Selection effects in implicit preferences look like circadian rhythms

What is it about?

Implicit racial preferences reveal whether a person likes their racial in-group or out-group better without relying on conscious awareness. People normally like their in-group more, but this is more true for people who do these tasks at night in an 'always available' implicit preference measure. It has been suggested that the difference in implicit preferences between morning participants and evening participants could be because of circadian rhythms.

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Why is it important?

We tested the circadian rhythm account by seeing whether three factors known to shift circadian rhythms (i.e., age, gender and daylight saving time) altered this morning/evening effect. They did not alter the effect in a consistent manner, which means that the morning/evening difference is probably due to different types of people doing the task in the morning and the evening. This research has important implications because it shows how selection effects (here, different types of people participating at different times of day) can lead to unnecessary psychological explanations of observations.