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PubMed1981

Visual and kinesthetic memory and integration of mentally retarded and nonretarded adults.

The verbal short-term memory finding (Brown, 1974) that retarded individuals often fail to adopt rehearsal strategies spontaneously was extended to situations involving visual and kinesthetic short-term memory. Subjects were presented with a distance either visually or kinesthetically and after either a filled or unfilled retention interval were asked to reproduce the distance either visually or kinesthetically. Both retarded and nonretarded subjects seemed to benefit from the opportunity to rehearse information over the unfilled retention interval. The performance of cultural-familial retarded subjects mirrored that of nonretarded subjects, but brain-damaged subjects did particularly poorly in crossmodal situations. In conditions involving kinesthetic reproduction, brain-damaged subjects systematically overestimated distances.

Adult↗
PubMed1981

Scaling spatial extent, velocity and duration of motion.

Experiments on magnitude estimation of spatial extent, velocity and duration of 11 moving stimuli which had low correlations between the stimulus attributes revealed psychophysical curves of different slopes and shapes for the three attributes of motion. A psychophysical power function with an exponent almost equal to 1.0 described the magnitude estimation of distance. Deviations in velocity judgments were observed with shortening the spatial extent of motion. Duration estimation determined by moving stimuli was found to differ significantly from the estimation of time intervals of the same range presented with stationary light stimuli (Marinova, Mitrani, Yakimoff, 1980). The results indicate that velocity cannot be regarded as a directly perceived attribute of motion. Distance only seems to be directly perceived.

Distance Perception↗
PubMed1980

Influence of visual conditioned stimulus characteristics on the form of Pavlovian appetitive conditioned responding in rats.

The influence of visual stimulus characteristics on the form of Pavlovian appetitive conditioned responding in rats was examined in three experiments. In Experiment 1, localized conditioned stimuli (CSs evoked behaviors mostly directed toward the CS source, and more diffuse CSs) evoked behaviors mostly directed toward the delivery site of the food unconditioned stimulus (US). In Experiment 2, localized CSs nearer the US delivery site evoked more CS-directed but less US site-directed behaviors than localized CSs farther from the US delivery site. In Experiment 3, the extent to which rats contacted CS sources depended on variation in a number of CS features casually described as affecting the feasibility of contact with those CSs. In all three experiments, some differences in behavior evoked by the various CSs were noted prior to conditioning; these differences were enhanced by conditioning and further magnified by discrimination training. These results are related to a hypothesis in which orienting responses play an important role in determining the character of Pavlovian conditioned responding.

Animals↗
PubMed1980

Cognitive mapping: knowledge of real-world distance and location information.

A series of experiments investigated how information about geographic environments is processed. In the first experiment, response time to decide which of two pairs of states or buildings were physically closer in the real world increased as the ratio of the interpair distances approached one. The second experiment examined spatial memory for the interrelationships among states and buildings. Subjects' reaction time to determine the accuracy of relative spatial positions of triads of states was a linear function of the degree of triad rotation from the 0 degrees Cartesian plane of a standard U.S. map. No linear rotation function was reported for triad rotations of buildings. In Experiment 3 a group of subjects unfamiliar with the campus tested in Experiments 1 and 2 learned the location of the buildings from a map only. This group's data reflected a linear trend of reaction time with degree of building triad rotation, similar to results with states in Experiment 2. Perhaps when an environment is primarily learned by a map, knowledge of the interpositions of items in the environment is formed in the single perspective of the map. When the environment is primarily learned through direct experience, knowledge of interpositions of items is more flexible and is processed from many perspectives.

Cognition↗
PubMed1980

The development of visual accommodation during early infancy.

4 experiments were conducted concerning the development of visual accommodation in 1- to 3-month-old infants. In experiments 1 and 2 dynamic retinoscopy was used to measure accomodation responses at 3 stimulus distances. The results of experiment 1 revealed better accommodative capability from 1 to 3 months than reported originally. The procedure of experiment 2 was somewhat different but the results confirmed those of experiment 1. In experiment 3, accommodative responses at 7 stimulus distances were carefully measured in a small number of infants. These data provided estimates of the shape of infants' accommodation functions. In experiment 4, we used infrared photography to measure infants' pupil diameters while they viewed the stimuli of experiments 1 and 2. 2 simple hypotheses of the developmental mechanisms which underlie early accommodative development were considered. First, development of the motor component of the accommodative system might determine accommodative development. Second, development of the sensory component of the accommodative system might determine the observed development. The first hypothesis was tentatively rejected because it is inconsistent with some clinical findings. Evaluation of the second hypothesis involved calculating infants' depth of focus. We used those depth-of-focus values to predict how well infants of different ages should accommodate if their only limitation were in the sensory component of the accommodative system. The agreement between those predictions and observed accommodation was excellent, suggesting that changes in depth of focus in the first 3 months are largely responsible for growth in accommodation. The theoretical implications of this finding are discussed.

