A phonological relationship between a prime and a target produces faci
litation when one or two initial phonemes are shared (low-similarity f
acilitation) but produces interference when more phonemes are shared (
high-similarity interference; Slowiaczek & Hamburger, 1992). Although
low-similarity facilitation appears to be a strategic effect (Goldinge
r, Luce, Pisoni, & Marcario, 1992), this result cannot generalize to h
igh-similarity interference because the two effects are dissociated (S
lowiaczek & Hamburger, 1992). In the present study, strategic processi
ng in high-similarity interference was investigated. The phonological
relatedness proportion (PRP) and the prime-target interstimulus interv
al (ISI) were varied in a shadowing experiment. Low-similarity facilit
ation was found only with a high PRP and long ISI, but high-similarity
interference was found regardless of PRP and ISI. These results sugge
st that strategies influence low-similarity facilitation, but high-sim
ilarity interference reflects automatic processing.