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PubMed1977

Eye fixation and attention as modifiers of perceived distance.

An error in the perceived distance of a physically stationary object results in an apparent horizontal motion of the object if the head is moved horizontally. Procedures have been developed to use this apparent motion to measure the apparent distance of the object. Research also has indicated that the apparent distance of an object will tend to be displaced toward the distance at which the eyes are fixated. In the present study head-motion procedures were used to measure the effect of eye fixation and attention upon the apparent distance of a point of light in two experiments. Substantial errors in perceived distance occurred in the predicted direction as a function of fixation distance. Attending to an object at a distance other than the distance of the fixated point of light had a much less effect upon the apparent distance of the point. It is concluded that the apparent conomitant motion which occurs in a variety of situations as a function of the distance of fixation indicates that substantial errors in perceived distance are common in most environments.

Attention↗
PubMed1993

Visual angle as a determinant of perceived interobject distance.

Two new experiments and a reanalysis of Toye's (1986) data are used to examine the relationship between true distance and perceived distance in natural scenes. In the first experiment, 8 subjects estimated 78 interobject distances, formed by all pairs of 13 objects, while viewing the objects from a fixed position. The results showed that estimated distance is a linear function of the visual angle between objects as well as of the true distance. This relationship results in distances perpendicular to the line of sight being overestimated in relation to true distances and to distances parallel to the line of sight. These findings were confirmed by reanalysis of a comparable data set from Toye. Since changes in the visual angle can come about through changes in alignment with the line of sight, viewing distance, or interobject distance, Experiment 2 was designed to determine whether the visual angle effect was due to one of these, or whether it was an independent effect. In Experiment 2, 8 subjects estimated six interobject distances from 12 viewing positions. The results showed that visual angle predicted estimated distance independently of how the change in visual angle came about, suggesting that the greater the visual angle between objects, the more their separation is overestimated.

Adult↗
PubMed2004

Regionalization of percutaneous transluminal coronary angioplasty and implications for patient travel distance.

CONTEXT: Minimum procedure volume thresholds have been proposed to improve outcomes among patients undergoing percutaneous transluminal coronary angioplasty (PTCA). How regionalization policies would affect patient travel distances is not known. OBJECTIVE: To examine the effect of regionalization of PTCA on patient travel distances. DESIGN, SETTING, AND PARTICIPANTS: A retrospective cohort study of discharge records, which were examined to determine hospital and operator procedure volumes, of 97,401 patients undergoing PTCA in New York, New Jersey, and Florida in 2001. Travel distances were measured at baseline and under 2 regionalization scenarios in which hospital-operator pairs not meeting minimum volume standards stopped providing services. MAIN OUTCOME MEASURES: Observed and expected patient travel distances, and risk-adjusted mortality. RESULTS: With a minimum volume standard of 175 per operator and 400 per hospital (class 1), 25% of patients had a shorter travel distance, 10% had a longer travel distance, and 65% experienced no change. Most patients with longer travel distances under this standard would travel no more than 25 miles farther, and most patients with shorter travel distances would save no more than 10 miles. With a minimum volume standard of 75 per operator and 400 per hospital (class 2), 11% of patients had a shorter travel distance, 2% had a longer travel distance, and 87% experienced no change. Under both standards, less than 1% of patients would travel more than 50 miles farther than their observed travel distance. Risk-adjusted mortality was higher for lower-volume hospital-operator pairs (1.2% for class 3 vs 0.9% for class 2 and 0.8% for class 1; P<.001 for both comparisons). CONCLUSION: Regionalization of PTCA would not increase travel distance for most patients; however, potential costs of regionalization not related to travel must be examined before such policies can be recommended.

Angioplasty, Balloon, Coronary↗
PubMed1995

Interproton distance bounds from 2D NOE intensities: effect of experimental noise and peak integration errors.

