  Is it true that if citizens understand hurricane probabilities, they will
make more rational decisions for evacuation? Finding answers to such questions
is not straightforward in the literature because the terms judgment and
decision making are often used interchangeably. This terminology conflation
leads to a lack of clarity on whether people make suboptimal decisions because
of inaccurate judgments of information conveyed in visualizations or because
they use alternative yet currently unknown heuristics. To decouple judgment
from decision making, we review relevant concepts from the literature and
present two preregistered experiments (N=601) to investigate if the task
(judgment vs. decision making), the scenario (sports vs. humanitarian), and the
visualization (quantile dotplots, density plots, probability bars) affect
accuracy. While experiment 1 was inconclusive, we found evidence for a
difference in experiment 2. Contrary to our expectations and previous research,
which found decisions less accurate than their direct-equivalent judgments, our
results pointed in the opposite direction. Our findings further revealed that
decisions were less vulnerable to status-quo bias, suggesting decision makers
may disfavor responses associated with inaction. We also found that both
scenario and visualization types can influence peoples judgments and decisions.
Although effect sizes are not large and results should be interpreted
carefully, we conclude that judgments cannot be safely used as proxy tasks for
decision making, and discuss implications for visualization research and
beyond.
