Although it is thought that within-compound associations are necessary for the
occurrence of both backward blocking and unovershadowing, it is not known whether
this variable plays a similar role in mediating the two phenomena. Similarly, the roles of
within-compound associations in forward blocking and in reduced overshadowing have
not been tested independently. The present experiments evaluated how the strength of
within-compound associations affects backward blocking, unovershadowing, forward
blocking and reduced overshadowing. Using an allergy task, the strength of withincompound
associations was varied by taking advantage of the participants’ prior
knowledge of common and uncommon food pairings. Backward blocking and
unovershadowing effects were only present when highly memorable compound cues
were used. Moreover, the magnitudes of both retrospective revaluation effects were
affected by the strength of within-compound associations. Forward blocking and
reduced overshadowing effects were independent of within-compound associations.
These results have important theoretical implications for causal learning research.
