Slant Perception in Near Space is Categorically Biased: Evidence for a Vertical Tendency
01 Oct 2010-Attention Perception & Psychophysics (Holtzbrinck Springer Nature Publishing Group)-Vol. 72, Iss: 7, pp 1875-1889
TL;DR: The visual and haptic perception of the geographical slant of surfaces within reach under full-cue conditions are examined to show that the perceived orientation of even these surfaces is biased and an exaggeration with respect to deviations from horizontal is shown to be present cross-modally.
Abstract: The geographical slants of hills are known to appear quite exaggerated. Here, we examine the visual and haptic perception of the geographical slant of surfaces within reach under full-cue conditions and show that the perceived orientation of even these surfaces is biased. An exaggeration with respect to deviations from horizontal is shown to be present cross-modally. Experiment 1 employed numerical estimation to show the effect for visually observed surfaces, while controlling for verbal numerical bias. Experiment 2 demonstrated that the bias is present even when manual measures show good calibration. Experiment 3 controlled for direction of gaze. Experiment 4 measured the same bias for haptic surfaces. Experiment 5 showed that the bias can also be observed using the nonnumeric task of angle bisection. These results constrain theories of geographical slant perception and appear most consistent with functional scale expansion of deviations from horizontal.
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TL;DR: Three different assessments of experimental demand indicate that even when the physical environment is naturalistic, and the goal of the main experimental manipulation was primarily concealed, artificial aspects of the social environment may still be primarily responsible for altered judgments of hill orientation.
Abstract: Experiments take place in a physical environment but also a social environment. Generalizability from experimental manipulations to more typical contexts may be limited by violations of ecological validity with respect to either the physical or the social environment. A replication and extension of a recent study (a blood glucose manipulation) was conducted to investigate the effects of experimental demand (a social artifact) on participant behaviors judging the geographical slant of a large-scale outdoor hill. Three different assessments of experimental demand indicate that even when the physical environment is naturalistic, and the goal of the main experimental manipulation was primarily concealed, artificial aspects of the social environment (such as an explicit requirement to wear a heavy backpack while estimating the slant of a hill) may still be primarily responsible for altered judgments of hill orientation.
114 citations
Cites methods from "Slant Perception in Near Space is C..."
...An imputed dissociation might be an artifact: Further evidence for the generalizability of the observations of Durgin et al. 2010....
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01 Dec 2011
TL;DR: In this paper, it is argued that the navigational problems in three dimensions are qualitatively as well as quantitatively different from those in two dimensions, and evidence suggests that, perhaps for this reason, horizontal and vertical space are processed separately in the vertebrate brain.
Abstract: A central theme in the study of animal navigation has been the extent to which such navigation requires the formation of an internal representation of space, the so-called " cognitive map." Although its properties remain disputed, it is now generally accepted that a map-like representation exists in the brain, and neurobiological studies, conducted in tandem with behavioral investigations, have done much to elucidate the neural substrate of the map as it operates in two dimensions. However, to date little is known about how the map encodes real-world, three-dimensional space. Using recent neurobiological and behavioral fi ndings, this issue is explored here. It is argued that the navigational problems in three dimensions are qualitatively as well as quantitatively different from those in two dimensions, and evidence suggests that, perhaps for this reason, horizontal and vertical space are processed separately in the vertebrate brain. The possible adaptive consequences of such an anisotropic. © 2011 Massachusetts Institute of Technology and the Frankfurt Institute for Advanced Studies. All rights reserved.
105 citations
TL;DR: It is argued that the mammalian spatial representation in surface-travelling animals comprises a mosaic of these locally planar fragments, rather than a fully integrated volumetric map, which may be true even for species that can move freely in all three dimensions.
Abstract: The study of spatial cognition has provided considerable insight into how animals (including humans) navigate on the horizontal plane. However, the real world is three-dimensional, having a complex topography including both horizontal and vertical features, which presents additional challenges for representation and navigation. The present article reviews the emerging behavioral and neurobiological literature on spatial cognition in non-horizontal environments. We suggest that three-dimensional spaces are represented in a quasi-planar fashion, with space in the plane of locomotion being computed separately and represented differently from space in the orthogonal axis – a representational structure we have termed “bicoded.” We argue that the mammalian spatial representation in surface-travelling animals comprises a mosaic of these locally planar fragments, rather than a fully integrated volumetric map. More generally, this may be true even for species that can move freely in all three dimensions, such as birds and fish. We outline the evidence supporting this view, together with the adaptive advantages of such a scheme.
97 citations
TL;DR: It is shown that the perceived declination of gaze, like the perceived orientation of surfaces, is coded on a distorted scale, and the theory is advanced that this scale expansion (by a factor of about 1.5) may serve a functional goal of coding efficiency for angular perceptual variables.
