Declines in Wavelength Discrimination and Shifts in Unique Hue with Hypoxia

INTRODUCTION: Hypoxia can be a problem for warfighters, compromising visual and cognitive performance. One area of study has been hypoxia-induced decrements in color vision.METHODS: The present study examined how hypoxia affected the perception of wavelengths associated with unique green and with unique yellow as well as discriminability by the blue vs. yellow (b-y) and the red vs. green (r-g) spectrally opponent color channels while breathing O2 levels found at sea level and at 5500 m. Measurements of wavelengths producing unique green (minimizing response by the b-y channel) and unique yellow (minimizing response by the r-g channel) preceded measurements of wavelength discriminability near those unique hues.RESULTS: Relative to sea level, unique yellow shifted to shorter wavelengths (0.54 nm) and unique green shifted to longer wavelengths (2.3 nm) under hypoxia. In terms of an equal psychophysical scale, both unique hues shifted by similar magnitudes. Wavelength discriminability of both color channels was compromised by statistically reliable amounts of 16–17% under hypoxia.DISCUSSION: These results were consistent with previous studies and the inference that postreceptor, M-cone neurons were differentially compromised by hypoxia. However, these measurable changes in color vision due to hypoxia were not perceived by the subjects.Bierman A, LaPlumm T, Rea MS. Declines in wavelength discrimination and shifts in unique hue with hypoxia. Aerosp Med Hum Perform. 2020; 91(5):394–402.

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A new transformation of cone responses to opponent color responses

Attention Perception & Psychophysics ◽

10.3758/s13414-020-02216-7 ◽

2021 ◽

Author(s):

Ralph W. Pridmore

Keyword(s):

Comparative Analysis ◽

Color Vision ◽

Lateral Geniculate Nucleus ◽

Literature Search ◽

The Other ◽

Response Curves ◽

Lateral Geniculate ◽

Opponent Color ◽

Cardinal Directions ◽

Unique Hues

AbstractIt is widely agreed that the color vision process moves quickly from cone receptors to opponent color cells in the retina and lateral geniculate nucleus. Many workers have proposed the transformation or coding of long, medium, short (LMS) cone responses to r − g, y − b opponent color chromatic responses (unique hues) on the following basis: That L, M, S cones represent Red, Green, and Blue hues, with Yellow represented by (L + M), while r − g and y − b represent the opponent pairs of unique hues. The traditional coding from cones to opponent colors is that L − M gives r − g, while (L + M) − S gives y − b. This convention is open to several criticisms, and a new coding is required. A literature search produced 16 studies of cone responses LMS and 15 studies of spectral (i.e., ygb) opponent color chromatic responses, in terms of response wavelength peaks. Comparative analysis of the two sets of studies shows the means are almost identical (within 3 nm; i.e., L = y, M = g, S = b). Further, the response curves of LMS are very similar shapes to ygb. In sum, each set can directly transform to the other on this proposed coding: (S + L) − M gives r − g, while L − S gives y − b. This coding activates neural operations in the cardinal directions r − g and y − b.

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The Impact of Environmental Stress on Cognitive Performance: A Systematic Review

Human Factors The Journal of the Human Factors and Ergonomics Society ◽

10.1177/0018720819839817 ◽

2019 ◽

Vol 61 (8) ◽

pp. 1205-1246 ◽

Cited By ~ 14

Author(s):

Kristy Martin ◽

Emily McLeod ◽

Julien Périard ◽

Ben Rattray ◽

Richard Keegan ◽

...

