The shape of holes

The shape of holes can be recognized as accurately as the shape of objects (Palmer, S. E. (1999). Vision science: photons to phenomenology. Cambridge, MA: MIT Press), yet the area enclosed by a hole is a background region, and it can be demonstrated that background regions are not represented as having shape. What is therefore the shape of a hole, if any? To resolve this apparent paradox, we suggest that the shape of a hole is available indirectly from the shape of the surrounding object. We exploited the fact that observers are faster at judging the position of convex vertices than concave ones (Perception 30 (2001) 1295), and using a figural manipulation of figure/ground we found a reversal of the relative speeds when the same contours were presented as holes instead of objects. If contours were perceived as belonging to the hole rather than the surrounding object then there would have been no qualitative difference in responses to the object and hole stimuli. We conclude that the contour bounding a hole is automatically assigned to the surrounding object, and that a change in perception of a region from object to hole always drastically changes the encoded information. We discuss the many interesting aspects of holes as a subject of study in different disciplines and predict that much insight especially about shape will continue to come from holes.     

How owls structure visual information

Recent studies on perceptual organization in humans claim that the ability to represent a visual scene as a set of coherent surfaces is of central importance for visual cognition. We examined whether this surface representation hypothesis generalizes to a non-mammalian species, the barn owl (Tyto alba). Discrimination transfer combined with random-dot stimuli provided the appropriate means for a series of two behavioural experiments with the specific aims of (1) obtaining psychophysical measurements of figure–ground segmentation in the owl, and (2) determining the nature of the information involved. In experiment 1, two owls were trained to indicate the presence or absence of a central planar surface (figure) among a larger region of random dots (ground) based on differences in texture. Without additional training, the owls could make the same discrimination when figure and ground had reversed luminance, or were camouflaged by the use of uniformly textured random-dot stereograms. In the latter case, the figure stands out in depth from the ground when positional differences of the figure in two retinal images are combined (binocular disparity). In experiment 2, two new owls were trained to distinguish three-dimensional objects from holes using random-dot kinematograms. These birds could make the same discrimination when information on surface segmentation was unexpectedly switched from relative motion to half-occlusion. In the latter case, stereograms were used that provide the impression of stratified surfaces to humans by giving unpairable image features to the eyes. The ability to use image features such as texture, binocular disparity, relative motion, and half-occlusion interchangeably to determine figure–ground relationships suggests that in owls, as in humans, the structuring of the visual scene critically depends on how indirect image information (depth order, occlusion contours) is allocated between different surfaces. Electronic Publication     

Effects of Interspersing Additional Brief Math Problems on Student Performance and Perception of Math Assignments: Getting Students to Prefer to Do More Work

Three experiments were conducted to assess the effects of the interspersing procedure on students' mathematics performance, perceptions of mathematics assignments, and preference for mathematics assignments when more work was added. In Experiment I, college students worked computation problems from two assignments. The control assignment contained 15 three-digit by two-digit problems (3 × 2) and the experimental assignments contained 18 3 × 2 problems and 6 additional interspersed one-digit by one-digit problems (1 × 1). Students then rated the assignments and chose one for homework. Results showed significantly more students preferred (i.e., chose it for homework) the experimental assignment with the additional target (i.e., 3 × 2) and interspersed problems. Furthermore, significantly more students rated this experiment as requiring less effort and being less difficult. Moreover, students' mathematics performance was not affected by the procedure. Experiment II strengthened the internal validity by showing that students did not prefer the experimental assignment because it contained more target problems. Experiment III showed that the interspersing procedure was not powerful enough to extend findings beyond the 20% level (i.e., 40 and 60% more conditions). Results showed how the interspersing procedure could be used to encourage students to choose to do more target computation tasks. Discussion focuses on the applied value of the interspersing procedure and plausible causal mechanisms that may account for current and past findings related to student choice and interspersing brief tasks.     

