The Single Category Implicit Associations’ Test (SC-IAT). Single Category Implicit Association tests (SC-IATs) are computerized sorting tasks in which, based on reaction times, impulsive preferences are measured. Very simplified in the Figure 1 (three times a computer screen with a keyboard – the ‘E’ and ‘I’-button emphasized), the procedure of a SC-IAT is displayed. The SC-IAT consists of a practice block, and two trial blocks. In a first practice block, participants learn to respond to attribute words (appearing in the center of the computer screen) which have to be categorized in two categories. In this example the attribute categories are ‘neutral’ and ‘annoying’, and are positioned on the left and right side at the top of a computer screen. The attribute words (see Table 1) that appear one by one in the center of the computer screen have to be classified to the attribute categories with either the left (E) or right (I) response key. Participants are to assign the word as fast and accurate as possible to the correct category by pressing the appropriate response key. The assignment of the left key (E) and right key (I) are balanced across participants. The attribute words can be neutral, negative or positive; in this study: annoying, reassuring, and threatening. In the two following blocks, people continue categorizing attribute words, but now the label category ‘Chlamydia screening’ is added to either one of the categories. In block 2, ‘Chlamydia screening’ is combined with ‘neutral’, while in block 3 ‘Chlamydia screening’ is combined with ‘annoying’ and vice versa. If, for example, there is a significant higher mean sorting reaction time when ‘Chlamydia Screening’ is combined with ‘Annoying’ compared to when it is combined with ‘Neutral’, respondents have an impulsive negative reactance towards Chlamydia screening; they associate Chlamydia screening more with the attribute annoying than with a neutral attribute.