Visual perceptions of smoothly curved surfaces from double-projected contour patterns.

This research was designed to examine how human observers are able to perceive the 3-dimensional structure of smoothly curved surfaces from projected patterns of surface contours. Displays were generated by using a method of double projection that made it possible to cover a surface with a wide range of contour patterns of varying geometric structure and to eliminate systematic variations of image shading. The compelling impression of 3-dimensional form from these patterns provides strong evidence that the ability of observers to perceptually interpret surface contours is considerably less restrictive than would be reasonable to expect on the basis of existing computational models. Results suggest that the perceptual analysis of surface contours is able to exploit statistical regularities of contour structure over appropriately large regions of visual space. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Updating displays after imagined object and viewer rotations.

Six experiments compared spatial updating of an array after imagined rotations of the array versus viewer. Participants responded faster and made fewer errors in viewer tasks than in array tasks while positioned outside (Experiment 1) or inside (Experiment 2) the array. An apparent array advantage for updating objects rather than locations was attributable to participants imagining translations of single objects rather than rotations of the array (Experiment 3). Superior viewer performance persisted when the array was reduced to 1 object (Experiment 4); however, an object with a familiar configuration improved object performance somewhat (Experiment 5). Object performance reached near-viewer levels when rotations included haptic information for the turning object. The researchers discuss these findings in terms of the relative differences in which the human cognitive system transforms the spatial reference frames corresponding to each imagined rotation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eye height scaling of absolute size in immersive and nonimmersive displays.

Eye-height (EH) scaling of absolute height was investigated in three experiments. In Experiment 1, standing observers viewed cubes in an immersive virtual environment. Observers' center of projection was placed at actual EH and at 0.7 times actual EH. Observers' size judgments revealed that the EH manipulation was 76.8% effective. In Experiment 2, seated observers viewed the same cubes on an interactive desktop display; however, no effect of EH was found in response to the simulated EH manipulation. Experiment 3 tested standing observers in the immersive environment with the field of view reduced to match that of the desktop. Comparable to Experiment 1, the effect of EH was 77%. These results suggest that EH scaling is not generally used when people view an interactive desktop display because the altitude of the center of projection is indeterminate. EH scaling is spontaneously evoked, however, in immersive environments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recovery of 3-D structure from motion is neither euclidean nor affine.

The relationship between simulated and judged depth separations for pairs of probe dots on planar surface patches was examined in a series of 6 experiments. The simulated slant of the patches was varied without varying the simulated depth separation of the probe dots by varying the depth gradient orthogonal to the direction determined by the probe dots on the image plane. Judged depth separation varied with mean slant for constant simulated depth separations. When observers judged depth separations along a closed path, the integral of the signed depths did not sum to zero, as would be required in Euclidean geometry. These results are inconsistent with the view that the mapping between simulated and perceived 3-D structure is affine and indicate that, in general, the perceived structure cannot be represented in either a Euclidean space or an affine space. Moreover, these results are consistent with a first-order temporal analysis of the optic flow. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Development of three-dimensional form perception.

In 3 experiments with infants and one with adults we explored the generality, limitations, and informational bases of early form perception. In the infant studies we used a habituation-of-looking-time procedure and the method of Kellman (1984), in which responses to 3-dimensional (3-D) form were isolated by habituating 16-wk-old Ss to a single object in 2 different axes of rotation in depth, and testing afterward for dishabituation to the same object and to a different object in a novel axis of rotation. In Exp I, continuous optical transformations given by moving 16-wk-old observers around a stationary 3-D object specified 3-D form to infants. In Exp II, we found no evidence of 3-D form perception from multiple, stationary, binocular views of objects by 16- and 24-wk-olds. Exp IIIA indicated that perspective transformations of the bounding contours of an object, apart from surface information, can specify form at 16 wks. Exp IIIB provided a methodological check, showing that adult Ss could neither perceive 3-D forms from the static views of the objects in Exp IIIA nor match views of either object across different rotations by proximal stimulus similarities. The results identify continuous perspective transformations, given by object or observer movement, as the informational bases of early 3-D form perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

2D observers for human 3D object recognition?

