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J E Cutting

Publications and source records attributed to J E Cutting.

At least 19 recordsLinked to original sources
PubMed1992

Wayfinding on foot from information in retinal, not optical, flow.

People find their way through cluttered environments with ease and without injury. How do they do it? Two approaches to wayfinding are considered: Differential motion parallax (DMP) is a retinal motion invariant of near and far objects moving against fixation; the information in optical flow (IOF) is a radial pattern of vectors, relying on decomposition of retinal flow. Evidence is presented that DMP guides wayfinding during natural gait, accounting for errors as well as correct responses. Evidence against IOF is also presented, and a space-time aliasing artifact that can contaminate IOF displays is explored. Finally, DMP and IOF are separated, showing they can yield different results in different environments. Thus, it is concluded that (a) DMP and IOF are different, (b) DMP and not IOF is used for wayfinding, (c) moving observers do not usually decompose retinal flow, and (d) optical flow may be a mathematical fiction with no psychological reality.

Adult↗
PubMed1992

Selectivity, scope, and simplicity of models: a lesson from fitting judgments of perceived depth.

When comparing psychological models a researcher should assess their relative selectivity, scope, and simplicity. The third of these considerations can be measured by the models' parameter counts or equation length, the second by their ability to fit random data, and the first by their differential ability to fit patterned data over random data. These conclusions are based on exploration of integration models reflecting depth judgments. Replication of Massaro's (1988a) results revealed an additive model (Bruno & Cutting, 1988), and Massaro's fuzzy-logical model of perception (FLMP) fit data equally well, but further exploration showed that the FLMP fit random data better. The FLMP's successes may reflect not its sensitivity in capturing psychological process but its scope in fitting any data and its complexity as measured by equation length.

Adult↗
PubMed1990

Compensation is unnecessary for the perception of faces in slanted pictures.

In four experiments, we explored the perception of facial distortions seen in pictures viewed from the side or from above or below. In all four, however, we disguised the slant of the picture surface by using a double-projection technique that removed binocular and monocular cues: Faces were digitized, distorted to mimic a particular slant behind the image plane, cropped to a frame, and presented to viewers for their judgments. In the first experiment, we found that simulated rotations around a horizontal axis (pictures seen as if from above or below) created more noticeable distortions in faces than did simulated rotations around a vertical axis (pictures seen as if from the left or right). In the second experiment, pursuing a result from the first but with a between-subjects design, we found that pictured faces with a slant around a vertical axis of 22 degrees were seen as having no more distortion than unslanted faces. In the third experiment, we placed each image within a frame slanted either in the same way as or differently from the picture, and found no effect of frame. In the fourth experiment, we determined that viewers had little ability to match appropriately slanted frames with slanted pictures. Thus, we claim that part of the reason why one can look at moderately slanted pictures without perceptual interference is that the distortions in the image are subthreshold, or perhaps within the bounds of acceptability. These results contrast with the generally accepted theory that viewers mentally compensate for distortions in moderately slanted pictures.

Attention↗
PubMed1988

Affine distortions of pictorial space: some predictions for Goldstein (1987) that La Gournerie (1859) might have made.

Goldstein (1987) studied the perception of pictures seen from the front and the side. Several distinctions arose from his results and analysis, but only one is central to the reanalysis presented here: The perceived orientation of objects within a picture with respect to the external world is a function of viewer position in front of the picture. For example, the eyes of a portrait subject appear to follow an observer who moves around a gallery. Viewed from many positions, such objects can be said to rotate, following a mobile viewer. Goldstein called this the differential rotation effect because those objects that point directly out of the picture (at 90 degrees) rotate most; those pointing at other angles rotate in decreasing amounts. Goldstein offered no theoretical model and little in the way of explanation for this effect. This Observation offers a model based on the affine geometry and the analyses of La Gournerie (1859). This analysis transforms pictorial space (the space behind a photograph or representational picture) by shears, compressions, and dilations according to the viewpoint of the observer in relation to the composition point of the picture. These effects account for Goldstein's differential rotation effect quite well.

Depth Perception↗
PubMed1988

Minimodularity and the perception of layout.