Accommodation, Ocular↗
PubMed1980

Reference points in spatial cognition.

The present research investigates the hypothesis that cognitive representations of large scale space contain elements that may be termed reference points, and that these points are used to define the position of adjacent places. The nature and function of reference points is explored in five experiments. Experiments 1 and 2 consist of tasks during which subjects judged the distance between known locations. The subjective distance between reference points and nonreference points was found to be asymmetrical, with the latter ordered in relation to the former. Experiments 3 and 4 employ reaction time tasks in which subjects attempted to verify the distance or direction from an anchor location to target locations. The data indicate that the relative referentiality of anchor and target locations influences verification time. The results of Experiments 1-4 suggest that reference points occur in spatial cognition and that these points provide an organizational structure that facilitates the location of adjacent points in space. Experiment 5 consists of a multiple regression analysis designed to clarify the semantic attributes of spatial reference points.

Cognition↗
PubMed1980

Visual fields and hysteria.

Hysteria has long been recognized as a cause of subjective visual field defects. This paper will review the visual field associated with hysteria and examine patient characteristic of those who have shown this type of visual field loss.

Age Factors↗
PubMed1995

The right questions to assess materials. Selecting distance learning material.

1. Distance learning provides real educational opportunities, equal to and complementary with, traditional taught programme approaches. 2. Important questions to ask about distance learning include relevance to practice, accessibility, quality assurance, assessment and value for money. 3. Distance learning need not be lonely and isolating, and can provide education that travels with students--important in today's professional context.

Distance Perception↗
PubMed1995

Relationship between visual acuity and observation distance.

The visual acuities of 17 young emmetropes and corrected ametropes were measured over the range of 7.5-0.19 m using a Bailey-Lovie chart. Accommodation stimulus-response measures were also taken over this range using retinoscopy to establish whether variations in visual acuity with observation distance could be attributed to accommodation behaviour. Tonic accommodation was recorded using the Canon R1 autorefractor and was compared with visual acuity and stimulus-response results. In general, visual acuity was found to be dependent on stimulus distance, being significantly reduced for most observers for the closest targets. There were three categories of observer performance for visual acuity as a function of observation distance; one group showing no change in visual acuity with distance, a second showing a flat function for distances 7.55-0.5 m, and then a decrease in visual acuity for shorter distances; and a third category that showed a maximum visual acuity in the 1.2-1.6 m region. This behaviour was unrelated to individual stimulus-response characteristics and there was no significant relationship between tonic accommodation and the distance where acuity was best for the third category observers.

Accommodation, Ocular↗
PubMed1994

[What visual information does the automobile driver need for safe driving in street traffic?].

In daytime traffic the driver experiences a tremendous input of visual information: His problem is to extract the relevant stimuli in order to have an adequate reaction. Traffic at dusk or nighttime, however, is characterized by the fact that even a driver with full visual function approaches his physiological limit. By assessing real traffic situations under various circumstances of weather and illumination (daytime, dusk, nighttime, city traffic, country road) limits of adaptation luminance, object size, object contrast and color are demonstrated. In addition, typical distributions of luminance in the visual field of the driver and the distributions of size and location of relevant objects are quantified. For glare situations typical values of glare angle and corneal illuminance of the glare light and the induced reduction of contrast are determined. Our data demonstrate the type of visual information required by the driver in order to drive safely in road traffic. These data allow conclusions to be made with respect to minimum requirements of visual function for car drivers.

Automobile Driver Examination↗
PubMed1993

Mental comparison: P300 component of the ERP reflects the symbolic distance effect.

The symbolic distance effect was studied in a numerical comparison task by means of behavioural measures and event-related potentials (ERP). Two numbers in the range from 11 to 20 were presented simultaneously and the subjects had to indicate if the right side number was smaller or larger than the left side number. Reaction time, error rate and ERPs were selectively averaged according to the numerical differences between the two numbers. The symbolic distance effect was confirmed: Reaction times and error rates decreased significantly with increasing difference between the two numbers. A significant distance effect was also found for both P300 amplitude and latency. The larger the numerical difference the larger the P300 amplitude and the P300 latency tended to be shorter. This finding suggests that the numerical difference is effective already during stimulus encoding.

