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PubMed2006

Perceptual considerations in the use of colored photographic and video stimuli to study nonhuman primate behavior.

The use of photographs, slides, computerized images, and video to study behavior is increasingly being employed in nonhuman primates. However, since these mediums have been designed to simulate natural coloration for normal trichromatic human vision, they can fail to reproduce color in meaningful and accurate ways for viewers with different visual systems. Given the range of color perception that exists both across and within different species, it is necessary to consider this variation in order to discern the suitability of these mediums for experimental use. Because of the high degree of visual similarity among humans, Old World monkeys, and apes, the use of photographic and video stimuli should be acceptable in terms of replicating naturalistic coloration and making noticeable color manipulations. However, among New World primates and prosimians, there exists a considerable degree of variation in color perceptual abilities depending on the species, sex, and allelic combination of the animals involved. Therefore, the use of these mediums to study behavior is problematic for these species, and should be done with caution.

Animals↗
PubMed2002

Color sensitivity and mood disorders: biology or metaphor?

BACKGROUND: A familiar but overlooked symptom in affective disorders is patient self-report of alterations in color sensitivity. Anecdotal and empirical evidence have suggested an association between mood and color sensitivity. The purpose of this pilot study was to test three hypotheses concerning the relationship between mood disorders and color sensitivity. METHODS: Using a cross-sectional survey design consisting of a sample of 120 inpatients and outpatients, color sensitivity was assessed by the patient's response to a self-report depression scale item, "I notice that everything seems gray/cloudy/drab/lacking color". RESULTS: Color sensitivity significantly correlated with depression in the total sample (P=0.001). The other two hypotheses approached significance but were not supported. DISCUSSION: These findings suggest there is evidence that color sensitivity is impaired during depression. Further research using a larger, more homogeneous sample and longitudinal design whereby measures of mood and color sensitivity are correlated before, during, and after treatment in depressed and manic patients would be justified. A study using ophthalmological instrumentation to measure color sensitivity would provide objective, 'hard' evidence of the association between color sensitivity and depression. CONCLUSIONS: Whether color perception is metaphorically reported by patients to describe their mood or a biological phenomenon remains to be validated. Findings seem to lend support to the conclusion that abnormalities in brain function alter retinal function.

Adult↗
PubMedDate not supplied

Color naming, unique hues, and hue cancellation predicted from singularities in reflection properties.

Psychophysical studies suggest that different colors have different perceptual status: red and blue for example are thought of as elementary sensations whereas yellowish green is not. The dominant account for such perceptual asymmetries attributes them to specificities of the neuronal representation of colors. Alternative accounts involve cultural or linguistic arguments. What these accounts have in common is the idea that there are no asymmetries in the physics of light and surfaces that could underlie the perceptual structure of colors, and this is why neuronal or cultural processes must be invoked as the essential underlying mechanisms that structure color perception. Here, we suggest a biological approach for surface reflection properties that takes into account only the information about light that is accessible to an organism given the photopigments it possesses, and we show that now asymmetries appear in the behavior of surfaces with respect to light. These asymmetries provide a classification of surface properties that turns out to be identical to the one observed in linguistic color categorization across numerous cultures, as pinned down by cross cultural studies. Further, we show that data from psychophysical studies about unique hues and hue cancellation are consistent with the viewpoint that stimuli reported by observers as special are those associated with this singularity-based categorization of surfaces under a standard illuminant. The approach predicts that unique blue and unique yellow should be aligned in chromatic space while unique red and unique green should not, a fact usually conjectured to result from nonlinearities in chromatic pathways.

Color↗
PubMed1992

Depth, motion, and static-flow perception at metaisoluminant color contrast.

Many experiments concerned with the role of color in depth and motion perception have applied isoluminant random-dot stereograms and cinematograms. The poor performance in the absence of luminance contrast has been associated with color-blindness of stereopsis and motion perception (Livingstone, M.S. & Hubel, D.H. (1987) J. Neurosci. 7, 3416-3468). Nevertheless, isoluminant stimuli are not fully accepted as appropriate tools in isolating central mechanisms (Logothetis, N.K., Schiller, P.H., Charles, E.R. & Hurlbert, A.C. (1990) Science 247, 214-217). In our experiments we use a broad luminance range to test whether color can contribute to a given mechanism when luminance contrast is present but has a strong "veto" effect from opposite luminance contrast, a condition we named "metaisoluminance." There is no fusion in stereopsis under polarity reversal, when only luminance information is given, and reversed-phi phenomenon is experienced for motion. As a third "matching" task, we included polarity-reversed random-dot Glass-patterns, which exhibit "static flow" and also show pattern reversal. We found that color can counteract the effects of polarity reversal by restoring stereoscopic fusion and reversed phi motion and does it with increased efficiency as the hue contrast increases. We found no such effect of color in Glass-patterns. Thus, we showed that the visual system for binocular depth and motion perception is not color-blind, although correlated hue information under metaisoluminance does not appear to yield shape perception.

