Page 160 - Emotions through the eyes of our closest living relatives- Exploring attentional and behavioral mechanisms
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                                Chapter 7
Furthermore, like in the adult PIAT, three different stimulus sets were created in which the positive and negative attribute images were varied. Again, for each stimulus set, we created four versions to control for order effects (see Table S2 in supplements and Figure S3B).
Equipment
The adult PIAT was performed on a Dell S2240Tb touchscreen (21.5 inch, 1920x1080 pixels, 12 ms response time). Children performed the PIAT on an Iiyama T1931SR-B1 touchscreen (19 inch, 1280x1024 pixels, 5 ms response time). Validation of the child PIAT attribute images was conducted on a Panasonic FZ-G1 ToughPad tablet (10.1 inch, 1920x1200 pixels).
Procedure
Participants were recruited by student assistants who approached zoo visitors that passed the test location during their visit. The assistants approached the visitors with information about the studies taking place in the zoo, and visitors were then asked if they were willing to participate in the current study. The goals of the study were deliberately kept vague and only minimal instructions were provided. Participants were told that the current test required them to categorize the big picture (of either a face or scene) into one of two categories on the upper left or right side of the screen, and that the test itself would provide them with feedback on their performance. They were also instructed to only use only one hand. After receiving consent from adult participants and the caregiver of child participants, individuals were seated behind the touchscreen. Participants started out with five practice trials in which they sorted images of flowers and bunnies to get a better idea of how the task looks and works. Next, they completed the five blocks of the PIAT. The task took about 10 minutes to complete. After completion, participants were thanked for their participation and fully debriefed.
Analyses
Analyses were performed in R, using the IATscores package (Richetin et al., 2015). We calculated a D-score using RobustScores (a function within IATscores) based on the following minimum performance criteria: reaction lower than 10,000 ms, and an error rate below 40% for the critical blocks (Greenwald et al., 2003; Nosek et al., 2014). Furthermore, in one of the stimulus sets used in 15 children (Stimulus Set 2, Version 2), one of the trials in critical block 3 wrongly presented participants with
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