The non-effect of images of half-naked women on economic behaviour

You can get away with a lot of crazy things in a lab experiment (tempered somewhat by the fact that whatever you propose has to be approved by an ethics committee). For example, this 2018 paper by Evelina Bonnier (Stockholm School of Economics) and co-authors describes a lab experiment where research participants were shown advertisements, of three kinds:

...a treatment where advertisements contain half-naked women dressed in bikini or underwear, a treatment where advertisements contain fully dressed women, or a control condition where there are no women present.

Participants were then tested on their risk taking preferences, their willingness to compete, and the mathematics performance. Specifically:

Risk taking is measured from having participants complete two multiple-price lists in which they face a series of decisions between two lotteries, where one is more risky than the other. Participants make 20 such choices and our measure of risk taking is defined as the fraction of more risky lottery choices. The competitiveness task... participants in a first stage perform a math task and get paid according to a piece-rate scheme. In a second stage, participants perform a similar math task and are paid according to a competitive winner-takes-all tournament scheme. In a third stage, participants get to choose between the two payment schemes before performing the task for a third time. Willingness to compete is measured from this binary choice. As a measure of math performance, we use the number of correctly solved math problems in the first non-competitive stage of the competitiveness task. 

The research participants were 648 students (331 men and 317 women) at the University of Copenhagen or the University of Valencia. Bonnier et al. find that there are:

...no treatment effects on any of the three main outcome measures for female participants. For men, we also find no effect on math performance or willingness to compete, but suggestive evidence that men take more risk after having been exposed to images of half-naked women... Moreover, we do not find a significant difference between the half-naked treatment and the fully dressed treatment on risk taking for men.

Risk taking was 4.8 percentage points higher among men who saw the images of half-naked women compared with the control group who saw no women (47.1% vs. 42.8%), but this difference was only statistically significant in some (but not all) analyses. That probably reflects that the real effect (if any) is quite small, and so you would need a much larger sample in order to robustly find any effect of half-naked pictures on men's risk taking behaviour. That there was no statistically significant effect for women probably accords with expectations, although risk taking was about 4 percentage points higher for women who saw images of fully dressed women than the control group women. Interestingly, although this difference was statistically insignificant, it was larger than the difference for men.

So, more research is needed on this topic, if we really wanted to know how exposure to images of half-naked women affects economic behaviour. And, of course, as Bonnier et al. note in their conclusion, in the interests of gender equity:

...it would be interesting to explore the effects of exposure to images of half-naked men.

[HT: Marginal Revolution, back in 2018]