Determinants of Emotional State


The physiological side to emotion has been discussed for centuries, even by Aristotle. A few decades ago, Stanley Schachter and Jerome Singer, two American psychologists, put their heads together one day and came up with the “two-factor theory of emotion”. This theory states that emotion results from a combination of two things: (a.) state of arousal, and (b.) an interpretative cognition. Also, it says that when people feel an emotion, they look for a reason as to why they feel that way. Schachter and Singer decided to test this theory with an experiment.

Stanley Schachter                                                                                                                   Jerome Singer

Three hypotheses were given:

  1. If a person experiences a state of arousal for which they have no immediate explanation, they will interpret that emotion with the cognitions available to them at the time.
    Example: You are walking down a dark, dirty alleyway at 2 AM (idiot!). Your heart is beating fast, you are trembling and your breathing is deep. You realise this is occurring because you are walking down this scary alleyway, and you conclude that you are feeling an emotion: fear.
  2. If a person experiences a state of arousal for which they have an appropriate explanation, then they will be unlikely to describe that emotion using alternative available cognitions.
    Example: You are walking home alone. Your breathing is deep, your heart is beating a little faster and you feel drowsy. You have just taken an injection at the hospital and you think: I am feeling this way because of the injection I took.
  3. If a person is put into a situation which, in the past, made them feel a certain emotion, then they will experience emotions if they are in a state of physiological arousal.

The sample was made up of 184 male college students at Minnesota University who were taking classes in Introductory Psychology. 90% of these students received two extra points on their final exam for every hour they spent as a participant. Since adrenaline was used in this study, the participants’ health records were checked to make sure that there would be no adverse side effects.

When the participant arrived, the experimenter took him to a private room. He was told that the aim of the experiment was to “look at the effects of vitamin injections on visual skills” and was asked if he had any problem with taking an injection of Suproxin (this was actually a made-up name). 184 (out of an original 195) subjects agreed and went ahead with the experiment.

The participant was injected by a doctor and given one of two things: (a.) adrenaline, also called epinephrine, or (b.) a placebo, which was just a salt and water solution.

The effects of adrenaline are: increased blood pressure, heart rate, blood sugar level, respiration rate and blow flow to the muscles and brain, but a decrease in blood flow to the skin. These effects usually result in palpitations, tremors, flushing and fast breathing. The effects begin after three minutes and last anywhere between ten minutes to one hour.

The saline solution of salt and water has absolutely no side effects.

There were four experimental conditions. The subjects were put into one of the following:

  1. Adrenaline ignorant: Subjects were given a shot of adrenaline and not told about any side effects.
  2. Adrenaline informed: Subjects were given a shot of adrenaline and told about all the side effects.
  3. Adrenaline misinformed: Subjects were given a shot of adrenaline and told about side effects which were actually false (like numb feet and headaches).
  4. Control group: They were given the placebo and not told about any side effects.

Remember, the subjects thought they were taking in Suproxin – a fake vitamin. After this, the second part of the experiment began.

The doctor left the room and the experimenter returned with a stooge (an actor). The stooge was introduced as another participant who had taken the same Suproxin injection. They were told to wait for 20 minutes so that the vitamin could be absorbed into the bloodstream, after which they would be given tests of vision. This part continued in two different ways, meaning there were two different conditions: the euphoria condition and the anger condition.

Euphoria condition
In this condition, the waiting room was systematically put into a state of mild mess. As the experimenter was leaving, he apologetically added that if the participant wanted any rough paper, rubber bands or pencils then they should help themselves. As soon as the experimenter left, the stooge would introduce himself again, make a few ice-breaker comments and then begin a standardised routine. He played with items and encouraged the participant to join him.

Anger condition
In this condition, the participants were told to complete a questionnaire. Before looking at the questionnaires, the stooge said to the participant that he thought it was unfair to receive injections without being told when they were first called. They became the questionnaire normally… until it got personal! Questions asking about private topics (e.g. How many times each week do you have sexual intercourse?) came up and the stooge became making a series of standardised comments which started off innocently but grew increasingly annoyed, until he finally ended in a rage.

The routine for both conditions (i.e. euphoria and anger) was standardised and the stooge never knew which condition (i.e. adrenaline informed, adrenaline misinformed, adrenaline ignorant or control group) the participant was in.

