Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
85 Cards in this Set
- Front
- Back
In method of limits testing the examiner
|
Manipulates the stimulus – either ascending or descending
|
|
In method of adjustment the subject
|
Manipulates the stimulus to match a standard
|
|
In method of constant stimuli the subject responds to
|
Independent measure – most accurate – a psychometric function is constructed – 50%response level – response independent
|
|
Scaling methods are used to determine the
|
Intensity of the sensation experienced by the subject
|
|
In direct scaling the subject
|
Assigns appropriate numbers to a series of stimuli according to the subjective impressions
|
|
Indirect scaling is broken down into
|
Comparative judgment and Categorical judgment
|
|
The four basic measurement scales are
|
1) nominal 2) ordinal 3) interval 4) ratio
|
|
Probability of correctly identifying a + = (sensitivity)
|
TP / (TP + FN) = hit rate
|
|
Probability of correctly identifying a – = (specificity)
|
TN / (TN + FP) =
|
|
|
|
|
Positive predictive value =
|
TP/ (TP +FP) probability that if labeled + is in fact +
|
|
Negative predictive value =
|
TN / (TN + FN) probability that if labeled – is in fact –
|
|
|
|
|
3 variables to describe color
|
1) hue 2) saturation 3) brightness
|
|
Hue is correlated with the
|
Wavelength of the light – photometric equivalent is dominant wavelength
|
|
Hue is best detected at
|
Blue green (490nm) and yellow red (590nm)
|
|
Saturation is a measures of the degree to which the
|
Stimulus is mixed with white – photometric equivalent is purity
|
|
Brightness is the
|
Luminosity of the color – photometric equivalent is luminance
|
|
Abney effect refers to
|
A change in hue associated with a change in purity (saturation)
|
|
Benzold Brucke effect refers to
|
A change in hue associated with a change in luminance - stimuli below 500nm look more blue with increased intensity- stimuli above 500nm look more yellow with increased intensity
|
|
Purdy effect is a
|
Change in saturation with a change in luminance
|
|
Best color discrimination for normals is
|
At 480-490nm (blue green) and 580nm (yellow)
|
|
For dicromats the best discrimination is at the ProtanopesDeuteranopesTritanopes
|
Neutral point 490nm495nm570nm
|
|
Additive primary colors are
|
Red, green, blue (yellow is a psychological primary)
|
|
Complementary colors when mixed produce
|
White or gray -
|
|
Additive color mixtures are a
|
Superimposition of 2 or more lights to produce a color
|
|
Metameric colors are colors that
|
Match in appearance but are composed of different wavelength mixtures
|
|
Simultaneous color contrast refers to the change in
|
The appearance of an object with a change in the surround color
|
|
Successive color contrast refers to a
|
Negative afterimage being the color of the complementary color
|
|
Color contingent aftereffects are due to
|
Fatigue/ adaptation of he system
|
|
The McCollough effect refers to an adaptation to
|
Orientation and color
|
|
Color constancy refers to the fact that
|
Relative colors remain constant with changes in luminance
|
|
Tristimulus values are the
|
Boundaries of visible spectrum (380-760nm)
|
|
Munsell color system attempts to have the
|
Notation correspond to the sensory experience
|
|
Munsell hues are located around a circle numbered
|
1-10 – there are 10 major hues and 100 total hues
|
|
The Munsell “value” refers to
|
Lightness and is along the vertical axis
|
|
The Munsell “chroma” refers to
|
Whiteness and is represented by a horizontal line from the center of the circle – scale form 0 to a maximum
|
|
The Munsell notation is given in
|
H/V/C hue/value/chroma
|
|
MacAdams ellipses are perceptual areas in the CIE diagram where
|
All colors will appear the same – even if physically different
|
|
Cones have the greatest sensitivity at
|
555nm (green/yellow)
|
|
Rods have the greatest sensitivity at
|
505nm (blue/green)
|
|
Anomalous trichromats Deuteranomaly ProtanomalyTritanomaly
|
Require 3 primary colors to create a match Most common of all deficiencies – requires more green to match color mixtures – M cones are mutated (535nm)Requires more red to match color mixtures – L cone defectiveRequires more blue to match color mixtures – S cone defective
|
|
Dichromats Protanope Deuteranope Tritanope
|
