Studies examining implicit memory performance in
Alzheimer's disease (AD) have yielded inconsistent
findings, with these patients demonstrating impaired performance
within some priming studies and intact performance within
others. The present study examined the role of task sensitivity
in detecting impaired priming in memory-impaired patients.
Twelve healthy older adults and 12 AD patients were administered
a picture fragment identification test. Task sensitivity
was increased by employing stimulus cues expected to produce
larger and more variable priming effects than obtained
in previous studies. A simple comparison of priming scores
revealed that the AD patients demonstrated significantly
impaired priming relative to normal control participants.
However, further analysis of priming in relation to certain
stimulus characteristics revealed that AD patients often
demonstrated impaired priming when overall priming effects
were large but relatively intact priming when priming effects
were small. These findings suggest that the prevention
of ceiling effects in control participants may aid in the
detection of impaired priming in patient populations. (JINS,
2001, 7, 294–301.)