Adult↗
PubMed1993

[Computer display work and rest position of the vergence system].

Subjects with different characteristics of the vergence system resting state (close or distant resting vergence, large and small increase upon depression of the eyes) worked with a VDU in a relatively high and a relatively low position for 1 1/2 hours. The directions of gaze were about -5 degrees and -35 degrees below the horizontal. A shorter observation distance was chosen with the lower VDU position than with the higher one, and it increased during the course of the work. In the high VDU position the increase was particularly strong for subjects with a distant resting vergence. The discrepancy between the angle of convergence during visual work and the resting vergence was larger in subjects with a distant resting vergence than in subjects with close one, and it was larger with the higher than with the lower VDU position (except in subjects with a minimal effect of eye depression on resting vergence). However, corresponding differences in visual fatigue as assessed by means of a questionnaire could not be found. Nevertheless the majority of subjects preferred the low VDU position. A number of additional consequences of a low VDU position support the conclusion that it would be advantageous for many users to tilt the display backward and to sink it below the level of the table surface.

Adult↗
PubMed1993

[Contrast sensitivity and defocus curve with various bifocal-IOL].

Simultaneous vision, the basic principle of all bifocal intraocular lenses (IOLs), provides increased depth of focus but also causes a loss in contrast. We therefore measured contrast acuity (CA) (Regan Charts) and the defocus curve at different pupil sizes in 14 patients with a TRUE VISTA bifocal IOL (TV) (Storz Co.), 10 patients with a 3M diffractive bifocal IOL (3M) (3M Co.) and 9 patients with a Nordan Aspheric Varifocal Silicone IOL (VF) (Wright Medical Inc.). CA at distance focus was best with VF; next was TV, and 3M showed the lowest values. At near focus, CA was best with 3M; next was TV, and VF showed the lowest values. Differences between VF and 3M were significant (P = 0.05; t-test). CA at near focus was significantly lower than at distance focus with TV and VF (TV: P = 0.0001; VF: P = 0.005). Pseudoaccommodation was 4.5 D with TV and 3M and 3D with VF. In conclusion, distance CA was best with VF but pseudoaccommodation was not sufficient for reading. Near CA was best with 3M while distance CA was somewhat reduced. TV showed good distance CA while near CA was still sufficient. TV therefore seems to provide a good compromise.

Accommodation, Ocular↗
PubMed1993

Visual guidance in infants' reaching toward suddenly displaced targets.

This experiment evaluated the role of visual input about the location of a target object and the location of the hand in reaching by infants and adults. 5- and 9-month-old infants were presented with illuminated toys to reach for in a dark room. On no-switch trials, the toy remained illuminated throughout the infant's reach, whereas on switch trials the first-lit toy was replaced during the reach by a second-lit toy at a different position. On approximately half of the trials of each type a luminescent marker was attached to the reaching hand. Adult subjects (tested without the hand marker) fully compensated to the second-lit toy on switch trials, during a second reaching segment. On switch trials, 9-month-olds partially adjusted to the second-lit toy when wearing the hand marker and did not adjust without it. On no-switch trials, 9-month-olds reached just as accurately with or without the hand marker. 5-month-olds were generally inaccurate in their reaching and were unaffected by the presence or absence of the hand marker. The findings suggest that during the development of reaching there is an increase in visual guidance during the approach phase of reaches.

Adult↗
PubMed1993

Follow-up of square drawing test in vestibular neuronitis.

The square drawing test (SDT) devised by Sekitani (1975), which is a modification of Fukuda's vertical writing test, was performed to evaluate vestibular dysfunction in 15 patients with vestibular neuronitis followed up for a long period. In particular, two parameters (distance and total length) were analyzed in the present study. Distance was analyzed by dividing the 15 cases into 3 groups. The largest group showed a tendency to shorten at an early stage. Total length was examined by dividing the 15 cases into 3 groups. The largest group showed a tendency towards macrographism at an early stage. It was found that as the degree of caloric responses recovered, the range of distance and total length decreased. Considering the correlation between parameters of the SDT (distance and total length) and caloric responses we concluded that the SDT is a feasible method to evaluate and follow up patients with vestibular dysfunction.

Adolescent↗