ABSTRACT
Color perception was tested using the Farnsworth-Munsell 100-Hue Test in a sample of persons with Gilles de la Tourette syndrome (GTS), and compared to norms from three age cohorts in the early second, fourth and sixth decades. Red-green color errors on the Farnsworth-Munsell did not appear to change appreciably as a function of age or GTS. Blue-yellow error scores did, however, increase with age and were exaggerated in the GTS group. It is concluded that sensory and perceptual disturbances are present in GTS as in other basal cell ganglia disorders. The results are discussed in terms of converging retinal dopaminergic mechanisms also associated with Parkinson's and Huntington's diseases and even with normal aging. Suggestions are offered that daily activities and behavior may be affected by spatial and chromatic deficiencies.
Subject(s)
Color Vision Defects/complications , Color Vision Defects/diagnosis , Tourette Syndrome/complications , Adult , Aging/physiology , Basal Ganglia/physiology , Cohort Studies , Color Perception Tests , Color Vision Defects/physiopathology , Dopamine/physiology , Female , Humans , Male , Middle Aged , Retina/physiology , Tourette Syndrome/physiopathologyABSTRACT
To test the hypothesis that accelerated aging factors may be responsible for previous findings of reduced performance by diabetics in a visual backward-masking task with colored stimuli, we compared masking performances of observers from three age cohorts (20-, 40-, and 60-yr.-olds). Since masking performance declined in a very similar fashion for all colors with age, it was concluded that the differential color-performance decrements associated with diabetes cannot be attributed to visual processes associated with normal aging. The application of the Lagged Accrual Model showed that sensory transmission time increases and asymptotic performance decreases as a function of age. Suggestions for the normative use of the present data and for further research are discussed.
Subject(s)
Aging/psychology , Color Perception , Perceptual Masking , Visual Perception , Adult , Age Factors , Color , Diabetes Mellitus/diagnosis , Diabetes Mellitus/psychology , Female , Humans , Male , Middle Aged , Models, Psychological , Photic Stimulation , Visual AcuityABSTRACT
On a visual backward masking task using color stimuli with an achromatic patterned mask, we compared the masking performances of 3 Type I diabetics with those of 9 participants in a control group. Analysis indicated that the diabetics show a marked decrement in performance with blue stimuli and a lesser decrement with red stimuli. Suggestions for further theoretical and parametric studies are discussed.
Subject(s)
Color Perception , Diabetes Mellitus, Type 1/psychology , Diabetic Retinopathy/psychology , Pattern Recognition, Visual , Perceptual Masking , Adult , Attention , Discrimination Learning , Female , Humans , Male , Orientation , PsychophysicsABSTRACT
The Ebbinghaus illusion was used to study size estimation as influenced by salient features of the central figure. Two groups of fourth graders, 9 boys and 11 girls, and two groups of seventh graders, 9 boys and 9 girls, judged the size of two central figures (an Oreo cookie or a black cardboard disc) with small and large black cardboard disc inducers. Responding showed the Oreo cookie was consistently perceived as larger than the cardboard disc when surrounded by the large inducing figures. The results are discussed in terms of an interaction between the geometric properties and salience of the central figure with the surrounds. This Oreo effect is not predicted by a strict version of the token-value hypothesis and differs from explanations based on contrast and conceptual similarity.
Subject(s)
Form Perception , Optical Illusions , Perceptual Distortion , Size Perception , Age Factors , Contrast Sensitivity , Discrimination, Psychological , Female , Humans , Judgment , Male , Models, PsychologicalABSTRACT
Using the Kanizsa triangle in a free-inspection paradigm, Gellatly has shown that subjects report seeing an illusory triangle while apparently not phenomenally aware of the inducing areas. It is argued that Gellatly's procedure may induce response processes which camouflage early sensory processes. By forcing subjects to choose between two response alternatives, it was shown that when they could just perceive the illusory triangle, they could also correctly discriminate the shape of the inducing elements. Under the free-inspection procedure, the duration threshold for seeing the illusory triangle was about 9 ms while the threshold for discriminating the shape of the inducing elements was about 2 ms. A static representation of the dynamic procedure used by Gellatly has been derived, which shows a novel effect of contour completion across boundaries resulting in a ghostly white triangle.
Subject(s)
Attention , Discrimination Learning , Optical Illusions , Pattern Recognition, Visual , Perceptual Masking , Adult , Contrast Sensitivity , Female , Humans , Male , Orientation , PsychophysicsABSTRACT
We have applied the Lagged Accrual Model of visual backward masking to a group of children (aged 10) and a group of adolescents (aged 15). The two groups did not differ on sensory transmission time, indicating that the speed of sensory transmission has already attained its maximum by age 10. The older group showed a significantly greater rate of information accrual and a greater amount of information extraction. An application of the model to previously published data revealed that very young children (aged 5) have slower sensory transmission times.
Subject(s)
Perceptual Masking , Visual Perception/physiology , Adolescent , Adult , Age Factors , Attention , Child , Child, Preschool , Female , Humans , Male , Memory , Models, Theoretical , Task Performance and Analysis , Time FactorsABSTRACT
A functional model is used to describe the effect of target intensity and target-set similarity on backward visual masking. The model consists of two distinct stages of visual information processing. The first stage is related to sensory transduction and transmission and is assumed to require a finite and measurable amount of time during which performance remains at chance. The second stage, associated with central processing, is characterized by a negatively accelerated growth function reflecting the accrual of effective information. Results show that the duration of the transmission stage is inversely related to target intensity. Surprisingly, the rate of information accrual is an interactive function of both target intensity and target-set similarity. The pattern of results is consistent with the interpretation that both intensity and similarity mediate their effect through a common mechanism--the accrual of effective information.
