On the optical theory of underwater vision in humans

Gislén, Anna; Gislén, Lars

doi:10.1364/josaa.21.002061

Cited by 10 publications

(6 citation statements)

References 17 publications

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“…The underwater photic environment is markedly different from that of air and visual functions may differ greatly between these media (Baddeley, 1968;Aksnes and Giske, 1993;Aksnes and Utne, 1997;Sandstrom, 1999;Utne-Palm, 2002;Gislen et al, 2003;Gislen and Gislen, 2004). This holds true for visually mediated interactions between species such as predation (Radke and Gaupisch, 2005;Van de Meutter et al, 2005) and within species such as courtship (Endler, 1987;Endler, 1991;Seehausen et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Prey detection by great cormorant (Phalacrocorax carbo sinensis)in clear and in turbid water

Strod

Izhaki

Arad

et al. 2008

Journal of Experimental Biology

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SUMMARYThe scattering and absorption of light by water molecules and by suspended and dissolved matter (turbidity) degrade image transmission and, thus, underwater perception. We tested the effects on visual detection of prey size and distance (affecting apparent prey size) and of low-level water turbidity in hand-reared great cormorants (Phalacrocorax carbo sinensis) diving for natural prey (fish) in a forced-choice situation. The cormorantsʼ detection of underwater prey relied on vision. The minimal tested subtending visual angle of the prey at detection ranged between ~34.2Ј (prey size constant; distance varied) and 9.5Ј (distance constant; prey size varied). For all tested distances (0.8-3.1·m) the mean detection success was significantly higher than the chance level. The probability of a correct choice declined significantly with increased distance, with Detection success=-0.034D+1.021 (where D is distance, r . It is concluded that (i) the subtending angle of natural prey at detection was lower than that of resolution of square-wave, high-contrast grating and (ii) turbidity, at levels significantly lower than commonly used in behavioural experiments, had a pronounced effect on visually mediated behaviour patterns.

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Section: Introductionmentioning

confidence: 99%

Prey detection by great cormorant (Phalacrocorax carbo sinensis)in clear and in turbid water

Strod

Izhaki

Arad

et al. 2008

Journal of Experimental Biology

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“…Their enactiveaquatic intelligence is embodied and enacts with objects and situations since it allows them to adapt to the problems posed by their aquatic environment. Their coupling is such that their children can see perfectly well underwater without the help of goggles, a finding that was of great interest to researchers (Gislén and Gislén, 2004). This lifestyle has led to major adaptations similar to those found in many marine animals, namely, their diving reflex and their clarity of vision underwater.…”

Section: Natural Learning Environmentsmentioning

confidence: 96%

How Enaction and Ecological Approaches Can Contribute to Sports and Skill Learning

et al. 2020

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The purpose of this paper is to explain learning in sports and physical education (PE) from the perspective of enactive and ecological psychology. The learning process is first presented from the enactive perspective, and some relevant notions such as sensemaking and sensorimotor schemes are developed. Then, natural learning environments are described, and their importance in the human development process is explained. This is followed by a section devoted to the learner's experience in which some research methods are explained, such as neurophenomenology, in addition to self-confrontation, interviews aimed at bringing out the meaning, sensations, and emotions that performers experience when they are immersed in their sport or a PE class. The sections on the ecological approach deal with the attunement, calibration, the education of intention, and the importance of representative experimental designs. The last section addresses the main similarities and differences between the two approaches. Finally, we state our theoretical position in favor of a common project that brings together the main elements of both post-cognitive approaches.

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“…As the rostral pupil is a near vertical slit, the series of blur circles making up the shadow of this slit on the retina will favor vertical features in the object space (e.g., vertical gratings). The tole of a constricted pupil in reducing aberrations and increasing the depth of-field remains an important element in marine matiimal vision (Gislen & Gislen, 2004). With a single fixed focal distance in air and another in water, a dolphin's extent of good vision is signiftcantly improved by a stopped-down iris.…”

Section: Theories Advanced To Explain Dolphin Vision-mentioning

confidence: 99%

Bottlenose Dolphin (<I>Tursiops truncatus</I>) Double-Slit Pupil Asymmetries Enhance Vision

Rivamonte¹

2009

aquatic mammals

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Geometries of the iris, retinal cell distributions, and the optical characteristics of the lens and cornea have evolved to optimize the visual adaptations ofthe bottlenose dolphin {Tursiops truncatus) to the oceanic environment. Under high ambient light conditions, the operculum ofthe iris shields the lens and forms two asymmetrical slit pupils. Under these conditions, light entering the eye is channeled and focused onto the two areas of the retina having a finer retinal mosaic of ganglion ceils (typically associated with higher image resolution). The paths of light determined hy tracing rays in the reverse direction through these pupils coincide with a dolphin's behaviorally observed preferred viewing directions. These rays aid in determining the interdependence between the graininess of the retinal mosaic and resolution spot sizes in the object space. For oblique forward and downward viewing directions in air. the larger icmporal pupil admits light which passes through the weakly refractive margin of a hifocal lens, counterbalancing the optically strong cornea in air. In water, light passing through the optically strong lens core is focused from a wide lateral and downward field-of-vision. Although other explanations for comparable aerial and underwater vision remain plausible, a dolphin eye model incorporating a bifocal lens offers an explanation consistent with ophthalmoscopic refractive state measurements. The model is also consistent with visual acuity study results conducted in air and in water under both high and low ambient light levels. From insight gained after applying a common data analysis technique to visual acuity studies conducted by other researchers and tracing oblique rays through the asymmetric double-slit pupils, a re-examination of explanatory hypotheses for the paradoxical observations of cotiiparable aerial and underwater vision is presented. Based in part on these findings and supportive evidence from dolphin vision researchers, the unique distinguishing characteristics of dolphin vision are summarized.

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On the optical theory of underwater vision in humans

Cited by 10 publications

References 17 publications

Prey detection by great cormorant (Phalacrocorax carbo sinensis)in clear and in turbid water

Prey detection by great cormorant (Phalacrocorax carbo sinensis)in clear and in turbid water

How Enaction and Ecological Approaches Can Contribute to Sports and Skill Learning

Bottlenose Dolphin (<I>Tursiops truncatus</I>) Double-Slit Pupil Asymmetries Enhance Vision

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