Luminance and color effects on localization of briefly flashed visual stimuli

1996 ◽  
Vol 13 (3) ◽  
pp. 567-573 ◽  
Author(s):  
Roger E. Graves
Keyword(s):  
Visual Stimuli ◽  
High Sensitivity ◽  
Luminance Contrast ◽  
Stimulus Size ◽  
Color Contrast ◽  
Visual Localization ◽  
Magnocellular Pathway ◽  
Localization Task ◽  
Parvocellular System ◽  
Green Background

AbstractVisual localization was studied by flashing small stimuli on a green background and requiring observers to press keys to indicate whether the stimulus appeared to the left or right of fixation. The results suggest that, for small (0.25 deg) briefly flashed (17 ms) stimuli at an eccentric location (10 deg), color contrast is not useable and localization presumably must rely on the magnocellular pathway. When stimulus size and duration were increased at 10-deg eccentricity, isochromatic stimuli could be localized at less than 10% luminance contrast (again suggesting use of the magnocellular high sensitivity luminance-contrast system), but isoluminant color-contrast stimuli could also be localized (suggesting use of the color-contrast sensitive parvocellular system). Thus, the results indicate that, dependent on stimulus conditions, both magnocellular and parvocellular pathways were utilized by normal observers in this localization task.

Occurrence of express saccades under isoluminance and low contrast luminance conditions

1991 ◽  
Vol 7 (5) ◽  
pp. 505-510 ◽  
Author(s):  
Heike Weber ◽  
Burkhart Fischer ◽  
Michael Bach ◽  
Franz Aiple
Keyword(s):  
Human Subjects ◽  
Reaction Times ◽  
Luminance Contrast ◽  
Saccade Target ◽  
White Background ◽  
Color Contrast ◽  
Express Saccades ◽  
Low Contrast ◽  
Green Background ◽  
White Target

AbstractSaccadic reaction times (SRTs) of three human subjects were analyzed. The gap paradigm was used (i.e. fixation point offset precedes target onset) to obtain high proportions of express saccades (i.e. saccades of extremely short reaction times) in the SRT distributions. In one set of experiments, the luminance of the (red) saccade target was varied from brighter to darker than the (green) background including an isoluminance condition. Express saccades were obtained in response to pure color contrast stimuli with about the same frequency and reaction time as to stimuli with both color and luminance contrast. In a second experiment, the luminance contrast of a white target on a white background was lowered below 10%. Again the number of express saccades was not reduced. Thus, in contrast to other perceptual phenomena the visual neural mechanisms underlying the generation of express saccades are not affected by isoluminance nor low contrast luminance.

Color stimuli perception in presence of light scattering

2006 ◽  
Vol 23 (3-4) ◽  
pp. 597-601 ◽  
Author(s):  
MARIS OZOLINSH ◽  
MICHÉLE COLOMB ◽  
GATIS IKAUNIEKS ◽  
VARIS KARITANS
Keyword(s):  
Visual Acuity ◽  
Light Scattering ◽  
Luminance Contrast ◽  
White Background ◽  
Color Contrast ◽  
Entire Area ◽  
Red Color ◽  
Blue Component ◽  
Different Color ◽  
Landolt C

Perception of different color contrast stimuli was studied in the presence of light scattering: in a fog chamber in Clermont-Ferrand and in laboratory conditions where light scattering of similar levels was obtained, using different light scattering eye occluders. Blue (shortest wavelength) light is scattered in fog to the greatest extent, causing deterioration of vision quality especially for the monochromatic blue stimuli. However, for the color stimuli presented on a white background, visual acuity in fog for blue Landolt-C optotypes was higher than for red and green optotypes on the white background. The luminance of color Landolt-C optotypes presented on a LCD screen was chosen corresponding to the blue, green, and red color contributions in achromatic white stimuli (computer digital R, G, or B values for chromatic stimuli equal to RGB values in the achromatic white background) that results in the greatest luminance contrast for the white–blue stimuli, thus advancing the visual acuity for the white-blue stimuli. Besides such blue stimuli on the white background are displayed with a uniform, spatially unmodulated distribution of the screen blue phosphor emission over the entire area of the screen including the stimulus C optotype area. It follows that scattering, which has the greatest effect on the blue component of screen luminance, has the least effect on the perception of white–blue stimuli.

