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PubMed1993

Two roads diverged: young children's ability to judge distance.

In the present studies, we investigated 4- and 5- to 6-year-old's ability to compare the distances covered by a direct route to a location and an indirect route to the same location. The distances ranged between 16 and 22 feet. The routes were visible from a single vantage point, and objects serving as landmarks were sometimes located along the routes. We found clear demonstrations of the two classic Piagetian distance errors--the direct-indirect error, in which children judge that a direct route and an indirect route cover the same distance, and the interposed object error, in which children judge that a route is shorter when it is segmented by an object located somewhere along the route. The interposed object error occurred because children focused on only one segment of the route, which was consistent with Piaget's explanation of the error. However, in contrast to Piaget, we found that about 40% of 4-year-olds could successfully avoid the direct-indirect error, and in addition, when the routes were visually displayed, they could also avoid the interposed object error. It is important that they also gave correct explanations for why the indirect route was longer, by referring to the fact that it was not straight. For these children at least, the interposed object error was due to difficulty they had representing routes, rather than to a misconception of distance. We suggest that future research should examine whether that may also be true for younger children.

Analysis of Variance↗
PubMed1993

Effective action by infants to contact objects by reaching and leaning.

The ability of infants aged 8-12 months to coordinate their arm and trunk movements to contact an object located in different positions was investigated in 2 experiments. In the first, 8- and 10-month-old infants reached for near objects but both reached and leaned for more distant ones indicating that they perceived that forward leaning extends the range of contact beyond that of reaching alone. In addition, arm and trunk movements were initiated simultaneously; visual information concerning object distance was sufficient to activate an integrated reaching-and-leaning response. Object distances were increased and a mechanical aid was provided on half the trials in the second experiment with 10- and 12-month-old infants. For both age groups the degree of leaning was reduced for objects that were out of reach without the aid. Only older infants were able to use the aid to extend partially their range of contact. Overall the results support the conclusions that, by at least 8 months, infants perceive that leaning extends their effective reaching space; by 10 months they perceive the limits within which reaching together with leaning is likely to be effective; and by 12 months they begin to perceive how this space may be extended by a mechanical aid.

Child Development↗
PubMed1995

Distance cues for vertical vergence adaptation.

Vertical vergence can be trained to respond to vertical and/or horizontal conjugate eye position, horizontal vergence, and vertical head tilt. This cross-coupling is manifest as a vertical phoria aftereffect (monocular vertical vergence response) that varies with direction and distance of gaze. The function of the spatially dependent adaptation is to maintain the calibration between vertical eye alignment and intended placement of the two retinal images. Oculomotor adaptation stabilizes our sense of spatial localization and calibrates a body-referenced coordinate representation of visual space that is necessary for visually guided motor responses. We have tested the possible association of vertical phoria adaptation with perceptual cues to distance in the absence of any other associated motor activity. During adaptive training, vertical disparity vergence was associated with variations of perceptual distance cues (including loom, overlap, relative size, and relative motion), oculomotor distance cues (horizontal vergence), or a combination of both classes of cues. We observed that in a 2-h period the open-loop (monocular) vertical vergence response could not be trained to occur as an aftereffect in association with the perceptual cues to distance, whereas it could be trained in association with oculomotor cues. We conclude that the spatial specificity of vertical vergence aftereffects caused by short-term adaptation results from an associated cross-coupling with supranuclear sources of oculomotor activity.

Adaptation, Ocular↗
PubMed1995

Effect of target proximity on transient myopia induced by equidioptric stimuli.

Transient myopia may be exhibited after sustained focus on a near target. This appears to be related to the within-task accommodative response. Although proximally induced accommodation has been shown to produce considerable transient myopia under open-loop conditions, its effect under naturalistic closed-loop conditions remains unclear. Accordingly, the present study examined the effect of target distance on transient myopia for equidioptric stimuli (5 D). A Canon R-1 autorefractor was used to assess the pre- and post-task refractive state objectively. Two tasks were performed monocularly and consisted of either accommodating on a near target at 20 cm (5 D) or a far target at 6 m viewed through a -5 D lens. The former task involved both blur and proximally induced accommodation, whereas the latter consisted of a blur stimulus only. Similar amounts of transient myopia were found under both conditions. These equivalent responses may be related to the relatively small output of proximally induced accommodation believed to be present under closed-loop conditions.

Accommodation, Ocular↗
PubMed1995

Abnormal transient myopia in symptomatic individuals after sustained nearwork.

After a sustained period of nearwork, some patients report slightly blurred distance vision for several seconds or even minutes. This presumed large and prolonged "abnormal transient myopia" has never been objectively documented. A Canon R-1 infrared autorefractor was used to assess distance refractive state every 2 s before and immediately after a binocular near task in three such individuals. Results showed a large post-task myopic shift, slowed baseline decay, and increased response variability as compared with that found in asymptomatic visually normal individuals. These findings suggested that this transient distance blur was related to the increased transient myopia resulting from one or more possible abnormalities related to the accommodative system.