Keyword(s):

Systematic Review ◽

Environmental Stress ◽

Task Performance ◽

Sea Level ◽

Cognitive Performance ◽

Cognitive Task ◽

Individual Characteristics ◽

Eligibility Criteria ◽

Healthy Human ◽

The Impact

Objective: In this review, we detail the impact of environmental stress on cognitive and military task performance and highlight any individual characteristics or interventions which may mitigate any negative effect. Background: Military personnel are often deployed in regions markedly different from their own, experiencing hot days, cold nights, and trips both above and below sea level. In spite of these stressors, high-level cognitive and operational performance must be maintained. Method: A systematic review of the electronic databases Medline (PubMed), EMBASE (Scopus), PsycINFO, and Web of Science was conducted from inception up to September 2018. Eligibility criteria included a healthy human cohort, an outcome of cognition or military task performance and assessment of an environmental condition. Results: The search returned 113,850 records, of which 124 were included in the systematic review. Thirty-one studies examined the impact of heat stress on cognition; 20 of cold stress; 59 of altitude exposure; and 18 of being below sea level. Conclusion: The severity and duration of exposure to the environmental stressor affects the degree to which cognitive performance can be impaired, as does the complexity of the cognitive task and the skill or familiarity of the individual performing the task. Application: Strategies to improve cognitive performance in extreme environmental conditions should focus on reducing the magnitude of the physiological and perceptual disturbance caused by the stressor. Strategies may include acclimatization and habituation, being well skilled on the task, and reducing sensations of thermal stress with approaches such as head and neck cooling.

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

Visual Neuroscience ◽

10.1017/s0952523806233182 ◽

2006 ◽

Vol 23 (3-4) ◽

pp. 331-339 ◽

Cited By ~ 55

Author(s):

DAVID L. PHILIPONA ◽

J. KEVIN O'REGAN

Keyword(s):

Color Naming ◽

Surface Reflection ◽

Unique Hues ◽

Neuronal Representation ◽

Underlying Mechanisms ◽

The One ◽

Unique Green ◽

Psychophysical Studies ◽

Hue Cancellation

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.

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Variations in normal color vision II Unique hues

Journal of the Optical Society of America A ◽

10.1364/josaa.17.001545 ◽

2000 ◽

Vol 17 (9) ◽

pp. 1545 ◽

Cited By ~ 119

Author(s):

Michael A. Webster ◽

Eriko Miyahara ◽

Gokhan Malkoc ◽

Vincent E. Raker

Keyword(s):

Color Vision ◽

Normal Color Vision ◽

Unique Hues

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Signals for color and achromatic contrast in the goldfish inner retina

Visual Neuroscience ◽

10.1017/s0952523814000157 ◽

2014 ◽

Vol 31 (6) ◽

pp. 365-371 ◽

Cited By ~ 2

Author(s):

DWIGHT A. BURKHARDT

Keyword(s):

Color Vision ◽

Field Potential ◽

Color Contrast ◽

Natural Environments ◽

Color Coding ◽

Response Curves ◽

Inner Retina ◽

Opponent Color ◽

Achromatic Contrast ◽

Goldfish Retina

AbstractA moving stimulus paradigm was designed to investigate color contrast encoding in the retina. Recently, this paradigm yielded suggestive evidence for color contrast encoding in zebrafish but the significance and generality remain uncertain since the properties of color coding in the zebrafish inner retina are largely unknown. Here, the question of color contrast is pursued in the goldfish retina where there is much accumulated evidence for retinal mechanisms of color vision and opponent color-coding, in particular. Recordings of a sensitive local field potential of the inner retina, the proximal negative response, were made in the intact, superfused retina in the light-adapted state. Responses to color contrast and achromatic contrast were analyzed by comparing responses to a green moving bar on green versus red backgrounds. The quantitative form of the irradiance/response curves was distinctly different under a range of conditions in 32 retinas, thereby providing robust evidence for red–green color contrast. The color contrast is based on successive contrast, occurs in the absence of overt color opponency, and clearly differs from previous findings in the goldfish retina for simultaneous color contrast mediated by color-opponent neurons. The form of the irradiance/response curves suggests that successive color contrast is particularly important when achromatic contrast is low, as often occurs in natural environments. The present results provide a parallel with the well-known principle of human color vision, first proposed by Kirschmann as the third law of color contrast, and may also have implications for the evolution of vertebrate color vision.

