Canopy Induced Displacement Evaluation

1980 ◽  
Vol 24 (1) ◽  
pp. 552-556
Author(s):  
Michael L. Frazier
Keyword(s):  
Optical Properties ◽  
Eye Position ◽  
Target Displacement ◽  
Acquisition Process ◽  
System Acquisition ◽  
The Right

This paper reports on the optical properties of an aircraft canopy. In this study, canopy induced target displacement is studied for nine possible eye positions. The following general trends are noted: (1) the average absolute target displacement increases as viewing height increased; (2) the range of elevation target displacement increases as viewing height increases; (3) the range of elevation target displacement increases at lower sight depression settings, independent of viewing height; and (4) there is considerable parallax between the right and left eyes at 1 inch above design eye position, but, virtually no parallax 1 inch below design eye position. This study concluded that pilot interface with aircraft optics should be evaluated early in the system acquisition process.

Human Factors Engineering Planning Aid

1987 ◽  
Vol 31 (3) ◽  
pp. 350-352
Author(s):  
Stephen C. Merriman
Keyword(s):  
Complex System ◽  
Human Factors ◽  
Human Factors Engineering ◽  
Planning Time ◽  
Acquisition Process ◽  
Engineering Program ◽  
System Acquisition ◽  
The Military ◽  
Made In

This paper describes the application of affordable program management software to the task of planning human factors programs conducted in support of complex system developments. A model of the military system acquisition process was developed and a model human factors engineering program was overlayed upon it. Interdependencies were created between the models so that changes made in the acquisition schedule would cause the human factors program to be automatically tailored. This approach has potential to reduce planning time and increase the quality of human factors plans.

Postural adjustments for online corrections of arm movements in standing humans

2011 ◽  
Vol 105 (5) ◽  
pp. 2375-2388 ◽  
Author(s):  
Julia A. Leonard ◽  
Valeriya Gritsenko ◽  
Ryan Ouckama ◽  
Paul J. Stapley
Keyword(s):  
Muscle Activity ◽  
Arm Movements ◽  
Task Demands ◽  
Target Displacement ◽  
Postural Adjustments ◽  
Central Target ◽  
Postural Muscle ◽  
Online Corrections ◽  
Standing Humans ◽  
The Right

The aim of this study was to investigate how humans correct ongoing arm movements while standing. Specifically, we sought to understand whether the postural adjustments in the legs required for online corrections of arm movements are predictive or rely on feedback from the moving limb. To answer this question we measured online corrections in arm and leg muscles during pointing movements while standing. Nine healthy right-handed subjects reached with their dominant arm to a visual target in front of them and aligned with their midline. In some trials, the position of the target would switch from the central target to one of the other targets located 15°, 30°, or 45° to the right of the central (midline) target. For each target correction, we measured the time at which arm kinematics, ground reaction forces, and arm and leg muscle electromyogram significantly changed in response to the target displacement. Results show that postural adjustments in the left leg preceded kinematic corrections in the limb. The corrective postural muscle activity in the left leg consistently preceded the corrective reaching muscle activity in the right arm. Our results demonstrate that corrections of arm movements in response to target displacement during stance are preceded by postural adjustments in the leg contralateral to the direction of target shift. Furthermore, postural adjustments preceded both the hand trajectory correction and the arm-muscle activity responsible for it, which suggests that the central nervous system does not depend on feedback from the moving arm to modify body posture during voluntary movement. Instead, postural adjustments lead the online correction in the arm the same way they lead the initiation of voluntary arm movements. This suggests that forward models for voluntary movements executed during stance incorporate commands for posture that are produced on the basis of the required task demands.

Vertical Disparity Can Alter Perceived Direction

Perception ◽  
10.1068/p3440 ◽  
2002 ◽  
Vol 31 (11) ◽  
pp. 1323-1333 ◽  
Author(s):  
Ellen M Berends ◽  
Raymond van Ee ◽  
Casper J Erkelens
Keyword(s):  
Three Dimensional ◽  
Visual Scene ◽  
Eye Position ◽  
Vertical Disparity ◽  
Vertical Scale ◽  
The Common ◽  
The Right ◽  
The Relationship ◽  
Straight Ahead ◽  
Stimulus Direction

It has been well established that vertical disparity is involved in perception of the three-dimensional layout of a visual scene. The goal of this paper was to examine whether vertical disparities can alter perceived direction. We dissociated the common relationship between vertical disparity and the stimulus direction by applying a vertical magnification to the image presented to one eye. We used a staircase paradigm to measure whether perceived straight-ahead depended on the amount of vertical magnification in the stimulus. Subjects judged whether a test dot was flashed to either the left or the right side of straight-ahead. We found that perceived straight-ahead did indeed depend on the amount of vertical magnification but only after subjects adapted (for 5 min) to vertical scale (and only in five out of nine subjects). We argue that vertical disparity is a factor in the calibration of the relationship between eye-position signals and perceived direction.

scholarly journals Decreased Visual Attention Further from the Perceived Direction of Gaze for Equidistant Retinal Targets

