With the help of five to eight ‘confederates’ (research assistants posing as naive participants), Solomon Asch in the 1950s found that when it came to making public judgments about the relative lengths of lines, some people were willing to agree with a majority view that was clearly wrong.

Asch’s finding was hugely influential, but a key criticism has been his use of confederates who pretended to believe unanimously that a line was a different length than it really was. They might well have behaved in a stilted, unnatural manner. And attempts to replicate the study could be confounded by the fact that some confederates will be more convincing than others. To solve these problems Kazuo Mori and Miho Arai adapted the MORI technique (Manipulation of Overlapping Rivalrous Images by polarizing filters; pdf), used previously in eye-witness research. By donning filter glasses similar to those used for watching 3-D movies, participants can view the same display and yet see different things.

Mori and Arai replicated Asch’s line comparison task with 104 participants tested in groups of four at a time (on successive trials participants said aloud which of three comparison lines matched a single target line). In each group, three participants wore identical glasses, with one participant wearing a different set, thereby causing them to observe that a different comparison line matched the target line. As in Asch’s studies, the participants stated their answers publicly, with the minority participant always going third.

Whereas Asch used male participants only, the new study involved both men and women. For women only, the new findings closely matched the seminal research, with the minority participant being swayed by the majority on an average of 3.44 times out of 12 key trials (compared with 4.41 times in the original). However, the male participants in the new study were not swayed by the majority view.

There are many possible reasons why men in the new study were not swayed by the majority as they were in Asch’s studies, including cultural differences (the current study was conducted in Japan) and generational changes. Mori and Arai highlighted another reason – the fact that the minority and majority participants in their study knew each other, whereas participants in Asch’s study did not know the confederates. The researchers argue that this is a strength of their new approach: ‘Conforming behaviour among acquaintances is more important as a psychological research topic than conforming among strangers,’ they said. ‘Conformity generally takes place among acquainted persons, such as family members, friends or colleagues, and in daily life we seldom experience a situation like the Asch experiment in which we make decisions among total strangers.’

Looking ahead, Mori and Arai believe their approach will provide a powerful means of re-examining Asch’s classic work, including in situations – for example, with young children – in which the use of confederates would not be practical.

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Mori, K., and Arai, M. (2010). No need to fake it: Reproduction of the Asch experiment without confederates. International Journal of Psychology, 45 (5), 390-397 DOI: 10.1080/00207591003774485

Christian Jarrett (@Psych_Writer) is Editor of BPS Research Digest