In human object recognition, converging evidence has shown that subjects' performance depends on their familiarity with an object's appearance. The extent of such dependence is a function of the inter-object similarity. The more similar the objects are, the stronger this dependence will be and the more dominant the two-dimensional (2D) image-based information will be. However, the degree to which three-dimensional (3D) model-based information is used remains an area of strong debate. Previously the authors showed that all models with independent 2D templates that allowed 2D rotations in the image plane cannot account for human performance in discriminating novel object views. Here the authors derive an analytic formulation of a Bayesian model that gives rise to the best possible performance under 2D affine transformations and demonstrate that this model cannot account for human performance in 3D object discrimination. Relative to this model, human statistical efficiency is higher for novel views than for learned views, suggesting that human observers have used some 3D structural information.     

Mental and manual rotation.

The relation between mental and manual rotation was investigated in 2 experiments. Experiment 1 compared the response times (RTs) of mental rotation about 4 axes in space with the RTs shown in the same task when participants were allowed to reorient the stimuli by means of rotational hand movements. For the 3 Cartesian axes, RT functions were quantitatively indistinguishable. Experiment 2 investigated interference between mental rotation and 4 kinds of simultaneously executed hand movements that did not reorient the stimuli. Interference was observed only when axes of manual and mental rotation coincided in space. Regardless of the hand used, concordant rotational directions facilitated, whereas discordant directions inhibited, mental rotation. The results suggest that mental object rotation and rotatory object manipulation share a common process that is thought to control the dynamics of both imagined and actually performed object reorientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Imagining projective transformations: aligned orientations in spatial organization

Four experiments were conducted to investigate whether variations in orientation that profoundly affect the ability to imagine rotations also affect the ability to imagine projective transformations. For a basic rectilinear object and the three simpler Platonic Solids, imagining projective transformations (e.g., the casting of a shadow) was quite successful when the objects were aligned with the direction of projection. For the solids, this alignment occurred when the objects were generalized cylinders about axes aligned with the projection. As the objects were made more oblique to the projection, performance deteriorated markedly. When the objects were moderately aligned with the projection, performance depended on the orientation of the object and the orientation of the projection to the environment. We suggest that the imagination of projection and of rotation is a type of problem solving in which spatial structures are organized in relation to initially given properties of the objects and transformations. When there is alignment among the various structural components, this process of imagination works efficiently. Without such alignment, nonexperts often fail. We suggest that aligned (i.e., parallel and perpendicular) orientations are effective in spatial imagination because they are categorically distinct and singular, and they provide a critical form of redundancy.     

Geometric complexity and object search in infancy.

In four experiments we investigated the role of geometric path type in infants' ability to make spatial inferences about the location of a hidden object after they themselves had been moved through space. Nine-month-old infants were moved along geometrically simple paths of rotation (Experiments 1 and 2) or translation (Experiment 3) or along geometrically complex paths of combined rotation and translation (Experiment 4). In all but the fourth experiment, infants were able to retrieve an object hidden before they were moved, as long as the object was not located behind them at test time. Direct comparisons among the conditions showed that moving infants along geometrically simple paths led to significantly better performance than moving them along geometrically complex paths. We found the length of a path, the time needed to traverse it, and the likelihood of fixation of the target to be unrelated to the infants' performance. These findings are discussed in the context of theories of the development of spatial knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perception of three-dimensional form from patterns of optical texture.

Investigated how patterns of optical texture provide information about the three-dimensional structure of objects in space. Four experiments were performed in which observers were asked to judge the perceived depth of simulated ellipsoid surfaces under a variety of experimental conditions. Results show that (a) judged depth increases linearly with simulated depth although the slope of this relation varies significantly among different types of texture patterns. (b) Random variations in the sizes and shapes of individual surface elements have no detectable effect on observers' judgments. (c) The perception of three-dimensional form is quite strong for surfaces displayed under parallel projection, but the amount of apparent depth is slightly less than for identical surfaces displayed under polar projection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tool use and the effect of action on the imagination.

