Extraneous factors in judicial decisionsHow tiredness and hunger affect judicial decisions (more than the legal evidence being reviewed)

The authors of this study analysed the decisions of experienced judges in parole reviews

They looked at what factors affected the likelihood of a judge returning a favourable review

Judges listened to parole hearings in three sessions broken up by two food breaks

My client has an excellent record of good behaviour

He’s making a good

case

09:00

My client has an excellent record of good behaviour

Perhaps I should give him

the benefit of doubt

09:55

My client has an excellent record of good behaviour

Is it time for a break yet?

10:50

Phew… I needed this!

11:00

My client has an excellent record of good behaviour

11:20 Good arguments

My client has an excellent record of good behaviour

12:15 Sometimes it’s so close to

call

My client has an excellent record of good behaviour

12:55 I’ve heard this all

before

I didn’t realise how

hungry I was!

13:00

My client has an excellent record of good behaviour

14:00 It seems like he’s

been making a real effort to reform

The chance of a prisoner being given parole would be around 65% at the start of the day, dropping to 0% just before the morning break

% c

hanc

e of

par

ole

0

20

40

60

80

Break Lunch

This would recover to 65% following the break before gradually dropping again until lunch

Lunch again had an immediate post break effect on the chance of parole before it would rapidly decline to 0% by the end of the day

Conclusions

1. The study showed that tiredness and hunger affected decision making more than any other factor. The only other factors that had even a small effect on the judges' decisions were the number of previous incarcerations and the availability of rehabilitation programs

2. As the judges’ willpower depleted, the default option of refusing parole became easier as it required no change

Reference

Extraneous factors in judicial decisions Proceedings of the National Academy of Sciences of the USA, April 26, 2011 vol. 108 no. 17 Shai Danziger, Jonathan Levav and Liora Avnaim-Pesso