Color Rule Research Articles

Neuronal activity related to rule and conflict in macaque supplementary eye field

Neuronal activity in macaque supplementary eye field (SEF) is enhanced during performance of the antisaccade task. This could be related to the selection of targets by a difficult rule (move to a location diametrically opposite the cue) or to conflict between the automatic tendency to look at the cue and the voluntary intention to look away. To distinguish between rule- and conflict-based mechanisms of enhancement, we monitored neuronal activity in the SEF during performance of a delayed response task in which monkeys selected saccade targets in response to peripheral visual cues. In spatial trials, the monkey had to select as target the location marked by the cue. In color trials, the monkey had to select as target the location associated with the color of the cue. ‘Color-congruent’ trials resembled spatial trials in that saccades were directed to the location occupied by the cue. Nevertheless, many SEF neurons were sensitive to the rule being used, with the majority firing more strongly under the color-rule condition. ‘Color-incongruent’ trials resembled ‘color-congruent’ trials in that a color rule guided target selection. Nevertheless, many SEF neurons were sensitive to the spatial relation between cue and saccade, with the majority firing more strongly on trials in which they were incongruent. We conclude that neuronal activity in the SEF is enhanced in connection both with the use of a more difficult rule and with conflict.

Neurons with object-centered spatial selectivity in macaque SEF: do they represent locations or rules?

In macaque monkeys performing a task that requires eye movements to the leftmost or rightmost of two dots in a horizontal array, some neurons in the supplementary eye field (SEF) fire differentially according to which side of the array is the target regardless of the array's location on the screen. We refer to these neurons as exhibiting selectivity for object-centered location. This form of selectivity might arise from involvement of the neurons in either of two processes: representing the locations of targets or representing the rules by which targets are selected. To distinguish between these possibilities, we monitored neuronal activity in the SEF of two monkeys performing a task that required the selection of targets by either an object-centered spatial rule or a color rule. On each trial, a sample array consisting of two side-by-side dots appeared; then a cue flashed on one dot; then the display vanished and a delay ensued. Next a target array consisting of two side-by-side dots appeared at an unpredictable location and another delay ensued; finally the monkey had to make an eye movement to one of the target dots. On some trials, the monkey had to select the dot on the same side as the cue (right or left). On other trials, he had to select the target of the same color as the cue (red or green). Neuronal activity robustly encoded the object-centered locations first of the cue and then of the target regardless of the whether the monkey was following a rule based on object-centered location or color. Neuronal activity was at most weakly affected by the type of rule the monkey was following (object-centered-location or color) or by the color of the cue and target (red or green). On trials involving a color rule, neuronal activity was moderately enhanced when the cue and target appeared on opposite sides of their respective arrays. We conclude that the general function of SEF neurons selective for object-centered location is to represent where the cue and target are in their respective arrays rather than to represent the rule for target selection.

Tracing a metameric match to individual variations of color vision

A metameric match made by an observer under established experimental conditions might not be the same as made by another, indicating that the color vision differs between the two observers. We have analyzed the variations of normal color vision using metameric surfaces. First, using a set of cone fundamentals, we modeled the matches of a theoretical observer with normal color vision on the Davidson & Hemmendinger (D&H) Color Rule. We also derived deviate cone fundamentals by changing the macular pigment density and the lens density, and by shifting the long-wave-sensitive photopigment along the wave-number axis. The results showed shifts in the matches for the deviate observer of no more than one sample on the D&H Color Rule, the largest shifts being due to lens density. Second, we modeled the matches made on the D&H Color Rule of 8 observers by computing their personalized cone fundamentals using their independently recorded measures of macular pigment density and lens density, and their Rayleigh matches. The results show that the use of personalized cone fundamentals provides a better prediction than the use of data from a theoretical observer. © 1998 John Wiley & Sons, Inc. Col Res Appl, 23: 379–389, 1998

