Visual Problems under Water

Barnard, EB

doi:10.1177/003591576105400917

Cited by 7 publications

(4 citation statements)

References 4 publications

(2 reference statements)

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“…1) is to locate the image of the object at approximately three-quarters of its physical distance, and thus to increase the angle subtended at the observer's eye by 413. In this calculation it is assumed that the angular size of the object is fairly small; otherwise the optical displacement and magnification are greater, and 'pin-cushion' distortion occurs (Barnard, 1961). It is also assumed that the eye is exactly at the water-air interface; and the refraction due to the glass in the face-mask is ignored.…”

mentioning

confidence: 99%

Water, Fog and the Size—distance Invariance Hypothesis

Ross

1967

British J of Psychology

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Objects generally appear too large under water. The usual explanation for this is that they are magnified by the change of refractive index between air and water. However, they are only magnified because they are optically nearer. If size constancy operates normally they should be seen the correct size but nearer, or enlarged in size but farther than the optical distance. The problem was investigated by requiring sixteen divers to make size and distance judgements of a range of white disks of different sizes set at various distances. Judgements were made for the same display both under water and on land. It was found that size judgements were greater under water, and that this corresponded to relative overestimation of distance. A weak form of size—distance invariance was found both under water and on land, but the relation between size and distance judgements was not the same in both conditions. Overestimation of size and distance was also found in a fog on land. It was suggested that the overestimation of distance in a fog and under water was due to the exaggerated reduction of brightness contrast with distance, which increases ‘aerial perspective’.

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mentioning

confidence: 99%

Water, Fog and the Size—distance Invariance Hypothesis

Ross

1967

British J of Psychology

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“…All masks were tempered. as yet, no standards for », but it is interesting to There are, diving masks, evaluate these results against the Nav-SubMedRschLab standards for glass and plastic piano visor s.-* 2 The masks would all meet these standards except for their visible trans mittance; this should be at least 90 percent. The compensating mask fails this by a wide margin, and the goggles and widefield mask are marginal failures.…”

Section: Optical Propertiesmentioning

confidence: 99%

Vision through Various Scuba Facemasks

Luria¹,

Ferris²,

McKay³

et al. 1972

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To determine whether there are differences in various measures of a diver's visual performance (such as acuity, depth perception, field of view, etc.) when wearing different, commercially available, SCUBA facemasks. FINDINGS There are statistically significant differences between the various facemasks for every visual process tested, except one. Some masks are superior for one purpose, however, and inferior for another purpose. APPLICATION The results are applicable for the selection of the proper facemask for use in any particular Naval diving mission in which the diver's task might emphasize one aspect of visual performance over another.

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“…For example, Glass et al 12 found that participants swayed less following long-duration water immersion compared to performance prior to exposure. They noted that proprioception 13 , somatosensation and vision 14 , possibly because human eyes evolved for viewing in air, are less informative of postural changes underwater and hypothesized that the sway changes may reflect a downweighting of these cues and a concomitant upweighting of vestibular input. Jarchow and Mast 15 reported that immersion and neutral buoyancy resulted in a head upward bias in the subjective horizontal body posture compared to performance on land in 3 of their 4 participants.…”

Section: Introductionmentioning

confidence: 99%

Vection underwater illustrates the limitations of neutral buoyancy as a microgravity analog

Bury¹,

Jenkin²,

Allison³

et al. 2023

npj Microgravity

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Neutral buoyancy has been used as an analog for microgravity from the earliest days of human spaceflight. Compared to other options on Earth, neutral buoyancy is relatively inexpensive and presents little danger to astronauts while simulating some aspects of microgravity. Neutral buoyancy removes somatosensory cues to the direction of gravity but leaves vestibular cues intact. Removal of both somatosensory and direction of gravity cues while floating in microgravity or using virtual reality to establish conflicts between them has been shown to affect the perception of distance traveled in response to visual motion (vection) and the perception of distance. Does removal of somatosensory cues alone by neutral buoyancy similarly impact these perceptions? During neutral buoyancy we found no significant difference in either perceived distance traveled nor perceived size relative to Earth-normal conditions. This contrasts with differences in linear vection reported between short- and long-duration microgravity and Earth-normal conditions. These results indicate that neutral buoyancy is not an effective analog for microgravity for these perceptual effects.

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Visual Problems under Water

Cited by 7 publications

References 4 publications

Water, Fog and the Size—distance Invariance Hypothesis

Water, Fog and the Size—distance Invariance Hypothesis

Vision through Various Scuba Facemasks

Vection underwater illustrates the limitations of neutral buoyancy as a microgravity analog

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