Here come the judge

The importance of meal breaks on decision making

I came across an interesting article in the Economist recently summarising a paper in the Proceedings of the National Academy of Sciences (Danzigera, Levavb, Avnaim-Pessoa, 2011). In the paper they describe analysing the decisions taken by eight judges ruling on parole decisions over a period of 10 months. What is interesting is that the decisions taken clearly varied dramatically in relation to the taking of meal breaks.

The judicial day is divided up into three sessions, with each session separated by a meal break. At the start of each session the percentage of favourable rulings is about 65%. This percentage falls to close to zero as the break approaches, returning to 65% after the break. It’s particularly striking because judges are trained to exclude causes of bias, and indeed the researchers found that race, or age or sex did not influence the decision. Equally the researchers excluded clever lawyers from the results. In fact the lawyers seemingly were as unaware of this phenomenon as the judges. Pretty interesting, if not shocking stuff, but what does it have to do with human factors in the process industries? After all, judges have long been lampooned for their insistence on regular and lengthy meals, just read any of the Rumpole books.

What appears to be happening is that the judges are suffering from a phenomenon of ‘mental depletion’ resulting from sustained decision making. As the session goes on, the process of decision becomes more difficult as mental resources and executive function is depleted. The individual therefore simplifies the decision process opting for the simplest conclusion, usually the status quo. In this case the status quo is the decision to deny parole.

The authors of the paper acknowledge that the reason for this behaviour isn’t established, but speculate on a number of causes. The most obvious possible cause is that of physical effects of lack of food, low blood sugar or similar, or what’s needed is simply a physical rest away from the cognitively demanding activity.

The authors of the paper speculate that this behaviour may have implications for other activities involving important sequential decisions or judgements, including legislative, medical and financial decisions. To that list I’d add some of the activities common to the process industries.

If this effect of simplification of decision making is transferable to other activities (and it has been observed in a number of different areas such as consumer purchasing decisions) then what are the implications on critical safety design decisions such as those made during a HAZOP? HAZOP sessions are notoriously difficult to sustain, and if a judge cannot maintain objectivity, what hope for a HAZOP team? As well as recording who was at the HAZOP and what their qualifications are, should we also be recording what they had for breakfast and when they stopped for lunch?

Another area we expect sustained decision making is that of the process operator or supervisor, not to mention the maintenance personnel or permit issuers. We’d all like to think that the quality of the decision making process remains unvaried throughout the day. Of course, the role of a process operator is not the same as a judge. Sustained vigilance is also a part of the process operators job, this itself is known to be cognitively demanding. We’re also familiar with the effects of sleepiness and fatigue that affect the shift worker and the influence of regular breaks on these aspects. This research emphasises that regular breaks also affect the cognitive processes in a direct and predictable fashion.

I see more and more process operators having to take breaks at their place of work, eating or drinking at their workstation as they monitor and control the process. If the cause of this erosion of decision making ability is simply glucose level, then perhaps there is no harm done. However, it is the process of taking a break from the labour of serial decision making that counts, then we owe it to them and us to ensure that regular breaks are taken and that there is sufficient cover to make them meaningful.

The article in The Economist is available here
I think it’s time we broke for lunch…

and the paper referenced is

Shai Danzigera, , Jonathan Levavb, and Liora Avnaim-Pessoa (2011). Extraneous factors in judicial decisions. Proceedings of the National Academy of Sciences of the United States of America published ahead of print April 11, 2011.