Abstract: Whereas most sensory information is coded on a logarithmic scale, linear expansion of a limited range may provide a more efficient coding for the angular variables important to precise motor control. In four experiments, we show that the perceived declination of gaze, like the perceived orientation of surfaces, is coded on a distorted scale. The distortion seems to arise from a nearly linear expansion of the angular range close to horizontal/straight ahead and is evident in explicit verbal and nonverbal measures (Experiments 1 and 2), as well as in implicit measures of perceived gaze direction (Experiment 4). The theory is advanced that this scale expansion (by a factor of about 1.5) may serve a functional goal of coding efficiency for angular perceptual variables. The scale expansion of perceived gaze declination is accompanied by a corresponding expansion of perceived optical slants in the same range (Experiments 3 and 4). These dual distortions can account for the explicit misperception of distance typically obtained by direct report and exocentric matching, while allowing for accurate spatial action to be understood as the result of calibration.
69 citations
TL;DR: A comprehensive three-parameter model based on the present data provides a good fit to a number of previous empirical observations measured in real environments and increases logarithmically with viewing distance and the increase was proportionally greater for shallow slants.
Abstract: It is known that the perceived slants of large distal surfaces, such as hills, are exaggerated and that the exaggeration increases with distance. In a series of two experiments, we parametrically investigated the effect of viewing distance and slant on perceived slant using a high-fidelity virtual environment. An explicit numerical estimation method and an implicit aspect ratio approach were separately used to assess the perceived optical slant of simulated large-scale surfaces with different slants and viewing distances while gaze direction was fixed. The results showed that perceived optical slant increased logarithmically with viewing distance and the increase was proportionally greater for shallow slants. At each viewing distance, perceived optical slant could be approximately fit by linear functions of actual slant that were parallel across distances. These linear functions demonstrated a fairly constant gain of about 1.5 and an intercept that increased logarithmically with distance. A comprehensive three-parameter model based on the present data provides a good fit to a number of previous empirical observations measured in real environments.
51 citations
References
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TL;DR: The proposed model has broad implications; notably, it has the potential to explain biases of the sort described in psychophysics as well as symmetries in similarity judgments, without positing distorted representations of physical scales.
Abstract: A model of category effects on reports from memory is presented. The model holds that stimuli are represented at 2 levels of detail: a fine-grain value and a category. When memory is inexact but people must report an exact value, they use estimation processes that combine the remembered stimulus value with category information. The proposed estimation processes include truncation at category boundaries and weighting with a central (prototypic) category value. These processes introduce bias in reporting even when memory is unbiased, but nevertheless may improve overall accuracy (by decreasing the variability of reports). Four experiments are presented in which people report the location of a dot in a circle. Subjects spontaneously impose horizontal and vertical boundaries that divide the circle into quadrants. They misplace dots toward a central (prototypic) location in each quadrant, as predicted by the model. The proposed model has broad implications; notably, it has the potential to explain biases of the sort described in psychophysics (contraction bias and the bias captured by Weber's law) as well as symmetries in similarity judgments, without positing distorted representations of physical scales.
720 citations
TL;DR: Perception informs people about the opportunities for action and their associated costs, and explicit awareness of spatial layout varies not only with relevant optical and ocular-motor variables, but also as a function of the costs associated with performing intended actions.
Abstract: Perception informs people about the opportu- nities for action and their associated costs. To this end, explicit awareness of spatial layout varies not only with relevant optical and ocular-motor variables, but also as a function of the costs associated with performing intended actions. Although explicit awareness is mutable in this respect, visually guided actions directed at the immediate environment are not. When the metabolic costs associated with walking an extent increase—perhaps because one is wearing a heavy backpack—hills appear steeper and distances to targets appear greater. When one is standing on a high balcony, the apparent distance to the ground is correlated with one's fear of falling. Perceiving spatial layout combines the geometry of the world with behavioral goals and the costs associated with achieving these goals.
630 citations
"Slant Perception in Near Space is C..." refers background in this paper
...…dissociations between conscious perception of geographical slant and perception for action (e.g., Bhalla & Proffitt, 1999; Creem & Proffitt, 1998; Proffitt, 2006; Proffitt et al., 1995) these reports depended on characterizing palm board measures (rotation of a unseen board by hand) as visually…...
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TL;DR: Recalibration of the transformation relating awareness and actions was found to occur over long-term changes in physiological potential (fitness level, age, and health) but not with transitory changes (fatigue and load).
