For valid preference elicitation, stated preference surveys must provide information on the good to be valued, and respondents must process and recall the information. Previous studies show that the amount and type of information can affect stated preferences and the validity of value estimates, but how respondents process this information has been less researched. Some studies find correlations between preferences and respondent engagement with the information, but our study is the first to randomly and exogenously manipulate factors of engagement in a stated preference survey. Drawing on stated preference guidance and psychological concepts, we estimate the effect of quiz questions (asking about the content of the information) and self -reference questions (asking how the information personally relates to the respondent) on (i) engagement, (ii) information recall, and (iii) stated preferences in a discrete choice experiment survey valuing the ecosystem services of urban gardens in the German cities of Berlin and Stuttgart. Our results indicate that respondents spend more time on the information page when confronted with quiz rather than self-reference questions. For both question types, we do not find effects on recall or stated preferences. The results suggest that questions which increase engagement offer no simple fix to enhance information processing. Thus, alternative ways of reinforcing engagement, comprehension, and information recall in stated preference surveys should be developed and applied