Tracing a metameric match to individual variations of color vision

A metameric match made by an observer under established experimental conditions might not be the same as made by another, indicating that the color vision differs between the two observers. We have analyzed the variations of normal color vision using metameric surfaces. First, using a set of cone fundamentals, we modeled the matches of a theoretical observer with normal color vision on the Davidson & Hemmendinger (D&H) Color Rule. We also derived deviate cone fundamentals by changing the macular pigment density and the lens density, and by shifting the long-wave-sensitive photopigment along the wave-number axis. The results showed shifts in the matches for the deviate observer of no more than one sample on the D&H Color Rule, the largest shifts being due to lens density. Second, we modeled the matches made on the D&H Color Rule of 8 observers by computing their personalized cone fundamen- tals using their independently recorded measures of macu- lar pigment density and lens density, and their Rayleigh matches. The results show that the use of personalized cone fundamentals provides a better prediction than the use of data from a theoretical observer. © 1998 John Wiley & Sons, Inc. Col Res Appl, 23, 379 -389, 1998

Poly-amino-enolates: First examples of odd alternant conducting polymers

The molecular and electronic structure of a series of poly-amino-enolates is calculated ab initio within the density functional formalism using Car-Parinello molecular dynamics. Within this series, the bandgap is found to vary from 1 to 6.5 eV and the valence band is found to consist entirely of non-bonding orbitals. Both these features are essentially reproduced by a simple Hückel model. By variation of the Hückel parameters the important factors which determine the bandgap are identified. Hückel analysis furthermore demonstrates that the poly-amino-enolates are first examples of odd alternant conjugated polymers which allows the effects of the hetero atom substitution to be rationalised in terms of Dewar's colour rules for odd alternant systems.

Structural characteristics and stellar composition of low surface brightness disk galaxies

We present UBVI surface photometry of a sample of low surface brightness (LSB) disk galaxies. LSB disk galaxies are fairly well described as exponential disks with no preferred value for either scale length, central surface brightness, or rotational velocity. Indeed, the distribution of scale lengths is indistinguishable from that of high surface brightness spirals, indicating that dynamically similar galaxies (e.g., those with comparable Rv^2) exist over a large range in surface density. These LSB galaxies are strikingly blue. The complete lack of correlation between central surface brightness and color rules out any fading scenario. Similarly, the oxygen abundances inferred from HII region spectra are uncorrelated with color so the low metallicities are not the primary cause of the blue colors. While these are difficult to interpret in the absence of significant star formation, the most plausible scenario is a stellar population with a young mean age stemming from late formation and subsequent slow evolution. These properties suggest that LSB disks formed from low initial overdensities with correspondingly late collapse times.

Concepts to design dyes in spectral sensitization

Dyes having desired light absorption can be designed on the basis of five simple, generally valid colour rules within the framework of the triad theory. To engineer dyes having desired relative positions of their frontier molecular orbital (FMO) energies, perturbational molecular orbital (PMO) theory proves to be useful provided that ideal polymethinic fragments are taken as basic structures to be perturbed instead of the hitherto used hydrocarbons or hydrocarbon ions.

Colors Do Look Different after a Lens Implant!

The author describes how colors of some familiar objects and scenes shifted when viewed with one of his eyes after a lens implant, compared to the other eye without implant. Estimates of the shifts are described with common color names. Some of the shifts were spectacular. Variations in the spectral transmission of the lens are believed responsible for the shifts. Implications affecting the choice of colors for interiors, fashions and other design uses are discussed. Appendices contain observations on additional colors and data for matches on the Glenn and D & H Color Rules.

Colour and constitution: linear free energy relationships and/or polymethinic colour rules?

Model considerations of 1-donor-4-acceptor-substituted butadienes and benzenes, of 4-, and 5-substituted models of 2-nitroanilines, and of nitro-substituted methylene blue show that triad theory and its polymethinic colour rules reveal of physico-chemical background of LFERs as well as their limitations whereas, on the other hand, polymethinic colour rules can be quantified, and exceptions can be explained, by using results of LFERs.

