We compare two perspectives on base-rate neglect (Kahneman
& Tversky, 1973) in probabilistic judgment. The evidential
impact perspective derives it from humans' focus on the
impact of evidence on belief, rather than conditional probabilities.
The Causal Models perspective derives it from humans'
inability to integrate information that is causally opaque,
as base-rates often are in such experiments. Because causal
and evidential-impact relations are often concomitant and confounded,
we designed an experiment that specifically teases
apart their respective influence on probabilistic judgment. Our
results support a combination of the two perspectives, with
causal transparency influencing the degree to which one engages
in evidential impact reasoning strategies.