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Biomedical subjects

L A Temme

Publications and source records attributed to L A Temme.

At least 19 recordsLinked to original sources
PubMed2001

The performance of the standard rate turn (SRT) by student naval helicopter pilots.

BACKGROUND: During flight training, student naval helicopter pilots learn the use of flight instruments through a prescribed series of simulator training events. The training simulator is a 6-degrees-of-freedom, motion-based, high-fidelity instrument trainer. From the final basic instrument simulator flights of student pilots, we selected for evaluation and analysis their performance of the Standard Rate Turn (SRT), a routine flight maneuver. METHODS: The performance of the SRT was scored with air speed, altitude and heading average error from target values and standard deviations. These average errors and standard deviations were used in a Multiple Analysis of Variance (MANOVA) to evaluate the effects of three independent variables: 1) direction of turn (left vs. right), 2) degree of turn (180 vs. 360 degrees); and 3) segment of turn (roll-in, first 30 s, last 30 s, and roll-out of turn). RESULTS: Only the main effects of the three independent variables were significant; there were no significant interactions. This result greatly reduces the number of different conditions that should be scored separately for the evaluation of SRT performance. The results also showed that the magnitude of the heading and altitude errors at the beginning of the SRT correlated with the magnitude of the heading and altitude errors throughout the turn. This result suggests that for the turn to be well executed, it is important for it to begin with little error in these two response parameters. CONCLUSIONS: The observations reported here should be considered when establishing SRT performance norms and comparing student scores. Furthermore, it seems easier for pilots to maintain good performance than to correct poor performance.

Aircraft↗
PubMed2001

The performance of standard vertical S-1 flight maneuvers by student U.S. Naval helicopter pilots.

BACKGROUND: During flight training, student U.S. Naval helicopter pilots learn the use of flight instruments through a prescribed series of simulator training events. We recorded the training flights of 76 student U.S. Naval helicopter pilots undergoing the simulator phase of basic flight instrument training. From the final basic instrument simulator flight, the Vertical S-I (VS) flight maneuver, a standard flight maneuver required of the students, was selected for analysis. This maneuver was chosen because the ideal performance was well described. METHODS: The training simulator is the 2B42 training device, a 6 degrees of freedom, motion-based, high-fidelity instrument trainer. The quality of the flight performance of the cohort of student aviators executing the VS was described using objective measures of deviation from the ideal flight path. The measures included air speed, altitude, and heading average error from target values and standard deviations. RESULTS: The distributions of these scores for the 76 student pilots were described and used to calculate a composite score that summarized a student's overall performance of the maneuver. The worst four, the best four, and a group of four average pilots were identified from their composite scores and their relative performance was compared. CONCLUSIONS: A graphical summary of each pilot's flight performance was developed, and from this performance summary a pattern became evident that suggested that differences in performance levels were related to the use of flight instruments.

Aircraft↗
PubMed1995

Jet pilot, helicopter pilot, and college student: a comparison of central vision.

Jet pilots (JP) (N = 44), helicopter pilots (HP) (N = 29), and college students (CS) (N = 41) were tested with a battery of vision tests designed to assess vision skills important for success as a naval aviator. Tests included measures of reaction time, high-contrast acuity, low-contrast acuity, spot detection, far-to-near gaze shift, near-to-far gaze shift, low-contrast acuity with glare, and dark focus. A Multi-Variate Analysis of Variance (MANOVA) compared the vision test performance of the three subject groups (JP, HP, and CS). Only with the Far-to-Near test was there no difference among the three groups. On all other tests, JP outperformed CS. The difference between HP and CS was less consistent and less dramatic than the difference between JP and CS. Only with the glare test were CS significantly better than HP. The results were interpreted as reflecting the influence of various selection factors, operational requirements, differential attrition, and age.

Adult↗
PubMed1992

Eyeglass use by U.S. Navy jet pilots: effects on night carrier landing performance.

