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Participants and overview Sixty ethnically Polish female students at a large Polish state university took part in the study. Their ages ranged from 19 to 26 (M = 21.26, SD = 1.64). All participants were tested individually in a student dormitory, and completed two tasks: (1) imagining a positive intergroup encounter under facial feedback manipulation and (2) measure of intergroup attitudes and stereotype content.

Materials Participants received a story of a student – similar to themselves – and were asked to imagine that they were in such a situation themselves. In the story, the main character (a Polish student) participated in an English language course in Great Britain where she met people from several countries and visited sites in London with them during the weekends. In the imagined contact condition, participants read an additional passage informing them specifically that the main character befriended a Romanian student, Oradea, who was the main character’s roommate. [...] After reading the story, participants received a questionnaire that included measures of attitudes and stereotyping of Romanians (hidden among the measures of attitudes towards other ethnic groups).

Attitude positivity Participants were asked to rate their feelings towards several national groups (including Romanians) using a set of graphical feeling thermometers with a scale that ranged from 0° = extremely unfavourable feelings to 100° = extremely favourable feelings. [...]

Stereotype content A two-item measure of stereotype content was used [...] in which participants were asked to rate (1) how competent and (2) how likeable a given target group is. Participants indicated their responses on a scale ranging from 1 (not at all) to 10 (to a great extent).

Procedure The study was ostensibly divided into two parts – participants learned that the first part concentrated on ‘attention focus’ and it would involve reading a fragment of narrative text while holding a pen in their mouth. The second part of the study was presented as a ‘questionnaire survey on their attitudes and opinions’. Participants were assigned orthogonally into one of four conditions. Thirty participants were assigned into a somatic configuration associated with smiling (by asking participants to keep a pencil in their front teeth, avoiding to touch the pencil with their lips). [...] Thirty participants were assigned into a somatic configuration that disabled smiling by blocking the zygomatic muscle [...]