Require 2 primary colors to make a match Missing erythrolabe – confuse red with any other color and B-G with white – best color discrimination for 492nm (blue green) – cannot discriminate at long wavelengthsMissing chlorolabe – confuse green with white – nearly normal photopic spectral sensitivity – discriminate best for 498nm (greener blue green) Missing cyanolabe – confuse yellow with white – normal photopic spectral sensitivity – best discrimination for 570nm (yellow green)
|
|
Rayleigh equation is the ratio of
|
Red to green needed to match yellow in an anomaloscope
|
|
Protanomalous trichromats will have one ratio but will
|
Require more red than normal
|
|
Deuteranomalous trihromats will have one ratio but
|
Require more green than normal
|
|
Protanopia causes a px to require
|
Less luminance of yellow to match brightness of pure red
|
|
Deuteranopia requires equal
|
Luminance to match yellow with pure red or green
|
|
Kollner’s rule Diseases of retina and ocular mediaDiseases of the ON and visual pathway
|
Applies to acquired color vision defects Blue yellow defectRed green defects
|
|
Brightness can be predicted by
|
The activity of non opponent cells
|
|
Hue can be predicted by
|
The activity of opponent cells
|
|
Saturation can be predicted by
|
The ratio of opponent to non opponent cells
|
|
Oculocentric localization references objects in space to
|
The entrance pupil of the observing eye (monocular)
|
|
Every point on the retina has a visual direction
|
Associated with it = local sign
|
|
Primary visual direction is the
|
Local sign associated with the fovea
|
|
Secondary visual directions are associated with
|
All other retinal elements – are relative to the primary visual dir
|
|
Oculocentric visual direction refers to the fact that
|
Secondary visual direction is always relative to the primary visual direction
|
|
In egocentric localization direction is in reference to
|
The cyclopean eye – occurs at the cortical level – requires the input of two oculocentric locatozations – binocular
|
|
Around a horoptor, binocular disparity is
|
Zero
|
|
Geometric effect occurs with magnification in the
|
Horizontal meridian (X90) – floor slants down and toward magnified eye – facing wall is skewed away from eye
|
|
Induced effect occurs with magnification in the
|
Vertical meridian (X180) – floor slants up and away from the magnified eye – facing wall is skewed toward the eye
|
|
Visually guided behavior is controlled by the
|
Superior colliculus
|
|
Minimum visual acuity determines the
|
Presence or absence of a target – rod function
|
|
Resolution refers to a
|
Response to separation between elements of a pattern
|
|
Recognition requires
|
Naming of the test object or a critical aspect of it
|
|
Contrast =
|
(Target luminance – background) / background luminance
|
|
Contrast =
|
(Lmax- Lmin) / (Lmax + Lmin)
|
|
In an Ames room the
|
Perceived distance is constant but retinal image size varies
|
|
Mueller Lyer illusion refers to
|
Lines of same length appearing unequal due to arrow heads
|
|
|
|
|
Weber’s law states that
|
The higher the background, the higher the change in stimulus necessary for the detection of an absolute difference
|
|
DeVries-Rose Law predicts the
|
Ideal threshold of a stimulus upon a background
|
|
Ricco’s law deals with
|
Spatial summation – better in scotopic system
|
|
Block’s law deals with
|
Temporal summation – better in photopic system
|
|
The critical duration for temporal summation is
|
100msec for rods; 10-15msec for cones
|
|
Korte’s law summarizes the optimum stimulus
|
For apparent motion
|
|
Alpha motion is a type of apparent motion where there
|
Is apparent expansion and ceontration – 2nd target is larger
|
|
Gamma motion is a type of apparent motion where
|
The second target is brighter
|
|
Sigma motion occurs when the target is constantly on
|
The fovea
|
|
Stroboscopic movement (Phi phenomena) is where the
|
Presentation of stationary stimuli gives rise to apparent motion
|
|
Brucke-Bartley effect refers to a
|
Flickering light looking brighter than a steady light
|
|
Granit Harper law refers to the fact that as the
|
Size of a CFF stimulus increases the CFF becomes higher
|
|
Ferry Porter law states that the
|
CFF is directly proportional to the log of the stimulus intensity
|
|
Backward masking aka metacontrast is when the
|
Mask stimulus is presented immediately after the test stimulus
|
|
Forward masking aka paracontrast occurs when the
|
Mask precedes the stimulus
|