The Trouble with Presentee-ism – The Effect of Inflammation on Decision Making

How often have you found yourself going to work despite feeling ill and knowing that a day in bed might be the sensible thing to do? Do you have a culture at work where people feel that they will be letting others down if they don’t come in – despite being ill? And how good are the decisions that you make when you are feeling under the weather?

New research suggests that the basis of our decision making is affected when we are ill. It has long been known - and you can probably verify this from your own experience - that sickness impairs mood and cognition. No one would choose to make critical decisions with a temperature of 103° F! But more specifically, when we are sick we don’t just feel tired. It seems we feel less pleasure in positive events, are more sensitive to negative events and are more susceptible to feeling depressed. What has now become clear is that changes in the brain are responsible for these feelings.

But how to study changes in performance during sickness ethically? It would not be ethical to take a group of people and make some of them sick intentionally. Harrison et al (2015) realised that there was an excellent naturally occurring situation where sickness occurs in a controlled fashion that was perfect for this type of study. They investigated decision making before and after people had been vaccinated against typhoid. This vaccination presents a challenge to the immune system in each person treated and results in a short-lived inflammatory response.

The authors of the study were particularly interested in how sickness might affect our sensitivity to reward and punishment. They hypothesised that sickness might make us less sensitive to reward but more sensitive to punishment. This was tested using a simple gambling task where the participants chose between two shapes. Each time they chose, there was a chance that they might win £1 (one shape would be linked to winning, other to no win or loss), lose £1 (one shape would be linked to losing, other to no win or loss) or that there would be no gain or loss (neither shape linked to win or loss). The same shape was always paired with the same gain or loss so participants learned over the course of many trials to pick the shapes which gained them money and to avoid the shapes that lost them money. Probability of winning or losing was kept constant (0.8:0.2 or 0.2:0.8 respectively).

This game was played by each participant either after injection with a saline solution (placebo condition: no sickness) or after a typhoid injection (sickness). After the typhoid vaccination, all participants demonstrated the appropriate inflammatory response which did not occur after the placebo injection.

The vaccinated group were found to choose the condition in which they gained £1 significantly less than the placebo the group suggesting reduced sensitivity to reward.

However, the vaccinated group also avoided the condition in which they lost £1 more than the placebo group suggesting increased sensitivity to punishment.

Brain imaging results showed that:

Sensitivity to gain was related to increased activity in the ventral striatum (part of the dopamine reward system).

Sensitivity to loss was related to increased activity in the insula (which receives information from the viscera indicating emotional responses and is associated with disgust).

Additionally when the responses in these areas were compared between the two groups, there was:

A significant reduction in the response to reward in the ventral striatum

A significant increase in the response to loss in the insula for the vaccinated group compared to the placebo group.

The vaccinated group were therefore showing a reduced response to reward and an increased response to punishment.

This research suggests that forcing yourself into work on days when you are feeling poorly has consequences beyond merely passing your germs on to others in your team. It suggests that you will make different decisions when ill from those you would make when healthy. Specifically, you are likely to take less risk and be more likely to find the safe option when ill. So coming to work when ill might cost your organisation financially as a result of this aversion to risk.

What should you take from this research?

  1. Illness changes the way that we assess reward and punishment making us more sensitive to loss or punishment and less sensitive to gain or reward.

  2. If employees need to be present when they are ill, be sure to increase praise and decrease criticism to help to keep them motivated.

  3. Illness will reduce the likelihood of taking risks that might otherwise benefit an organisation.

  4. You can look after yourself and your organisation better by not struggling in to work when ill!

  5. Managers can look after their employees and their organisation by not encouraging a culture of presentee-ism. If someone is ill – send them home.

This blog is based on the following research:

Harrison, N.A., Voon, V., Cercignani, M., Cooper, E.A., Pessiglione, M. & Critchley, H.D. (2015) A neurocomputational account of how inflammation enhances sensitivity to punishments versus rewards. Biological Psychiatry, doi:10.1016/j.biopsych.2015.07.018

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