Brightness differences influence the evaluation of affective pictures.

We explored the possibility of a general brightness bias: brighter pictures are evaluated more positively, while darker pictures are evaluated more negatively. In Study 1 we found that positive pictures are brighter than negative pictures in two affective picture databases (the IAPS and the GAPED). Study 2 revealed that because researchers select affective pictures on the extremity of their affective rating without controlling for brightness differences, pictures used in positive conditions of experiments were on average brighter than those used in negative conditions. Going beyond correlational support for our hypothesis, Studies 3 and 4 showed that brighter versions of neutral pictures were evaluated more positively than darker versions of the same picture. Study 5 revealed that people categorised positive words more quickly than negative words after a bright picture prime, and vice versa for negative pictures. Together, these studies provide strong support for the hypotheses that picture brightness influences evaluations.

Motivating blood donors to recruit new donors: experimental evaluation of an evidence-based behavior change intervention.

OBJECTIVE: A sustainable, evidence-based intervention to motivate current blood donors to recruit new donors was evaluated using a quasi-experimental, in-service trial at three donation centers. DESIGN: Participating blood donors in three conditions (N = 734), received (1) an evidence-based leaflet designed to enhance recruitment motivation and five postcards facilitating recruitment and donor registration, (2) five postcards alone, or (3) no materials. MAIN OUTCOME MEASURES: Self-reported donor recruitment by donors was measured at 1-week and 6-week follow-up. RESULTS: At 1-week and at 6-week follow-up, donors in both intervention conditions reported talking to more people about donation and asking more people to donate than control participants. Intervention participants also reported persuading more people to register as a donor than control participants. Results indicated that postcards plus leaflet was somewhat more effective than the postcards alone. Donors' intentions to recruit at 1-week follow-up mediated the behavioral effects at 6-week follow-up. CONCLUSION: Motivating and facilitating recruitment of new blood donors through existing donors has the potential to continually replenish the donor population.