The effect of experimental and integration errors on the calculation of interproton distances from NOE intensities is examined. It is shown that NOE intensity errors can have a large impact on the distances determined. When multiple spin ('spin diffusion') effects are significant, the calculated distances are often underestimated, even when using a complete relaxation matrix analysis. In this case, the bias of distances to smaller values is due to the random errors in the NOE intensities. We show here that accurate upper and lower bounds of the distances can be obtained if the intensity errors are properly accounted for in the complete relaxation matrix calculations, specifically the MARDIGRAS algorithm. The basic MARDIGRAS algorithm has been previously described [Borgias, B.A. and James, T.L. (1990) J. Magn. Reson., 87, 475-487]. It has been shown to provide reasonably good interproton distance bounds, but experimental errors can compromise the quality of the resulting restraints, especially for weak cross peaks. In a new approach introduced here, termed RANDMARDI (random error MARDIGRAS), errors due to random noise and integration errors are mimicked by the addition of random numbers from within a specified range to each input intensity. Interproton distances are then calculated for the modified intensity set using MARDIGRAS. The distribution of distances that define the upper and lower distance bounds is obtained by using N randomly modified intensity sets. RANDMARDI has been used in the solution structure determination of the interstrand cross-link (XL) formed between 4'-hydroxymethyl-4,5',8-trimethylpsoralen (HMT) and the DNA oligomer d(5'-GCGTACGC-3')2 [Spielmann, H.P. et al. (1995) Biochemistry, 34, 12937-12953]. RANDMARDI generates accurate distances bounds from the experimental NOESY cross-peak intensities for the fixed (known) interproton distances in XL. This provides an independent internal check for the ability of RANDMARDI to accurately fit the experimental data. The XL structure determined using RANDMARDI-generated restraints is in good agreement with other biophysical data that indicate that there is no bend introduced into the DNA by the cross-link. In contrast, isolated spin-pair approximation calculations give distance restraints that, when applied in a restrained molecular dynamics protocol, produce a bent structure.

Algorithms↗
PubMed1994

Human ocular responses to translation of the observer and of the scene: dependence on viewing distance.

Recent experiments on monkeys have indicated that the eye movements induced by brief translation of either the observer or the visual scene are a linear function of the inverse of the viewing distance. For the movements of the observer, the room was dark and responses were attributed to a translational vestibulo-ocular reflex (TVOR) that senses the motion through the otolith organs; for the movements of the scene, which elicit ocular following, the scene was projected and adjusted in size and speed so that the retinal stimulation was the same at all distances. The shared dependence on viewing distance was consistent with the hypothesis that the TVOR and ocular following are synergistic and share central pathways. The present experiments looked for such dependencies on viewing distance in human subjects. When briefly accelerated along the interaural axis in the dark, human subjects generated compensatory eye movements that were also a linear function of the inverse of the viewing distance to a previously fixated target. These responses, which were attributed to the TVOR, were somewhat weaker than those previously recorded from monkeys using similar methods. When human subjects faced a tangent screen onto which patterned images were projected, brief motion of those images evoked ocular following responses that showed statistically significant dependence on viewing distance only with low-speed stimuli (10 degrees/s). This dependence was at best weak and in the reverse direction of that seen with the TVOR, i.e., responses increased as viewing distance increased. We suggest that in generating an internal estimate of viewing distance subjects may have used a confounding cue in the ocular-following paradigm--the size of the projected scene--which was varied directly with the viewing distance in these experiments (in order to preserve the size of the retinal image). When movements of the subject were randomly interleaved with the movements of the scene--to encourage the expectation of ego-motion--the dependence of ocular following on viewing distance altered significantly: with higher speed stimuli (40 degrees/s) many responses (63%) now increased significantly as viewing distance decreased, though less vigorously than the TVOR. We suggest that the expectation of motion results in the subject placing greater weight on cues such as vergence and accommodation that provide veridical distance information in our experimental situation: cue selection is context specific.

Animals↗
PubMed1996

A Bayesian evolutionary distance for parametrically aligned sequences.

There is an inherent relationship between the process of pairwise sequence alignment and the estimation of evolutionary distance. This relationship is explored and made explicit. Assuming an evolutionary model and given a specific pattern of observed base mismatches, the relative probabilities of evolution at each evolutionary distance are computed using a Bayesian framework. The mean or the median of this probability distribution provides a robust estimate of the central value. The evolutionary distance has traditionally been computed as zero for an observed homology of 20 bases with no mismatches; we prove that it is highly probable that the distance is greater than 0.01. The mean of the distribution is 0.047, which is a better estimate of the evolutionary distance. Bayesian estimates of the evolutionary distance incorporate arbitrary prior information about variable mutation rates both over time and along sequence position, thus requiring only a weak form of the molecular-clock hypothesis. The endpoints of the similarity between genomic DNA sequences are often ambiguous. The probability of evolution at each evolutionary distance can be estimated over the entire set of alignments by choosing the best alignment at each distance and the corresponding probability of duplication at that evolutionary distance. A central value of this distribution provides a robust evolutionary distance estimate. We provide an efficient algorithm for computing the parametric alignment, considering evolutionary distance as the only parameter. These techniques and estimates are used to infer the duplication history of the genomic sequence in C. elegans and in S. cerevisiae. Our results indicate that repeats discovered using a single scoring matrix show a considerable bias in subsequent evolutionary distance estimates.

