Engineering data compendium. Human perception and performance. User's guide

The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design and military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from the existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by systems designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is the first volume, the User's Guide, containing a description of the program and instructions for its use

The perception of stereoscopic surfaces

Human stereoscopic vision depends upon the slightly different geometrical projections of the world to the two eyes. Horizontal disparities between the eyes produce the sensation of depth. But what is stereopsis for. One theory is that stereopsis extracts the spatial derivatives of horizontal disparity for the perception of shape and surface orientation. Discrimination tasks are devised here which compare sensitivity to the slant and curvature of stereoscopic surfaces with sensitivity to relative depth, both within and across tasks. Contrary to previous studies, where cues other than the second derivative were available, best Weber fractions for disparity curvature disrimination by these methods are no better than 15%. This compares with 6% for disparity gradient and 3.5 % for relative disparity. Discrimination of the orientation, size (or separation) and position of cyclopean corrugated surfaces reveals these stimulus attributes are discriminated as accurately as their counterparts in the luminance domain, provided the spatial scale is quite coarse. Other analogous results include the independence of spatial discriminations on relative disparity, the meridional anisotropy for cyclopean orientation discrimination and a range of relative disparity effects analogous to classical simultaneous contrast effects in luminance vision. It was also found, contrary to a previous study, that cyclopean textures could be segregated pre-attentively. These findings taken together imply that disparity is processed by spatial filters in a similar manner to luminance. This view of stereoscopic vision allows a fresh look at an old phenomenon: the stereoscopic slant anisotropy. An explanation is proposed on the basis of interactions between cyclopean spatial filters and a representation of disparity upon which they act. If sensitivity is a guide to function, stereopsis is for estimating the position, location, size and orientation of nearby objects, but probably not for estimating their shape

Engineering Data Compendium. Human Perception and Performance, Volume 1

The concept underlying the Engineering Data Compendium was the product an R and D program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design of military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by system designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is Volume 1, which contains sections on Visual Acquisition of Information, Auditory Acquisition of Information, and Acquisition of Information by Other Senses

Encoding of relative location of intensity changes in human spatial vision

The psychophysical experiments and numerical modelling reported in the present study are an investigation into the encoding of relative location of intensity changes in the human visual system. The study attempted, successfully, to explain some geometric illusions resulting from closely spaced image features ('crowding'), and determined the nature of information necessary for making judgments about the separation of intensity changes for different stimulus configurations. Experiments performed fell into two basic categories; those concerned with spatial interference, and studies of spatial interval judgments. The first set of experiments, studying spatial interference with relative localisation for intensity changes, was based on measurements made with stimuli composed of lowpass filtered bars and edges. The most successful model, which accounted for all of the data, was Watt and Morgan's (1984, 1985) MIRAGE; the results suggest that a good explanation of some geometric illusions can be derived using the principles of low-level vision. Spatial interference is strong evidence for combination of information across spatial scales, and the MIRAGE algorithm makes some highly accurate predictions. Relating the separation of image features is a fundamental task for the visual system, but there is no clear understanding of what information the system has available to perform this task. The second set of experiments explored the perception of separation, and precision of judgments of separation, for bars with a variety of orthoaxial contrast profiles. The data indicate that information is combined across spatial scales (as in MIRAGE) under certain circumstances in making separation judgments; this combination of information across scale occurs when the information on the scales combined is in agreement (ie. all scales have some task-related information), but when variance is added on coarser scales which is not relevant to the task, the system is capable of selecting the finest scales of filters available, and using only the information in the finest scale. This adaptive scale-selection process operates even at very brief exposure durations