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PubMed1983

Children and adults' distance estimations in a large-scale environment: effects of time and clutter.

In two experiments adults (mean age = 19-5), sixth graders (mean age = 11-8), fourth graders (mean age = 9-8), and second graders (mean age = 7-8) walked a straight line distance through a large-scale environment. Subjects were then asked to estimate the time taken to traverse each half of the walk and to estimate the distance between objects seen along the walk. In Experiment 1 each half of the walk was traversed in the same amount of time but contained a different number of objects (clutter). Time and distance estimates were related, but were not affected by the number of intervening objects encountered between locations. In Experiment 2 subjects again encountered a different number of objects along each half of the walk but each half was traversed in varying amounts of time. Again, time and distance estimates were related, and there was no clutter effect. There were no consistent developmental differences across the two experiments. It was concluded that (1) Thorndyke's clutter effect does not occur across all types of spatial cognition tasks, and (2) children and adults tend to relate time and distance across a variety of distance estimation tasks.

Adolescent↗
PubMed1984

Distance distortions in children's cognitive maps: an examination of the information storage model.

Second graders (mean age = 7-8), fourth graders (mean age = 9-8), and sixth graders (mean age = 11-11) walked two paths located in and around their school. Children in the Unsegmented condition estimated the distance and time taken to walk a path that was relatively undifferentiated in terms of the number of qualitatively different areas of the school through which it passed. Children in the Segmented condition made the same estimates for a path that went through different areas (segments) of the school (i.e., cafeteria, hall, vestibule, and outside the building). Children at all three grade levels estimated that the distance traversed in the Segmented condition was longer than the distance in the Unsegmented condition. This difference was not significant on the time measure. It was concluded that (1) paths with a large number of segments are perceived as being longer than paths of the same length with fewer segments, (2) distances along paths with few segments are underestimated, (3) distances along paths with many segments may be overestimated as a function of developmental level, and (4) only younger children may have used time to estimate distance.

Child↗
PubMed2004

Distance learning in post-qualifying nurse education.

There has been a prolific development of distance education in nursing during the previous decade. This has not been supported by an increase in research activity to generate the knowledge that is required to support these developments. In response to this, within a wider action research approach, a team of academics undertook a study to examine post-qualifying nurses' experiences of distance learning, and the impact of distance education on lecturing staff. Five teaching modules, delivered through distance learning, were selected for the study using a matrix sampling technique. Data collection took place at key points during these modules: at the commencement of study students and lecturers were asked to maintain a diary account of their experiences, students were sent questionnaires at the mid point of the module ( n=115, 30.4% return rate), and at the end of the module the students and lecturers participated in one of nine group interviews (students =15; LECTURERS = 15). Findings suggest that distance education is an effective learning medium that enables students to balance learning with personal and work commitments. Students and lecturers face a transitional period when embarking on distance education and this involves the development of new understandings and skills to successfully adapt to this approach to education.

Attitude of Health Personnel↗
PubMed2000

Running from the shadow: psychological distancing from others to deny characteristics people fear in themselves.

Four experiments tested the hypothesis that people distance themselves from others who display characteristics they fear in themselves. In Study 1, participants were given false feedback that they were high or low in repressed anger and were given information about a person who became angry and responded in a violent or nonviolent manner. High anger feedback participants distanced themselves only from the violent person. In Study 2, high anger feedback led to distancing from a violent other but not a dishonest other, whereas dishonesty feedback led to distancing from a dishonest other but not a violent other. The results of Studies 3 and 4 replicated and extended the distancing effect with an anger induction: Participants who were insulted distanced themselves from an angry/violent person, and verbalizing their emotions about being insulted eliminated this effect. Implications for understanding defenses against undesirable self-attributions are discussed.

Analysis of Variance↗
PubMed2007

What counts as by? Young children's use of relative distance to judge nearbyness.

The authors investigated how 3- and 4-year-old children and adults use relative distance to judge nearbyness. Participants judged whether several blocks were by a landmark. The absolute and relative distance of the blocks from the landmark varied. In Experiment 1, judgments of nearbyness decreased as the distance from the landmark increased, particularly for 4-year-olds and adults. In Experiment 2, 4-year-olds and adults were more likely to judge objects at an intermediate distance as by the landmark when intervening objects were absent than when intervening objects were present. In Experiment 3, participants of all ages were more likely to judge objects at a short distance as by the landmark when intervening objects were absent. Reliance on relative distance to judge nearbyness becomes more systematic and applicable to larger spatial extents across development.