The purpose of this study was to test the hypothesis that the night carrier landing performance of pilots who do not need prescriptive eyeglasses to fly is better than the performance of pilots who do. Night carrier landing scores (NCLS), age, career jet flight hours, and total career flight hours were obtained for 122 U.S. Navy fighter pilots participating in air combat maneuver training at NAS, Oceana, VA. of the pilots with NCLS, 16 used a prescribed spectacle correction while flying, 106 did not. This study compared the NCLS of the two groups of pilots, those with glasses and those without. We found no significant difference in NCLS between the two groups of pilots--even when the pilots were matched on the basis of age and flight experience. We conclude that pilots who have a refractive error and are required to wear an eyeglass correction while flying perform night carrier landings as well as the pilots who have no refractive error and are permitted to fly with no eye glass correction.

Adult↗
PubMed1991

Visual contrast sensitivity of U.S. Navy jet pilots.

Good visual contrast sensitivity (CS) is often described as a visual capability important for success as a military aviator and so has been suggested as a physical standard for personnel selection and retention. To evaluate this idea, we measured the CS of 135 U.S. Navy fighter pilots ranging in age from 24 to 44 years (mean = 30.20, S.D. = 4.06) and compared these to the CS of non-aviators. We obtained the non-aviator data from published studies of other investigators who used similar procedures with the same widely used, commercially available apparatus (Nicolet CST 2000). In addition to this comparison, we correlated the pilots' CS with their air-to-air target detection distances measured during air combat maneuver training and to their night carrier landing performance scores. The major findings were: 1) The mean CS of the aviators and the non-aviators were within +/- 1.0 S.D. of each other in most instances, and those few instances where a greater difference was found were parsimoniously explained by methodological and procedural factors; 2) sensitivities to different spatial frequencies were highly correlated among themselves, indicating much redundancy among the measurements; 3) there was no evidence of a relationship between CS and air-to-air target detection distances or night carrier landing performance.

Adult↗
PubMed1991

Visual acuity of the U.S. Navy jet pilot and the use of the helmet sun visor.

Visor wear habits, evaluative comments and vision test data were obtained from interviews of 126 Navy fighter pilots. The interviews revealed that many pilots use their helmet sun visor whenever they fly, some use it only during certain flight operations, and others never use it. Study 1 (conducted at 343 cd/m2) revealed a decrease in low contrast visual acuity attributable to helmet sun visor use in the presence of a glare source. These findings prompted a second study of the visual effects of visor transmittance. Low-contrast spot detection, acuity, and contrast sensitivity were measured at an operationally realistic daytime illumination level (6870 cd/m2) in subjects viewing through filters ranging from 6.3% to 50.1% transmission. (Standard visor transmission is 12 +/- 4%.) Results showed that filter density, and consequently the illuminance reaching the eyes, could be varied over a wide range without critically affecting these visual functions. Prevailing environmental illuminance should be considered when selecting sun visors or sunglasses. These results have implications for optimizing visual performance through visors.

Adult↗
PubMed1991

Prescriptive eyeglass use by U.S. Navy jet pilots: effects on air-to-air target detection.

Air-to-air target detection distances, age, career jet flight hours, and total career flight hours were obtained for 167 U.S. Navy fighter pilots participating in air combat maneuver training at Naval Air Station, Oceana, VA. Of the pilots sampled, 22 used a prescribed spectacle correction while flying; 145 did not. We compared the air-to-air target detection distances between the two groups of pilots, those with corrective glasses and those without. Sunglasses and tinted filters were not factors in the present study. The results strongly suggest that, as a group, the pilots without glasses were able to detect targets at a greater distance than the pilots with glasses. When the pilots were matched on the basis of age and flight experience, the difference in air-to-air target detection capabilities of the two groups increased. The pilots without glasses were able to detect their adversary at a distance more than 20% farther than the pilots with glasses.

Adult↗
PubMed1990

Optical factors in judgments of size through an aperture.

