How do you make decisions?
Major depression can have profound effects on decision making, causing apparently irrational decisions, for example, not choosing to change behavior in ways that will likely lead to rewards, and choosing instead a course of action that is likely to be unrewarding.
Traditional psychological theories of depression have focused on the notion that the problem is a distorted perception of the likelihood of a reward (see option valuation below). As a result most psychotherapies assume that if you show someone who is depressed evidence that one choice is most likely to be rewarded, then the person will make that choice.
Therapists will tell you that this strategy doesn’t always work.
You show the depressed person that when they limit sleep to no more than 8 and a half hours their mood is better and they have more energy. If the person still doesn’t make that choice you assume that you have not offered convincing arguments and redouble your efforts.
But recent research suggests that the distortion in decision making is not in the assessment of which choice will more likely be rewarded, but rather that depressed people seem not to have the same “bias” towards making decisions that will be rewarded.
In the example about restricting sleep (see picture) people who are not depressed are much more likely to choose to limit sleep than not to limit sleep, all other factors being equal. But, researchers now find that people with depression are not as likely to choose to limit sleep, even when they know the likelihood of feeling better. In other words, they lack the “response bias” for rewarded choices.
Reward processing impairment
Researchers have studied “reward processing impairment” from a number of angles, both neurological and behavioral. A recent meta-analysis looked at the results of experiments in which both depressed and healthy volunteers performed tasks that were directed at receiving a reward, either of money or of points. Results confirm that, as noted above, depressed individuals have an impaired ability to decide to place effort towards the higher-rewarded tasks or actions.
The research breaks down the decision-making process into six steps, with several sub-steps in each, as follows:
- Option Generation – “brainstorming” or figuring out what your options are.
- Decision Making – choosing one option
A. Option valuation, where you decide whether the potential reward is worth the risk
B. Reward bias, where you choose the one that has the highest potential reward.
- Anticipation – Thinking about how great the reward is going to be.
- Action and effort – going for it
A. Reward response vigor, where you act quickly to go for the choice you have made.
- Consummation – getting the reward.
- Reinforcement learning – learning from experience how to get more reward in the future.
The results show that persons with depression have impaired ability to process reward and risk, most notably in the category of reward bias: choosing the most potentially rewarding of the options available. Small to medium impairments were also shown in option valuation and reinforcement learning.
Implications for therapy
The implication of this for therapy, (and for dealing with one’s own depressed mood), is that the task is not to see the likely outcomes more clearly but rather to understand that depression biases you towards choices that are not rewarded.
This irrational bias actually fits with how depressed people talk about their choices. They will try to explain the unrewarded choice by saying that they felt that they did not “deserve” the reward. Or they felt that they couldn’t make the rewarded choice, as though some force they could not control was moving them in the other direction
However, it is not usually beyond one’s control to make a rewarded choice, yet there is a shift in bias such that depression leads to a greater tendency to choose things that are not rewarded. You still can make the rewarded choice, but it may require more effort, more thought, and more care.
Therapists need to understand that a clear understanding of what the choice is, or what good it will do to make that choice may not be the depressed person’s main problem. Rather, they may need help to overcome the feeling that they simply can’t make the decision to follow a more highly rewarded action plan without encouragement to overcome reward processing impairment.
Halahakoon DC, Kieslich K, O’Driscoll C, Nair A, Lewis G, Roiser JP. Reward-Processing Behavior in Depressed Participants Relative to Healthy Volunteers: A Systematic Review and Meta-analysis. JAMA Psychiatry. Published online July 29, 2020. doi:10.1001/jamapsychiatry.2020.2139