Wetenschap - 26 maart 2015

War children share less

Joris Tielens

War diminishes willingness to cooperation in children whose mothers were traumatized by war during pregnancy. This finding has emerged from economic experiments done by behavioural economist Francesco Cecchi in Uganda.

Cecchi studied aggression and competition in young people in Sierra Leone. Some of the young people had experienced violence during the war there. ‘When I was in Kenema in eastern Sierra Leone, a football tournament was just being held there between teams from different neighbourhoods. My colleague Maarten Voors and I thought we could make use of that and offered a money prize for the winner in order to increase the element of competition. We then counted the number of red and yellow cards.’

Cecchi also played an economic behaviour game with the footballers. They were given a sum of money and could choose whether to keep it or give all or part of it to someone else. This enabled him to measure the degree of altruism present. ’Young people who had experienced an intense conflict acted more selflessly towards their teammates. And at the same time they got more red cards during the football match.’ In short: war increases the bond with teammates but increases the aggression and competition towards outsiders. The remarkable thing is that Cecchi also found an effect among children who were still unborn during the period of war and violence. He studied the consequences of the trauma of mothers who were raped or subjected to violence by Joseph Koni’s Lord’s Army in northern Uganda.


Interviews are an unreliable method of measuring the effect of traumas. So Cecchi looked for another indicator. He found one in what is known as the ‘digit ratio’: the proportional length of the index finger and the ring finger. It is known from the medical literature that hormonal changes caused by trauma in the mother lead to a lower digit ratio in children. Cecchi tested whether the digit ratio is a reliable indicator in this case. Using a questionnaire he demonstrated that mothers of children with a low digit ratio indeed often suffered from post-traumatic stress syndrome (PTSD) as a result of violence or rape during the war. Cecchi then played a well-known behavoural game involving sweets (see box) with the children. The children of mothers who had been traumatized during pregnancy were far less willing to share with others.

Sharing sweets The ‘public goods game’ which Cecchi used works like this: make two sets of six cards as illustrated. Give each of the six players one of each type of card and ask them to choose, anonymously and without consultation, between taking three sweets and giving none to anyone else, or giving all three players one sweet each. More social-minded people will take the latter option and if everyone does so, they all end up with six sweets. Individualistic people will go for the first option, and if everyone does that, they all end up with three sweets. ‘Freeriders’ will hope that others will play sociably but make the individualistic choice themselves in order to get the best deal.

Cecchi, whose supervisor was Erwin Bulte, got his PhD last week. He is the first of four researchers to complete doctoral research done with funding from the Vici grant (1.5 million euros) Bulte received from science funding organization NWO in 2010. A distinctive feature of Bulte’s work is his used of economic experiments, following in the footsteps of French economist Esther Duflo. Economists use such experiments to measure the results of development projects or people’s preferences, instead of extrapolating them from theories or models.