Adult↗
PubMed2006

Global-scale location and distance estimates: common representations and strategies in absolute and relative judgments.

The authors examined whether absolute and relative judgments about global-scale locations and distances were generated from common representations. At the end of a 10-week class on the regional geography of the United States, participants estimated the latitudes of 16 North American cities and all possible pairwise distances between them. Although participants were relative experts, their latitude estimates revealed the presence of psychologically based regions with large gaps between them and a tendency to stretch North America southward toward the equator. The distance estimates revealed the same properties in the representation recovered via multidimensional scaling. Though the aggregated within- and between-regions distance estimates were fitted by Stevens's law (S. S. Stevens, 1957), this was an averaging artifact: The appropriateness of a power function to describe distance estimates depended on the regional membership of the cities. The authors conclude that plausible reasoning strategies, combined with regionalized representations and beliefs about the location of these relative to global landmarks, underlie global-scale latitude and distance judgments.

Cognition↗
PubMed2004

Perceiving distance accurately by a directional process of integrating ground information.

By itself, the absolute distance of an object cannot be accurately judged beyond 2-3 m (refs 1-3). Yet, when it is viewed with reference to a flat terrain, humans accurately judge the absolute distance of the object up to 20 m, an ability that is important for various actions. Here we provide evidence that this is accomplished by integrating local patches of ground information into a global surface reference frame. We first show that restricting an observer's visual field of view to the local ground area around the target leads to distance underestimation, indicating that a relatively wide expanse of the ground surface is required for accurate distance judgement. Second, as proof of surface integration, we show that even with the restricted view, the observer can accurately judge absolute distance by scanning local patches of the ground surface, bit by bit, from near to far, but not in the reverse direction. This finding also reveals that the surface integration process uses the near-ground-surface information as a foundation for surface representation, and extrapolation to the far ground surface around the target for accurate absolute distance computation.

Darkness↗
PubMed1994

The effect of knowledge of object distance on accommodation during instrument viewing.

We present data in which instrument accommodation was measured while knowledge of object distance was varied. The accommodative feedback loop was 'semiopen'--an intermediate state between the closed-loop and open-loop conditions of previous experiments. The semiopen-loop situation mimicked the degraded-image conditions which are frequently encountered during instrument viewing. The results show that for some subjects knowledge of object distance is a more powerful cue for instrument accommodation than is the optical distance of the object; however, for the majority of subjects this is not the case. We also found that subjects whose accommodation is influenced by knowledge of object distance tend to have a more proximal dark focus than those whose accommodation is independent of knowledge of object distance. We propose that the Mandelbaum effect, in which involuntary accommodation occurs when a transparency is superimposed between the observer and the object of regard, could account for the accommodative behavior of all subjects. However, the Mandelbaum effect would have to be interpreted more broadly than before. In the broader interpretation, the transparency could be cognitive (ie known distance) rather than physical.

Accommodation, Ocular↗
PubMed2003

A comparison of visual and nonvisual sensory inputs to walked distance in a blind-walking task.

Two experiments were conducted in order to assess the contribution of locomotor information to estimates of egocentric distance in a walking task. In the first experiment, participants were either shown, or led blind to, a target located at a distance ranging from 4 to 10 m and were then asked to indicate the distance to the target by walking to the location previously occupied by the target. Participants in both the visual and locomotor conditions were very accurate in this task and there was no significant difference between conditions. In the second experiment, a cue-conflict paradigm was used in which, without the knowledge of the participants, the visual and locomotor targets (the targets they were asked to walk to) were at two different distances. Most participants did not notice the conflict, but despite this their responses showed evidence that they had averaged the visual and locomotor inputs to arrive at a walked estimate of distance. Together, these experiments demonstrate that, although they showed poor awareness of their position in space without vision, in some conditions participants were able to use such nonvisual information to arrive at distance estimates as accurate as those given by vision.