Enhancing the Mobile User Experience Through Colored Contrasts

2019 ◽  
pp. 863-876
Author(s):  
Jean-Éric Pelet ◽  
Basma Taieb
Keyword(s):  
Behavioral Intentions ◽  
Negative Contrast ◽  
Positive Contrast ◽  
Mobile User ◽  
Structural Equations ◽  
Color Contrast ◽  
Affective States ◽  
Positive Effects ◽  
Green Background ◽  
Managerial Implications

This chapter examines the effects of the mobile-phone website colored contrasts and the affective states of the consumer (emotions and moods) and trust, respectively, on intention to revisit, buy on, and recommend the mobile website. For this purpose, a factorial plan 2x2 was developed, and a mobile website, with two different alternatives, was designed especially for the experiment: positive contrast (yellow text on green background) and negative contrast (green text on yellow background). The research was conducted on French consumers. Three-hundred twelve valid responses were collected through online and personal survey questionnaires. Data was analysed using the method of structural equations. The results show the significant effects of mobile website's color contrast on behavioral intentions. Perceived dominance and trust towards the website have positive effects on behavioral intentions, whereas mood has non-significant effects on behavioral intentions. Managerial implications are discussed.

Enhancing the Mobile User Experience Through Colored Contrasts

2018 ◽  
pp. 6070-6082
Author(s):  
Jean-Éric Pelet ◽  
Basma Taieb
Keyword(s):  
Behavioral Intentions ◽  
Negative Contrast ◽  
Positive Contrast ◽  
Mobile User ◽  
Structural Equations ◽  
Color Contrast ◽  
Affective States ◽  
Positive Effects ◽  
Green Background ◽  
Managerial Implications

This study examines the effects of the mobile-phone website colored contrasts and the affective states of the consumer (emotions and moods) and trust respectively on intention to revisit, buy on and recommend the mobile website. For this purpose, a factorial plan 2x2 was developed and a mobile website, with two different alternatives, was designed especially for the experiment: positive contrast (yellow text on green background) and negative contrast (green text on yellow background). The research was conducted on French consumers. 312 valid responses were collected through online and personal survey questionnaires. Data was analysed using the method of structural equations. The results show the significant effects of mobile website's color contrast on behavioral intentions. Perceived dominance and trust towards the website have positive effects on behavioral intentions, whereas mood has non-significant effects on behavioral intentions. Managerial implications are discussed.

scholarly journals The relation of phase noise and luminance contrast to overt attention in complex visual stimuli

2006 ◽  
Vol 6 (11) ◽  
pp. 1-1 ◽  
Author(s):  
W. Einhauser ◽  
U. Rutishauser ◽  
E. P. Frady ◽  
S. Nadler ◽  
P. Konig ◽  
...  
Keyword(s):  
Phase Noise ◽  
Visual Stimuli ◽  
Luminance Contrast ◽  
Overt Attention

Visual Evoked Potentials Under Luminance Contrast and Color Contrast Stimulation in Glaucoma Diagnosis

2000 ◽  
Vol 9 (6) ◽  
pp. 428-437 ◽  
Author(s):  
Folkert K. Horn ◽  
Antonio Bergua ◽  
Anselm Jünemann ◽  
Matthias Korth
Keyword(s):  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Luminance Contrast ◽  
Color Contrast ◽  
Glaucoma Diagnosis ◽  
Visual Evoked

scholarly journals Sensitivitas dan Spesifisitas Metode KOH 20% + Tinta Parker Blue Black Dibandingkan dengan KOH 20% pada Dermatomikosis Superfisialis

2020 ◽  
Vol 9 (2) ◽  
pp. 218
Author(s):  
Firda Ulfa Ramadhani ◽  
Diana Tri Ratnasari Ratnasari ◽  
Masfufatun Masfufatun
Keyword(s):  
Sensitivity And Specificity ◽  
High Sensitivity ◽  
Rapid Diagnosis ◽  
Color Contrast ◽  
Research Subjects ◽  
Cross Sectional ◽  
Routine Diagnosis ◽  
Fungal Element ◽  
Cross Sectional Design ◽  
The Right

