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Retrieval from semantic memory and its implications for Alzheimer's disease
D Rohrer1, J T Wixted, D P Salmon
1Department of Psychology, University of California, San Diego, USA.
Journal of Experimental Psychology. Learning, Memory, and Cognition
|September 1, 1995
Summary
Generating category examples is faster from smaller sets, and slower with added tasks. Alzheimer's patients showed faster response times, suggesting semantic memory issues stem from fewer items, not slower retrieval.
Area of Science:
- Cognitive Psychology
- Neuroscience
- Linguistics
Background:
- Understanding semantic memory retrieval is crucial for cognitive research.
- Alzheimer's disease (AD) impacts memory, but the precise nature of semantic memory deficits is debated.
- Response latency in exemplar generation tasks offers insights into retrieval processes.
Purpose of the Study:
- To investigate the factors influencing semantic memory retrieval speed.
- To differentiate between item reduction and retrieval slowing as causes of AD-related semantic memory impairment.
Main Methods:
- Three experiments were conducted using a voice key and computer to record response latencies during category exemplar generation.
- Experiment 1 manipulated category size to assess the impact of search set size.
- Experiment 2 introduced a concurrent secondary task to evaluate processing load.
- Experiment 3 compared response latencies of Alzheimer's disease patients and elderly controls.
Main Results:
- Mean response latency was faster for smaller categories, indicating faster retrieval from reduced search sets.
- A concurrent secondary task significantly increased response latency, suggesting processing load slows retrieval.
- Alzheimer's participants exhibited faster mean response latencies than elderly controls.
Conclusions:
- Findings suggest that semantic memory impairments in Alzheimer's disease are primarily due to a reduction in available semantic items.
- This contrasts with a general slowing of retrieval processes.
- Response latency paradigms are valuable for characterizing memory deficits in neurodegenerative diseases.