Spatial knowledge in a young blind child

A set of eight experiments demonstrate spatial knowledge in a 2-year-old congenitally blind child and sighted blindfolded controls. Once the blind child had traveled along specific paths between objects in a novel array, she was able to make spatial inferences, finding new routes between those objects (Experiment 1). She could also do so when the routes were between places in space, not occupied by objects (Experiment II). Deviations from precisely straight routes in Experiments I and II were not due to faulty inferences, but probably came from imprecise motor control, since the same deviations occured when inferences were not required—when the child moved to a place designated by a sound source (Experiment III). This child's performances could not be accounted for by artifactual explanations: sound cues, experimenter bias, and echolocation were ruled out (Experiments IV, V, VI). Further, sighted blindfolded controls performed at roughly the same level (Experiment VII). Finally, Experiment VIII shows that the blind child could access her spatial knowledge for use in a simple map-reading task. We conclude that the young blind child has a system of spatial knowledge, including abstract, amodal rules     

Spatial representation by blind and sighted children

Spatial representation by 72 blind and blindfolded sighted children between the ages of 6 and 11 was tested in two experiments by mental rotation of a raised line under conditions of clockwise varied directions.Experiment 1 showed that the two groups were well matched on tactual recognition and scored equally badly on matching displays to their own mentally rotated position.Experiment 2 found the sighted superior in recall tests. There was a highly significant interaction between sighted status and degree of rotation. Degree of rotation affected only the blind. Their scores were significantly lower for rotating to oblique and to the far orthogonal directions than to near orthogonal test positions. On near orthogonals the blind did not differ from the sighted.Age was a main effect, but it did not interact with any other variable. Older blind children whose visual experience dated from before the age of 6 were superior to congenitally blind subjects, but not differentially more so on oblique directions.The results were discussed in relation to hypotheses about the nature of spatial representation and strategies by children whose prior experience derived from vision or from touch and movement.     

Spatial updating relies on an egocentric representation of space: Effects of the number of objects

Models of spatial updating attempt to explain how representations of spatial relationships between the actor and objects in the environment change as the actor moves. In allocentric models, object locations are encoded in an external reference frame, and only the actor’s position and orientation in that reference frame need to be updated. Thus, spatial updating should be independent of the number of objects in the environment (set size). In egocentric updating models, object locations are encoded relative to the actor, so the location of each object relative to the actor must be updated as the actor moves. Thus, spatial updating efficiency should depend on set size. We examined which model better accounts for human spatial updating by having people reconstruct the locations of varying numbers of virtual objects either from the original study position or from a changed viewing position. In consistency with the egocentric updating model, object localization following a viewpoint change was affected by the number of objects in the environment.     

Spatial perception in the blind.

It is often that the spatial senses (vision, hearing and the tactual senses) operate as distinct and independent modalities and, moreover, that vision is crucial to the development of spatial abilities. However, well controlled studies of blind persons with adequate experience show that they can function usefully in space. In other words, vision is not a necessary condition for spatial awareness. On the other hand, thought the blind may be equal or even superior to the sighted when performing spatial tasks within the body space, they may be deficient, either developmentally or absolutely, in tasks which involve events at a distance from the body, principally in auditory localization. One possible explanation of the differences between blind and sighted (McKinney, 1964; Attneave & Benson, 1969, Warren, 1970) is that vision is the primary spatial reference, and inputs from other modalities are fitted to a visual map. Several criticisms of this theory are adduced and an alternative theory derived from Sherrington (1947), in which all sensory inputs map on to efferent patterns, is sketched.     

Cognitive representation of auditory space in blind football experts

ObjectivesWe compared the mental representation of sound directions in blind football players, blind non-athletes and sighted individuals.DesignStanding blindfolded in the middle of a circle with 16 loudspeakers, participants judged whether the directions of two subsequently presented sounds were similar or not.MethodStructure dimensional analysis (SDA) was applied to reveal mean cluster solutions for the groups.ResultsHierarchical cluster analysis via SDA resulted in distinct representation structures of sound directions. The blind football players' mean cluster solution consisted of pairs of neighboring directions. The blind non-athletes also clustered the directions in pairs, but included non-adjacent directions. In the sighted participants' structure, frontal directions were clustered pairwise, the absolute back was singled out, and the side regions accounted for more directions.ConclusionsOur results suggest that the mental representation of egocentric auditory space is influenced by sight and by the level of expertise in auditory-based orientation and navigation.     