Three studies examined the claim that hand movements can facilitate imagery for object rotations but that this facilitation depends on people's model of the situation. In Experiment 1, physically turning a block without vision reduced mental rotation times compared with imagining the same rotation without bodily movement. In Experiment 2, pulling a string from a spool facilitated participants' mental rotation of an object sitting on the spool. In Experiment 3, depending on participants' model of the spool, the exact same pulling movement facilitated or interfered with the exact same imagery transformation. Results of Experiments 2 and 3 indicate that the geometric characteristics of an action do not specify the trajectory of an imagery transformation. Instead, they point to people's ability to model the tools that mediate between motor activity and its environmental consequences and to transfer tool knowledge to a new situation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Minimal information to determine affine shape equivalence.

Participants judged the affine equivalence of 2 simultaneously presented 4-point patterns. Performance level (d′) varied between 1.5 and 2.7, depending on the information available for solving the correspondence problem (insufficient in Experiment 1a, superfluous in Experiment 1b, and minimal in Experiments 1c, 2a, 2b) and on the exposure time (unlimited in Experiments 1 and 2a and 500 ms in Experiment 2b), but it did not vary much with the complexity of the affine transformation (rotation and slant in Experiment 1 and same plus tilt in Experiment 2). Performance in Experiment 3 was lower with 3-point patterns than with 4-point patterns, whereas blocking the trials according to the affine transformation parameters had little effect. Determining affine shape equivalence with minimal-information displays is based on a fast assessment of qualitatively or quasi-invariant properties such as convexity/concavity, parallelism, and collinearity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detection of information specifying the motion of objects by 3- and 5-month-old infants.

Two studies investigated the ability of 56 3.5- and 5-mo-olds to recognize and discriminate among different motions of rigid objects. In each study, Ss were habituated to 1 of 2 motions made by several different objects. After reaching criterion, they were tested with a novel object making the familiar motion and a novel one. At 5 mo, Ss discriminated (a) the translation of an object from rotation plus translation, (b) translation alone from rotation alone, (c) full rotation on the vertical axis from oscillation on the vertical axis, and (d) rotation to the left and rotation to the right. At 3.5 mo, Ss responded differently only in the 1st case, and it was less clear that they were discriminating on the basis of motion. Three additional studies, with 64 5-mo-olds, suggested that texture on the surface of the object and the projected contour were both important to the discrimination of the different motions. Results are discussed in terms of disruptions in the optic array. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of the combined cortical thickness of the second metacarpal with Sharp's method for scoring hand microradiographs in rheumatoid arthritis

OBJECTIVE: To compare the correlation and specificity of the combined cortical thickness of the second metacarpal (CCT-MC) with Sharp's method (SM) for scoring joint erosions and joint space narrowing in rheumatoid arthritis (RA) and to compare the degree of interobserver agreement between the 2 methods. METHODS: Hand microradiographs of 22 women with RA, functional classes III and IV, were scored independently by 3 rheumatologists using the CCT-MC and the CCT of the middle phalanx and SM. RESULTS: (1) There was a highly significant correlation between the total SM score and the CCT-MC for the 3 observers (r = 0.61, p = 0.0026), but not between the CCT of the middle phalanx and SM (r = 0.15, p = 0.53). There was a lower degree of agreement between the observers for SM erosion scores compared to the CCT-MC (intraclass correlation 0.88 for the CCT-MC and 0.63 for the SM); (2) Both joint space narrowing and erosion scores correlated highly with the CCT-MC (r = -0.60, p = 0.004; and r = -0.51, p = 0.014, respectively); (3) CCT-MC measurements are more closely related to the inner (d) as opposed to the outer (D) diameter of the 2nd metacarpal; (4) The mean time to obtain the CCT-MC score was 3.43 min (SD = 1.38) versus 9.83 min (SD = 3.20) for SM (p = 0.0001); (5) the derivative, (D2-d2)/D2, was significantly correlated with SM (r = -0.72, p = 0.0002) and its erosion and joint space narrowing components (r = -0.63, p = 0.0019; and r = -0.71, p = 0.0002, respectively). CONCLUSION: The CCT-MC is a rapid, practical method with higher agreement among observers compared to SM and correlates highly with SM scores for joint damage in RA. CCT-MC appears to have a higher degree of specificity than other sites for CCT measurement. The CCT-MC is more closely related to the inner diameter than the outer diameter, which supports the notion that the principal site of accelerated bone loss due to RA in the hand occurs at the endosteal surface. The CCT-MC should be further assessed with respect to monitoring radiological progression in RA.     