Awareness↗
PubMed2004

The contributions of static visual cues, nonvisual cues, and optic flow in distance estimation.

By systematically varying cue availability in the stimulus and response phases of a series of same-modality and cross-modality distance matching tasks, we examined the contributions of static visual information, idiothetic information, and optic flow information. The experiment was conducted in a large-scale, open, outdoor environment. Subjects were presented with information about a distance and were then required to turn 180 before producing a distance estimate. Distance encoding and responding occurred via: (i) visually perceived target distance, or (ii) traversed distance through either blindfolded locomotion or during sighted locomotion. The results demonstrated that subjects performed with similar accuracy across all conditions. In conditions in which the stimulus and the response were delivered in the same mode, when visual information was absent, constant error was minimal; whereas, when visual information was present, overestimation was observed. In conditions in which the stimulus and response modes differed, a consistent error pattern was observed. By systematically comparing complementary conditions, we found that the availability of visual information during locomotion (particularly optic flow) led to an 'under-perception' of movement relative to conditions in which visual information was absent during locomotion.

Adolescent↗
PubMed2002

Correlation between hand preference and distance of focusing points of two eyes in the horizontal plane.

Relationships among hand preference, ocular dominance, and the degree of ocular shifting were studied in 78 right-handed and 16 left-handed subjects. Ocular dominance was assessed with the Miles test. The shifting degree of eye was assessed using a modified Miles test. The shifting distance of the right-eye was marginally greater, although significant, in the left-handers as compared to the right-handers. The shifting distance of the left-eye was greater in the right-handers than in the left-handers. The distance of focusing points of two eyes in the horizontal plane was greater in the right-handers than in the left-handers. In the total sample, there was a significant negative Pearson correlation between hand-preference and the shifting distance of the right-eye, and there was a positive correlation between hand-preference and the shifting distance of the left-eye. In addition, there was a significant positive correlation between hand preference and the distance of focusing points of two eyes. These results suggest that hand preference may be related to the degree of ocular asymmetry.

Adolescent↗
PubMedDate not supplied

Heterogeneity of long-distance migration in studies of genetic structure.

One of the assumptions of migration matrix methods of population structure is that long-distance migrants are all sampled from a genetically homogeneous 'outside world'. This assumption has not often been tested. This paper examines migration and surname data from four towns in historical Massachusetts in order to examine this assumption and potential genetic effects of heterogeneous long-distance migration. Analysis of migration data shows that the rate of long-distance migration is significantly different for the four towns. The distributions of source populations for long-distance migrants into each town are significantly different. Surname analysis shows that in spite of the violation of the assumption of long-distance migrant homogeneity, there is little effect on the degree and pattern of within-group and among-group variation for these towns. This lack of effect seems related to genetic homogeneity of the long distance migrants.

Emigration and Immigration↗
PubMed1989

Viewing distance affects stereoscopic tilt created with spatial frequency disparity.

A controversy exists as to whether stereoscopic tilt created with interocular differences in spatial frequency is based on perception of spatial frequency disparity or positional disparity. To determine which hypothesis is correct, we investigated the influence of viewing distance on perceived tilt. Tilt was induced by having observers view, at three viewing distances, dichoptic spatial frequency grating patterns differing in frequency by 25%. By appropriate physical scaling of the size of the patterns, their spatial frequency and angular width remained unchanged as distance varied. Under such conditions, the spatial frequency disparity hypothesis predicts no effect of distance, whereas the positional disparity hypothesis predicts a significant effect of distance (due to stereoscopic depth constancy) on the magnitude of tilt. The results showed that perceived tilt does covary with distance, a result consistent with only the positional disparity hypothesis.

Adolescent↗
PubMed2003

Development and testing of an instrument to measure interactions in synchronous distance education.