2011 ◽  
Vol 23 (3) ◽  
pp. 661-669 ◽  
Author(s):  
Daniela Balslev ◽  
Emma Gowen ◽  
R. Chris Miall
Keyword(s):  
Visual Attention ◽  
Visual Processing ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Eye Position ◽  
Eye Muscle ◽  
Visual Hemifield ◽  
Proprioceptive Signal ◽  
Visual Targets ◽  
Attention Systems ◽  
The Right

The oculomotor and spatial attention systems are interconnected. Whereas a link between motor commands and spatial shifts in visual attention is demonstrated, it is still unknown whether the recently discovered proprioceptive signal in somatosensory cortex impacts on visual attention, too. This study investigated whether visual targets near the perceived direction of gaze are detected more accurately than targets further away, despite the equal eccentricity of their retinal projections. We dissociated real and perceived eye position using left somatosensory repetitive transcranial magnetic stimulation (rTMS), which decreases cortical processing of eye muscle proprioceptive inflow and produces an underestimation of the rotation of the right eye. Participants detected near-threshold visual targets presented in the left or right visual hemifield at equal distance from fixation. We have previously shown that when the right eye is rotated to the left of the parasagittal plane, TMS produces an underestimation of this rotation, shifting perceived eye position to the right. Here we found that, in this condition, TMS also decreased target detection in the left visual hemifield and increased it in the right. This effect depended on the direction of rotation of the right eye. When the right eye was rotated rightward and TMS, we assume, shifted perceived gaze direction in opposite direction, leftward, visual accuracy decreased now in the right hemifield. We suggest that the proprioceptive eye position signal modulates the spatial distribution of visual processing resources, producing “pseudo-neglect” for objects located far relative to near the perceived direction of gaze.

Primate premotor cortex: modulation of preparatory neuronal activity by gaze angle

1995 ◽  
Vol 73 (2) ◽  
pp. 886-890 ◽  
Author(s):  
D. Boussaoud
Keyword(s):  
Neuronal Activity ◽  
Premotor Cortex ◽  
Target Position ◽  
Delay Period ◽  
Coordinate Space ◽  
Eye Position ◽  
Related Activity ◽  
Visuomotor Task ◽  
Small Spot ◽  
The Right

1. This study investigated whether the neuronal activity of a cortical area devoted to the control of limb movements is affected by variations in eye position within the orbit. Two rhesus monkeys were trained to perform a conditional visuomotor task with an instructed delay period while maintaining gaze on a fixation point. 2. The experimental design required each monkey to put its hand on a metal touch pad located at arm's length and fixate a small spot of light presented on a computer screen. Then a visual cue came on, at the fixation point or elsewhere, the color of which instructed the monkey to move its limb to one of two touch pads according to a conditional rule. A red cue meant a movement to the left, whereas a green one instructed a movement to the right. The cue lasted for a variable delay period (1-3 s), and the monkey had to wait for its offset, the go signal, before performing the correct response. The fixation point and the cues were presented at various screen locations in a combination that allowed examination of whether eye position and/or target position modulate the neuronal activity. Because the monkeys' heads were fixed, all changes in eye position reflected movements in a craniocentric, head-centered, coordinate space. 3. The activity of single neurons was recorded from dorsal premotor cortex (PMd). For most neurons (79%), the activity during the instructed delay period (set-related activity) reflects the direction of the upcoming limb movement but varies significantly with eye position.(ABSTRACT TRUNCATED AT 250 WORDS)

On the laws of polarization and double refraction in regularly crystal­lized bodies. By David Brewster, LL. D. F. R. S. and Edin. In a letter to the Right Hon. Sir Joseph Banks, Bart. G. C. B. P. R. S

1833 ◽  
Vol 2 ◽  
pp. 92-93
Keyword(s):  
Optical Properties ◽  
General Principle ◽  
General View ◽  
Double Refraction ◽  
Primitive Form ◽  
General Law ◽  
Combined Action ◽  
The Right ◽  
Polarization Of Light ◽  
High Degree

In the different inquiries which the author has already laid before this Society, his attention was often directed to the phenomena of regular crystals; but he only lately succeeded in reducing under a general principle all those complex appearances which result from the combined action of more than one axis of double refraction. In this paper Dr. Brewster gives a general view of the present state of our knowledge respecting the double refraction and polarization of light, and afterwards traces the steps which led him to the discovery of the general law. He began his researches by the examination of 165 crystals, in 145 of which he discovered the property of double refraction. In 80 he was able to ascertain whether they had one or more axes; and by examining the tints which they exhibited at va­rious angular distances from the axes, whence the forces emanate, he has been led to a general principle, which embraces all the phenomena and extends to the most complex as well as to the most simple de­velopment of the polarizing forces. This general principle, says Dr. Brewster, is in no respect an empyrical expression of the facts which it represents, nor is it supported by any empyrical data. Founded on the principles of mechanics, it is a law rigorously physical, by which we are enabled to calculate all the tints of the coloured rings, and all the phenomena of double refraction, with as much accuracy as we can compute the motions of the heavenly bodies. The faculty of depolarization, explained by the author in a former paper, has been considered as sufficient indication of two separate images; and upon this principle it has been stated that all crystals are doubly refractive whose primitive form is neither the cube nor the regular octohedron: but this is incorrect; for some of these crystals possess a doubly refracting structure in a high degree. Ad­mitting the statement, however, it could not have been used as a rule for determining whether a crystal refracts doubly or singly; for it is more difficult to detect the primitive form than to examine the optical properties. Tungstate of lime, for instance, would have been reckoned a crystal without double refraction, when Haüy believed its primitive form to be the cube, although it is highly doubly refractive.