Budgerigars (Melopsittacus undulatus) Copy Virtual Demonstrators in a Two-Action Test.

Juvenile budgerigars (Melopsittacus undulatus) observed thin film transistor video playback of a virtual conspecific demonstrator using its beak to remove a stopper from a food box, either by pulling the object upward or by pushing it downward. Simultaneously (Experiment 1) or subsequently (Experiment 2), the observers were offered a similar stopper box and rewarded with access to food for each removal response, regardless of its direction. Observers of upward movement made a greater proportion of up responses in total and showed a stronger tendency to increase the proportion of up responses over test trials than observers of downward movement. These findings provide the first demonstration of which the authors are aware that birds are able not only to detect and respond to a moving video image but also to copy its movements. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The impact of visual exploration on judgments of whether a gap is crossable.

When observers look down into a gap in the ground plane, their judgments of the widest gap they can step across (gapmax) decrease as gap depth increases (Y. Jiang & L. S. Mark, 1994). This study investigated the possibility that Jiang and Mark's viewing conditions did not afford observers a sufficient opportunity to perform exploratory movements needed to detect information about gap width. Experiment 1 showed that the gap depth by gaze interaction disappeared only when restrictions were not imposed on observers' exploratory activities (eye, head, and body movements). Experiment 2 showed that observers tended to see the vertical surface as slanted away from them, which made the bottom of the surface appear farther away from them than the top. Only when observers were able to view the gap binocularly under conditions that did not restrict exploratory activity did their slant perception improve and their gapmax judgments no longer covary with gap depth. The data indicate that the exploratory movements of prospective actors are essential for the pickup of information about their action capabilities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Information integration about object–object relationships by chimpanzees (Pan troglodytes).

Three experiments tested the ability to integrate information about object–object relationships in 2 chimpanzees. In Experiment 1, the subjects were trained to match 1 part of a 2-part object to its other part, match a tool to its assembled object, match a container to its tool, and match a tool to its container. In Experiment 2, the subjects were trained to match a picture of the sample. One subject learned this type of matching task and was then tested on whether she could choose the pictures of related items in Experiment 1. Although the subject was reinforced irrespective of her choices, she chose pictures of items related to the sample when there was no picture of the sample. Experiment 3 showed that the subject was able to match a picture of the item among related items. The results suggest that the subject might integrate information about relationships acquired in Experiment 1 and organize it to make networks of related items. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of distance between objects and distance from the vertical axis on shape identity judgments

In three experiments, we independently manipulated the angular disparity between objects to be compared and the angular distance between the central axis of the objects and the vertical axis in a mental rotation paradigm. There was a linear increase in reaction times that was attributable to both factors. This result held whether the objects were rotated (with respect to each other and to the upright) within the frontal-parallel plane (Experiment 1) or in depth (Experiment 2), although the effects of both factors were greater for objects rotated in depth than for objects rotated within the frontal-parallel plane (Experiment 3). In addition, the factors interacted when the subjects had to search for matching ends of the figures (Experiments 1 and 2), but they were additive when the ends that matched were evident (Experiment 3). These data may be interpreted to mean that subjects normalize or reference an object with respect to the vertical upright as well as compute the rotational transformations used to determine shape identity.     

Processing idiomatic expressions: Effects of semantic compositionality.

Three experiments tested the main claims of the idiom decomposition hypothesis: People have clear intuitions on the semantic compositionality of idiomatic expressions, which determines the syntactic behavior of these expressions and how they are recognized. Experiment 1 showed that intuitions are clear only for a very restricted number of expressions, but for the majority of idioms, they are not consistent across speakers. Experiment 2 failed to support the claim that semantic compositionality influences the syntactic flexibility of idioms. Finally, Experiment 3 showed that idioms are more quickly recognized than their literal counterparts, regardless of compositionality and syntactic flexibility. All of the findings were at odds with the tenets of the idiom decomposition hypothesis. The theoretical implications of the results with respect to idiom processing and the notion of compositionality are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)