帕金森病人的图形辨别障碍

对56名帕金森病人用视觉形状辨别测验(VFDT)进行了测查,44名年龄、文化水平与帕金森组相当的正常人作为对照组。结果发现帕金森病人对图形辨别有明显障碍。对帕金森病人在图形辨别障碍中的特点进行了分析,并对其可能机制进行了讨论。     

Determination of visual figure and ground in dynamically deforming shapes

Figure/ground assignment - determining which part of the visual image is foreground and which background - is a critical step in early visual analysis, upon which much later processing depends. Previous research on the assignment of figure and ground to opposing sides of a contour has almost exclusively involved static geometric factors - such as convexity, symmetry, and size - in non-moving images. Here, we introduce a new class of cue to figural assignment based on the motion of dynamically deforming contours. Subjects viewing an animated, deforming shape tended to assign figure and ground so that articulating curvature extrema - i.e., "hinging" vertices - had negative (concave) contour curvature. This articulating-concavity bias is present when all known static cues to figure/ground are absent or neutral in each of the individual frames of the animation, and even seems to override a number of well-known static cues when they are in opposition to the motion cue. We propose that the phenomenon reflects the visual system's inbuilt expectations about the way shapes will deform - specifically, that deformations tend to involve rigid parts articulating at concavities.     

与《告别中医中药》论者商榷

《告别中医中药》一文的立论和方法是不可取的;《告别中医中药》一文的四点论据还需商榷,《告别中医中药》一文与党的中医政策和构建社会主义和谐社会有着不和谐的声音.中医和西医与其他自然科学一样在各自起作用的范围内存在和发展.     

The homogeneity effect on figure/ground perception in infancy

We examined whether the homogeneity of the two profiles of Rubin's goblet affects figure/ground perception in infants. We modified the two profiles of Rubin's goblet in order to compare figure/ground perception under four test patterns: (1) two profiles painted with horizontal lines (horizontal-line condition), (2) two profiles painted middle gray (uni-color condition), (3) one profile painted light gray and the other dark gray (two-color condition), and (4) a goblet painted with concentric circles (concentric-circles condition). In the horizontal-line condition the homogeneity of the profile was strengthened, and in the two-color condition the homogeneity of the profile was weakened compared to the uni-color condition, which was an original Rubin's goblet. In the concentric-circles condition the homogeneity of the reversed areas of the horizontal-line were strengthened.     

Identity leadership and social identification within sport teams over a season: A social network analysis

ObjectivesThis study explored the relationships between identity leadership and social identification in sport teams over the course of a season using social network analysis.MethodsParticipants from 23 competitive sport teams (N = 388, M_age = 20.7 years) indicated the extent to which each of their teammates displayed various forms of identity leadership (i.e., identity prototypicality, identity advancement, identity entrepreneurship, identity impresarioship) and the extent to which these same teammates were seen to identify with the team (assessed by ingroup ties, cognitive centrality, ingroup affect) early and later in a season. Quadratic assignment procedure correlations and multiple quadratic assignment procedure regressions examined the relationships between the different types of networks for each team across time.ResultsAthletes who perceived team members to show greater identity leadership perceived those same teammates to identify more strongly with the team both early (rs_average > .46) and later (rs_average > 0.48) in the season. Averaged across teams, identity entrepreneurship early in the season was most strongly associated with both perceived ingroup ties (β_average = .24) and ingroup affect (β_average = 0.13) later in the season, while identity impresarioship was most strongly associated with cognitive centrality (β_average = .16). In the reversed direction, perceptions of ingroup ties early in the season were most strongly associated with all identity leadership dimensions later in the season (.28 < β_average < 0.38).ConclusionsCollectively, these findings provide evidence of a mutually reinforcing bidirectional link such that teammates who are seen as actively contributing to promote a sense of ‘us’ among team members are also more likely to be seen as identifying strongly with the team.     

Trust of an Automatic Ground Collision Avoidance Technology: A Fighter Pilot Perspective

The present study examined the antecedents of trust among operational Air Force fighter pilots for an automatic ground collision avoidance technology. This technology offered a platform with high face validity for studying trust in automation because it is an automatic system currently being used in operations by the Air Force. Pilots (N = 142) responded to an online survey which asked about their attitudes toward the technology and assessed a number of psychological factors. Consistent with prior research on trust in automation, a number of trust antecedents were identified which corresponded to human factors, learned trust factors, and situational factors. Implications for the introduction of novel automatic systems into the military are discussed.