Australasian Science: Australia's authority on science since 1938

Too Many Choices

By Tim Hannan

Decisions are most easily made when the right number of options are available.

Much of everyday human behaviour involves making decisions, whether it is selecting between possible solutions to problems at work or deciding what to eat for lunch. It’s often assumed that having a greater number of options from which to choose is always to be preferred. However, research has found that when too many options are present, people experience “choice overload” and have difficulty coming to a decision. A new study by a team from Caltech has highlighted the neural mechanisms underlying aspects of decision-making, and proposed that making good decisions requires having the right number of options – not too many, and not too few.

Prior research into decision-making has established that people’s behaviour is influenced by the number of possible options. One study involved researchers setting up a table of jam samples in a grocery store, and inviting customers to both taste and purchase a jar. On some occasions six samples were displayed, and on others 24 varieties. When six samples were displayed, customers were around ten times more likely to make a purchase than when 24 options were available – even though they were more likely to stop and sample when the larger number of options was displayed.

The results of this and other studies have been interpreted as evidence that decision-making can be negatively impacted by having too many choices: the person is overwhelmed and takes the easier path of not making any decision. In a real-world example cited by researchers, the attempt by the Swedish government to partially privatise its social security system by encouraging people to move retirement savings into private funds saw many not make any decision at all, possibly because several hundred funds were proposed as options.

In the study published in October in Nature Human Behavior (https://goo.gl/JXNJfZ), the researchers asked participants to select landscape photos for printing on a coffee mug, with each presented with either six, 12 or 24 pictures from which to make a selection. The researchers examined their patterns of brain activity through functional magnetic resonance imaging, focusing on the patterns of activity in the anterior cingulate cortex and the striatum, two regions known to be associated, respectively, with judging the costs and benefits of decisions and with judging overall value.

The results approximated an inverted-U curve, in that activity was highest in these regions for participants presented with 12 options while lower for those given either six or 24 options. The researchers interpreted these findings as supporting the notion that decisions are influenced by two factors: a weighing up of the potential value of the decision (in this case, the likelihood of getting an attractive picture for a mug), and a judgement of the amount of effort that must be applied to make the decision.

The theory is that the inverted-U pattern reflects the interaction between the anterior cingulate cortex and the striatum in making decisions. On the one hand, increasing the number of options from six to 12 increases the perceived potential reward, but as the number increases further the effort to make the decision becomes too high.

Thus, in this experiment, the six-item set of pictures was too small to trigger the “potential reward” mechanism, while the 24-item set was perceived as too large so that decision-making required substantially more effort than was worthwhile. At 12 options, the potential reward and effort required are in the “Goldilocks zone” of being just right.

It should be noted that while the researchers identified a specific optimal number in this study, this does not mean that 12 is the sweet spot for decision-making in general. The study’s authors have suggested that, in most cases, the ideal number of options for decision making is likely to be somewhere in the range of 8 to 15, with the precise figure likely to depend on the desirability of the reward, the understanding of the consequences of the decision, and the difficulty of comparing and evaluating options.

The study suggests that some of the decisions we make everyday are not helped by the number of options presented to us: how many types of toothpaste do we need to see on supermarket shelves? It also offers an explanation for informal voting on Senate ballot papers: there are simply too many unsuitable candidates for voters to be able to determine who should be put last.


A/Prof Tim Hannan is Head of the School of Psychology at Charles Sturt University, and the Past President of the Australian Psychological Society.