The level of don’t know (DK) responses recorded in surveys are impacted by both social desirability (SD) and satisficing (SC). Both, SD and SC are known to be sensitive to survey mode and can inflate the rate of non-committal responses. It is assumed that Web surveys mitigate interviewer effects, and thus social desirability. However, this is a dualism as Web surveys also tend to exhibit higher levels of Don’t Know. This mechanic of survey design is poorly understood and there is little available, practical guidance on reducing mode effects that tend to increase the level of Don’t Know selection. Our first research question addresses the level of don’t know responses in Web surveys. We investigate how different presentations of don’t know answers in this mode affect the number of respondents selecting those options. As many studies are now employed in a multi-mode manner, inconsistency in don’t knows between modes introduce noise into the data. As such, our second objective takes a comparative approach to modes, by analyzing the different outcomes between online and telephone surveys. To answer these questions we deployed a survey experiment, administered online in four countries (n=1000). So far, most studies have used data from lagged surveys. But in our case, the telephone benchmark surveys were conducted (n=1000) concurrently. The paper will focus on examining whether different question designs result in different outcomes in the level of don’t know within the same mode. Furthermore, we will show, which question formats limit the differences between modes—online and telephone surveying. Finally, as this research is based on a multi-country survey, we will test, whether different formats work differently across countries. The paper will conclude with how researchers can successfully bridge modes in order to limit the “questionnaire design mode effect” on the answering behavior of respondents.