A new take on the bystander effect

A new study by Thomas et al. (2016) provides evidence that when deciding whether to help, we take into account the perspective of the other bystanders – whether they know that help is needed, whether they know that we know that help is needed, whether they know that we know they know that help is needed, and so on.

They conducted three experiments, in which participants responded to a (fictional) person who needed help from at least one volunteer. Participants were in groups of two or five people and were asked to imagine that they rented stalls at a market, earning $1 a day. Occasionally the market manager needed help from one merchant to get supplies and whoever helped would suffer a loss of half their earnings for that day. If no one helped, the manager would fine all merchants $1 for the day. Players knew the scenarios were fictional but that the money at stake was real.

The researchers varied how the participants were informed about the manager's need for help, and what they were told about the knowledge of the other participants in their group. For example, in one condition, the participants were told that the need for help had been announced by loudspeaker, so everyone knew. In another, they alone were told by private messenger.

The findings show that people's decision to help varied with the participants’ judgments about how likely it was that other people would help based on what they knew. In the loudspeaker condition, in which everyone knew that help was needed (and everyone knew that everyone else knew), the classic "diffusion of responsibility" finding was replicated – players were less likely to help when in a group of five than a group of two. But in the other conditions, the outcomes were more complex: for example, when participants knew that help was needed but that other merchants were ignorant, they were more likely to help. But when other merchants knew help was needed, and they didn't know that the participant knew help was needed, then the participant was less likely to offer to help. (Presumably rationalising that s/he could always “plead ignorance” that help was needed.)

This act of thinking about what other people know about what we know they know (i.e. we know that they know that they have been asked to help, but they don’t know that we have also been asked to help, and so on) is "recursive mentalising" and the researchers concluded that this is what causes participants to strategically shirk when they think others feel compelled to help.

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