Fluency-Based Memory Decisions in Alzheimer’s Disease: A Matter of Source Detection?

Objective: The primary aim of this study was to test whether differences in the ability of patients with Alzheimer Disease (AD) and healthy participants to detect alternative sources of fluency can account for differences observed in the use of fluency - i.e., the ease with which information is processed - as a cue for memory.
Method: Twenty-two patients with AD and 22 matched controls were presented with three forced-choice visual recognition tests. In each test, an external source of fluency was provided by manipulating the perceptual quality of the items during the test phase. The detectability of the perceptual manipulation varied in each test (i.e., 10%, 20%, or 30% contrast reduction were given).
Results: Data indicated that AD patients rely on fluency in a similar extent than older adults as long as they demonstrate intact detection of differences in the perceptual quality of the items. Specifically, it appears that patients’ ability to visually discriminate stimuli differing in terms of their perceptual quality is critical for patients to be able to implement strategies to appropriately use or correctly disqualify fluency during a recognition task.
Conclusion: Overall, these findings suggest that the disruption of some basic cognitive processes could prevent AD patients to experience fluency in a similar extent than healthy controls. However, when the ability to detect differences in the perceptual quality of the stimuli was taken into account, patients appeared to be as able as controls to rely on fluency to guide their memory decisions.