Absence of binocular interaction between spatial and color attributes of visual stimuli

The hypothesis that induction of the McCollough effect (spatially selective color aftereffects) entails adaptation of monocularly driven detectors tuned to both spatial and color attributes of the visual stimulus was examined in four experiments. The McCollough effect could not be generated by displaying contour information to one eye and color information to the other eye during inspection, even in the absence of binocular rivalry. Nor was it possible to induce depth-specific color aftereffects following an inspection period during which random-dot stereograms were viewed, with crossed and uncrossed disparity seen in different colored light. Masking and aftereffect in the perception of stereoscopic depth were also nonselective to color; in both cases, perceptual distortion was controlled by stereospatial variables but not by the color relationship between the inspection and test stimuli. The results suggest that binocularly driven spatial detectors in human vision are insensitive to wavelength.     

Sex differences in verbal skills: Use of spelling-sound and lexical information

An experiment is described in which possible sex differences in lexical and phonological skills were investigated. A spelling test was used which could not be done on a phonological basis alone and which entailed lexical access for good performance. Women were judged on the evidence for this task to have better lexical ability than men, but no difference was found on a task designed to tap knowledge and use of phonological information in the form of spelling-sound correspondences.     

Spatial and movement-based heuristics for encoding pattern information through touch

Seven experiments investigated the heuristics people use to encode spatial pattern information through touch. Observers traced a tangible pathway with one hand and then answered questions about either the euclidean line between the pathway endpoints or the pathway itself. Parameters of the euclidean line were held constant, while characteristics of the felt pathway were manipulated. Experiments 1-4 showed that blindfolded sighted and blind observers increasingly overestimated the length of the euclidean line as the length of the explored pathway increased. This indicates a movement-based heuristic for encoding distance. Experiments 5-7 indicated that judgments of the position of the euclidean line did not vary with the position of the felt pathway or the extent to which it deviated from that line. Instead, the results indicated that observers relied on implicit spatial axes, which are movement independent, to judge position. These and other results have implications for theories of haptic encoding of spatial pattern and for the construction of tangible graphics displays.     

Memory for targets in a multilevel simulated environment: Evidence for vertical asymmetry in spatial memory

In two experiments, adult participants explored a symmetrical three-tiered computer-simulated building that contained six distinctive objects, two on each floor. Following exploration, the objects were removed, and the participants were asked to make direction judgments from each floor, indicating the former positions of the objects on that floor and on higher and lower floors. Relative tilt error scores indicated a bias, in that targets that were higher than the test location were judged as consistently lower than their actual positions and targets that were lower than the test location were judged as consistently higher than their actual positions. Absolute tilt errors revealed an asymmetry, with more accurate and less variable tilt errors for judgments directed to lower floors than for judgments directed to higher floors. Experiment 3 ruled out an account of the findings that does not relate them to spatial memory. The results suggest that the superiority of downward over upward spatial judgments, previously reported in two-dimensional visual-spatial tasks, extends to navigational spatial memory.