scholarly journals On new properties of light exhibited in the optical phenomena of mother-of-pearl, and other bodies to which the superficial structure of that substance can be communicated. By David Brewster, LL. D . F. R. S. Edin. and F. S. A. Ed. In a letter addressed to the Right Hon. Sir Joseph Banks, Bart. K. B. P. R. S

1832 ◽  
Vol 1 ◽  
pp. 502-504
Keyword(s):  
Optical Properties ◽  
Angular Distance ◽  
Transmitted Light ◽  
The Third ◽  
The Common ◽  
Optical Phenomena ◽  
The Right

The first section of this paper is devoted to the optical properties peculiar to mother-of-pearl; the second to the communication of these properties to other bodies; the third to the consideration of the cause of these phenomena; and the fourth to the description of the peculiar species of polarization produced by this substance. Dr. Brewster observes, mother-of-pearl is composed of laminae, much resembling in their arrangement those of the agate; that when it is imperfectly polished, a coloured image of a candle is seen in it by reflection in the neighbourhood of the common image, having its blue extremity towards this image, and being always situated, with respect to it, in the direction of an axis of extraordinary reflection, the angular distance varying with the inclination and situation of the rays, and being also different in magnitude in different specimens, but always observing certain laws. There is also a mass of coloured light, crimson at great angles of incidence, and green at smaller, beyond the regular coloured image, its distance varying according to a different law; becoming brighter when the substance is polished, and varying also with its thickness. Similar appearances are observed in a surface obtained by fracture; but a higher polish produces a new coloured image on the opposite side of the common image, and nearly as bright as the former, which is rendered somewhat less brilliant by the operation of polishing. Similar appearances, but somewhat less distinct, are observed when a candle is viewed through a thin piece of mother-of-pearl; and it is remarkable, that the image which is the brighter when seen by reflection, is the less bright when seen by transmission. When the opposite surfaces happen to have different axes of extraordinary reflection, they produce the appearance of four images in the transmitted light.

scholarly journals III. Experiments on the depolarisation of light as exhibited by various mineral, animal, and vegetable bodies, with a reference of the phenomena to the general principles of polarisation. By David Brewster, LL. D. F. R. S. Edin and F. S. A. Edin. In a letter addressed to the Right Hon. Sir Joseph Banks, Bart. K. B. P. R. S

1815 ◽  
Vol 105 ◽  
pp. 29-53 ◽  
Keyword(s):  
Optical Properties ◽  
General Principle ◽  
Gum Arabic ◽  
Natural Philosopher ◽  
Double Refraction ◽  
Short Account ◽  
Vegetable Products ◽  
Direct Experiment ◽  
The Right ◽  
Iceland Spar

Dear Sir Towards the end of the year 1812, when I was engaged in examining the light transmitted through diaphanous bodies, I discovered the property which many of them possessed of depolarising the rays of light, or of depriving them of the po­larity which they had received, either by reflection from the surface of a transparent body, or by transmission through a plate of agate. A short account of these experiments, which were exhibited to many of my friends in Edinburgh, was soon afterwards published in my treatise on new philosophical instruments. As this singular property was possessed by numerous sub­stances that exhibited no marks of double refraction, and even by animal and vegetable products, such as horn, tortoise­ shell, and gum Arabic, it appeared necessary to distinguish it by a new name, and to refer it to a species of crystalliza­tion different from that of doubly refracting crystals. The circumstance, however, of agate and Iceland spar possessing the faculty both of polarising and depolarising light, and the constant relation in the position of the axes which regulated these apparently opposite actions, induced me to think that the two classes of phenomena had the same origin. This opinion was afterwards strengthened by an experiment with a bundle of glass plates, in which light was depolarised by polarising it in a new plane; but in applying the principle to other phenomena, I was baffled in every attempt to generalise them. By extending, however, and varying the experiments; by examining the optical properties of every substance which I could command, and by comparing their structure with the phenomena which they exhibited, I have been led to the general principle to which they all belong, and to a series of results which, from their very nature, could not easily have been established by direct experiment. These conclusions, independently of their optical consequences, are peculiarly in­teresting to the chemist and the natural philosopher, by dis­closing the structure of organised substances, and exhibiting new relations among the bodies of the animal, the vegetable, and the mineral kingdoms.

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