In natural vision, information overspecifies the relative distances between objects and their layout in three dimensions. Directed perception applies (Cutting, 1986), rather than direct or indirect perception, because any single source of information (or cue) might be adequate to reveal relative depth (or local depth order), but many are present and useful to observers. Such overspecification presents the theoretical problem of how perceivers use this multiplicity of information to arrive at a unitary appreciation of distance between objects in the environment. This article examines three models of directed perception: selection, in which only one source of information is used; addition, in which all sources are used in simple combination; and multiplication, in which interactions among sources can occur. To monocular spatial information, using all combinations of the presence or absence of relative size, height in the projection plane, occlusion, and motion parallax. Visual stimuli were computer generated and consisted of three untextured parallel planes arranged in depth. Three tasks were used: one of magnitude estimation of exocentric distance within a stimulus, one of dissimilarity judgment in how a pair of stimuli revealed depth, and one of choice judgment within a pair as to which one revealed depth best. Grouped and individual results of the one direct and two indirect scaling tasks suggest that perceivers use these sources of information in an additive fashion. That is, one source (or cue) is generally substitutable for another, and the more sources that are present, the more depth is revealed. This pattern of results suggests independent use of information by four separate, functional subsystems within the visual system, here called minimodules. Evidence for and advantages of minimodularity are discussed.

Attention↗
PubMed1988

Additivity, subadditivity, and the use of visual information: a reply to Massaro (1988).

Previously we (Bruno & Cutting, 1988) explored the perception of spatial relations among objects laid out in a computer-generated environment. In his commentary on our article, Massaro (1988) raised several issues. The most important is from his reanalysis, which indicated that--because of a subadditive trend in the results--additive and multiplicative strategies fit our data in Experiment 1 about equally well. In reply, we performed a different analysis. Results corroborate subadditivity--and hence multiplicative information combination--in Experiment 1 but provide no evidence for it in Experiments 2 and 3. On the whole, then, the results still support additivity more strongly than any other combination rule and thus support our notion of minimodularity.

Depth Perception↗
PubMed1987

Rigidity in cinema seen from the front row, side aisle.

Pictures and cinema seen at a slant present the optics of virtual objects that are distorted and inconsistent with their real counterparts. In particular, it should not be possible for moving objects on slanted film and television screens to be seen as rigid, at least according to rules of linear perspective. Previous approaches to this problem have suggested that some process (perhaps cognitive) rectifies the optics of objects in slanted pictures to derive true shape and preserve shape constancy. The means for this rectification is usually thought to be based on recovery of true screen slant. In three experiments I show that this account is unnecessary and insufficient to explain the perception of rotating, rectangular objects in slanted cinema. I present data in favor of an alternate view, one in which the information is sufficient for perceivers to determine rigidity in an object on slanted screens, at least for parallel projections. In the human visual system, local measurements of objects are apparently made according to projective geometry; in those measurements, small amounts of certain distortions in projection are tolerated. Stimuli that appear nonrigid are ones that violate certain local principles, known as Perkins's laws, of projections of rectangular solids.

Humans↗
PubMed1984

Three gradients and the perception of flat and curved surfaces.

Researchers of visual perception have long been interested in the perceived slant of a surface and in the gradients that purportedly specify it. Slant is the angle between the line of sight and the tangent to the planar surface at any point, also called the surface normal. Gradients are the sources of information that grade, or change, with visual angle as one looks from one's feet upward to the horizon. The present article explores three gradients--perspective, compression, and density--and the phenomenal impression of flat and curved surfaces. The perspective gradient is measured at right angles to the axis of tilt at any point in the optic array; that is, when looking down a hallway at the tiles of a floor receding in the distance, perspective is measured by the x-axis width of each tile projected on the image plane orthogonal to the line of sight. The compression gradient is the ratio of y/x axis measures on the projected plane. The density gradient is measured by the number of tiles per unit solid visual angle. For flat surfaces and many others, perspective and compression gradients decrease with distance, and the density gradient increases. We discuss the manner in which these gradients change for various types of surfaces. Each gradient is founded on a different assumption about textures on the surfaces around us. In Experiment 1, viewers assessed the three-dimensional character of projections of flat and curved surfaces receding in the distance. They made pairwise judgments of preference and of dissimilarity among eight stimuli in each of four sets. The presence of each gradient was manipulated orthogonally such that each stimulus had zero, one, two, or three gradients appropriate for either a flat surface or a curved surface. Judgments were made were made for surfaces with both regularly shaped and irregularly shaped textures scattered on them. All viewer assessment were then scaled in one dimension. Multiple correlation and regression on the scale values revealed that greater than 98% of the variance in scale values was accounted for by the gradients. For the flat surfaces a mean of 65% of the variance was accounted for by the perspective gradient, 28% by the density gradient, and 6% by the compression gradient. For curved surfaces, on the other hand, a mean of 96% of the variance was accounted for by the compression gradient, and less than 2% by either the perspective gradient or the density gradient.(ABSTRACT TRUNCATED AT 400 WORDS)

