Causal directionality belongs to one of the most fundamental aspects of cau
sality that cannot be reduced to mere covariation. This paper is part of a
debate between proponents of associative theories, which claim that learner
s are insensitive to the causal status of cues and outcomes, and proponents
of causal-model theory, which postulates an interaction of assumptions abo
ut causal directionality and learning. Some researchers endorsing the assoc
iationist view have argued that evidence for the interaction between cue co
mpetition and causal directionality may be restricted to two-phase blocking
designs. Furthermore, from the viewpoint of causal-model theory, blocking
designs carry the potential problem that the predicted asymmetries of cue c
ompetition are partly dependent on asymmetries of retrospective inferences.
The present experiments use a one-phase overshadowing paradigm that does n
ot allow for retrospective inferences and therefore represents a more unamb
iguous test of sensitivity to causal directionality. The results strengthen
causal-model theory by clearly demonstrating the influence of causal direc
tionality on learning. However, they also provide evidence for boundary con
ditions for this effect by highlighting the role of the semantics of the le
arning task.