Color Perception↗
PubMed1994

[Dependence of the sensitivity of the central visual field on hemoglobin-oxygen saturation].

Retinal function is very sensitive to changes in hemoglobin oxygen saturation. Characteristic ophthalmological symptoms of oxygen deficiency are: changes in color perception, visual field defect, eye flickering, reduction of visual acuity, seeing double images, defects in neural image interpretation. To test the dependency of changes in the central visual field sensitivity on different degrees of oxygen saturation, 48 probands (48 monocular tests) 20-50 years of age were examined in the altitude simulation chamber of the Aviation Medicine Institute of German Air Force at zero altitude (= 500 m) and at 10,000 ft (ca. 3,500 m height). Three types of experiments were performed: determination of abnormal quotient using a Heidelberg anomaloscope; determination of changes in color vision by saturated and disaturated panel D-15 test; determination of differences in light sensitivity for white, red, blue and green light by a threshold test using a Humphrey Field Analyzer (640) as perimeter. At zero level (500 m) hemoglobin-oxygen saturation was 97% +/- 1%. At 10,000 ft this value decreased to 83% +/- 3%. Hypoxic hypoxia caused neither significant AQ changes nor did it induce reproducible changes in color vision by the panel D-15 test. However, anoxia resulted in significant (P < 0.01) differences in light sensitivity in phototopic range.

Adult↗
PubMed1997

The characteristics of interaction between color and motion perception in primary open angle glaucoma.

PURPOSE: To investigate the characteristics of interaction between color and motion perception in primary open angle glaucoma (POAG) and measure motion perception of B, G and R cones, thus find a more sensitive method to diagnose the visual nerve damage in POAG. METHODS: Motion perceptions of B, G and R cones were isolated by blue, green and red vertical line stimulus displayed on the yellow, purple and blue background respectively, then measured the displacement threshold and flicking threshold of motion perception from each cones in POAG, and compared it with the age-match normals. RESULTS: The displacement threshold and flicking threshold of motion perception from B, G and R cones were all damaged in POAG compared with the normals, and the motion perception of G and B cones was deficits more obviously than the R cones. CONCLUSION: These findings support the suggestion that color provides an input to human motion perception. Magnocellular and parvocellular pathway may be significantly damaged in POAG, which indicates, that the combination of Motion Perception and color testing may reveal preclinical visual nerve damage in early POAG.

Adult↗
PubMed1993

Positron-emission tomographic localization of abnormalities of brain metabolism in patients with minimal hepatic encephalopathy.

Many patients with compensated cirrhosis without overt hepatic encephalopathy have deficits in visual-spatial perception, a condition we call minimal hepatic encephalopathy. Five patients with alcohol-induced cirrhosis and nine control subjects underwent positron-emission tomographic imaging of the brain with 18F-fluorodeoxyglucose. Patients also underwent neuropsychological and clinical chemistry tests. The patients had mild arterial hyperammonemia (62 +/- 13 mumol/L, range = 11 to 35 mumol/L) and other abnormalities typical of patients with cirrhosis. The patients' mean percentile scores on the digit symbol and block design subtests, from the Wechsler Adult Intelligence Scale (revised), and Purdue pegboard test were 11 +/- 7, 24 +/- 7 and 7 +/- 8 (right hand). Tests of vocabulary, memory, and new learning were normal. The technique of statistical parametric mapping was used to identify regions where cerebral 18F-fluorodeoxyglucose uptake and metabolism were abnormal. We noted significant reductions in the cingulate gyrus, a center mediating attention, target analysis and response formulation and significant increases in visual associative regions subserving motion and color perception and object orientation. We suggest that minimal hepatic encephalopathy is due to a deficit in the detection and formulation of responses to visual stimuli, a function of the cingulate, which is a part of the anterior attentional system of the brain. Increases in 18F-fluorodeoxyglucose metabolism may be compensatory. These studies show that brain regions differ in their sensitivity to the agents that cause hepatic encephalopathy and that positron-emission tomography is useful in studying the pathophysiology of this disorder.

Adult↗
PubMed2004

Ergonomic concerns with lightbar guidance displays.