Accommodation, Ocular↗
PubMed1995

[Expectancy effect in recognition of persons, or: on the tendency to corroborate perceptual hypotheses].

Two policemen who had been following and observing two young men for several hours appeared as witnesses in a criminal court case. They claimed that they had observed the young men from a distance of 375 meters putting concrete slabs onto a railway track. In order to determine whether person identification is possible at a distance of 375 meters, a field experiment was carried out. The results show that person identification at a distance of 375 meters is almost impossible. Any spontaneous identification with the naked eye is based on expectations. When using a pair of binoculars, identification is possible, but the rate of false alarms is higher than 60 percent. The results are discussed with reference to theories of perceptual and social psychology.

Adult↗
PubMed1995

[Recall errors in locating cities on a map].

Three experiments investigated whether hindsight bias--a systematic distortion of the recollections of numerical estimates--is also observed with visuo-spatial material. Subjects estimated the location of 20 German cities on an empty map, received feedback about the true locations, and were then requested to recall their earlier estimates. Additionally, we tested each subject's intelligence, field dependency, and visuo-spatial abilities. In experiment 1, in which experimental and control items (i.e. those with and without feedback) were given to the same subjects, hindsight bias was observed, but only in one out of three dependent measures. The same pattern of results emerged in experiment 2, despite the use of a different mode of data collection. Experiment 3, in which experimental and control items were given to different subjects, found a strong hindsight bias in all three dependent measures. The personality features showed no correlation with the amount of individual hindsight bias. All three experiments provided evidence that hindsight bias occurs with visuo-spatial material.

Adult↗
PubMed1996

The effect of pupil and observation distance on the contrast sensitivity function.

Measuring the contrast sensitivity function (CSF) is becoming more frequent in the analyses that are routinely done in optometric practice. This measurement is generally done in far vision, and the observation distance and its effects are not considered to significantly alter this function. Among these effects we should point out the accommodation of the visual optical system to the stimulus and the errors in accommodation associated with this, changes in pupil diameter and therefore in retinal illumination when the observation distance changes, the different level of aberrations (spherical aberration, astigmatism) for different cases, and so on. All of these factors contribute to the fact that the contrast sensitivity of a visual system varies according to the accommodative stimulus. In this study we attempt to clarify the influence of these different parameters by evaluating the CSF for three observation distances. The study was done in monocular vision, with a natural pupil and with a 3 mm artificial pupil that made it possible to maintain the same level of retinal illumination for all distances.

Accommodation, Ocular↗
PubMed1997

Size scaling and spatial factors in visual attention.

This study investigates the effect of the visibility of near and far letter distractors on target processing by scaling the size of the distractor letters to compensate for changes in resolution across the visual field. In Experiment 1, scaled and unscaled distractors were presented at varied stimulus onset asynchronies. Results showed that scaling the size of distractor letters in relation to their distance from the target was effective in producing strong compatibility effects. Scaled distractors presented prior to, or simultaneously with, the target were found to interfere with target processing whether they were near or far from the target. Experiment 2 used scaled distractors and varied the presentation location and the amount of time for processing prior to the presentation of the target. Compatibility effects were found to vary by location and by the exposure duration of the distractor. The finding of distance effects at far locations supports a space-based visual-attention mechanism with a wide attention beam (Steinman, Steinman, & Lehmkuhle, 1995).

Adult↗
PubMed1976

Effects of stimulus-response variables on the choice reaction time of mildly retarded adults.

Nonretarded and mildly retarded adults were compared in two experiments on an 8-choice reaction time (RT) task. Stimulus lights were either distant or close. Both groups responded more slowly when stimuli were distant, this effect being more marked for retarded subjects. Patterns of latencies suggested that, compared with nonretarded subjects, retarded subjects inspected information input for longer periods of time and made more inspections before responding. Faster RTs to stimuli nearest the ends and midline of the display and to stimulus repetitions indicated that retarded subjects were more reliant upon more discriminable cues in the stimulus display.

Adolescent↗
PubMed1976

The adjustment of reaching behavior to object distance in early infancy.

The prehensile activity and looking behavior of 2- and 5-month-old infants were videotaped in the presence of objects placed within and beyond possible contact distance. There was only a consistent adjustment of reaching behavior to stimulus distance in the case of the 5-month-old group. The distance discrimination evident in the prehensile activity of the older infants was paralleled by a reduction in the amount of attention paid to far objects.

Attention↗
PubMed1998

Cognitive channels computing action distance and direction.

