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At least 1,603 records · Page 89Linked to original sources
PubMed2001

Effect of "inside-out" and "outside-in" attitude displays on off-axis tracking in pilots and nonpilots.

BACKGROUND: Pilots employing helmet-mounted displays spend sustained periods of time looking off-axis, necessitating the inclusion of attitude symbology on the helmet to maintain spatial awareness. We examined how fundamentally different attitude references, a moving-horizon ("inside-out") or a moving-aircraft ("outside-in"), affected pilot and nonpilot attitude control when looking on- or off-axis. Both a rear-view and a side-view outside-in perspective were depicted to investigate the effect of control-display compatibility. METHODS: Subjects performed a compensatory pitch-roll tracking task either looking on-axis or 90 degrees off-axis using three symbologies: 1) a compressed pitch ladder with horizon line; 2) a 3-D aircraft representation viewed from the rear; and 3) a 3-D aircraft representation viewed from the side. Tracking error in roll and pitch, control bias, and subjective ratings were collected and analyzed. RESULTS: There was no significant difference in the tracking performance of U.S. Air Force pilots in pitch and roll using the inside-out or outside-in rear-view formats on- and off-axis, although they preferred the inside-out format. Nonpilots tracked significantly better using the outside-in rear-view format, which they also preferred. Both groups tracked poorly using the outside-in side-view format and control-display compatibility had no important effect. CONCLUSIONS: Pilots are equally adept using outside-in and inside-out displays. Given that an outside-in display may better reflect a person's inherent frame of reference for orientation (as evidenced by the nonpilots' superior performance with it), the results seem to indicate that pilots, through experience, have adapted to an inside-out frame of reference.

Accommodation, Ocular↗
PubMed1975

A developmental study of Piaget's groupement model of the emergence of speed and time concepts.

3 key predictions of Piaget's groupement model of middle-childhood cognition were examined in the speed and time concept areas: (a) The respective composition and reverse operations of 2 of the 8 structures posited in the groupement model (Groupement I and Groupement V) should emerge synchronously in each of the 2 concept areas. (b) The 2 structures themselves should emerge synchronously in each of the 2 concept areas. (c) Between the 2 concept areas, the 2 structures should both emerge in the speed area before either emerges in the time area. The findings failed to support either prediction a or prediction b, and they were only partially consistent with prediction c. However, the findings concerning predictions a and b were consistent with other recent developmental evidence on the emergence of groupement structures in concept areas other than speed and time.

Age Factors↗
PubMed2001

Encoding of geometric and landmark information in the left and right hemispheres of the Avian Brain.

Chicks were trained binocularly to find food buried under sawdust in the center of a square enclosure. When tested in an enclosure made larger or smaller in size, binocular and left-eyed chicks searched mainly on the basis of relative distance of the food from the enclosure walls, whereas right-eyed chicks searched on the basis of absolute distance. Moreover, binocular and left-eyed chicks relied mainly on global spatial information (i.e., distances from the walls), whereas right-eyed chicks also used information provided by visual landmarks. These results suggest that the right hemisphere of the avian brain (fed mostly by the left eye) is primarily concerned with encoding of relational spatial information, whereas the left hemisphere (fed mainly by the right eye) is concerned with absolute metric information, possibly as part of an encoding strategy based primarily on local (both spatial and nonspatial) cues.

Animals↗
PubMed2001

Referent cognitions theory: the role of closeness of reference points in the psychology of voice.

The most generally accepted and best documented manipulation in procedural justice experiments is varying whether or not participants are allowed an opportunity to voice their opinion about a decision. To better understand the psychology of voice, the authors focus on Referent Cognitions Theory (RCT). It is argued that thus far RCT has not been used to explain the psychology of voice and that previous RCT research suffers from methodological problems and has been more outcome oriented than necessary. Two experiments resolve these problems and show that people react more strongly to procedures (especially no-voice procedures) when reference points are close as opposed to distant. These findings suggest that closeness of reference points plays an important role in the psychology of voice. The findings expand RCT in significant ways and indicate that insight into the role of reference points is essential for understanding the psychology of justice.

Cognition↗
PubMed1975

Vision in the water without a facemask.

Distance and size estimates and stereoacuity judgments were made in water by divers, both with and without facemasks. Without the mask, only stereoacuity was markedly degraded. Distance estimates were slightly more accurate, despite a great decrease in the range of visibility. Size estimates were slightly too small. Divers with refractive errors did not appear to be more handicapped than those with normal vision.

Distance Perception↗
PubMed1975

Ratio scale measurement of the perceived lengths of lines.

In Experiments 1 and 2, magnitude and category estimates of perceived line length difference were used to rank order 36 pairs of lines with respect to the psychological length difference between the lines forming a pair. In Experiment 3 magnitude estimates of line length ratios were used to order the same 36 pairs with respect to the psychological length ratio between the lines comprising a pair. A nonmetric analysis of the rank-order of the difference and ratio judgments was used to construct a ratio scale of perceived line length. Perceived line length was found to be a power function of physical line length with an exponent of .46. In Experiments 4 and 5, magnitude and category estimates of line length similarity were obtained. A nonmetric analysis of these data indicated that similarity judgments were monotonic inverses of judgments of psychological ratios.

