AP Psychology Study Resource: Schachter Singer Theory

As you prepare for your AP Psychology exam, you will encounter many theories of emotion. One of the most important is the Schachter Singer theory of emotion, which is also known as the two-factor theory of emotion. It was developed by Stanley Schachter and Jerome E. Singer in the early 1960s. We have elucidated the most essential facets of this theory below.

The Schachter Singer theory states that each emotion is composed of two, intertwined factors: physiological arousal and a cognitive label. When an individual experiences an emotion, he or she experiences an often ambiguous state of physiological arousal to which the individual then ascribes a cognitive label which is highly dependent on factors in the individual’s immediate environment. Misleading factors in the immediate environment often lead to the misattribution of a state of physiological arousal.

What Is the Schachter Singer Theory

The Schachter Singer theory consists of three primary ideas:

  1. When an individual experiences a state of physiological arousal for which they have no apparent explanation, the individual will describe the state of arousal in terms of the cognitions in their immediate environment, even if the subsequent description is inaccurate.
  2. When an individual experiences a state of arousal for which they have an apparently veracious explanation, the individual is unlikely to search for any alternate explanation in the immediate environment.
  3. When an individual is in a situation similar to situations that have caused emotions in previous experiences, the individual will only experience a similar emotion if they are in a state of physiological arousal.

Each of these theses centers on the underlying relationship between physiological arousal (or lack thereof) and the role of cognitions available in the immediate environment. This relationship can serve to facilitate tenuous connections when no sensible cognition is immediately available, and it can serve obfuscate valid cognitions when a more obvious connection is more immediately available. The initial Schachter Singer experiment and similar experiments thereafter clarify the nature of this relationship.

Schachter-Singer Theory Experiments

In the initial experiment designed by Schachter and Singer, participants were given a fictitious drug that was ostensibly intended to improve the eyesight of all participants. This drug was in fact epinephrine, a stimulant that causes increased blood pressure, heart rate, and perspiration. The participants that received the epinephrine were divided into four groups.

Epinephrine Informed

The epinephrine informed group was told the fictitious drug they were being given would cause the side-effects caused by epinephrine. Based on this explanation, the epinephrine informed group had a readily available explanation for the physiological arousal they experienced when the stimulant took effect.

After the epinephrine had been administered, participants in this group reported the least prevalent feelings of anger and euphoria, presumably because they had the most logical and readily available cognition to explain the arousal they experienced.

Epinephrine Misinformed

The epinephrine misinformed group was told to expect a set of side-effects inconsistent with the effects of epinephrine. Based on this explanation, this group did not have a veracious explanation for the state of physiological arousal they experienced after the administration of the medication.

Participants in this group reported the highest levels of euphoria and frustration, presumably based on their inability to explain the sense of arousal they experienced based on the information and medication they had been given.

Epinephrine Ignorant

The epinephrine ignorant group was told nothing about the incipient state of physiological arousal. Based on this lack of an explanation, this group did not have a veracious explanation for the state of arousal they experienced after being given the epinephrine. After the drug’s administration, this group reported significant feelings of euphoria and frustration, although not as significant as those in the epinephrine misinformed group, presumably based on their inability to find an immediately available explanation for their feelings of physiological arousal.


In this experiment, the control group was given a placebo that had no effect on their state of physiological arousal and no explanation about what to expect. Based on this lack of stimulation and explanation, the group had minimal need to explain an absence of physiological arousal. As a whole, the control group expressed a minimal level of euphoria or frustration; however, participants in the epinephrine informed group did express slightly lower levels of euphoria and frustration.

Dutton and Aron

Shortly after the publication of the Schachter Singer theory, Dutton and Aron conducted an experiment in which they attempted to induce a state of physiological arousal without using any narcotics. To that end, Dutton and Aron designed an experiment in which male participants walked across one of two bridges. The “arousing” bridge was a suspect suspension bridge over a deep, ominous ravine while the “control” bridge was a stable structure over an auspicious landscape.

At the conclusion of each bridge was an attractive young woman who gave the participants an ambiguous picture about which they were instructed to write a brief narrative. The hypothesis was that participants crossing the suspension bridge would feel a sense of physiological arousal based on their crossing and subsequently mis-attribute their physiological arousal to the attractive young woman waiting at the end of the bridge.

Dutton and Aron tested their hypothesis by reading the narratives the participants submitted and assessing each narrative for sexual content. The experimenters found their hypothesis confirmed, as the narratives written by the men who crossed the “arousal” bridge were replete with sexual content ,whereas the narratives written by the participants who crossed the “control” bridge were largely innocuous.

Schachter and Wheeler

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In Schachter and Wheeler’s experiment, participants were given either epinephrine, chlorpromazine, or a placebo before watching a short comedy. As we mentioned above, epinephrine is a stimulant. Chlorpromazine is a tranquilizer which, in small doses, causes a lower heart rate, drowsiness, and numbness. After the short comedy, participants were asked to rate the comedic value of the film they had been shown.

As expected, the participants who had received the epinephrine found the film funnier than the other participants. The participants who had received the chlorpromazine found the film the least entertaining, while the placebo group fell somewhere in between. In theory, this demonstrates each group’s willingness to base their present physiological arousal on the cognitions available in their immediate environment.

Is the Schachter Singer Theory Valid?

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The Schachter Singer theory has been criticized for its reliance on the autonomic nervous system, which signals that cognitive factors play a role in formation of emotions without providing an informative account of the process, especially the central nervous system’s role in the process. Aside from this critique, two well-known experiments sought to replicate some portion of Schachter and Singers original experiment but were unable to confirm the veracity of Schachter and Singer’s original findings.

Marshall and Zimbardo

In Marshall and Zimbardo’s attempt to recreate the phenomenon identified by Schachter and Singer, they administered either epinephrine or a placebo without any explanation of potential side effects in an amount determined by their body weight, a deviation from the original experiment, to participants shortly before the participants were exposed to either a neutral or euphoric confederate. The hypothesis was that participants who had received epinephrine before exposure to a euphoric confederate would attribute their physiological arousal to the confederate instead of the drug.

Based on the reported experiences of participants, there was no viable correlation between the post-epinephrine exposure to a euphoric confederate and similar feelings of euphoria. In fact, participants reported little discernable difference in sensation when exposed to the euphoric confederate in comparison to exposure to the neutral confederate.


Maslach conducted a similar experiment in 1979 in which he used hypnosis rather than epinephrine or any other drug. In Maslach’s experiment, one group of participants was hypnotized while the other groups served as a control group. The hypnosis group was primed to feel angry or euphoric in reference to certain cues. After the hypnosis portion, participants were exposed to a confederate who presented either euphoric or angry behavior followed by two other confederates, both of which presented euphoric behavior.

The results of both observation and self-reporting found that participants, while in a state of physiological arousal, felt angry regardless of whether the behavior of their ostensible confederate was euphoric or angry. Contrary to his original thesis that subjects would adopt the prerogative of their confederates while in a state of physiological arousal, Maslach ultimately concluded he had insufficient evidence to make a connection between a state of physiological arousal and negative emotions; though he was careful to note his results may have been skewed as participants are more likely to report negative emotions than positive emotions.


As you prepare for your exam, keep in mind the following principles as they reflect the most essential points of Schachter Singer theory (also known as the two-factor theory of emotion.) The two factors in this theory are a state of physiological arousal and a cognitive label: what a person feels and what that person chooses to ascribe the feeling to. 
This can lead to misattributions of emotion because the easiest and most available cognitive label is often not the true source of the relevant emotion. Misattributions of this sort are most common when an individual experiences an emotion they are accustomed to attributing to an established source.