Animals↗
PubMed2001

Shortening of mandibular linear distance with multivector distraction.

It was noted that when a multivector distractor is used, there is shortening of the linear distraction distance when the gonial angle is reduced and the transverse distance is increased. The purpose of this study was to measure the distance change at the mandibular corticotomy site when the gonial angle is reduced or the transverse distance is increased. The Synthes multivector distractor was used in this experiment. After initial linear distraction, the distractor was activated by angular and transverse adjustments to achieve an angular, a transverse, and a combined angular and transverse reorientation. The length of the pin from the distractor to the tip of pin was evaluated at 15, 20, and 25 mm. With the pins place at 180 degrees , the distractor arm length was evaluated at 30, 35, 40, 45 and 50 mm apart, respectively. The distance change between the ends of the pins was measured by means of a caliper. For angular activation, one turn shortened the linear distraction distance at the pin end by 1.5 to 2.2 mm. For transverse activation, one turn shortened the linear distraction distance by 1.1 to 2 mm. For combined angular and transverse activation, one turn of angular activation plus one turn of transverse activation shortened the linear distraction distance by 2.2 to 3.2 mm. For angular activation, increasing the pin length did not alter the distance between the pin ends for any of the specific activations. Increase in the distractor arm length in angular reduction resulted in significant increase in the shortening. For transverse increase, alteration in the distractor arm length resulted in the same shortening. Increase in the pin length resulted in increased shortening at the pin ends. When the transverse and angular activation were combined, the shortening was 80% of the combined measurements. The distance between the pin ends will reflect the distance between the bone segment at that site. It will be different at the outer cortex of the bone. These measurements will be valuable in planning the extent of additional linear distraction needed, when the angle is reduced or transverse distance is increased with the use of a multivector distractor. Alteration in the distractor arm length and pin length has a significant effect on the extent of shortening.

Biomechanical Phenomena↗
PubMed1992

Relationships between amino acid sequences determined through optimum alignments, clustering, and specific distance patterns: application to a group of scorpion toxins.

Optimum alignment in all pairwise combinations among a group of amino acid sequences generated a distance matrix. These distances were clustered to evaluate relationships among the sequences. The degree of relationship among sequences was also evaluated by calculating specific distances from the distance matrix and examining correlations between patterns of specific distances for pairs of sequences. The sequences examined were a group of 20 amino acid sequences of scorpion toxins originally published and analyzed by M.J. Dufton and H. Rochat in 1984. Alignment gap penalties were constant for all 190 pairwise sequence alignments and were chosen after assessing the impact of changing penalties on resultant distances. The total distances generated by the 190 pairwise sequence alignments were clustered using complete (farthest neighbour) linkage. The square, symmetrical input distance matrix is analogous to diallel cross data where reciprocal and parental values are absent. Diallel analysis methods provided analogues for the distance matrix to genetical specific combining abilities, namely specific distances between all sequence pairs that are independent of the average distances shown by individual sequences. Correlation of specific distance patterns, with transformation to modified z values and a stringent probability level, were used to delineate subgroups of related sequences. These were compared with complete linkage clustering results. Excellent agreement between the two approaches was found. Three originally outlying sequences were placed within the four new subgroups.

Amino Acid Sequence↗
PubMed1991

Ocular responses to translation and their dependence on viewing distance. II. Motion of the scene.