The spatiotopic representation of visual objects across time

Each eye movement introduces changes in the retinal location of objects. How a stable spatiotopic representation emerges from such variable input is an important question for the study of vision. Researchers have classically probed human observers' performance in a task requiring a location judgment about an object presented at different locations across a saccade. Correct performance on this task requires realigning or remapping retinal locations to compensate for the saccade. A recent study showed that performance improved with longer presaccadic viewing time, suggesting that accurate spatiotopic representations take time to build up. The first goal of the study was to replicate that finding. Two experiments, one an exact replication and the second a modified version, failed to replicate improved performance with longer presaccadic viewing time. The second goal of this study was to examine the role of attention in constructing spatiotopic representations, as theoretical and neurophysiological accounts of remapping have proposed that only attended targets are remapped. A third experiment thus manipulated attention with a spatial cueing paradigm and compared transsaccadic location performance of attended versus unattended targets. No difference in spatiotopic performance was found between attended and unattended targets. Although only negative results are reported, they might nevertheless suggest that spatiotopic representations are relatively stable over time.     

Distinct mechanisms for the representation of moving and static objects

The visual system has been suggested to integrate different views of an object in motion. We investigated differences in the way moving and static objects are represented by testing for priming effects to previously seen ("known") and novel object views. We showed priming effects for moving objects across image changes (e.g., mirror reversals, changes in size, and changes in polarity) but not over temporal delays. The opposite pattern of results was observed for objects presented statically; that is, static objects were primed over temporal delays but not across image changes. These results suggest that representations for moving objects are: (1) updated continuously across image changes, whereas static object representations generalize only across similar images, and (2) more short-lived than static object representations. These results suggest two distinct representational mechanisms: a static object mechanism rather spatially refined and permanent, possibly suited for visual recognition, and a motion-based object mechanism more temporary and less spatially refined, possibly suited for visual guidance of motor actions.     

Depth representation of moving 3-D objects in apparent-motion path

Apparent motion is perceived when two objects are presented alternately at different positions. The internal representations of apparently moving objects are formed in an apparent-motion path which lacks physical inputs. We investigated the depth information contained in the representation of 3-D moving objects in an apparent-motion path. We examined how probe objects-briefly placed in the motion path-affected the perceived smoothness of apparent motion. The probe objects comprised 3-D objects which were defined by being shaded or by disparity (convex/concave) or 2-D (flat) objects, while the moving objects were convex/concave objects. We found that flat probe objects induced a significantly smoother motion perception than concave probe objects only in the case of the convex moving objects. However, convex probe objects did not lead to smoother motion as the flat objects did, although the convex probe objects contained the same depth information for the moving objects. Moreover, the difference between probe objects was reduced when the moving objects were concave. These counterintuitive results were consistent in conditions when both depth cues were used. The results suggest that internal representations contain incomplete depth information that is intermediate between that of 2-D and 3-D objects.     

先天性音乐障碍的音高空间表征能力研究

利用音高空间表征任务、心理旋转任务和音高辨别任务,探讨先天性音乐障碍者音高空间表征能力、心理旋转加工能力和音高辨别能力。结果发现：先天性音乐障碍组音高空间表征任务标准差、心理旋转任务错误率和音高辨别任务错误率均显著高于控制组。 这些结果表明先天性音乐障碍并非音乐特异性障碍,而是音乐相关性障碍。     

Spatial constraints on attention to speech in the blind

When sighted persons try to identify one of two speech utterances coming from different directions, they display both a frontal position advantage, i.e., better recognition of inputs from the front than of those from the rear, and a right-side advantage, better recognition of inputs from the right than of those from the left. The present study demonstrates a dissociation of the two effects in blind subjects (N = 10) who showed no frontal position advantage together with a right-side advantage superior to that of control sighted subjects (N = 16). There was no systematic difference between congenitally blind subjects and noncongenitals. The absence of frontal position advantage in the blind is consistent with the notion that this effect originates in the habit of sighted listeners to orient toward the source of heard speech. The occurrence of at least normal right-side advantage in the blind does not support recent suggestions of reduced lateralization of language functions in such subjects.     