This article reviews some ergonomic factors associated with agricultural guidance displays. Any technology or management decision that improves the efficiency of an agricultural operation can be considered an aspect of precision farming. Agricultural guidance displays are one such tool because they help to reduce guidance error (i.e., skipping and overlapping of implements within the field), which result in improper application of crop inputs at increased cost. Although each of the guidance displays currently available functions using a different principle, their key objective is to communicate useful guidance information to the operator of the agricultural machine. The case with which the operator obtains the required information depends on a number of ergonomic factors, such as color perceptibility, flash rate, attentional demand, display size, viewing distance, and height of placement of the display in the cab. Ergonomics can be defined as the application of knowledge to create a safe, comfortable, and effective work environment. Consequently, it is critical to consider ergonomics when designing guidance displays or when locating a display in the tractor cab. Without considering ergonomics, it is unlikely that the efficiency of the human-machine system can be optimized.

Agriculture↗
PubMed2004

Visual sensation during phacoemulsification and intraocular lens implantation using topical and regional anesthesia.

PURPOSE: To evaluate patients' visual sensations at different stages of phacoemulsification and posterior chamber intraocular lens (PC IOL) implantation under topical and regional anesthesia. SETTING: Department of Ophthalmology, United Christian Hospital and Tseung Kwan O Hospital, Kowloon, Hong Kong, China. METHODS: Seventy-six consecutive patients having phacoemulsification were randomized to a topical anesthesia group (n = 35) or regional anesthesia group (n = 41). The topical anesthesia group received lidocaine hydrochloride 2% gel (Xylocaine) and the regional anesthesia group, a peribulbar or retrobulbar injection of lignocaine 2%. The patients' visual sensations, including light and color sensations, shape of objects, and visual patterns, were evaluated at different stages of surgery. RESULTS: Two patients (4.9%) in the regional anesthesia group and none in the topical anesthesia group experienced total loss of light sensation throughout surgery (P =.50). There was a significant association between color perception and the type of anesthesia at stages 1 and 2 (P<.05) but not at stages 3, 4, and 5 (P>.05). The perception of objects and visual patterns had no association with the type of anesthesia at any stage (P>.05). Of all patients in the study, 56 (73.7%) reported color changes as surgery proceeded. Both groups saw waves, defined as curves with periodic fluctuations in amplitude, at all stages. The perception of some colors and a rectangular moving object was significantly associated with the type of anesthesia at some or all stages (P<.05). CONCLUSIONS: Patients having phacoemulsification and PC IOL implantation under topical or regional anesthesia had a wide spectrum of visual sensations that were similar at most stages of surgery. Patients in the topical anesthesia group perceived more colors at the early stages and more blue throughout surgery than patients in the regional anesthesia group.

Aged↗
PubMed1995

Vision in dogs.

Compared with the visual system in human beings, the canine visual system could be considered inferior in such aspects as degree of binocular overlap, color perception, accommodative range, and visual acuity. However, in other aspects of vision, such as ability to function in dim light, rapidity with which the retina can respond to another image (flicker fusion), field of view, ability to differentiate shades of gray, and perhaps, ability to detect motion, the canine visual system probably surpasses the human visual system. This has made the dog a more efficient predator in certain environmental situations and permits it to exploit an ecological niche inaccessible to humans.

Animals↗
PubMed1987

A central binocular mechanism affects chromatic adaptation.

Two experiments explored the role of central binocular mechanisms in color perception. The first experiment examined the effect of adapting to simultaneous, binocularly fused fields. Each eye adapted to a slowly flickering (0.5 Hz) long-wavelength light. The two eyes were adapted either inphase (both eyes stimulated at the same moment) or out-of-phase (only one eye stimulated at any given moment). Both adapting procedures shifted equilibrium yellow toward longer wavelengths, but a significantly greater shift was found when adapting light stimulated both eyes simultaneously. This reveals that a central binocular mechanism affects chromatic adaptation. The second experiment tested whether the binocular mechanism could shift equilibrium yellow measurements made with both eyes (identical, binocularly fused fields presented to each eye) outside of the range of measurements established by left-eye monocular viewing and right-eye monocular viewing. Differences were found between monocular left-eye and monocular right-eye color appearance under conditions of moderate chromatic adaptation, but binocularly fused measurements fell within the range established by the monocular results. This is consistent with the view that central mechanisms serve to keep the two eyes in balance, rather than systematically alter color appearance from colors perceived under monocular viewing.

Adaptation, Ocular↗
PubMedDate not supplied

[Spectral filters as a method of therapeutic correction].

