Using RGB displays to portray color realistic imagery to animal eyes

RGB displays effectively simulate millions of colors in the eyes of humans by modulating the relative amount of light emitted by 3 differently colored juxtaposed lights (red, green, and blue). The relationship between the ratio of red, green, and blue light and the perceptual experience of that light has been well defined by psychophysical experiments in humans, but is unknown in animals. The perceptual experience of an animal looking at an RGB display of imagery designed for humans is likely to poorly represent an animal’s experience of the same stimulus in the real world. This is due, in part, to the fact that many animals have different numbers of photoreceptor classes than humans do and that their photoreceptor classes have peak sensitivities centered over different parts of the ultraviolet and visible spectrum. However, it is sometimes possible to generate videos that accurately mimic natural stimuli in the eyes of another animal, even if that animal’s sensitivity extends into the ultraviolet portion of the spectrum. How independently each RGB phosphor stimulates each of an animal’s photoreceptor classes determines the range of colors that can be simulated for that animal. What is required to determine optimal color rendering for another animal is a device capable of measuring absolute or relative quanta of light across the portion of the spectrum visible to the animal (i.e., a spectrometer), and data on the spectral sensitivities of the animal’s photoreceptor classes. In this article, we outline how to use such equipment and information to generate video stimuli that mimic, as closely as possible, an animal’s color perceptual experience of real-world objects

Voicing women\u27s resistance within religious studies: An interrogation of rational choice theory

While women are generally oppressed within hierarchical and patriarchal religious traditions, researchers continue to detail the ways women negotiate power and construct meaning in religion. Within this thesis I interrogate the use of rational choice theory, a prominent theory utilized to describe religious behavior, as a framework for the analysis of women\u27s religious experience and agency. I compare two texts, Brenda Brasher\u27s Godly Women: Fundamentalism and Female Power and Jeanette Rodriguez\u27s Our Lady of Guadalupe: Faith and Empowerment Among Mexican-American Women, in order to illustrate the inadequacies of rational choice theory in describing the religious experiences of marginalized women. I claim that rational choice theory does not articulate the relationships of power implicit within gender, does not describe embodied experience, and denies the cultural embeddedness of religion. I attribute the prominence of rational choice theory to a Protestant bias in the field of religious studies. The dominance of Protestant perspectives within the field of religious studies has mandated what can be considered religious, solidified institutional power, contributed to the marginalization of the oppressed, and rendered problematic the agency of many persons whose religious practices do not fit the Protestant mold. In an effort to transform the field of religious studies, in this thesis, I emphasize the importance of alternate readings of women\u27s experience. Theories like rational choice that stress belief and focus on the individual\u27s religious experience uncritically impose limiting religious ideology upon female subjects. Rather than rely on rational choice theory, researchers need to pursue alternate explanations that demonstrate how women negotiate agency in their religious lives, resisting oppressive ideology and repressive religious practices

The jumping spider Saitis barbipes lacks a red photoreceptor to see its own sexually dimorphic red coloration

Examining the role of color in mate choice without testing what colors the study animal is capable of seeing can lead to ill-posed hypotheses and erroneous conclusions. Here, we test the seemingly reasonable assumption that the sexually dimorphic red coloration of the male jumping spider Saitis barbipes is distinguishable, by females, from adjacent black color patches. Using microspectrophotometry, we find clear evidence for photoreceptor classes with maximal sensitivity in the UV (359 nm) and green (526 nm), inconclusive evidence for a photoreceptor maximally sensitive in the blue (451 nm), and no evidence for a red photoreceptor. No colored filters within the lens or retina could be found to shift green sensitivity to red. To quantify and visualize whether females may nevertheless be capable of discriminating red from black color patches, we take multispectral images of males and calculate photoreceptor excitations and color contrasts between color patches. Red patches would be, at best, barely discriminable from black, and not discriminable from a low-luminance green. Some color patches that appear achromatic to human eyes, such as beige and white, strongly absorb UV wavelengths and would appear as brighter “spider-greens” to S. barbipes than the red color patches. Unexpectedly, we discover an iridescent UV patch that contrasts strongly with the UV-absorbing surfaces dominating the rest of the spider. We propose that red and black coloration may serve identical purposes in sexual signaling, functioning to generate strong achromatic contrast with the visual background. The potential functional significance of red coloration outside of sexual signaling is discussed

Technical and conceptual considerations for using animated stimuli in studies of animal behavior

© The Author (2016). Rapid technical advances in the field of computer animation (CA) and virtual reality (VR) have opened new avenues in animal behavior research. Animated stimuli are powerful tools as they offer standardization, repeatability, and complete control over the stimulus presented, thereby "reducing" and "replacing" the animals used, and "refining" the experimental design in line with the 3Rs. However, appropriate use of these technologies raises conceptual and technical questions. In this review, we offer guidelines for common technical and conceptual considerations related to the use of animated stimuli in animal behavior research. Following the steps required to create an animated stimulus, we discuss (I) the creation, (II) the presentation, and (III) the validation of CAs and VRs. Although our review is geared toward computer-graphically designed stimuli, considerations on presentation and validation also apply to video playbacks. CA and VR allow both new behavioral questions to be addressed and existing questions to be addressed in new ways, thus we expect a rich future for these methods in both ultimate and proximate studies of animal behavior

I spy with my little eye: a simple behavioral assay to test color sensitivity on digital displays

