Serial position effects in dementia of the Alzheimer type.

BACKGROUND

The aim of the present study was to analyse serial position effects for immediate and delayed free recall in patients with dementia of the Alzheimer type and controls. EXPERIMENT 1: 44 patients with dementia of the Alzheimer-type and 24 non-demented controls were asked for immediate and delayed free recall of 12 schematic drawings of common objects presented at the rate of 10 s/picture. Steep primacy effects were obtained at all delays in controls. By contrast, primacy effects were significantly impaired in patients with dementia at all delays of recall. Small immediate and delayed recall recency effects were found in both, patients and controls. EXPERIMENT 2: 19 patients with dementia of the Alzheimer type and 21 controls were asked for immediate and delayed free picture recall with presentation rates of 10, 5 and 1 s/picture. Again, primacy effects were significantly impaired in demented patients versus controls. With shorter presentation times, immediate recall recency effects were more pronounced than with longer presentation times, and no delayed recall recency effects were found.

CONCLUSIONS

Primacy effect is impaired for immediate and delayed recall in dementia of the Alzheimer type. By contrast, immediate recall recency effect and possibly also long-term recency effect are preserved. The loss of the primacy effect contributes to the impairment of episodic memory in dementia of the Alzheimer type. Therefore further research is warranted into pharmacological and psychological interventions that might re-establish the primacy effect. Possibly, the orientation of demented patients might be improved by psychological techniques that rely on long-term recency effect.