Spectral filters were used for additional correction of vision in 67 patients: in 15 adults with initial cataracts (intensive yellow filter), 26 children with albinism (yellow-brown filter), 14 children with macular hypoplasia (orange filter), and 12 children with aphakia after removal of congenital cataracts (yellow filter). Selection of the filter density is carried out using a special method including visocontrastometry, examination of sensitivity to lateral light, and study of color perception thresholds. Use of filters resulted in improvement of the vision acuity by 43.5% in patients with initial cataracts, by 10% in those with albinism, by 20% in those with macular hypoplasia, and by 22% in those with aphakia; moreover, an improvement of the frequency-contrast characteristics was observed, as well as a reduction of photophobia, and a reduction of vision amplitude in patients with nystagmus. The possible applications of spectral correction are discussed.

Adult↗
PubMed1976

Color vision and hue categorization in young human infants.

Two studies examined the organization of color perception in 4-month-old human infants. In Study 1, infants looked at selected spectral stimuli repeatedly until their visual attention waned. The stimuli represented instances of basic adult hue categories - blue, green, yellow, and red. Following habituation, infants were shown a series of wavelengths which were the same as or different from the stimuli first seen. Analyses of infant attention during this dishabituation phase of the study indicated that infants categorize wavelengths by perceptual similarity; that is, they see hues in the spectrum much as adults do. In Study 2, a group of infants who looked at the alteration of two wavelengths from the same hue category habituated as did the group of infants who looked at the repitition of a single wavelength from that category, but a group of infants who looked at two wavelengths from different categories habituated at a slower rate. Data from the two studies suggest a high degree of organization of the color world prior to language acquisition.

Association↗
PubMed1998

Visual dysfunction in Parkinson's disease.

Several abnormalities of visual function have been demonstrated in Parkinson's disease (PD) by both electrophysiologic and psychophysical testing. Prolonged visual evoked potential latencies and abnormal electroretinographic patterns, both of which respond to levodopa therapy, have been demonstrated in Parkinson's disease patients and in primates with experimental parkinsonism suggesting that retinal dopamine deficiency is an important factor in the pathogenesis of PD visual dysfunction. Abnormalities of color perception, especially in the blue-green axis, and of visual contrast sensitivity (VCS) have also been well documented in PD patients. Although VCS impairment is likely related to retinal dopaminergic dysfunction, the fact that this visual abnormality is orientation-specific raises the possibility of visual cortex involvement as well. Visual abnormalities in PD are usually clinically occult and not likely to be uncovered during a routine neurological examination or by ordinary high contrast visual acuity testing. The clinician must be aware, however, that several forms of disability ranging from gait freezing to visual hallucinations may be linked to an underlying impairment of visual function in Parkinson's disease.

Color Perception↗
PubMed2003

Color measurements as quality criteria for clinical shade matching of porcelain crowns.

STATEMENT OF PROBLEM: The ability of a dentist to select and communicate an acceptable shade match to a dental laboratory may be the most important factor in esthetic restorative dentistry. PURPOSE: The purpose of this study was to evaluate the use of instrumental color measurement in clinical shade matching of porcelain-fused-to-metal (PFM) and all-porcelain crowns. The relative effects of clinical and laboratory factors related to shade matching for PFM and all-porcelain crowns were also evaluated. MATERIALS AND METHOD: Forty patients treatment planned to receive PFM or all-porcelain crowns made up the study population. The patients were randomly divided into two groups for shade selection: conventional visual assessment and photocolorimetric analysis. At the preparation appointment, a photograph was taken of the target tooth along with four shade guide tabs selected by the two visual observers. The crown was fabricated by either visual selection or by the lowest E* values determined from the photographs and a spectrophotometer. The same dental laboratory fabricated all 40 restorations. At the cementation appointment, clinical criteria were used to evaluate anatomy/contour, surface texture, and the amount of glaze as it relates to color perception before the restoration was cemented. RESULTS: The mean E* between the reference tooth before preparation and the crown before cementation in the visual assessment group was 10.49 (+/- 14.6), whereas the mean E* in the photocolorimetric group was 8.99 (+/- 5.7). Analysis of data showed that the observers and the colorimetric technique were perfect (E* = 0) 41% of the time and varied (E* = 0.1 or higher) 59% of the time. Data collected further showed no significant difference or correlation between shade selection methods and the evaluated clinical criteria. CONCLUSIONS: These results provide evidence that there is no significant difference in shade selection using the conventional visual assessment by two experienced clinicians or the photocolorimetric technique. CLINICAL SIGNIFICANCE: The use of photocolorimetric analysis in shade selection can serve as a reliable alternative to conventional visual shade selection. This method is useful for clinicians who have difficulty with shade selection.

