The occurrence of processing bias manifested by the modified Stroop ta
sk does not require that the subjects be aware of the stimuli presente
d. Earlier studies have shown that even when stimuli are backwardly ma
sked so that conscious identification is prevented, patients suffering
from Generalised Anxiety Disorders slow down colour-naming masks that
are preceded by threatening words. In non-patient samples, processing
bias on the modified Stroop task is related to the level of trait anx
iety. We tested whether this preconscious processing bias is related t
o anxiety per se and whether it also occurs in specific phobias. Indee
d, in a group of 37 spider phobics, the intensity of phobic complaints
was significantly associated with interference measures on both the m
asked and the unmasked modified Stroop task. Preconscious processing b
ias was not associated with treatment gain. Interference on the masked
and unmasked Stroop task was reduced after treatment. Though the lack
of a no treatment control group precludes definite conclusions, our f
indings suggest that preconscious biases are influenced by behaviour t
herapy. Results are critically discussed. Copyright (C) 1997 Elsevier
Science Ltd