1. The ocular following responses induced by brief (100-ms) movements of the visual scene were examined for their dependence on viewing distance in 5 monkeys (Macaca mulatta). The horizontal positions of both eyes and the vertical position of one eye were recorded using the electromagnetic search-coil technique. Accommodation was monitored in selected experiments by use of an infrared optometer. Test patterns (random dots) were back-projected onto a translucent tangent screen facing the animal. Six viewing distances were used (range, 20-150 cm), the size and speed of the image on the screen being adjusted for each so as to preserve a constant retinal image. 2. Response measures based on the amplitude of the first peak in the eye acceleration profile or the eye velocity achieved at specific times all indicated that ocular following responses were inversely related to viewing distance, the relationship being linear for the earliest measures. On average, the sensitivity to viewing distance was comparable with that reported for the translational vestibuloocular reflex (TVOR) in the preceding paper: as viewing distance increased from 20 cm, ocular following decremented at a mean rate (+/- SD) of 17 +/- 3% per m-1, while the TVOR decremented at a mean rate (+/- SD) of 18 +/- 1% per m-1. 3. Ocular following responses showed the postsaccadic enhancement described by Kawano and Miles regardless of viewing distance. To a first approximation, the effects of postsaccadic enhancement and viewing distance summed linearly. 4. The dependence of ocular following on speed showed the progressive saturation previously described by Miles et al. at all viewing distances, the peak eye velocity achieved being inversely related to the viewing distance, indicating that the saturation must originate upstream of the dependence on viewing distance. Under normal viewing conditions, this speed saturation will tend to offset the dependence on viewing distance because the retinal slip speeds experienced by the moving observer will tend to vary inversely with viewing distance, resulting in greater saturation with nearer viewing. 5. Wedge prisms were used to dissociate vergence and accommodation and indicated that ocular following responses were sensitive to selective increases in either vergence (base-out prism with the screen at 100 cm) or accommodation (base-in prism with the screen at 20 cm). However, as with the TVOR, the magnitude of the effects showed considerable variability from one animal to another and, in some particular animals, from one direction to another.(ABSTRACT TRUNCATED AT 400 WORDS)

Acceleration↗
PubMed2006

Effects of distance and gaze position on postural stability in young and old subjects.

Visual stabilization of posture is known to improve when the distance to target fixation decreases; this is attributed to increased angular size of retinal slip induced by body sway. At near distance, however, the eyes converge and efferent or afferent oculomotor signals could also be involved in posture stabilization. The goal of this study is to test whether the distance effect exists for both young and elderly and to test the role of vergence itself and of gaze position. Eighteen young (25.3 years) and 17 elderly (61.6 years) subjects were asked to fixate a target in quiet stance presented either at close (40 cm) or at far distance (200 cm); the vergence angle was 9 degrees and 2 degrees , respectively. For each distance, three gaze positions were studied straight-ahead (0 degrees ), 15 degrees up or down. We found a decrease in the surface of center of pressure (CoP), of standard deviation of antero-posterior and lateral body sway and of speed variance at near distance that occurs for both young and elderly. At far distance, the surface of CoP is smaller for 15 degrees up or down gaze in comparison with straight-ahead position, but at near distance there is no such gaze position effect. In an additional experiment, subjects fixated a target at far distance (200 cm) but prisms were used to cause the eyes to converge by an amount similar to that required for 40 cm viewing distance. The use of prisms decreased surface of CoP to values similar to those for natural near viewing distance. The effect of gaze position and of convergence (experiment with prisms) leads us to suggest that in addition to retinal slip, the ocular motor signals and perhaps related neck muscle activity are involved in postural stabilization. Finally, the elderly presented higher speed variance of CoP than the young subjects even though the surface itself was similar to adult values. We suggest that increment of speed variance is the first sign of senescence in postural control.

Adaptation, Physiological↗
PubMed2006

Distance impairs postural stability only under binocular viewing.