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Variations in normal color vision. V. Simulations of adaptation to natural color environments

Visual Neuroscience ◽

10.1017/s0952523808080942 ◽

2009 ◽

Vol 26 (1) ◽

pp. 133-145 ◽

Cited By ~ 11

Author(s):

IGOR JURICEVIC ◽

MICHAEL A. WEBSTER

Keyword(s):

Color Vision ◽

Color Perception ◽

Color Appearance ◽

Normal Color Vision ◽

Natural Color ◽

Outdoor Scenes ◽

Different Seasons ◽

Spectral Statistics ◽

Unique Hues ◽

Different Color

AbstractModern accounts of color appearance differ in whether they assume that the perceptual primaries (e.g., white and the unique hues of red, green, blue, and yellow) correspond to unique states determined by the spectral sensitivities of the observer or by the spectral statistics of the environment. We examined the interaction between observers and their environments by asking how color perception should vary if appearance depends on fixed responses in a set of color channels, when the sensitivities of these channels are adapted in plausible ways to different environments. Adaptation was modeled as gain changes in the cones and in multiple postreceptoral channels tuned to different directions in color–luminance space. Gains were adjusted so that the average channel responses were equated across two environments or for the same environment during different seasons, based on sets of natural outdoor scenes (Webster et al., 2007). Because of adaptation, even observers with a shared underlying physiology should perceive color in significantly and systematically different ways when they are exposed to and thus adapted by different contexts. These include differences in achromatic settings (owing to variations in the average chromaticity of locations) and differences in perceived hue (because of differences in scene contrasts). Modeling these changes provides a way of simulating how colors might be experienced by individuals in different color environments and provides a measure of how much color appearance might be modulated for a given observer by variations in the environment.

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The robustness of a simple dynamic model of island biodiversity to geological and eustatic change

10.1101/2021.07.26.453064 ◽

2021 ◽

Author(s):

Pedro Santos Neves ◽

Joshua W. Lambert ◽

Luis Valente ◽

Rampal S. Etienne

Keyword(s):

Sea Level ◽

Simulated Data ◽

Oceanic Islands ◽

Sea Level Changes ◽

Land Bridge ◽

Sea Level Fluctuations ◽

Continental Islands ◽

Island Biodiversity ◽

And Shifts ◽

And Sea Level

Aim: Biodiversity on islands is affected by various geo-physical processes and sea-level fluctuations. Oceanic islands (never connected to a landmass) are initially vacant with diversity accumulating via colonisation and speciation, followed by a decline as islands shrink. Continental islands have species upon formation (when disconnected from the mainland) and may have transient land-bridge connections. Theoretical predictions for the effects of these geo-processes on rates of colonisation, speciation and extinction have been proposed, but methods of phylogenetic inference assume only oceanic island scenarios without accounting for island ontogeny, sea-level changes or past landmass connections. Here, we analyse to what extent ignoring geodynamics affects the inference performance of a phylogenetic island model, DAISIE, when confronted with simulated data that violate its assumptions. Location: Simulation of oceanic and continental islands. Methods: We extend the DAISIE simulation model to include: area-dependent rates of colonisation and diversification associated with island ontogeny and sea-level fluctuations, and continental islands with biota present upon separation from the mainland, and shifts in rates to mimic temporary land-bridges. We quantify the error made when geo-processes are not accounted for by applying DAISIE's inference method to geodynamic simulations. Results: We find that the robustness of the model to dynamic island area is high (error is small) for oceanic islands and for continental islands that have been separated for a long time, suggesting that, for these island types, it is possible to obtain reliable results when ignoring geodynamics. However, for continental islands that have been recently or frequently connected, robustness of DAISIE is low, and inference results should not be trusted. Main conclusions: This study highlights that under a large proportion of island biogeographic geo-scenarios (oceanic islands and ancient continental fragments) a simple phylogenetic model ignoring geodynamics is empirically applicable and informative. However, recent connection to the continent cannot be ignored, requiring development of a new inference model.