Color↗
PubMed1968

The LSD syndrome. A review.

lsd (lysergic acid diethylamide) is a powerful bio-active substance related to serotonin in structure. Its actions generally affect autonomic, sensory and psychological functions. Autonomic stimulation is varied. Sensory responses are usually visual, involving heightened and distorted color perception and fusion of sensory impressions. Psychological responses include a feeling that a unique experience is occurring; feelings of depersonalization; pronounced fluctuation of mood; time and space distortions; autistic phenomena; fluctuation of aggressive drives (usually reduction); and spontaneous reoccurrence of the lsd experience. THE SUBJECTIVE RESPONSES CAN BE RELATED TO THREE BASIC PHENOMENA: (1) expectation; (2) loss of characteristic modes of perceptual and cognitive patterning; and (3) hypersuggestibility. THE MAJOR ADVERSE REACTIONS ARE: (1) chronic drug dependence including subsequent personality changes and depressive reactions; and (2) acute ego dissolution. These reactions usually occur in already emotionally ill people. Most of these users fall into two groups, those with unresolved identity problems and those with severe ego abnormality. The majority of adverse reactions are of the chronic drug dependence type and are usually seen in adolescents and young adults who have not negotiated the age-appropriate tasks of forming and integrating the various identities that are the composite of their life experiences.lsd helps alleviate these stresses via some of its psychological properties as discussed. It also provides a nidus for the formation of a subculture where goals for social, sexual and vocational achievement are lower and idiosyncratic modes of adaptation are better tolerated. A smaller group of users who have serious reactions such as psychosis, rage reactions, homicidal and suicidal ideation are usually found to have preexisting ego abnormality such as ambulatory schizophrenia, chronic impulse disorders and borderline states. Although adverse reactions most often appear to be related to pre-morbid psychopathology, this is not invariably so. Further, there is as yet no reliable method to determine who will have an adverse reaction and what the nature of that reaction will be.

Color Perception↗
PubMed1996

Visual cortical dysfunction in Alzheimer's disease evaluated with a temporally graded "stress test" during PET.

OBJECTIVE: Visual-processing abnormalities commonly contribute to typical Alzheimer's disease symptoms, but their detailed pathophysiology remains unknown. To investigate why patients with Alzheimer's disease have greater difficulty performing visuoconstructive (magnocellular-dominated) tasks than face- or color-perception (parvocellular-dominated) tasks, the authors measured brain activation in response to a temporally graded visual stimulus (neural stress test) during positron emission tomography. METHOD: The stress test measured regional cerebral blood flow (CBF) in response to a patterned flash stimulus in the resting state (0 Hz in the dark) and at frequencies of 1, 2, 4, 7, and 14 Hz. Ten patients with Alzheimer's disease and 12 age- and sex-matched comparison subjects were studied. RESULTS: The striate response at 7 Hz and 14 Hz (the degree of regional CBF increase from that at 0 Hz) was significantly less in the patients than in the comparison subjects, whereas the change in regional CBF at the lower frequencies did not differ between groups. In bilateral middle temporal association areas activated by motion and dominated by magnocellular input, regional CBF at 1 Hz (the frequency with maximal apparent motion) was significantly greater than at 0 Hz in the comparison subjects but not in the patients. CONCLUSIONS: The magnocellular visual system normally responds to high-frequency input and motion; the failure of response in the striate cortex at high but not low frequencies in the Alzheimer's patients suggests greater magnocellular than parvocellular dysfunction at these levels. Activation failure in the middle temporal areas in the patients supports magnocellular dysfunction. The finding that the Alzheimer's disease group had abnormal visual cortical function emphasizes the importance of clinical visuospatial evaluation of patients with Alzheimer's disease to fully understand symptom production and to plan interventions.

Aged↗
PubMed1976

Color perimetry.

Seven subjects were studied to determine the reproducibility of color isopters utilizing a Tubingen perimeter with targets equated for radiant energy and separate for heterochromatic flicker luminance. Achromatic threshold recognition of targets for equal luminance gave smaller isopters with longer wavelengths (red). Color recognition thresholds, on the other hand, showed large blue, midzone red and green, and small yellow isopters. The target recognition and color recognition thresholds for equal energy targets gave smaller red isopters. The data support Traquair's contention that all color isopters would be equivalent if hue, saturation, and intensity were equated. Clinically, the detection of subtle peripheral and central field defects might reside in the use of appropriately selected equally bright-colored targets.

Color Perception↗