Adolescent↗
PubMed1975

Feedback versus motor programming in the control of aimed movements.

In the Fitts paradigm the subject moves a stylus to the left or right of an initial rest position to reach targets that vary in size and in distance from the initial position. The classic finding for relatively long movements is that movement time, measured from leaving the initial position until contact with the target, depends on both distance and target size according to a relationship known as "Fitts' law." By contrast, reaction time, measured from the signal to move until the stylus leaves the initial position, is independent of these parameters. While replicating these results for long movements, the present data show a different pattern for very short movements, for which Fitts' law no longer holds and for which reaction time increases as the size of the target is decreased. These findings were interpreted as implying that long movements are under feedback control, whereas short movements are predominately programmed and ballistic. This conclusion was supported by the additional finding that elimination of visual feedback was more disruptive to the long than to the short movements.

Adolescent↗
PubMed2002

Viewpoint dependency in the recognition of dynamic scenes.

In 3 experiments, the question of viewpoint dependency in mental representations of dynamic scenes was addressed. Participants viewed film clips of soccer episodes from 1 or 2 viewpoints; they were then required to discriminate between video stills of the original episode and distractors. Recognition performance was measured in terms of accuracy and speed. The degree of viewpoint deviation between the initial presentation and the test stimuli was varied, as was both the point of time presented by the video stills and participants' soccer expertise. Findings suggest that viewers develop a viewpoint-dependent mental representation similar to the spatial characteristics of the original episode presentation, even if the presentation was spatially inhomogeneous.

Adult↗
PubMed2003

Design of a multi-sensor sonar system for indoor range measurement as a navigational aid for the blind.

This paper reports the methodology for the design of a sonar-based ranging and guidance system. The intended application of the system is to help a blind person avoid obstacles as he/she navigates his/her environment. Six sonar transceivers are arranged radially on a headgear worn by the user. The transceivers detect discrete range data at discrete-time sampling instances. A panoramic map of the environment is generated from the discrete-space sensory data. The paper emphasizes the challenges faced during the measurement of omnidirectional ranging information in indoor environments. Situations have been identified where erroneous range readings are generated due to channel cross talk caused by echo bouncing off multiple surfaces. Several sonar control and measurement schemes were developed and tested to avoid these situations. The results and performance of these different control schemes are compared in this paper. A microcontroller-based system commands the sonar ping sequences, acquires the echo return times and computes the ranges. The set of range data is transmitted to a PC, which utilizes the information to build a spatialized audio map of the surrounding obstacles. The hardware and software layout for the system are described in this paper.

Acoustics↗
PubMed1992

Accommodative response during distance optometric test procedures.

The control of accommodation is an essential requirement during the clinical optometric assessment of distance vision. Accordingly, the aim of the present study was to examine the steady-state accommodative response during a number of conventional clinical procedures carried out at a viewing distance of 6m (20 feet). Accommodation was measured subjectively to Snellen letters using a Hartinger coincidence optometer during distance viewing, simulated retinoscopy and following the introduction of cylindrical and prismatic lenses in 13 visually-normal, young adults. No significant change in the mean accommodative response was induced by any of the techniques described, with subjects exhibiting a lead of accommodation of approximately 0.25D for all conditions. The results demonstrate the robustness of accommodation to apparently substantial changes in stimulus conditions.

Accommodation, Ocular↗
PubMed1992

[A telescopic system for distance consisting of contact lens and spectacle lens for low vision patients].

A telescopic system for distance consisting of a negative contact lens (-10.0 - -20.0 D) as the eye piece and a positive spectacle lens (+8.0 - +16.0 D) as the objective, a modification of the Galilean telescope was examined. First the system was tried in 15 normal subjects, whose visual acuity was reduced to 20/200 or less by providing several occlusion membranes, and results were compared with customary full correction for distance. The best improvement of their vision by this system was achieved when the dioptric power of the spectacle was between +11.0 D and +13.75 D. This system was then applied to 78 eyes (61 patients) with visual acuity of 20/100 or less. Subjective improvement of vision was found in 55% of those patients' eyes. Eight patients out of 26 patients whose better eye acuity was 20/100 or less wanted to use this system and received prescription to result in the visual improvement, as evidenced by their continued use. This system can provide aid for low vision correction for distance.

Adolescent↗
PubMed1992

Biometric aspects of diffractive multifocal intraocular lenses.

A retrospective biometric study was done on 132 patients with diffractive multifocal intraocular lenses. The two principal focal points induced by the intraocular lens were refracted for distance in each patient. The difference in diopters between the refractions was obtained, and the A constant (SRK formula series) and anterior chamber depth (ACD, Binkhorst formula) were calculated. Our results showed the A constant was 116.46. This value was consistent and not affected by the axial length of the eye in the 22mm to 24.5mm range. In patients who had emmetropia with the intraocular lens power implanted alone, the constant was equal to 116.3. The ACD was 3.94mm. This value was lower in shorter eyes and higher than 3.94mm in longer eyes. On the basis of the data obtained, when the SRK-II formula is used, an A constant of 116.4 should be used in preoperative biometric calculations.

Anthropometry↗