Colors do look different after a lens implant!

AbstractThis note describes how colors of some familiar objects and scenes shift when viewed with one of the author's eyes after a lens implant compared to the other eye without implant. Estimates of the shifts are described with common color names. Some shifts were found to be spectacular! Variations in the spectral transmission of the lens is believed to explain the shifts. Implications affecting the choice of clors for interiors, fashions, and other design uses are discussed. An appendix contains data on matches on the Glenn and D & H Color Rules.

A rapid method to assess crystalline lens pigment density in vivo.

A procedure for rapidly estimating lens pigment density, based upon metameric matches on the D & H Color Rule, is described. A computational nomograph to convert settings to lens densities is provided. This procedure was validated in a sample 126 normal observers, and shown to produce data comparable to more complex laboratory testing procedures. The speed and simplicity of this procedure suggest that it may be useful for monitoring changes in lens pigment density in groups exposed to high levels of environmental, laboratory or industrial ultraviolet light.

Comparison of methods for assessing observer metamerism

AbstractStudies on observer metamerism reported so far are classified into two series. One is studies based on the color‐matching functions of Stiles's 20 observers. The other is experimental studies by using the Davidson and Hemmendinger (D‐H) Color Rule and color‐normal actual observers. The large discrepancy of the degree of observer metamerism between the above two series of studies was analyzed by using the color‐matching functions of Stiles's 20 observers and the D–H Color Rule. The results confirmed that the discrepancy in the observer‐metamerism indices was caused by different computational procedures used for deriving the indices.

The Color Rule: A Device for Color‐Vision Testing

AbstractThe D & H Color Rule, available since 1967, is useful as a color‐vision test and to check on the specification of secondary standard illuminants. The data of several authors are combined for ready availability as a diagnostic aid. Normal trichromats make responses with the Color Rule that are dependent on age. The apparent yellowing of the lens results in the same change in responses on the Color Rule as by an illuminant change of 50–75 MK−1.

Cool white, Ultralume, and Vita-Lite fluorescent lamps for use in color vision testing.

Thirty-one normal and 20 color vision-deficient persons were tested with the Hardy-Rand-Rittler (HRR) Pseudoisochromatic Plates, Farnsworth's D-15 and 100-Hue tests, and the Davidson & Hemmendinger (D & H) Color Rule using Vita-Lite, Ultralume, and Cool White fluorescent lamps to determine their usefulness for color vision measurement. The persons with deficient color vision were classified with a Nagel anomaloscope. The Macbeth Easel lamp was the reference for determining relative lamp performance. No normal was misclassified with any of the lamps. Scores with the Vita-Lite lamp were qualitatively and quantitatively most similar to those with the Macbeth lamp. The Ultralume gave intermediate results, and the Cool White was the least satisfactory substitute. Norms for the metameric D & H Color Rule for each lamp were different, which prevented intercomparisons. Best separation of the scores of deficient from normal persons with the D & H Rule occurred with the Macbeth and Vita-Lite lamps. Better performance with the Vita-Lite and Ultralume lamps can be expected from protans with the HRR and 100-Hue Tests and poorer performances from deutans on the HRR tests than with the standard Macbeth Lamp. The Cool White lamp was judged an unsuitable substitute for color vision testing.

Screening optometric patients by questionnaire: methods of improving response.

Mailed questionnaires are a quick and cheap means of obtaining data, but they have two disadvantages. They often produce low response rates irrespective of the nature of the group sampled, and they may seem inappropriate for clinical samples with visual problems. High response rates are needed for reliable results and valid conclusions. This paper presents a set of techniques enabling high response rates to be obtained. It also reports research showing that such techniques are appropriate even for the partially sighted.

Algorithmic Aspects of Plan Generation and Enumeration

Plans composed from elements of rectangular grids are considered. A general approach towards the generation and enumeration of nonequivalent plans is presented. It is shown that for these plans there is a minimum colouring which permits easy detection of isomorphs without the need for external storage devices. The notions of threading patterns and colour rules are introduced. Four specific algorithms for different types of plans involving rectangular elements are developed.

