In the age of digitalization and globalization, an abundance of information is available, and our
decision environments have become increasingly complex. However, it remains unclear under
what circumstances complexity affects risk taking. In two experiments with monetary lotteries
(one with a stratified national sample), we investigate behavioral effects and provide a cognitive
explanation for the impact of complexity on risk taking. Results show that complexity, defined as
the number of possible outcomes of a risky lottery, decreased the choice probability of an option
but had a smaller and less consistent effect when evaluating lotteries independently. Importantly,
choices of participants who spent more time looking at the complex option were less affected by
complexity. A tendency to avoid cognitive effort can explain these effects, as the effort associated
with evaluating the complex option can be sidestepped in choice tasks, but less so in valuation
tasks. Further, the effect of complexity on valuations was influenced by individual differences in
cognitive ability, such that people with higher cognitive ability showed less complexity aversion.
Together, the results show that the impact of complexity on risk taking depends on both, decision
format and individual differences and we discuss cognitive processes that could give rise to these
effects