Passive and interactive virtual reality (VR) environments are becoming increasingly popular in the field of behavioral neuroscience. While the technique was originally developed for human observers, corresponding applications have been adopted for the research of visual-driven behavior and neural circuits in animals. RGB color reproduction using red, green and blue primary color pixels is generally calibrated for humans, questioning if the distinct parameters are also readily transferable to other species. In particular, a visual image in the RGB color space has a clearly defined contrast pattern for humans, but this may not necessarily be the case for other mammals or even non-mammalian species, thereby impairing any interpretation of color-related behavioral or neuronal results. Here, we present a simple method to estimate the sensitivity of animals to the three primary colors of digital display devices based on the performance of object motion-driven visuomotor reflexes and demonstrate differences in the color sensitivity between Xenopus laevis and Ambystoma mexicanum (Axolotl)

Understanding the retinal basis of vision across species

The vertebrate retina first evolved some 500 million years ago in ancestral marine chordates. Since then, the eyes of different species have been tuned to best support their unique visuoecological lifestyles. Visual specializations in eye designs, large-scale inhomogeneities across the retinal surface and local circuit motifs mean that all species' retinas are unique. Computational theories, such as the efficient coding hypothesis, have come a long way towards an explanation of the basic features of retinal organization and function; however, they cannot explain the full extent of retinal diversity within and across species. To build a truly general understanding of vertebrate vision and the retina's computational purpose, it is therefore important to more quantitatively relate different species' retinal functions to their specific natural environments and behavioural requirements. Ultimately, the goal of such efforts should be to build up to a more general theory of vision

Case report: Awake insertion of the intubating laryngeal mask airway using dexmedetomidine sedation

No Abstract

The Perceptual and Decision-Making Processes Guiding Species and Sex Recognition and Rival Assessment in the Jumping Spider Lyssomanes viridis

<p>The goal of this dissertation was to better clarify the sensory and cognitive capabilities and limitations of a size-constrained animal. Because visually-guided behaviors are more experimentally tractable than behaviors guided by other sensory modalities, I chose to study a small animal with an unusually good visual system and a suite of apparently visually-guided behaviors, the jumping spider <i>Lyssomanes viridis</i> (Salticidae). Jumping spiders' principal eyes, which are adapted for the perception of shape and pattern, have the highest measured acuity of any arthropod, but also the narrowest field of view, making salticids a particularly interesting study system for measuring the capabilities and limitations of a tiny animal with small yet apparently highly functional eyes. For my dissertation, I examined the amount and type of visual information gathered in high-stakes encounters; i.e. species and sex recognition and male-male contests over females. In salticids, the wrong assessment of species and sex or fighting ability carries with it the risk of injury or even death. Thus, more information, and especially high-resolution information, should be particularly adaptive in such encounters, and should provide us with a good proxy of the perceptual and cognitive capabilities and limitations of this small animal. </p><p>In chapter two, I assayed the amount and type of visual information gathered in the context of species and sex recognition, and tested for crossmodal interactions between pheromones and visual cues. Using computer-animated stimuli, I found that, although males took the time necessary to visually scan both the face and legs of other spiders before deciding whether to threaten, court, or ignore them, their conspecific visual recognition templates were fairly coarse, and resulted in them making numerous misidentifications and frequently courting heterospecific salticids. This was especially true in the presence of conspecific female pheromones. Pheromones appeared to exert further top-down effects on visual recognition of conspecifics by bringing visual recognition templates into working memory, as was inferred from the fact that males spent less time examining conspecific images in the presence of conspecific female pheromones. Pheromones also increased the probability that a non-conspecific spider bearing even a slight resemblance to a conspecific female spider would be recognized and courted as a conspecific female. However, pheromones usually did not hasten the recognition of non-conspecific images; this indicates that males' poorer recognition accuracy in the presence of pheromones was not a result of males' spending less time visually examining non-conspecific images. </p><p>In chapter three, I looked for correlations between various visual features and contest success in order to determine what types of visual information opponents could theoretically use to assess their opponents' resource holding potential in contests over females. I found that all measured size-related traits correlated strongly with contest success, but that coloration did not, except in the rare cases in which a smaller male won a contest. In these encounters, males who won, despite being smaller, had less red chelicerae than their opponents. Finally, in chapter four, I used the results of chapter three to begin assessing whether the traits that correlate with contest success are actually assessed by males, and in particular, whether they are assessed visually. To do this, I presented males with various sizes of computer-animated opponents, and found that males were less likely to threaten larger opponents. Thus, males seem to be using visual cues to gather information about the size of their opponents. Whether they evaluate overall size, or more specifically, the size of their opponents' weapons, will be addressed in future work.</p>Dissertatio

Immunological dependence of plant-dwelling animals on the medicinal properties of their plant substrates: a preliminary test of a novel evolutionary hypothesis

We present preliminary evidence for a novel evolutionary hypothesis, i.e., that animals living on plants high in antimicrobial secondary metabolites could, via drift or selection, evolve weakened immune defenses and an immunological dependence on the antimicrobial properties of their plant substrate and/or the volatile mix in the air surrounding their plant. Animals experience immunological stress during developmental transitions, so we evaluated our hypothesis by testing for an effect of plant substrate on hatching success in the jumping spider Lyssomanes viridis, a species that constructs its egg sacs on Liquidambar styraciflua leaves. Compared with other sympatric species, L. styraciflua is known to be high in potent volatile broad-spectrum antimicrobial compounds, most notably, the monoterpene terpinen-4-ol, a well-studied antimicrobial agent known from tea tree oil. We found that L. viridis experience higher hatching success on L. styraciflua than on other sympatric species or plastic substrate controls and that L. viridis has a chemically mediated preference for this plant. In contrast to other spiders' compact, densely woven egg sacs, L. viridis' egg sacs are sparsely woven and the eggs widely spaced, maximizing the eggs' surface area exposed to volatiles coming off the leaf. Similar architectures exist in distantly related taxa, suggesting convergent evolution. Our theoretical framework and preliminary results open up an unexplored frontier-the possibility that any number of plant-dwelling species may depend upon on the antimicrobial properties of the plant tissues they inhabit