| Abstract: | This experiment sought further support for the view that early stage Alzheimer's disease (AD) disrupts cognitive structures that cast experience into a temporal framework. Forty participants, evenly divided between normal elderly (NE) and persons diagnosed with mild AD, viewed 19 lists of 14 pictures each. Following the presentation of each list participants were asked to identify the most recently experienced picture (target) from 3 pictures. A second stimulus was a picture never previously seen; the third picture was a distracting item that had appeared in the list on either one or three occasions. The results show that whereas choice accuracy of the NE group remained largely unimpaired regardless of the delay between the target and the judgment task or the frequency of the distractor, the AD participants exhibited large and profound deficits in temporal judgments, especially when distractor frequency was greater than the more recent event. In effect, the AD group relied on how often an event occurred rather than the time of its occurrence. This finding is consistent with previous research that found AD patients deficient in forming a temporal representation of their experience. |