Superficial dermatomycosis is a fungal infection of the skin, nail and hair. Based on the pathogen, this infection can be divided into dermatophytosis, phytiriasis versicolor and candidiasis. The rapid diagnosis for this infection is the key point to deliver the right theraphy. The supporting investigation for this infection can be performed directly using KOH. The KOH 20% solution has an indistict color contrast, that cause the fungal element seemed transparent. The observant expertise would be required for this case. The alternative method to enhance sensitivity and specificity of KOH is to add dyes such as Blue Black parker ink. The objectives of this research was to observe the sensitivity and specificity of KOH 20% + blue black parker ink in comparisson with KOH 20% method in superficial dermatomycosis. The research method was cross sectional design analitical obsevation with 30 research subjects. The samples were taken from superficial dermatomycosis lesion swabs. These samples were tested using KOH 20% solution and KOH 20% + blue black parker ink solution in Siti Khodijah Muhammadiyah Hospital, Sepanjang and dr. Makmuri Clinics, Surabaya. The results demonstrated that the sensitivity of KOH 20% solution and KOH 20% + blue black parker ink solution were 86.67% and 93.33%, respectively. The specificity of KOH 20% solution and KOH 20% + blue black parker ink solution were 100% and 100%, respectively. It can be concluded from the research that KOH 20% + blue black parker ink solution can be used for the routine diagnosis for superficial dermatomycosis due to the high sensitivity and specificity.

Achromatic luminance contrast sensitivity in X-linked color-deficient observers: An addition to the debate

2013 ◽  
Vol 31 (1) ◽  
pp. 99-103 ◽  
Author(s):  
MÁRTA JANÁKY ◽  
JUDIT BORBÉLY ◽  
GYÖRGY BENEDEK ◽  
BALÁZS PÉTER KOCSIS ◽  
GÁBOR BRAUNITZER
Keyword(s):  
Contrast Sensitivity ◽  
Dynamic Condition ◽  
Static Condition ◽  
Luminance Contrast ◽  
Dynamic Conditions ◽  
Male Volunteers ◽  
Spatial Frequencies ◽  
Parvocellular System ◽  
Lower Frequencies

AbstractIt is a matter of debate whether X-linked dichromacy is accompanied by enhanced achromatic processing. In the present study, we used sinusoidally modulated achromatic gratings under photopic conditions to compare the contrast sensitivity (CS) of protanopes, deuteranopes, and normal trichromats. 36 male volunteers were examined. CS was tested in static and dynamic conditions at nine different spatial frequencies. The results support the assumption that X-linked color-defective observers are at an advantage in terms of achromatic processing. Both protanopes and deuteranopes had significantly better CS than controls in both the static and the dynamic conditions. In the static condition, the advantage was observed especially at higher spatial frequencies, whereas in the dynamic condition, it was seen also at lower frequencies. The results are interpreted in terms of decreased chromatic modulation of the luminance channel and the early plasticity of the parvocellular system.

The effect of chromatic and luminance information on reaction times

2010 ◽  
Vol 27 (3-4) ◽  
pp. 119-129 ◽  
Author(s):  
BEATRIZ M. O’DONELL ◽  
JOSE F. BARRAZA ◽  
ELISA M. COLOMBO
Keyword(s):  
Reaction Time ◽  
Stimulus Intensity ◽  
Color Space ◽  
Reaction Times ◽  
Luminance Contrast ◽  
Stimulus Size ◽  
Square Root ◽  
Chromatic Stimulus ◽  
Cone Pathway ◽  
Series Of Experiments

AbstractWe present a series of experiments exploring the effect of chromaticity on reaction time (RT) for a variety of stimulus conditions, including chromatic and luminance contrast, luminance, and size. The chromaticity of these stimuli was varied along a series of vectors in color space that included the two chromatic-opponent-cone axes, a red–green (L–M) axis and a blue–yellow [S − (L + M)] axis, and intermediate noncardinal orientations, as well as the luminance axis (L + M). For Weber luminance contrasts above 10–20%, RTs tend to the same asymptote, irrespective of chromatic direction. At lower luminance contrast, the addition of chromatic information shortens the RT. RTs are strongly influenced by stimulus size when the chromatic stimulus is modulated along the [S − (L + M)] pathway and by stimulus size and adaptation luminance for the (L–M) pathway. RTs are independent of stimulus size for stimuli larger than 0.5 deg. Data are modeled with a modified version of Pieron’s formula with an exponent close to 2, in which the stimulus intensity term is replaced by a factor that considers the relative effects of chromatic and achromatic information, as indexed by the RMS (square-root of the cone contrast) value at isoluminance and the Weber luminance contrast, respectively. The parameters of the model reveal how RT is linked to stimulus size, chromatic channels, and adaptation luminance and how they can be interpreted in terms of two chromatic mechanisms. This equation predicts that, for isoluminance, RTs for a stimulus lying on the S-cone pathway are higher than those for a stimulus lying on the L–M-cone pathway, for a given RMS cone contrast. The equation also predicts an asymptotic trend to the RT for an achromatic stimulus when the luminance contrast is sufficiently large.

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