Abstract: In 4 experiments, it was shown that hills appear steeper to people who are encumbered by wearing a heavy backpack (Experiment 1), are fatigued (Experiment 2), are of low physical fitness (Experiment 3), or are elderly and/or in declining health (Experiment 4). Visually guided actions are unaffected by these manipulations of physiological potential. Although dissociable, the awareness and action systems were also shown to be interconnected. Recalibration of the transformation relating awareness and actions was found to occur over long-term changes in physiological potential (fitness level, age, and health) but not with transitory changes (fatigue and load). Findings are discussed in terms of a time-dependent coordination between the separate systems that control explicit visual awareness and visually guided action.
577 citations
"Slant Perception in Near Space is C..." refers background or methods or result in this paper
...The palm board production data from Bhalla and Proffitt (1999), however, are consistent with the observation of Durgin et al....
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...In Figure 13, we have plotted existing verbal numeric estimation data for large-scale hills in terms of signed error (computed from Table 2 in Bhalla & Proffitt, 1999)....
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...Although several reports have argued for dissociations between conscious perception of geographical slant and perception for action (e.g., Bhalla & Proffitt, 1999; Creem & Proffitt, 1998; Proffitt, 2006; Proffitt et al., 1995) these reports depended on characterizing palm board measures (rotation…...
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...The palm board production data from Bhalla and Proffitt (1999), however, are consistent with the observation of Durgin et al. (2010) that palm boards are set much too low for surfaces within reach, because palm boards, like hills, are consciously perceived as being much steeper than they are....
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...The palm board production data are from the baseline condition in Experiment 2 of Bhalla and Proffitt (1999)....
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TL;DR: The writer has recently proposed the theory that visual space-perception is reducible to the perception of visual surfaces, and that distance, depth, and orientation, together with the constancy of objects, may all be derived from the properties of an array of surfaces.
Abstract: The writer has recently proposed the theory that visual space-perception is reducible to the perception of visual surfaces, and that distance, depth, and orientation, together with the constancy of objects, may all be derived from the properties of an array of surfaces.' The notion of completely empty space is asserted to be irrelevant for the theory of space-perception. The perception of space between objects, in this theory, depends on the experience of contours against a general background, and on the impression of one surface behind another. The fundamental 'sensations' of space are assumed to be the impressions of surface and edge. If the theory is valid, there should be discoverable variables in stimulation for the essential properties or qualities of a surface, and these should prove to be the effective stimuli for space-perception. What is called for is a listing of the properties or qualities-a phenomenological study-and a search for the corresponding stimulus variables-a program of psychophysical experiments.
455 citations
"Slant Perception in Near Space is C..." refers background or methods in this paper
...Gibson (1950) measured frontal tendency using hand gestures to reduced-cue stimuli (texture gradients)....
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...Discussion Gibson (1950) measured frontal tendency using hand gestures to reduced-cue stimuli (texture gradients)....
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...It is possible that the flattening found in Experiments 1 and 2 was due to frontal tendency (Gibson, 1950); however, the principal bias function is independent of direction of gaze and seems to be related to the categorical the surface that had a geographical slant of 50º (depending on the height…...
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...We have documented similar biases in haptic perception, and we have shown that these biases are not due to frontal tendency (Gibson, 1950)....
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...Using a vertical palm board measure, Gibson (1950) observed evidence of a frontal tendency in estimates of slant from texture gradients....
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TL;DR: It is proposed that the perceived exaggeration of geographical slant preserves the relationship between distal inclination and people’s behavioral potential, thereby enhancing sensitivity to the small inclines that must actually be traversed in everyday experience.
Abstract: People judged the inclination of hills viewed either out-of-doors or in a computer-simulated virtual environment Angle judgments were obtained by having people (1) provide verbal estimates, (2) adjust a representation of the hill’s cross-section, and (3) adjust a tilt board with their unseen hand Geographical slant was greatly overestimated according to the first two measures, but not the third Apparent slant judgments conformed to ratio scales, thereby enhancing sensitivity to the small inclines that must actually be traversed in everyday experience It is proposed that the perceived exaggeration of geographical slant preserves the relationship between distal inclination and people’s behavioral potential Hills are harder to traverse as people become tired; hence, apparent slant increased with fatigue Visually guided actions must be accommodated to the actual distal properties of the environment; consequently, the tilt board adjustments did not reflect apparent slant overestimations, nor were they influenced by fatigue Consistent with the fact that steep hills are more difficult to descend than to ascend, these hills appeared steeper when viewed from the top
436 citations
"Slant Perception in Near Space is C..." refers background in this paper
...Haptic misperception of palm board orientation has led to the mistaken impression that palm boards are accurate measures of hill orientation (e.g., Creem & Proffitt, 1998; Proffitt et al., 1995)....
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...…between conscious perception of geographical slant and perception for action (e.g., Bhalla & Proffitt, 1999; Creem & Proffitt, 1998; Proffitt, 2006; Proffitt et al., 1995) these reports depended on characterizing palm board measures (rotation of a unseen board by hand) as visually guided actions....
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