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PubMed1983

Induced esophoric shifts in eye convergence and illusory distance in reduced and structured viewing conditions.

Two experiments measured distance judgments in reduced and structured viewing conditions before and after induced phoria. Experiment 1 induced phoria shifts with three 5-min. intervals of close handwork (i.e., needle threading) that had naturalistic characteristics of observers (a) choosing their own viewing distance, (b) moving their heads freely, and (c) viewing in a well-illuminated, structured environment. The handwork induced a 1.20-diopter esophoric shift and a 1.22-cm overestimation of distance under reduced test conditions. The handwork induced no measurable illusion under structured viewing conditions. Experiment 2 induced phoria shifts with 10 min. of fixation on a target 11 cm away. This procedure induced a 4.65-diopter esophoric shift, a 6.34-cm overestimation of distance in reduced conditions, and a 2.31-cm overestimation of distance in structured conditions. We argue that visual and motor information interact to determine perceptions and that induced esophoric shifts in everyday situations may shape the nature of that interaction.

Adaptation, Ocular↗
PubMed1983

Presentation- and test-trial effects on acquisition and retention of distance and location.

Acquisition and retention effects of presentation and test trials on movement distance (Experiment 1) and location (Experiment 2) were examined under three multitrial training methods. Three groups of 15 government employees performed three training trial cycles consisting of six trials each. Training methods emphasized either presentation-trial repetition, test-trial repetition, or presentation- and test-trial alternation within cycles. After training, both short- (3 min.) and long-term (24 hr.) retention scores were recorded. Absolute error revealed that (a) presentation-trial repetition promoted acquisition of both distance and location but resulted in extensive short- and long-term forgetting; (b) test-trial repetition produced error increases within cycles, potentiated presentation-trial effectiveness during acquisition, and enhanced long-term retention of both distance and location; (c) presentation- and test-trial alternation promoted distance and location acquisition and produced distance retention intermediate to that of the other two methods. Experiment 3 provided data to support the interpretation that test-trial retention benefits are a function of movement execution mode.

Adult↗
PubMed1996

The effects of dorsal versus ventral hippocampal, total hippocampal, and parietal cortex lesions on memory for allocentric distance in rats.

To test for the contribution of the parietal cortex and hippocampus to memory for allocentric spatial cues, the authors trained rats on a go/no-go task that required the rat to remember the distance between two visual cues. Total hippocampal lesions impaired working-memory representation for allocentric distance, whereas parietal cortex lesions resulted in only a transient impairment. In a second experiment, neither hippocampal nor parietal cortex lesions impaired allocentric distance discrimination. A third experiment showed that both the dorsal and ventral areas of the hippocampal formation must be destroyed to impair working memory for allocentric distance information. There appears to be a dissociation between the hippocampus and parietal cortex in mediating memory for allocentric distance information.

Animals↗
PubMed2004

Clark's nutcrackers (Nucifraga columbiana) and the effects of goal--landmark distance on overshadowing.

Three groups of Clark's nutcrackers (Nucifraga columbiana) were trained to find a goal location defined by an array of 4 landmarks that varied in goal--landmark distance. The arrays for each group differed in the distance of the closest landmark and contained goal--landmark distances that were common across groups, allowing for the examination of the effects of both relative and absolute goal--landmark distance on encoding of a landmark array. All 3 groups readily learned the task and were subsequently tested in probe tests with only single landmarks from the array available. Search error in tests with single landmarks was compared both within and across groups. Results demonstrated that both relative and absolute goal-landmark distances are important in spatial search.

Animals↗
PubMed1998

Electric fish measure distance in the dark.

Distance determination in animals can be achieved by visual or non-visual cues. Weakly electric fish use active electrolocation for orientation in the dark. By perceiving self-produced electric signals with epidermal electroreceptors, fish can detect, locate and analyse nearby objects. Distance discrimination, however, was thought to be hardly possible because it was assumed that confusing ambiguity could arise with objects of unknown sizes and materials. Here we show that during electrolocation electric fish can measure the distance of most objects accurately, independently of size, shape and material. Measurements of the 'electric image' projected onto the skin surface during electrolocation revealed only one parameter combination that was unambiguously related to object distance: the ratio between maximal image slope and maximal image amplitude. However, slope-to-amplitude ratios for spheres were always smaller than those for other objects. As predicted, these objects were erroneously judged by the fish to be further away than all other objects at an identical distance. Our results suggest a novel mechanism for depth perception that can be achieved with a single, stationary two-dimensional array of detectors.

Animals↗
PubMed1995

Effects of distance on vocal intensity.