The advance of computer and network technology has made it possible for students to flexibly acquire real-time information through distance education, allowing life-long learning. As in previous studies, the researchers found that students generally experienced less instructional interaction in distance education as compared to the traditional classroom setting. The purpose of this study was to develop and test a reliable and valid instrument to evaluate instructional interactions in synchronous distance education. Based on a literature review and researcher experience, a 36-item interaction scale was developed and administered to 100 students from two different schools. Data were collected and the reliability and validity of the scale were tested. The results showed that the scale had a Cronbach's alpha coefficient of 0.901. Factor analysis was used to test the construct validity and 29 items were extracted and divided into seven different interaction factors. These seven factors explained 72.69 % of the total variance. Furthermore, the results showed that the scale had good internal consistency and construct validity, and would therefore provide an effective and useful tool for evaluating interaction in synchronous distance education. Use of this instrument can help teachers to understand interactions taking place in a synchronous distance education environment and provide guidance for the future development of distance education programs for various disciplines.

Adult↗
PubMed1999

Increasing confidence in vergence as a cue to distance.

Multiple cues contribute to the visual perception of an object's distance from the observer. The manner in which the nervous system combines these various cues is of considerable interest. Although it is accepted that image cues play a significant role in distance perception, controversy exists regarding the use of kinaesthetic information about the eyes' state of convergence. We used a perturbation technique to explore the contribution of vergence to visually based distance estimates as a function of both fixation distance and the availability of retinal information. Our results show that the nervous system increases the weighting given to vergence as (i) fixation distance becomes closer; and (ii) the available retinal image cues decrease. We also identified the presence of a strong contraction bias when distance cues were studied in isolation, but we argue that such biases do not suggest that vergence provides an ineffectual signal for near-space perception.

Adolescent↗
PubMed1994

Dissociation between perception and visuomotor transformation during reproduction of remembered distances.

1. In complete darkness subjects were presented with two visual stimuli whose distance was randomly varied. The subjects were required to reproduce the interstimulus remembered distance in two conditions. In one condition (reproduction by pointing) they pointed to a virtual position in space. In the other condition (visual reproduction) they used two other visual stimuli. One of them was fixed, and the other could be manually moved. Constant and variable errors were measured in the two conditions. 2. Constant error varied between the two conditions. In the pointing task subjects slightly overestimated the shorter distances, and underestimated the longer ones. During visual reproduction, they consistently overestimated all distances, and the error of overestimation tended to increase with distance. Statistical comparison between the errors in the two conditions was significant. Variable error increased with distance in both conditions, but did not show any significant difference between the two tasks. 3. The results of the present experiment support the hypothesis that perception and visuo-motor transformation are two separate processes in which the same object attributes are independently analysed. However, the finding that variable error did not change between the two tasks suggests that some stages are common to the two processes.

Adult↗
PubMed2005

Path integration in a three-dimensional maze: ground distance estimation keeps desert ants Cataglyphis fortis on course.

In this study, we investigate the ability of desert ants to gauge the ground distances of sloped sections in a three-dimensional (3D) outbound path. Ground distance estimation, as opposed to a simple measurement of walking distances, is a necessary prerequisite for precise path integration in undulating terrain. We trained ants to visit a feeder along a path that included an angular turn as well as a 'hill', resulting in an outbound path with a distinct 3D structure. We then observed the ants' return path in a test field on level ground. From the angles of the ants' return path on the test field one can infer which property of the hill segment was fed into the ants' path integration module, the actual walking distance or the ground distance. The results show clearly that it is the ground distance that Cataglyphis fortis feeds into its path integrator, and suggest that the ants are able to keep an accurate home vector also in hilly terrain.

Animals↗
PubMed1999

Distance estimation with night vision goggles: a little feedback goes a long way.

Immediate feedback was given to correct observers' estimates of distance in an experiment in which those estimates were made outdoors at night while observers wore night vision goggles (NVGs). Initially observers made unguided estimates of distances between marked positions in an open field. Those distances ranged from 7.6 m (25 ft) to 64 m (210 ft). Later the same observers made more estimates. After each of these they were told the measured distance between the positions. During this training, the observers' height from the ground plane was either at a standing position or at an elevated position raised 2.3 m (7 ft 7 in) from standing position. After the training--either immediately after, a week later, or at both times--observers made unguided estimates of distance for a second time. These latter estimates of ground distance made with the NVGs were improved. Average improvement of the observers' estimates persisted for at least one week after training. This training can be applied to improve clearance estimates and estimates of hover height for pilots of rotary-wing aircraft.

Aerospace Medicine↗