  Disinformation is proliferating on the internet, and platforms are responding
by attaching warnings to content. There is little evidence, however, that these
warnings help users identify or avoid disinformation. In this work, we adapt
methods and results from the information security warning literature in order
to design and evaluate effective disinformation warnings. In an initial
laboratory study, we used a simulated search task to examine contextual and
interstitial disinformation warning designs. We found that users routinely
ignore contextual warnings, but users notice interstitial warnings -- and
respond by seeking information from alternative sources. We then conducted a
follow-on crowdworker study with eight interstitial warning designs. We
confirmed a significant impact on user information-seeking behavior, and we
found that a warning's design could effectively inform users or convey a risk
of harm. We also found, however, that neither user comprehension nor fear of
harm moderated behavioral effects. Our work provides evidence that
disinformation warnings can -- when designed well -- help users identify and
avoid disinformation. We show a path forward for designing effective warnings,
and we contribute repeatable methods for evaluating behavioral effects. We also
surface a possible dilemma: disinformation warnings might be able to inform
users and guide behavior, but the behavioral effects might result from user
experience friction, not informed decision making.
