Emotion & Decisions

What role do emotions play in decision making?  Traditionally, many Western thinkers regarded emotion as a cause of poor judgement, arguing that we should make decisions on the basis of reason alone.  However, a relatively new theory called the somatic marker hypothesis argues just the opposite - that without emotions, humans are incapable of effective decision making.  

Try it Out

You are a doctor, called in to a village of 600 people, in which everyone in the village has been affected by a deadly illness.  There are two treatments you can give to the villagers. 

  • If you give Treatment A, then 400 people are expected to die.

  • If you give Treatment B, then there is a 33% chance that nobody will die, and a 66% chance that everyone will die.

Which treatment would you give?
Are decisions strictly rational?

Did you choose Treatment B?  If so, you are amongst the 78% of participants who chose this option in a research study (carried out by Kahneman and Tversky).  Evidently, most people are willing to take a risk with Treatment B, in the hope that nobody will die.  However, participants' decisions changed when the wording of the two treatments was framed differently:

  • If you give Treatment A, you will save 200 people.

  • If you give Treatment B, there is a 33% chance you will save everybody, and a 66% chance that you will save nobody.

This time, a large majority of participants (72%) chose Treatment A, evidently because they thought it was better to be cautious and save at least some people, rather than take a risk and potentially save nobody.  In reality, of course, the two sets of choices are exactly the same.  There is no factual difference between Treatment A saving 200 people out of 600, or allowing 400 people out of 600 to die.  And yet, framing the outcomes as a gain ("people will be saved") or as a loss ("people will die") has a huge impact on the decisions that people make.

According to traditional economic theory, humans make decisions on the basis of rational, cost-benefit analysis.  This experiment (along with many others) clearly illustrates that humans are not strictly rational decision makers, and that emotions play a big role in the choices we make.  One of the most consistent findings in behavioral economics is that people find losses extremely painful, even more so than equivalent gains are pleasurable.  For instance, if you work a part-time job, you'd be pretty happy if your boss gives you an extra $20 as a bonus for a job well done, but this will pale in comparison to how upset you would be if your boss deducted $20 from your pay as a penalty for being late.  This could explain why people tend to choose Treatment B in the first scenario, when the choices are framed as losses.  The prospect of letting people die is so emotionally distressing that people will take big chances to avoid any loss, even if there is a possibility of even greater death.
Somatic marker hypothesis

Do you ever make a decision because it just "feels right"?  According to the somatic marker hypothesis, formulated by Antonio Damasio, emotions play a crucial role in guiding decisions.  "Somatic markers" are feelings in the body that are linked to emotions, like rapid heartbeat as a signal for fear, or nausea as a signal for disgust.  According to the somatic marker hypothesis, these feelings have a strong influence on our decisions.  Typically, when making choices, there is a huge amount of complex and conflicting information to consider.  For instance, if you are trying to decide between two universities, you might notice that University A has a slightly better reputation, and you liked the architecture on campus, but University B is in a city with better weather, and a great live music scene.  When faced with these sorts of difficult decisions, according to Damasio, we follow our gut feelings - if we notice more positive emotions when thinking about University B, that's the school we will choose.  

Damasio first developed the somatic marker hypothesis when working with patients who had suffered brain damage to a region called ventromedial prefrontal cortex (vmPFC), a region of the brain which is believed to play a role in noticing somatic markers and taking these feelings into account when making decisions.  Patients with damage to the vmPFC were able to think totally rationally, but often made poor decisions, even when they had made the bad decision before and suffered negative consequences.  This is because patients with vmPFC damage can't incorporate emotional feelings into their decision making process, and this makes it difficult to learn from past mistakes.  For instance, when asked to choose which restaurant they would like to go to for dinner, people with vmPFC damage might spend hours rationally calculating the pros and cons of different restaurants, while being incapable of choosing the restaurant that will actually make them happy.

Video Activity

Watch the following video in which Damasio discusses patients with VMPFC damage, and try to answer the following questions:

  • What abilities do these brain damaged patients still have? What do they lack?

  • Why are emotions important in making decisions?