Visually guided, goal-directed reaching requires encoding action distance and direction from attributes of visual landmarks. We identified a cognitive mechanism that seemingly performs visual motor extension before action initiation and replicated and extended previous results that identified a mechanism for visual motor mental rotation. We find that humans systematically delay action onset while newly planning increasingly distant arm movements beyond a visual landmark, consistent with an internal representation for visual motor extension. Onset times also changed systematically during concurrent mental rotation and visual motor extension computations required to process new directions and distances. Visual motor extension associated with reaching slowed when participants needed to plan action direction within the same time frame, whereas mental rotation efficiency was unaffected by concurrent needs to prepare action distance. In contrast to parallel direction and distance computations needed for direct aiming to a visual target, the planning of new directions and distances likely occurs at distinct times. When considered with previous findings, the current results suggest the existence of an intermediate component of motor preparation that engages a covert mechanism of cognitive motor planning.

Adolescent↗
PubMed2002

Multifocal glasses impair edge-contrast sensitivity and depth perception and increase the risk of falls in older people.

OBJECTIVES: To determine the extent to which multifocal glasses impair contrast sensitivity and depth perception at critical distances required for detecting hazards in the environment and whether multifocal glasses use increases the risk of falls in older people. DESIGN: One-year prospective cohort study. SETTING: Falls Laboratory, Prince of Wales Medical Research Institute. PARTICIPANTS: One hundred fifty-six community-dwelling people aged 63-90. MEASUREMENTS: Contrast sensitivity, depth perception, accidental falls. RESULTS: Eighty-seven subjects (55.8%) were regular wearers of multifocal (bifocal, trifocal, or progressive lens) glasses. These subjects performed significantly worse in the distant depth perception and distant edge-contrast sensitivity tests in conditions that forced them to view test stimuli through the lower segments of their glasses. Multifocal glasses wearers were more than twice as likely to fall in the follow-up period than nonmultifocal glasses wearers (odds ratio (OR) = 2.29, 95% confidence interval (CI) = 1.06-4.92), when adjusting for age, poor vision, reduced lower limb sensation and strength, slow reaction time, and increased postural sway. Multifocal glasses wearers were also more likely to fall because of a trip (OR = 2.79, 95% CI = 1.08-7.22), when outside their homes (OR = 2.55, 95% CI = 1.14-5.70), and when walking up or down stairs (P <.01). The population attributable risks of regular multifocal glasses use were 35.2% for any falls, 40.9% for falls due to a trip, and 40.9% for falls outside the home. CONCLUSIONS: The study findings indicate that multifocal glasses impair depth perception and edge-contrast sensitivity at critical distances for detecting obstacles in the environment. Older people may benefit from wearing nonmultifocal glasses when negotiating stairs and in unfamiliar settings outside the home.

Accidental Falls↗
PubMed2004

Auditory-visual temporal integration as a function of distance: no compensation for sound-transmission time in human perception.

In a psychophysical outdoor experiment with human subjects, the point of subjective simultaneity (PSS) of auditory and visual stimuli was measured for distances from 1 to 50 m. Repetitive sound and light pulses were presented with various stimulus-onset asynchronies, and subjects judged which modality came first. With increasing distance of the stimuli the PSS shifted in a linear relation toward delays of the light behind the sound. The slope of the regression line (3 ms/m) almost exactly corresponded to that of the temporal disparities resulting from the lower velocity of sound compared to light. These data refute the hypothesis proposed recently that there could be an 'implicit estimation' of sound-arrival time. The brain seems to eliminate such crossmodal temporal disparities by the integration of auditory and visual stimuli that fall into a time window, but not by specific compensatory processes that use an estimate of the sound delay.

Acoustic Stimulation↗
PubMed1989

Effect of differences in binocularity on perceived absolute distance.

1. Using a 0.9 x 4.0 m visual alley, perceived absolute distance was studied in four groups of subjects: binocular, cross-eyed, monocular, and induced-monocular individuals. 2. A power function between the different physical and perceived distances was adjusted and the relative and absolute errors made by the observers were calculated. Despite a tendency to overestimate distance in the monocular group, no significant differences were detected among groups. 3. The data suggest that, under natural-cue conditions, binocularity is not a determining factor for the perception of absolute distance.

Distance Perception↗
PubMed1996

Perception of back vowels: effects of varying F1 - F0 Bark distance.

In a study of vowel height perception using front vowels, Hoemeke and Diehl [J. Acoust. Soc. Am. 96, 661-674 (1994)] found that F1 - F0 distance was the best predictor of perceived vowel height for the phonological distinction [+/- high], while for two other vowel height distinctions F1 alone was the best predictor. Further, the [+/- high] identification function was defined by a sharp boundary located at 3- to 3.5-Bark F1 - F0 distance. One hypothesis offered was that F1 - F0 distance had cue value for the [+/- high] distinction because of an underlying quantal region on the F1 - F0 distance dimension. However, the results are also predicted if it is supposed that F1 - F0 distance is a cue for vowel height only for pure height distinctions. The present study further tested these possibilities, using back vowels. The results allowed us to reject both as general explanations of vowel height perception. However, the results were consistent with a third possible explanation, namely, that phonetic quality is determined by the tonotopic distances between any adjacent spectral peaks (e.g., F3 - F2, F2 - F1, and F1 - F0), with greater perceptual weight accorded to smaller distances.

Humans↗