Prior studies indicate that postural stability under binocular viewing is not better than under monocular viewing. This was tested at the distances of 145 cm [Fox, C.R. (1990). Some visual influences on human postural equilibrium: binocular versus monocular fixation. Perception and Psychophysics, 47 (5), 409-422] and 90 cm [Isotalo, E., Kapoula, Z., Feret, P.H., Gauchon, K., Zamfirescu, F., & Gagey, P.M. (2004). Monocular versus binocular vision in postural control. Auris Nasus Larynx, 31 (1), 11-17]. On the other hand, postural stability is known to decrease with distance increase. We re-examined the effect of binocular versus monocular viewing on postural stability at near and far distances (40 and 200 cm), and for both young (25.7+/-2.7 years), and old subjects (61.2+/-4.6 years). For both groups of subjects, proximity decreased the area of CoP, the standard deviation of antero-posterior sway (SDy) and the variance of speed. The group of elderly presented increased variance of speed at far distance in comparison with young subjects. The novel finding is the interaction between distance and viewing condition. Under binocular viewing, the area of CoP was significantly higher at far distance than at near; in contrast, monocular viewing produced similar CoP values at both distances. Increased instability at far distance when both eyes are viewing is attributed to decreased sensitivity to binocular disparity cues and to visual motion in depth resulting from body sway. Monocular viewing would provide similar stability at far and at near distance, because sensitivity to lateral visual motion, detected monocularly, decreases less with distance than sensitivity to binocularly detected motion in depth. Alternatively, such monocular viewing could increase subject's attention and lead to tighter postural control regardless of the distance.

Adult↗
PubMed1995

Memory for novel and familiar spatial and linguistic temporal distance information in hypoxic subjects.

Hypoxia is known to cause damage to the hippocampus as well as memory impairments in humans. Subjects who have experienced a hypoxic episode and age-, gender-, and education-matched control subjects were tested for memory for spatial and linguistic temporal distance information using sentences and spatial locations. Each test contained a familiar component based on information that is meaningful and is thought to be stored as part of the knowledge system (prior knowledge) as well as a novel component based on new information. Subjects were presented a list of eight-word sentences or eight spatial locations (Xs) on a grid on a Macintosh computer and tested for memory for temporal distances. Temporal distance is defined as the number of items that occur between the two test items, in the study phase. Compared to control subjects, hypoxic subjects were impaired across all temporal distances on the novel spatial and linguistic tasks. As the temporal distance increased, hypoxic subjects showed some improvement in memory performance. In addition, memory of familiar temporal distance information was also assessed. Hypoxic subjects were impaired, compared to control subjects, for familiar temporal distance information. For hypoxic subjects there was a proportionally greater impairment for novel compared to familiar spatial and linguistic temporal distance information. There was a significant difference in their performance on the familiar temporal distance tasks compared to their performance on the novel tasks. Prior knowledge appears to attenuate the deficits seen in the familiar temporal distance tasks. It appears that hypoxia may cause more selective damage to the hippocampus and this damage is sufficient to produce profound memory impairments for primarily novel and less severe memory impairments for familiar spatial and linguistic temporal distance information.

Adult↗
PubMed1994

Convergence responses to monocularly viewed objects: implications for distance perception.

In four experiments the role of dark vergence and the implied distance from the familiar-size and suggested-size cues to distance on the convergence response was investigated. A nonius-alignment technique was used to measure the convergence response in total darkness (dark vergence) and the fusion-free convergence response to monocularly viewed objects presented at a distance of 75 cm under otherwise reduced stimulus conditions. Observers also estimated the size and distance of the objects. The results indicated a significant association between individuals' dark-vergence distances and the convergence distances to the objects. Furthermore, the convergence response was influenced by the implied distance from the familiar-size cue but not by the implied distance from size suggestions. Both the familiar-size and the suggested-size cues influenced reports of distance. The implications of these findings for distance perception are discussed with particular reference to the familiar-size cue to distance.

Adult↗
PubMed2001

Distance perception within near visual space.

We investigated the perception of distance of visual targets with constant size and luminance presented between 20 and 120 cm from subjects' eyes. When retinal disparity cues were present, the subjects could reproduce very accurately the distance of a seen reference in this area. When only extraretinal information was available, distance perception was still correct for distances of 40 cm or less. However, distances beyond 60 cm were underestimated. When forced to evaluate the distance between a reference and themselves, e.g. when evaluating the absolute distance or half the distance or twice the distance of a reference, subjects used an egocentric plane of reference located on average 10.4 cm in front of their eyes. Measurements of binocular eye movements indicated a clear relationship between vergence angle and target distance. The egocentric plane of reference at 10.4 cm also corresponds to the maximum achievable vergence. These results suggest that ocular convergence can be used as a reliable cue for distance within the arm's reaching space.

Adult↗
PubMed1976

An apparatus for indirect measurement of perceived distance.