Depth Perception↗
PubMed1983

Four assumptions about invariance in perception.

The term invariance has become more central to current views of perception. I take this as a good trend, but the term is rooted in mathematics, and its use in perception brings with it a host of assumptions that have generally been unexamined. The purpose of this article is to state some of these assumptions and assess their validity, with the hope that we can continue to find the term useful while acknowledging its limitations. The assumptions discussed are that (a) mathematics is an appropriate descriptive language for perception, (b) mathematical truths are transportable into perception without change of meaning, (c) mathematical imports are useful in explaining perception, and (d) perceptual invariants, like their mathematical counterparts, are absolute and not subject to threshold considerations.

Humans↗
PubMed1979

Perception of wheel-generated motions.

Data are presented on an old and familiar Gestalt demonstration--perceiving wheel-generated motions--in which the perceived motions of a rolling wheel are shown not to be obviously derived from the motions of the parts. The history of study of this phenomenon is presented, and contradictions in the literature are noted. The focus for experimentation is on the contrasting approaches found in Johansson's perceptual vector analysis and Wallach's arguments for the priority of object-relative displacement in the extraction of invariants. Johansson's approach asserts that common vectors are extracted from moving events first, whereas Wallach asserts that the motion of objects relative to each other is first. These two approaches yield different predictions about what ought to be seen when different configurations are viewed in rotation. In five experiments viewers rated how wheellike the movement of various point-light systems attached to a rolling wheel appeared to be. Results support Wallach's views over Johansson's. Viewer judgments of goodness in wheellike motion correspond highly with a mathematical description of the parameters of cycloidal motion for the geometric center of any system of lights on a rolling wheel. This specification can be made only after the extraction of object-relative displacement information. Number of lights and order of symmetry influence viewer judgments to a much lesser degree, and placement of a light at the wheel's center matters not at all.

Form Perception↗
PubMed1978

A biomechanical invariant for gait perception.

Viewers can determine the gender of a walker from sagitally projected, dynamic displays of point-lights attached to prominent joints. This article explores three interrelated approaches in search of a biomechanical invariant that viewers might use. The first, an index of torso structure, accounts for the data handsomely but seems inappropriate because it is not directly revealed in the dynamic stimuli. The second, a dynamic index of visible torsion in the trunk of a walker, also fits the data well but seems to have a logical problem and a difficulty in accounting for performance in certain conditions of several previous studies. The third has the strengths of the first two indices, and it can account for some other data as well. It is the center of moment and is a "deeper", more general description of the invariant. This center is a point around which all movement occurs. It can be thought of as one specification of the gestalt law of common fate and may be helpful for the study of movement perception in general.

Biomechanical Phenomena↗
PubMed1978

Generation of synthetic male and female walkers through manipulation of a biomechanical invariant.

Synthetic versions of human walkers were generated by computer as point-light displays. Previously it had been determined that the natural gaits of males and females differ according to the extent of movement at the shoulder and the hip. These movements were measured and then used to synthesize the stimuli used in the present study. These stimuli are shown here to be identified by untrained viewers as male when the shoulder movement is greater than the hip movement, and female when the configuration is reversed. Because of the coherence of the display lights representing the shoulder and hip are not necessary for gender recognition, although they do increase performance level. Hypernormality and heavy-footedness in gait are also discussed. Finally, all results are linked to an underlying biomechanical invariant, the center of moment.

Biomechanical Phenomena↗