An expression is derived relating retinal image size to object size when the object is seen through a pupil forming an aperture stop for the eye. The image size is related to object position, pupil position, and state of accommodation of the eye on the assumption that the chief ray determines the image of an out-of-focus object. Data obtained by Biersdorf and Baird agree with the expression. The expression is used as the basis of a quantitative discussion of Hennessy's informal experiment and Roscoe's zoom lens hypothesis.

Accommodation, Ocular↗
PubMed1989

Speed of accommodation and age.

The time needed to change accommodation from a near to a far target or from a far to a near target (0.457 and 5.486 m) was measured with a psychophysical threshold procedure in 65 U.S. Navy fighter pilots. The age of the pilots ranged from 24 to 44 years. The speed of accommodative change, far-to-near (FN), slowed with age in a statistically significant fashion; however, near-to-far (NF) did not appreciably slow with age. The intrasubject variability was greater FN than NF but there was not a statistically significant dependence of variability upon age.

Accommodation, Ocular↗
PubMed1989

The time required for U.S. Navy fighter pilots to shift gaze and identify near and far targets.

The speed with which 163 U.S. Navy fighter pilots can shift their line of sight and discriminate high contrast acuity targets was measured. The targets were simultaneously projected onto two screen; one at 18 ft and one at 18 inches in front of the subject's eyes. Subjects were required to fixate first one screen and then as rapidly as possible, shift gaze to the other screen. The minimum exposure duration required to correctly resolve both targets was measured. For 65 subjects, the test target was 1.0 min of visual angle (mva); for 98 subjects the target was 2.0 mva. The major findings are: 1) both Far-to-Near and Near-to-Far mean times significantly slowed with age; 2) there was no significant difference between the Far-to-Near and the Near-to-Far mean times with the oldest subject (44 years of age) excluded; 3) the within-subject standard deviation Far-to-Near increased with age and was significantly greater than the Near-to-Far standard deviation, which did not increase with age; 4) there was a significant correlation between the mean Near-to-Far speeds and the night carrier landing performance of the aviators.

Accommodation, Ocular↗
PubMed1988

Dark focus measured in Navy jet tactical fighter pilots.

Visual accommodation was measured with the laser-Badal optometer in 98 U.S. Navy fighter pilots who were in a dark environment without visual stimuli. The average dark focus of the pilots was 0.25 diopters of myopia; 40% were either emmetropic or hyperopic in the dark. Only 4% had as much dark myopia as 50% of a sample of 220 college students. Although the jet fighter pilots, as a population, differed from college students in terms of dark focus, it remains to be determined whether the remarkable dark focus of the pilots was a function of training or selection. The dark focus measurements of the pilots were compared to their mean night carrier landing scores and their mean target detection slant range scores--the distance at which an adversary aircraft is first sighted during an air combat maneuver training engagement. Neither the night carrier landing scores nor the target detection slant range scores correlated significantly with dark focus measurements.

Adult↗
PubMed1985

Peripheral visual field is radially organized.

The visibility of vertical, horizontal, and 45 degrees oblique square wave gratings was measured at 10 to 45 degrees of eccentricity along the vertical, horizontal, and the 45 degrees oblique meridians. A forced-choice orientation identification response to the stimulus grating and a subjective rating of the confidence in response accuracy were the response measurements. The best seen grating orientation was always the one parallel to the meridian upon which it was presented. Along the vertical and horizontal meridians the most poorly seen orientation was the one perpendicular to the meridian. Along the 45 degrees oblique meridians the horizontal grating was as poorly seen as the meridian perpendicular to the grating orientation, except in the infranasal quadrant of the field. Pinhole experiments show these results unlikely to be due to off-axis optical aberrations. It is hypothesized that the radial organization of the peripheral visual field is due to underlying neural factors ontogenically determined, not due to environmental adaptations.

Form Perception↗
PubMed1985

Eccentricity perception in the periphery of normal observers and those with retinitis pigmentosa.

