Different influence of backward masking on visual pattern recognition in the early stages of presenile dementia and normal ageing
✍ Scribed by Dr. Gottfried Müller; Steffen Weisbrod; Fritz Klingberg
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 544 KB
- Volume
- 7
- Category
- Article
- ISSN
- 0885-6230
No coin nor oath required. For personal study only.
✦ Synopsis
The effect of backward masking with illumination of all fields or with a checkerboard pattern, respectively, on the recognition of pattern + or T was measured on four groups of subjects: 21 presenile onset DAT patients, 16 patients with a questionable vascular dementia of the same age (CVD group), 15 age-matched control subjects (EC group) and 16 younger control subjects (YC group, mean age 22 years). The pattern stimulus had a duration of 20 ms and was followed by the masking stimulus pattern (20 ms duration) with increasing intervals in steps of 5 ms. The mean recognition threshold (RT) for each of the four possible pattern-mask combinations was measured in five trials. The RTs decreased within the five trials in all groups. DAT patients and CVD patients adapted with different speeds during the five trials. We found a small significant R T difference between elder and younger control subjects, whereas patients had increased RTs in the first trial and differences in the four variants in the further trials compared with age-matched controls. The test contributes to a set o f data for diagnosis and differential diagnosis in the early stages of presenile dementia.
KEY wom-Presenile onset dementia of Alzheimer type, vascular dementia, normal ageing, visual recognition threshold, backward masking.