and cognitive label (“I’m scared”) which then leads to fear (emotion). For Lazarus’ Cognitive-mediational Theory arousal (seeing the snake) leads to appraisal, which leads to fear/heart pounding and sweating.

Extensions of the Schachter-Singer Theory

One implication of the Schachter-Singer theory is that physiological activation from one source can essentially transfer to the next thing we encounter, and this can affect our judgment of the new thing. For example, imagine that you’re running late to see a comedy show, so you end up jogging to get there. The Schachter-Singer theory would say that your sympathetic nervous system is already activated by running, so you would feel subsequent emotions (in this case, amusement) more strongly. In other words, the theory would predict that you’d find the comedy show funnier than if you had walked there.

Limitations of the Schachter-Singer Theory

In 1979, Gary Marshall and Philip Zimbardo published a paper attempting to replicate part of Schachter and Singer’s results. Marshall and Zimbardo ran versions of the study where participants were injected with either epinephrine or a placebo (but were not told of its true effects) and then interacted with a euphoric confederate. According to the Schachter and Singer theory, participants given epinephrine would be expected to have higher levels of positive affect, but this didn’t happen—instead, participants in the placebo group reported higher levels of positive emotions.

In one review of research studies testing the Schachter-Singer theory, psychologist Rainer Reisenzein concluded that the support for the Schachter-Singer theory is limited: although there is evidence that physiological activation can affect how we experience emotions, the available research has rather mixed results and leaves some questions unanswered. However, he points out that the Schachter-Singer theory has been incredibly influential, and has inspired a wide range of research studies in the field of emotion research.