The vocal response of speakers to change of distance from a listener is in dispute. Warren (1968) found that speakers obeyed the inverse square law when compensating for distance changes; that is, they decreased their vocal intensity by 6 dB when distance was halved. However, speakers in a study of Johnson, Pick, Siegel, Cicciarelli, and Garber (1981) changed their vocal intensity by much less than 6 dB. This study was an attempt to reconcile the conflicting results and to gain better understanding of what people know implicitly about the effects of distance on intensity. Speakers in the present study significantly changed their vocal intensity to compensate for changes in distance, but by a maximum of 2.46 dB. Possible reasons for the different results are discussed.

Adult↗
PubMed2002

Distance learning: an option for your future?

Distance learning programs are proving to be very popular for advancing nursing education from both a continuing education and academic degree perspective. Whether one is exploring opportunities to maintain perianesthesia certification or to pursue an advanced academic degree, distance learning technologies offer many feasible options. The following article provides prospective distance learning students with a brief description of distance learning, including its history and evolution. Distance learning technologies are reviewed and key elements that can determine student satisfaction and success are discussed.

Education, Distance↗
PubMed2001

Distance learning in nursing.

OBJECTIVES: To inform oncology nurses about distance-learning technologies and to offer suggestions for how nurses can locate, appropriately select, and use distance learning to their benefit. DATA SOURCES: Published articles, research studies, and review articles pertaining to distance education and learning in nursing. CONCLUSIONS: Distance learning offers new opportunities for nurses who are seeking basic or advanced degrees, certificates, or lifelong learning for professional development. IMPLICATIONS FOR NURSING PRACTICE: Oncology nursing practice is a dynamic specialty and requires the nurse to be a lifelong learner. Distance learning facilitates this requirement.

Certification↗
PubMed1983

Apparent relative size in the judgment of apparent distance.

In experiment 1 judgments of the apparent distance of comparison figures (squares or triangles) were obtained under reduction conditions. These comparison figures were either shaped the same as or different from equidistant standard figures, and were half, equal to, or double the area of the standard figures. Apparent distance was found to be a linear function of the relative area of the comparison figure both in same-shape and different-shape stimulus pair conditions. In addition, apparent distance was found to be a function of perceived area, because in different-shape conditions triangles were generally seen to be closer than squares even when the real area of the standard and comparison was equal. The results of experiment 2 and 3 provide some evidence that the effect of different shapes of standard and comparison on apparent distance is due to the observers' perception of the height rather than the area of figures. The series of experiments shows that the traditional transactionalists' explanation of relative size as a cue for distance is inadequate.

Adult↗
PubMed1992

Spectral content as a cue to perceived auditory distance.

Changes in the spectral content of wide-band auditory stimuli have been repeatedly implicated as a possible cue to the distance of a sound source. Few of the previous studies of this factor, however, have considered whether the cue provided by spectral content serves as an absolute or a relative cue. That is, can differences in spectral content indicate systematic differences in distance even on their first presentation to a listener, or must the listener be able to compare sounds with one another in order to perceive some change in their distances? An attempt to answer this question and simultaneously to evaluate the possibly confounding influence of changes in the sound level and/or the loudness of the stimuli are described in this paper. The results indicate that a decrease in high-frequency content (as might physically be produced by passage through a greater amount of air) can lead to increases in perceived auditory distance, but only when compared with similar sounds having a somewhat different high-frequency content, ie spectral information can serve as a relative cue for auditory distance, independent of changes in overall sound level.

Acoustic Stimulation↗
PubMed1998

Cues to viewing distance for stereoscopic depth constancy.

A veridical estimate of viewing distance is required in order to determine the metric structure of objects from binocular stereopsis. One example of a judgment of metric structure, which we used in our experiment, is the apparently circular cylinder task (E B Johnston, 1991 Vision Research 31 1351-1360). Most studies report underconstancy in this task when the stimulus is defined purely by binocular disparities. We examined the effect of two factors on performance: (i) the richness of the cues to viewing distance (using either a naturalistic setting with many cues to viewing distance or a condition in which the room and the monitors were obscured from view), and (ii) the range of stimulus disparities (cylinder depths) presented during an experimental run. We tested both experienced subjects (who had performed the task many times before under full-cue conditions) and naïve subjects. Depth constancy was reduced for the naïve subjects (from 62% to 46%) when the position of the monitors was obscured. Under similar conditions, the experienced subjects showed no reduction in constancy. In a second experiment, using a forced-choice method of constant stimuli, we found that depth constancy was reduced from 64% to 23% in naïve subjects and from 77% to 55% in experienced subjects when the same set of images was presented at all viewing distances rather than using a set of stimulus disparities proportional to the correct setting. One possible explanation of these results is that, under reduced-cue conditions, the range of disparities presented is used by the visual system as a cue to viewing distance.

Cues↗
PubMed1999

Some recent studies on the extraretinal contribution to distance perception.

