Priming for line drawings of real and nonreal objects
was examined in an object decision task for 16 patients
with Alzheimer's disease (AD) and 16 normal elderly
control (NC) participants. In two study phases, participants
decided if objects were real or nonreal. In an implicit
test phase, real/nonreal decisions were made for studied
and unstudied objects, and priming was measured as the
difference in decision speed or accuracy between studied
and unstudied objects. In an explicit test phase, yes/no
recognition was measured for real and nonreal objects.
AD patients had impaired explicit memory for real and nonreal
objects and intact repetition priming for real objects.
By the latency measure, both AD and NC groups showed priming
for nonreal objects but in opposite ways. Classification
decisions about studied relative to nonstudied nonreal
objects were slower for the AD patients, whereas such decisions
were faster for the NC participants. Classification decisions
of both groups were less accurate for repeated nonreal
objects. These results support the claim that AD patients
with mild cognitive impairment show normal perceptual priming.
The AD inhibition for studied nonreal objects is discussed
in terms of the decision conflict that occurs when recollection
of source is not available to counter the influence of
familiarity. (JINS, 1998, 4, 435–446.)