The perception of the eccentricity of a suprathreshold light flash (III/4e) presented in a Goldmann perimeter was measured in four ophthalmologically normal observers and three young observers with retinitis pigmentosa (RP). The task was to indicate the perceived distance from central fixation of each light flash by making a mark on a 180-mm line drawn on a sheet of paper. In the center of the line was a hash mark. Observers were instructed that the hash mark should correspond to fixation and the ends of the line to the limits of the visual field. The vertical, horizontal, and both 45 degree oblique meridians were tested. The results showed that: 1. The extent of the field along the tested meridian determined perceived eccentricity, i.e., eccentricity of 45 degrees in the temporal field of normals was perceived as equally eccentric as 30 degrees in the superior field. 2. The central 20 degrees were taken to represent more of the perceptual field than any other 20 degrees. 3. Along a meridian, the eccentricity which extends from fixation to 16% of the way to the field limit along the meridian is perceived as extending to 25% of the field by normal observers. 4. On the other hand, observers with RP reported that along a meridian the eccentricity extending from fixation to 8% of the field limit is perceived as extending to 25% of the field. Kinetic primary with the II/4 target showed no evidence of field constriction in observers with RP. However, losses in sensitivity are evident starting at about 10 degrees. Full field single flash electroretinograms were unrecordable in the observers with RP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1981

Radiation therapy in and about the retina, optic nerve, and anterior visual pathway. Psychophysical assessment.

Visual changes may develop in patients receiving radiation therapy for malignant neoplasms in and about the optic nerve and anterior visual pathway. Cases have been studied using a series of psychophysical tests, including kinetic perimetry, increment threshold determinations, Flashing Repeat Static Test, and sustained- and transient-like functions. A characteristic time-dependent reduction in sensitivity has been identified in these patients. This finding, in addition to the presence of nerve fiber bundle defects, appears to place the pathologic changes in the axon of the ganglion cell posterior to the lamina cribrosa. Any change in the sustained- and transient-like functions, the organization of which appears to be in the neural retina, was seen only if a concomitant radiation retinopathy was identified.

Adenocarcinoma↗
PubMed1980

Different functional changes recorded in open angle glaucoma and anterior ischemic optic neuropathy.

The retinal ganglion cell exhibits two types of functional change. The difference in response appears to depend on whether or not the retrobulbar portion of the optic nerve is actively involved. This may imply differences in the myelinated and non-myelinated portions of the optic nerve and associated structures. In open angle glaucoma, alterations in the sustained- and transient-like functions but not in the flashing repeat static test are found. That is, there are changes in spatial neural interactions, but there is no evidence of a visual fatigue or saturation-like effect. In optic nerve radiation damage without evidence of retinal vascular changes, in optic neuritis secondary to multiple sclerosis, chiasmal lesions, and ischemic optic neuropathy (considered here) varying degrees of visual fatigue or saturation-like effects are demonstrated with little or no change in the sustained- or transient-like functions.

Aged↗
PubMed1980

Anomalous pigment epithelial photoreceptor relationships and receptor orientation.

In order to further investigate the factors influencing retinal receptor orientation, three patients with local disturbances of the receptor/pigment epithelium (PE) interface have been evaluated. Psychophysical and clinical tests have been used to characterize the observed abnormalities. The following conclusions are made. Receptor orientation is lost following a serous detachment of the neurosensory retina and can recover following reattachment of the retina. Orientation may be retained despite the presence of serous detachment of the PE, loss of the light/dark component of the electro-oculogram, and vitelliform-like lesions between the receptors and the PE.

Adult↗
PubMed1980

Transient-like function and associated retinal capillary anomalies. Analysis of a patient with early retinopathy secondary to juvenile-onset diabetes mellitus.

A juvenile diabetes patient exhibiting limited early microvascular changes in the retina has been studied intensively. Like some others showing early signs of diabetic retinopathy, he manifests anomalies in a retinally based transient-like function. At all points tested in this case the sustained-like function was found to be normal. Because his functional and anatomic anomalies are stable and cover a reasonably extensive area of visual field and retina, it is possible to attempt correlative studies with other visual response functions. The transient-like function proves to be a more sensitive indicator of anomaly in this patient than static perimetry or critical flicker frequency.

Adolescent↗