Research: Bechara et al

Aim:  Investigate the effects of vmPRC damage on decision making


  • Two groups of participants: 5 people with vmPRC damage, and 13 healthy controls

  • Participants played an online "gambling" game, in which they had to select one of 4 decks of cards, labelled A, B, C, and D (see picture below).  After clicking on the deck, participants were told they either won or lost a certain amount of money

  • Decks A and B would give higher and higher losses as the game went on, and thus participants would be expected to realize these were "bad" decks and avoid them

  • In addition, a test of skin conductive responce was used to measure players' emotional reaction to the game


  • Normal controls (without brain damage) quickly learned to avoid decks A and B.  After only 10 trials, these participants exhibited a "stress" reaction (as measured by skin conductive response) when hovering their mouse over decks A and B

  • Participants with brain damage continued choosing the "bad" decks, and showed no stress reaction to the bad decks


  • This study suggests that participants with vmPRC damage do not experience somatic markers, and this leads to poor decisions

  • Emotional feelings are necessary for good decision making


  • This study's findings support the somatic marker hypothesis.  Experiencing a stress response to the "bad" decks guided healthy participants away from choosing them

  • This was a small study (only 5 participants had vmPRC damage), so should be replicated with a larger sample size

  • The findings of this study are correlational, as they simply compared two groups of participants without manipulating an independent variable.  There may be other differences between healthy participants and those with vmPRC damage (other than somatic markers) that could explain the results
Evaluation of Somatic marker hypothesis

  • The somatic marker hypothesis explains how emotions help guide decision making, challenging the traditional Western view that emotions are the enemy of rational thought

  • The somatic marker hypothesis identifies a specific region of the brain (vmPRC) which is involved in processing emotional feelings.  The role of the vmPRC in decision making is supported in case studies of brain damaged patients, as well as research on the Iowa gambling task

  • The somatic marker hypothesis can help explain why people might engage in risky behavior, like having unprotected sex or using drugs.  Some people may lack the feeling of emotional distress that would stop them from doing something risky, and instead be motivated by the excitement of risk taking

  • The somatic marker hypothesis needs to be tested in more experiments, using a greater variety of empirical approaches (not just the Iowa gambling task).  Until then, it is an intruiging idea in need of better evidence

  • I can discuss research by Kahneman & Tversky on framing effects ("saving 200 people" vs "400 will die"), illustrating the role that emotion plays in decision making

  • I can explain the somatic marker hypothesis, including the role of the vmPRC in processing emotional feelings that are crucial for making decisions

  • I can describe the Aim, Procedure, Findings and Conclusion of Bechara at al (Iowa Gambling task), as well as Evaluating the study

  • I can discuss the strengths and limitations of the somatic marker hypothesis
Quiz Yourself!

1.  Which of the following conclusion is supported by Kahneman & Tversky's research on framing effects?

(a) People are willing to take risks in order to save as many people as possible

(b) When it comes to life and death situations, most people are able to put aside their emotions and think rationally to save as many people as possible

(c) People are willing to take risks to avoid losses

(d) People avoid taking risks when human lives are at stake

2.  Which statement best describes the role of emotion in decision making, according to the somatic marker hypothesis?

(a) Strong emotions lead people to make poor decisions

(b) Rational decision making leads people to maximize their gains and minimize losses

(c) Patients with vmPRC damage have cognitive defects that impair decision making

(d) Emotional feelings help guide people in making optimal decisions

3.  According to the somatic marker hypothesis, why can't people with vmPRC damage make effective decisions?

(a) They do not process emotional feelings that may stem from previous experiences

(b) They do not properly consider the pros and cons of different options

(c) They suffer from cognitive impairments, as the frontal cortex is involved in thinking

(d) They cannot use reason to temper the effects of strong emotion

4.  What sentence best describes the findings of the Iowa gambling task?

(a) Healthy participants exhibit a physiological stress response, leading to poor decisions

(b) Healthy participants exhibit a physiological stress response, leading to effective decisions

(c) vmPRC-damaged patients exhibit a physiological stress response, leading to poor decisions

(d) vmPRC-damaged patients exhibit a physiological stress response, leading to effective decisions

5.  Which research design best describes the Iowa gambling task?

(a) Laboratory experiment

(b) Field experiment

(c) Case study

(d) Quasi experiment (correlational study)

​1 - C, 2 - D, 3 - A, 4 - B, 5 - D