The Similarity Effect and Republican Obstructionism

The GOP’s “just say ‘no'” response to the Obama agenda has been surprisingly successful. They got away with nearly crashing the economy and they managed to turned public opinion against health care reform at a time when the economy and the President’s approval were far from rock bottom. Although a number of economic, political, and strategic factors likely helped shape public opinion, this blog is about psychology, and from a psychological standpoint all signs point to the influence of the “similarity effect.”

The similarity effect essentially says that when evaluating two options the presence of a third option that’s similar to one of the first two will bias choices away from the similar options. For example, if you can’t decide whether to order pizza or Thai food, and then I offer the option to order Malaysian, chances are you’ll decide to order pizza. A new study shows this effect can even influence decisions in life or death moral quandaries (and thus it’s probably strong enough to influence political preferences).

The study examined people’s approval of actions in a modified trolley problem. In the standard trolley problem subjects are told there is a runaway train that will kill five people. They are then asked if they would approve of flipping a switch to redirect the trolley onto a track with one person, or approve of stopping the train by pushing a fat person in its path. Even though both actions are effectively the same (killing one person to save five people), subjects generally approve of flipping the switch but disapprove of pushing the person off the bridge.

In the modified trolley problem two groups of subjects were given three choices (action, action, and nothing) instead of just two (action and nothing). Both groups were told they could push the person into the train’s path (one dies, five are saved) or do nothing (five die.) However, one group was told they could also flip a switch to redirect the train onto a track with two people, while the other group was told they could flip a switch to redirect the train onto a track with four people. The difference was that for the first group the third option was similar to pushing the person off the bridge (letting two people die instead of one), while for the second group the third option was similar to doing nothing (letting four people die instead of five).  The researchers found that when flipping the switch was similar to doing nothing, pushing the person off the bridge had the highest approval rating and doing nothing was the least approved option. However, when flipping the switch was similar to pushing the person off the bridge, doing nothing had the highest approval rating.  The mere presence of the “switch” option had drastic effects on people’s approval of the pushing and inaction options.

The application to public policy is relatively simple. When it’s just “Obamacare” and “No Obamacare,” democrats may have a sufficient amount of support. However, when the discussion starts to include Obamacare with a public option, Obamacare without a public option, Obamacare with medicare for all, and Obamacare with stricter abortion requirements, the similarity of all those options starts to make “No Obamacare” more appealing. The same thing may have happened with financial regulation and the debt ceiling negotiations. Always saying “no” may seem uncreative and unproductive, but thanks to the similarity effect it works.
Shallow, C., Iliev, R., & Medin, D. (2011). Trolley problems in context Judgment and Decision Making, 6 (7), 593-601


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