The Davidson and Hemmendinger Color Rule as a Color Vision Screening Test

The Davidson and Hemmendinger (DH) color rule was evaluated for color vision screening of normal and congenital color-defective subjects. Ninety-eight normal and 14 color-defective subjects were tested on the color rule under Macbeth illumination of 5,400 K. The color-defective subjects were also tested on the Nagel anomaloscope, the Farnsworth D-15, and the H-R-R pseudoisochromatic plates. The DH color rule performed as accurately as the anomaloscope and was superior to the other two tests in detecting anomalous trichromats and in discriminating protanomalous subjects. The color rule also discriminated dichromats from anomalous trichromats. For severe color-defective subjects (dichromats, achromats), the color rule was more time-consuming than the other tests and discrimination was less certain. Response patterns on the DH color rule and response variability of the different classifications are reported.

Use of blood typing to confirm principles of coat-color genetics in horses.

The chestnut rule in equine coat-color genetics asserts that the inter se mating of chestnut horses never produces bay, black, brown or gray offspring. The gray rule asserts that a gray offspring must have at least one gray parent. Nine alleged exceptions to the chestnut rule, all involving bay offspring, and eight alleged exceptions to the gray rule, including four offspring that were also exceptions to the chestnut rule, were examined for parent-offspring genetic incompatibilities in as many as 17 genetic systems of blood-group markers. In all except one of the 17 cases it was possible to show that parentage had been incorrectly assigned. In 9 of the 16 exclusions it was possible to exclude the stallion irrespective of the mare and in one of the 16 exclusions it was possible to exclude the mare irrespective of the stallion. The percentage of exclusions, i.e., 94, was closely in line with expectation based on the established efficacy of these tests, about 90 percent, in excluding the incorrect stallion or stallions in paternity cases. Although the results strongly uphold the validity of the chestnut and gray rules in equine coat-color inheritance, they do not completely exclude the possibility that there could be rare exceptions to one or the other or both color rules. Insofar as equine registries may be concerned, the results clearly indicate that no alleged exception to the color rules should be considered eligible for registry in the absence of these tests.

Conditional Concept Learning and Cognitive Style

It was predicted that (a) Ss with an analytic cognitive style would out-perform Ss with a global cognitive style on compound-cue problems which could be learned by either a conditional rule or a color rule, and (b) global and analytic Ss would perform equally on a single-cue problem which could be solved only by a conditional rule. 36 analytic and 36 global Ss learned one of the two problems. Analysis showed that analytic Ss performed significantly better than global Ss only on the compound-cue problem. The results suggested that the better performance of analytic Ss is limited to problems which require some degree of stimulus differentiation. It was further suggested that additional research on hypothesis-testing might help clarify the differences in performance between analytic and global Ss.

Metameric ‘Color Rule’ matches of normal, colour deficient, cataractic, and aphakic observers

SUMMARYMetameric matches on the ‘color rule’ under various kinds of illumination, principally of colour temperature 6500°K and 2400°k, were established for colour normal people of both sexes, various ages and ethnic origin. The matches shift in a way which is explicable by the yellow discoloration of the lens and possibly other optic media, with age and general pigmentation.Individuals defective in colour perception differ ‐ as a group ‐ from normal people not only in the position of the average match co‐ordinates, but mostly also in a wider tolerance of accepted matches. By combining average match with tolerance area a useful criterion can be shown to exist for discriminating between normal, protanomalous and deuteranomalous people and to a lesser extent between the two principal classes of dichromats. Similar distinctions can be derived by inspecting the orientation and position of tolerance areas, which for red‐green defects are diagonally oriented but in one tritan defective appeared horizontal.The versatility, cheapness and convenience of the ‘color rule’ for colour vision studies in the field is pointed out.