Two methods of measuring perceived distance are contrasted. One of these, called a direct method, accepts the observer's direct response to perceived distance as a valid measure of the distance perceived. The other, called an indirect measure, uses the observer's direct response to a perception that is not perceived distance but which has a known relation to perceived distance in order to calculate the distance perceived. There are indications that the direct measure of perceived distance provided by the verbal report sometimes will be modified by cognitive factors. A procedure and apparatus for an indirect measure is suggested which is likely to be free of the cognitive effects found in verbal reports of distance. This apparatus adjusts the distance around which the line-of-sight to the object pivots as the head is moved laterally. The pivot distance at which no apparent motion of the object occurs with head motion is a measure of the perceived distance of the object.

Cognition↗
PubMed2002

Observation distance and recognition of photographs of celebrities' faces.

Subjects were tested to assess the distance at which they could recognize the faces of celebrities (more specifically, a set of 44 portrait photographs of movie and television actors). The set of test photographs was shown initially at a distance of 200 ft. and then closer in increments of 20 ft. When the actor in a given photograph was identified, either by name, character role, or by the movie or television show in which the actor had starred, the recognition-distance was recorded and the photograph was removed from the test set. Those which were not recognized (even at the closest distance) were not included in the data summaries or statistical analysis. In calculating recognition-distance for each photograph, the values were adjusted to reflect the distance at which recognition would have occurred if all the faces were of normal size. The upper limit for recognition, as defined by the distance above which only 10% of the faces are identified, was just over 160 ft. for women, and just under 200 ft. for men. There was also a significant difference in mean recognition distance between women and men. The large range of recognition-distance (across photographs and across subjects) argues that the distance is not controlled primarily by the feature detail provided in a given photograph or by the discrimination and recall skills of the observer. More likely it is a function of diverse memory associations, so that the distance at which each photograph is recognized will depend on such factors as frequency and recency of exposure, perceived attractiveness, and how much the subject admires the celebrity.

Adult↗
PubMed2004

Effect of deception of distance on prolonged cycling performance.

This study examined the effect of deception of distance end-point on prolonged cycling performance. 21 subjects were randomly allocated to three groups (n = 7 per group). Each group completed three self-paced time-trials separated by one day. Subjects were told that each trial was a 30-km time-trial and were required to complete the distance in the fastest time possible. Following the initial trial of 30 km, one group completed Trial 2 with a longer distance (long distance group; 36 km), another group with a shorter distance (24 km; short distance group), and the third group as control (30 km; control). Each group then completed a third time-trial of 30 km. At no time was the deception of distance in Trial 2 disclosed to the subjects, and all sources of physiological and mechanical feedback were withheld during the trials. Data from Trials 1 and 3 were analysed by repeated-measures analysis of covariance. Time to complete Trial 1 was similar among groups (approximately 65 min.). Following the deception in Trial 2 the time to complete the 30 km in Trial 3 was increased for the short distance group, decreased for the long distance group, whilst the time for the control group remained unchanged. The times to complete the 30 km on Trials 1 and 3 were matched by changes in power output throughout the trials. It is concluded that subjects deceived of the actual distance completed will complete the subsequent performance trial based on perceived effort rather than on actual distance.

Adult↗
PubMed2004

Mirror vision: perceived size and perceived distance of virtual images.

We investigated spatial perception of virtual images that were produced by convex and plane mirrors. In Experiment 1, 36 subjects reproduced both the perceived size and the perceived distance of virtual images for five targets that had been placed at a real distance of 10 or 20 m. In Experiment 2, 30 subjects verbally judged both the perceived size and the perceived distance of virtual images for five targets that were placed at each of five real distances of 2.5-45 m. In both experiments, the subjects received objective-size and objective-distance instructions. The results were that (1) size constancy was attained for a distance of up to 45 m, (2) distance was readily discriminated within this distance range, although virtual images produced by the mirror of strong curvature were judged to be farther away than those produced by the mirrors of less curvature, and (3) the ratio of perceived size to perceived distance was described as a power function of visual angle, and the ratio for the convex mirror was larger than that for the plane mirror. We compared the taking-into-account model and the direct perception model on the basis of a correlation analysis for proximal, virtual, and real levels of the stimuli. The taking-into-account model, which assumes that visual angle is transformed into perceived size by taking perceived distance into account, was supported by an analysis for the proximal level of stimuli. The direct perception model, which assumes that there is no inferential process between perceived size and perceived distance, was partially supported by an analysis for the distal level of the stimuli.

Adult↗