Some recent studies on the extraretinal contribution to distance perception are reviewed. These experiments demonstrate that vergence can provide reliable information for judgments on the distance of proximal targets in the absence of all other cues. We argue that, although vergence is an unreliable cue at large fixation distances and is subject to a strong contraction bias when studied in isolation, these facts do not imply a minor role for vergence in near-space perception. When additional depth and distance cues are added, the contribution of vergence information becomes more complicated. We present results which indicate that the different cues to depth and distance are combined in a manner that can result in unexpected distortions of visual space. A simple heuristic model which can produce the observed distortions is outlined.

Accommodation, Ocular↗
PubMed1980

Effects of situational stress and sex on interpersonal distance preference.

The prediction that people prefer greater distance between themselves and others when they anticipate a stressful situation was tested. The sex of the "other" was expected to have an interactive effect on distance preference. Written descriptions of settings in which people anticipated future situations of high and low stress were presented and Ss indicated seating preference. When anticipating more stressful situations, more distance from another person was preferred. Males preferred to sit closer to the opposite sex while females preferred to sit closer to the same sex. These findings are consistent with an interpretation of interpersonal distance as a moderator of stress. The sex of the Ss and of their interaction partners must be considered in studies of interpersonal distance preference.

Choice Behavior↗
PubMed1996

The reverse social distance scale.

A "reverse" Social Distance Scale was created by modifying Bogardus's Social Distance Scale, to measure minority groups' perceptions of the social distance established by the majority group between itself and minority groups. The Reverse Social Distance Scale (Guttman's coefficient of reproducibility = 0.99) differentiated between the African American students and the other two groups of minority students in the present sample--Hispanic students and Others--but did not differentiate between the latter two groups. The relationships between the participants' choices of self-identification terms and their scores on the Reverse Social Distance Scale were varied.

Adult↗
PubMed1992

Assessing the differences in distance of interstate migration, 1980.

"This study examines distance of 1975-80 interstate migration [in the United States] and several explanations for the relations between distance and characteristic of migrants and locations.... Observations are individual records from the 1980 one-in-ten-thousand PUMS files. The sample is restricted to nonblack, noninstitutionalized head of households, age 25 to 64 in 1980.... We find outmigration is shaped by characteristics of individuals; however, distance of migration is shaped by characteristics at locations. Findings lend support to an interpretation of distance reflecting psychic costs and information and are consistent with a cost/benefit view of factors contributing to distance of migration."

Americas↗
PubMed2005

Twelve tips for supporting online distance learners on medical post-registration courses.

There is an increased interest in online distance learning programmes targeted at medical professionals as they are often marketed as providing an ideal way to study due to the flexibility to access high quality materials anywhere, any time and any place. Traditionally, however, online distance learning programmes have low retention rates. Online distance learners are distinctive students who have more constraints than traditional face-to-face students such as time issues as many are working full-time and have family commitments. Lack of student support has been identified as a major factor in students dropping out of online distance learning courses. This article examines the characteristics of a good support system for online distance learning courses and provides practical advice on implementation from development through to evaluation.

Computer-Assisted Instruction↗
PubMed2004

Making distance education accessible for students who are deaf and hard-of-hearing.

Distance education is based on providing learning "anytime, anywhere." The design of many distance education courses, however, may actually erect barriers to the full participation of some students with disabilities, particularly those with hearing impairments. Without careful consideration, distance education could become learning anytime, anywhere, but not for anybody. It is not only unethical, but also illegal to ignore the special needs of these learners. The specific impact of such legislation on distance education for those students with hearing impairments will be addressed. Students with disabilities are often faced with a double digital divide that must be bridged. Universal design uses an excellent proactive approach to closing this digital divide caused by inaccessible courses. Each medium of transmission in distance education poses unique access barriers. Even within the same medium, what is best for one student or class may not be the most ideal accommodation in another situation. Individualized accommodation methods will be examined, and specific technologies and software will be discussed.

Communication Devices for People with Disabilities↗
PubMed2004

Adult attachment style and interpersonal distance.

We tested for an association between adults' attachment style and their regulation of interpersonal physical distance. In Study 1, the stop-distance paradigm was used to derive measures reflecting tolerance of and reactiveness to spatial-intrusion. As predicted, university students who were classified as avoidantly attached (by a 3-category attachment style measure) were less tolerant of close interpersonal physical proximity than were securely attached individuals. Further, they were more reactive to spatial-intrusion by a male (but not a female) adult. In Study 2, we measured the distance that participants chose to sit from an interviewer. Participants' ratings on a 4-category measure were used to classify them into an attachment style and to derive measures of positive self model and positive other model. Results revealed that fearfully avoidant adults were distinguished by their choice of far interpersonal distances. Across subjects, the measure of positive self model made a unique contribution to choice of interpersonal distance, but the measure of positive other model did not. In summary, the data provide evidence of an association between adults' comfort with interpersonal emotional closeness (attachment style) and their comfort with and regulation of interpersonal physical closeness.

Adult↗