The time required to recognize that two perspective drawings portray objects of the same three-dimensional shape is found to be (i) a linearly increasing function of the angular difference in the portrayed orientations of the two objects and (ii) no shorter for differences corresponding simply to a rigid rotation of one of the two-dimensional drawings in its own picture plane than for differenc...

The asymptotic behavior of Einstein-Rosen waves at null innnity in 4 dimensions is investigated in all directions by exploiting the relation between the 4-dimensional space-time and the 3-dimensional symmetry reduction thereof. Somewhat surprisingly, the behavior in a generic direction is better than that in directions orthogonal to the symmetry axis. The geometric origin of this diierence can ...

The present experiment was designed to examine the roles of painted linear perspective cues, and the convexity bias that are known to influence human observers' perception of three-dimensional (3D) objects and scenes. Reverse-perspective stimuli were used to elicit a depth-inversion illusion, in which far points on the stimulus appear to be closer than near points and vice versa, with a 2 (Type...

We developed psychometric tests of spatial orientation ability, in which people are shown a two-dimensional array of objects, imagine taking a perspective within the array, and indicate the direction to a target object from this perspective. Patterns of errors on these tests were consistent with experimental studies of perspective taking. Characteristic errors and verbal protocols supported the...

The present study compared the relative effectiveness of differential perspective and vergence angle manipulations in scaling depth from horizontal disparities. When differential perspective and vergence angle were manipulated together (to simulate a range of different viewing distances from 28 cm to infinity), approximately 35% of the scaling required for complete depth constancy was obtained....

INTRODUCTION 4 RELEVANCE OF INDIVIDUAL PERFORMANCE 4 DEFINITION OF PERFORMANCE 5 PERFORMANCE AS A MULTI-DIMENSIONAL CONCEPT 6 TASK PERFORMANCE 6 CONTEXTUAL PERFORMANCE 6 RELATIONSHIP BETWEEN TASK AND CONTEXTUAL PERFORMANCE 7 PERFORMANCE AS A DYNAMIC CONCEPT 7 PERSPECTIVES ON PERFORMANCE 8 INDIVIDUAL DIFFERENCES PERSPECTIVE 8 SITUATIONAL PERSPECTIVE 11 PERFORMANCE REGULATION PERSPECTIVE 13 RELAT...

The theory of conjugate points in the calculus of variations is reconsidered with a perspective emphasizing the connection to finite-dimensional optimization. The object of central importance is the spectrum of the second-variation operator, analogous to the eigenvalues of the Hessian matrix in finite dimensions. With a few basic properties of this spectrum, one can gain a new perspective on th...