Page 159 - Emotions through the eyes of our closest living relatives- Exploring attentional and behavioral mechanisms

Validation of the Pictorial Implicit Association Test
consisted of six images of faces of men of Moroccan or Dutch descent with a neutral expression and formed a subset of the Radboud Faces Database (Langner et al., 2010) (see Table S1.1 and Figure S2A in the supplements). For the attributes, we selected the six most negatively and most positively rated images from the International Affective Picture System (Lang et al., 2007), excluding images showing humans as those may interfere with measuring inter-ethnic attitudes (Table S1.2 and Figure S2B in supplements). All images were presented in color, and all images were presented twice during the two critical blocks.
To control for an effect of attribute image type on the results, three different stimulus sets were created (Figure S3A in supplements). In all sets, we used the same faces to depict the “Moroccan” and “Dutch” superordinate category, but varied the images depicting the positive and negative category. For example, in the first version of the stimulus set, the positive attribute was represented by a seal pup and the negative attribute by a building on fire. For each stimulus set, we created four different versions in order to control for order effects and stimulus location effects within the task.
Images that served as category indicators were 300x300 pixels and were
presented in the top-left and top-right corner of the screen. In the experimental
trials (block 3 and 5, but see Task) a combined image of a face and a positive or
negative attribute was shown on the top-left and top-right corner of the screen with
a dimension of 500x225 pixels (see Figure 1B). Finally, images that needed to be
categorized appeared in the lower-center part of the screen and were 400x300 pixels
(attributes, i.e., positive/negative scenes) or 450x450 pixels (concepts, i.e., faces). 7
Children
The faces used as stimuli in the adult PIAT were also used in the child PIAT. Some IAPS images can be upsetting or frightening for young individuals, thus we opted to use cartoons instead. Positive and negative attribute images were changed to cartoon heroes and villains from animated tv-shows (see Table S1.3 and Figure S2C in the supplements for an overview of the selected images). All these attribute images were rated based on valence and arousal by children, and thus validated before we commenced the study (see Table S1.3 in supplements for an overview of the results). Like in the adult PIAT, we used six different positive and negative attributes, each consisting of a hero or villain from the same cartoon (Figure S2C in supplements). The child PIAT followed the same procedure and task presentation as the adult PIAT (i.e., the presentation order between practice and critical blocks were counterbalanced).
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