The visual representation of three-dimensional, rotating objects.

Depth rotations can reveal new object parts and result in poor recognition of "static" objects (Biederman & Gerhardstein, 1993). Recent studies have suggested that multiple object views can be associated through temporal contiguity and similarity (Edelman & Weinshall, 1991; Lawson, Humphreys & Watson, 1994; Wallis, 1996). Motion may also play an important role in object recognition since observers recognize novel views of objects rotating in the picture plane more readily than novel views of statically re-oriented objects (Kourtzi & Shiffrar, 1997). The series of experiments presented here investigated how different views of a depth-rotated object might be linked together even when these views do not share the same parts. The results suggest that depth rotated object views can be linked more readily with motion than with temporal sequence alone to yield priming of novel views of 3D objects that fall in between "known" views. Motion can also enhance path specific view linkage when visible object parts differ across views. Such results suggest that object representations depend on motion processes.     

Mental representation of three-dimensional objects in visual problem solving and recognition

Subjects inspected sets of flat, separated orthographic projections of surfaces of potential three-dimensional objects. After solving problems based on these orthographic views, subjects discriminated between isometric views of the same objects and drawings of distractor structures. Recognition of the isometrics, which had never been shown during the problem solving phase of the experiment, was excellent. In addition, recognition of isometrics corresponding to problems that had been solved correctly when presented in orthographic form was significantly superior to recognition of isometrics based on problems solved incorrectly. In Experiment 2, conditions were included in which either orthographic or isometric views functioned as problem solving or recognition displays. Only in the case of orthographic problem solving followed by isometric recognition (Experiment 1) was the superiority of recognition for correctly-solved problems over incorrectly-solved problems obtained. The pattern of results suggests that viewers construct mental representations embodying structural information about integrated, three-dimensional objects when asked to reason about flat, disconnected projections.     

The representation of moving 3-D objects in apparent motion perception

In the present research, we investigated the depth information contained in the representations of apparently moving 3-D objects. By conducting three experiments, we measured the magnitude of representational momentum (RM) as an index of the consistency of an object’s representation. Experiment 1A revealed that RM magnitude was greater when shaded, convex, apparently moving objects shifted to a flat circle than when they shifted to a shaded, concave, hemisphere. The difference diminished when the apparently moving objects were concave hemispheres (Experiment 1B). Using luminance-polarized circles, Experiment 2 confirmed that these results were not due to the luminance information of shading. Experiment 3 demonstrated that RM magnitude was greater when convex apparently moving objects shifted to particular blurred convex hemispheres with low-pass filtering than when they shifted to concave hemispheres. These results suggest that the internal object’s representation in apparent motion contains incomplete depth information intermediate between that of 2-D and 3-D objects, particularly with regard to convexity information with low-spatial-frequency components.     

Spatial representation of a two-dimensional pattern

The purpose of this study was (a) to determine if vision and kinesthesis contribute differentially to the coding of a specific two-dimensional pattern and (b) to identify the effect of repetition on the spatial representation of this pattern. The reproductions of a specific pattern presented visually were compared with those of a pattern presented kinesthetically. The results showed that vision and kinesthesis had contributed equally to the coding of the directional components of the pattern. However, there was dominance of visual information over kinesthetic information when coding the distance between the intersecting points of the pattern, especially at the beginning of the process. Generally speaking, the visual or kinesthetic repetition, or both, have increased favourably the precision with which a specific pattern was reproduced in distance and direction.