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Biological and evolutionary responses to transgressive-regressive cycles

The Paleontological Society Special Publications ◽

10.1017/s2475262200007644 ◽

1992 ◽

Vol 6 ◽

pp. 204-204

Author(s):

George R. McGhee

Keyword(s):

Environmental Change ◽

Sea Level ◽

Evolutionary Biology ◽

Biological Response ◽

Quantitative Relationship ◽

Marine Organisms ◽

Rate Of Change ◽

Relative Sea Level ◽

Direct Function ◽

And Shifts

Transgressive-regressive cycles involve environmental change and therefore, under the predictions of the theory of natural selection, biological response is expected. The nature, magnitude, and instrumentation of that response is, however, less well understood and difficult to predict. Generally the magnitude of biological response would be expected to be a direct function of the magnitude of the environmental change produced by alterations in sea level. However, this may not be the case. Moreover, the magnitude of environmental perturbation seen may itself not be a direct function of the magnitude, range, or even rate of sea level rise or fall.Biological responses to transgressive-regressive cycles are highly variable, yet may be empirically demonstrated. Although the reality of faunal changes can be observed, the precise forcing mechanism or mechanisms driving those changes may be hypothetical at best. The observed iterative morphological series seen in shallow water Jurassic ammonites, for example, appear to be produced by a complex interplay of species adaptation to changes in local habitat and response to immigration from oceanic realms, both of which are ultimately driven by relative sea level. Likewise, changes in diversity and species composition in Devonian shallow marine communities appear to be produced by the effect of variable sedimentation rates and shifts in the oxygen minimum zone, both of which also are related to changes in relative sea level.Published onlap-offlap sequence curves, as such, may offer very little to the paleobiologist interested in the evolutionary behavior of marine organisms. Additional geographic and areal data are required if any rigorous quantitative relationship between relative sea level and evolutionary biology is to be formulated. In the Devonian, for example, it can be demonstrated that a total lack of correlation exists between the evolutionary biology of major benthic marine organisms (brachiopods) and relative sea level as projected from onlap-offlap curves. It could be hypothesized that the rate of change of sea level is more important to organisms than relative sea level itself, though most hypotheses concerning the biological effect of sea level are explicitly framed in terms of relative sea level (usually invoking the species-area effect). Again, onlap-offlap curves alone offer little in testing such a rate hypothesis, as it can also be demonstrated that no correlation exists between the derivative of the Devonian relative sea level curve and the evolutionary biology of the Brachiopoda.

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Efficacy of Dry Electroencephalography and Cognitive Assessment in Identifying Normobaric Hypoxia in Designated Aviators

Proceedings of the Human Factors and Ergonomics Society Annual Meeting ◽

10.1177/1071181319631218 ◽

2019 ◽

Vol 63 (1) ◽

pp. 59-62

Author(s):

Sabrina Drollinger ◽

Steve Linnville ◽

Jeff Phillips ◽

Dallas Snider ◽

Lee W. Sciarini

Keyword(s):

Cognitive Functioning ◽

Sea Level ◽

Cognitive Performance ◽

Cognitive Assessment ◽

Additional Research ◽

Normobaric Hypoxia ◽

Flight Performance ◽

Pilot Performance ◽

Naval Aviators ◽

The Impact

The purpose of this study was to investigate the use of EEG and cognitive functioning assessments to identify hypoxia in naval aviators. Naval aviators were brought slowly to a 6,096 m exposure to induce normobaric hypoxia while completing a cognitive assessment and a simulated flight task. There were significant reductions in cognitive performance at 6,096 m when compared to sea level. There were no significant changes in EEG-recorded brainwave activity during the 6,096 m exposure compared to sea level. There were also no significant decrements in flight performance at 6,096 m. Additional research is needed to better understand the impact of hypoxia on brainwave activity and pilot performance.

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