Design and Procedure
GIST
The study was approved by the ethics committee of the Max Planck Institute for Human Development and the University of Granada. Participants were provided with information about the frequency of benefits and side effects of 3 painkilling medications (i.e., aspirin, ibuprofen, and paracetamol) in comparison with a placebo. The clinical evidence was taken from 3 Cochrane reviews,Illustration of the stimuli: the graphical (panel A) and numerical (panel B) representation of the statistical information about the painkillers.After providing informed consent and stating demographic characteristics, participants were randomly assigned to the “no choice” or “choice” conditions and were provided with information about the medications. Within the “no choice” condition, half of the participants were randomly assigned to receive the numerical representation of the information, while the other half was randomly assigned to receive the graphical representation of the information. Within the “choice” condition, participants saw a brief example of what the numerical and graphical representation would look like and could decide which one they wanted to receive.All participants received an actual printout of the information, either as numerical or graphical representation, and were asked a series of questions about the medication with the printout directly in front of them (T1). These questions concerned comprehension of the information, subjective evaluations of perceived accessibility of the information, and subjective attractiveness ratings of the representation (see the “Measures” section for details on those and all subsequent variables). Next, participants returned the printout with the representation to the experimenter and filled out the graph literacy and numeracy scale. Then, there was a 120 min break. During this break, participants attended to a lecture and a practice exercise about a topic unrelated to the current research (healthy nutrition in adolescents). After this break, participants received a task in which they had to recall the same knowledge questions that they had answered previously but without being provided with the information (T2).In sum, the independent variables were condition (“no choice” v. “choice”), whether participants worked with the numerical or the graphical representation of the information, and their graph literacy. The dependent variables were comprehension and recall of both verbatim and gist knowledge (and we generally use the term 