The adrenaline misinformed condition was not run in the anger sequence. This is because it was originally created as a control condition so if it was included in the euphoria sequence, that would be enough to evaluate any effects of being in the adrenaline misinformed condition. A second sequence was not needed.

To summarise the above, look below:

EUPHORIA  –  Adrenaline ignorant/Adrenaline informed/Adrenaline misinformed/Control
ANGER          –  
Adrenaline ignorant/Adrenaline informed/Control

The researchers made observations of the participants’ emotional response through a one-way mirror and took self-report measures from the subjects. A self-report questionnaire contained a number of mock questions but there were a few crucial ones that measured mood and emotion, for example: How irritated, angry or annoyed would you say you feel at present?

When the participants completed the questionnaire, the experimenter told them the experiment was over and explained the deception in detail. They also answered any questions and swore the subjects to secrecy. Finally, the participants answered a last questionnaire about the experimental experience with adrenaline and if they had any suspicions about being deceived. It turns out that 11 of the participants were so suspicious that their data was automatically discarded!

The results showed that participants who received adrenaline injections showed significantly more sympathetic arousal, compared to the placebo group. This was measured by pulse rate and self-ratings on palpitation, tremor, numbness, itching and headaches. Five participants were excluded because they did not show any relevant symptoms after receiving adrenaline.

In the euphoria condition, adrenaline-misinformed participants were the most happiest, then it was the adrenaline-ignorant group. This shows that these participants were more susceptible to the stooge because they had no explanation of why their bodies were experiencing certain arousals. The informed group felt the least happy. This is because they knew the reason behind their emotional arousal.

In the anger condition, the adrenaline-ignorant group felt the angriest, then the placebo group. The least angry group was the adrenaline-informed group. Again, this is because they had an explanation to their emotions whereas the other groups had none.

Looking at the above, the original hypotheses were supported by the experimental results.

The behaviour was measured through a one-way mirror and it supported the results from self-reports.

Type of research method
This was a laboratory experiment with manipulated variables and scientific apparatus.

Independent variable
There were two independent variables: the information given to the subjects about the injection they were given (i.e. were they ignorant, informed or misinformed?) and the situation they had to experience (i.e. anger or euphoria).

Dependent variable
The emotional arousals of the participant.


  1. High level of control: There was an extremely high level of control in this experiment. This means that there is less chance of any extraneous variables affecting the results.
  2. Replicable: The procedure was completely standardised in terms of allocating random participants, giving each group member the same information, following a standard sequence in both conditions and even keeping the stooge unaware. This means that, overall, this experiment can be easily replicated and the accuracy of the results can be checked, meaning that it is possible to check the reliability of the results.
  3. Control over demand characteristics: The use of a one-way mirror to observe the participants’ reactions meant that there was much less chance of any demand characteristics occurring. If the participants knew someone was watching them, they may have behaved differently.


  1. Lack of ecological validity: The experiment was conducted in an artificial setting but the main reason for its lack of ecological validity was the way the researchers induced emotions into the participants. Usually, humans are aware of an event before they experience an emotional arousal. Here, the participants were artificially provoked into a state of arousal.
  2. Not generalisable: The sample was made up of male students from the same university. This means the results cannot be generalised to females or people from other areas. The sample is unrepresentative; we can argue that females may experience emotions differently to males.

Ethical issues

  1. Informed consent: The participants did give consent to receive an injection, although they did not know that it was adrenaline.
  2. Deception: Participants were deceived about the adrenaline (they thought it was Suproxin), they were deceived about the nature of the experiment, they were deceived by the stooge… you get the picture.
  3. Confidentiality: Yes, the confidentiality of participants was seemingly respected. No one was publicly named.
  4. Emotional or physical harm: Since the medical records of participants were checked beforehand, there was no physical harm. There was also nothing to suggest that participants were emotionally harmed, although they may have felt feelings of awkwardness or embarrassment in the anger condition.
  5. The right to withdraw: Schachter and Singer did not seem to stop any participants from leaving the experiment. In fact, a few participants who did not want to receive an injection left at the beginning.
  6. Debriefing: Participants were thoroughly debriefed after the experiment, given answers to any questions they had and also sworn to secrecy. So, eventually, they were told about what was actually going on.

Reference: Schachter, S. and Singer, J. E. (1962). Cognitive, Social and Physiological Determinants of Emotional State. Psychological Review.