Margaret A. Hagen

On a neglected variable in theories of pictorial perception: Truncation of the visual field

Theoretical analyses of pictorial perception have concentrated on the consequences of conflicting flatness and depth information in pictures, but have failed to consider the perceptual effects of the truncation of the visual field attendant on any pictorial display. The importance of this variable both for methods of testing pictorial information and for theory building was demonstrated. Under four different viewing conditions, adults were asked to scale the size and distance of five isoceles triangles at five different distances. The four conditions were unobstructed static monocular view, peephole view, view through a rectangular frame, and view of all the stimuli photographed in a slide. The slopes of the peephole, truncation, and slide conditions’ scaling functions were all significantly smaller than the slope of the untruncated Monocular condition, and the Y-intercepts were all greater. A decrease in over-constancy in the size functions indicated a similar effect for all three truncated conditions. Results are interpreted as supporting the hypothesis that truncation of the visual field, both in pictures and in peephole views of the real world, causes a frontal shift in the localization of the visible field, with a resultant compression of perceived size and distance.

The effects of binocular and motion-generated information on the perception of depth and height

The perception of distance and size in the presence of optical gradient information was investigated under four viewing conditions—binocular view with and without head motion, and monocular view with and without head motion. Subjects (60 adults) matched distance intervals (from 15 to 127 cm) and heights of a target triangle (from 5 to 15 cm) by adjusting the length of a metal tape. Both linear and power functions were fitted to each individual’s distance judgments, and the competing perceptual models were compared. For both models, it was found that binocular information was sufficient to specify relative, but not absolute, distance, that monocular information was sufficient to specify an orderly relation between target distance and judgment but not absolute distance, that average error was less in the binocular conditions, and that perceived distance was not affected in either condition by the addition of head motion. The analysis of size judgments revealed that monocular and binocular judgments did not differ, that matches made with and without head motion did not differ, and that, in all conditions, matches exceeded target heights by an average 30% to 40%. Judged size was also analyzed as a function of target distance. In all conditions but monocular view with head motion, the effect of distance was to increase size judgments. The distance judgments support the hypothesis (Purdy, 1958) that the binocular stimulus carries information that the monocular stimulus does not; they fail to support the hypothesis (Gibson, 1966) that observer motion adds information to the static stimulus. The size judgments support neither hypothesis but suggest an independence of perceived size from perceived distance.

Hudson Pictorial Depth Perception Test: cultural content and question with a Western sample.

Summary Since the Hudson Pictorial Depth Perception Test currently provides the main source of evidence about cross-cultural pictorial depth perception, an investigation was designed to study the effects of culturally relevant subject matter, identification of pictorial content, and specific questioning employed in the test with a Western reared S group (N = 160 elementary and college students). Two forms of the Hudson Test were used: The African form is composed of the six hunting scenes used by Hudson. An American version of the test was designed to duplicate the pictorial information in the African version. Half the Ss were asked Hudsons question containing the word “nearer,” and half were asked the question with “aiming” (or “throwing”). Both the familiarity of the cultural content and the specific terms used in questioning strongly influenced performance. There is evidence of a gradual developmental change in sensitivity to depth cues when portrayed in Hudsons test, but not when those cues appear i...

A refutation of the hypothesis of the superfidelity of caricatures relative to photographs

The experiment was designed to test the hypothesis that caricatures, relative to photographs, are ‘superfaithful’ carriers of information for facial recognition. Subjects were shown fifteen pictures of peoples faces and were then asked to pick those same people out of a set of fifty-four pictures. There were three sets of pictures: caricatures, profile-view photographs, and three-quarter-view photographs. There were nine groups of subjects: for three groups the exposure and test stimuli were in the same medium, for six groups the test stimuli were in one of the media not previously seen. Points were scored for the number of people correctly identified and the number of false positives. Facial recognition within medium was very good, but was seriously disrupted by any medium shift, especially those involving caricatures. It is argued that the superfidelity of caricature may be manifest only when the task involves recognition of actual persons rather than their pictures.

Cultural Effects on Pictorial Perception: How Many Words Is One Picture Really Worth?

Why would anyone study pictorial perception cross-culturally? Two reasons are given in the literature. The first is to identify group differences among cultures in their understanding of pictorial materials. This reason is pragmatic. Pictures are ubiquitous in urban, industrialized cultures and we rely on their information-carrying value in teaching, testing, transportation, communications, industry, etc. In the past, the unspoken assumption has been that specific experience with pictures was not a necessary prerequisite to understanding them since it was commonly held that a picture was indeed worth at least a thousand words. However, this unspoken assumption was not always supported by the experiences of people in nonurban/industrialized cultures. Reports began to appear on the general inadequacy of pictorial materials as universal and culture-independent instruments of communication and the cross-cultural picture work was begun. The aim of the work is to identify groups failing to perceive in the previously expected manner and to isolate the causes of that failure, e. g., absence of Western schooling.

The development of sensitivity to cast and attached shadows in pictures as information for the direction of the source of illumination

The development of the perception of cast and attached shadows as information in pictures for the direction of the light source was studied with children in kindergarten, third and sixth grades, and adults in college. Subjects viewed photographs of objects under four different positions of illumination, with either cast or attached shadows alone, or with both present. Error in angular displacement from the correct position of the light source was 76.5° for kindergarten children, 40.5° for those in the third grade, 34.9° for those in the sixth, and 18.0° for college students. Neither position of light nor type of object affected performance. Results are discussed in the context of a developmental hypothesis of changing interpretation of the relations between pictorial and nonpictorial space from childhood to adolescence.

How to make a visually realistic 3D display

What is a three-dimensional display? A 3D display is basically a picture a complex picture, a picture of a whole world you want the user to be able to enter. That world nmst carry in fommtion that is easy to understand about the state of the system and the possible actions and present options open to the user. A display that is well-designed does not require long periods of training to master. A well-designed display takes advantage of the perception and action knowledge base the user already has flom acting and interacting in the ordinary world. To make it possible for the user to enter and interact with the 3D world of the display, the display designer must follow the well established rules of creating visually realistic 3D pictures. Most of the rules for creating realistic pictures are just a subset of the rules for describing visual perception of the ordinary 3D world. As we shall see below, this subset must be coupled with the rules governing pelception of projections on a plane.

DEVELOPMENT OF ABILITY TO PERCEIVE AND PRODUCE PICTORIAL DEPTH CUE OF OVERLAPPING

The perception of the pictorial depth cue of overlapping was studied in children 3, 5, and 7 yr. old. Both a sequential and a simultaneous picture/object-matching task were used to test sensitivity. All age groups successfully perceived the depth relation information provided by pictorial overlapping. Height on the picture plane, which projectively covaries with overlapping, was not consistently used as a depth cue by any age group. Childrens drawings were also analyzed for the presence of distance information. The drawings of the 3- and 5-yr.-old children contained no overlapping cues and indicated a general lack of understanding of the third dimension behind the picture plane. Seven-yr.-old children showed the beginnings of this understanding through their use of size perspective and height on the picture plane as depth cues. For all ages the production of the overlapping cue lags behind its perception.

Generative Theory: A Perceptual Theory of Pictorial Representation

Publisher Summary This chapter presents the proposition that cultural and historical options in styles of depiction that appear to be radically different are instead closely related perceptually. The purpose of perceptual theory is to explain the acquisition of knowledge of the world. The nature of perceptual inference is where perceptual theorists differ, and this difference pervades their descriptions of the perceptual stimulus, the nature of perceptual activity and the perceptual product, and their entire empirical approach to the problems of perception. A theory is required that acknowledges the empirical validity and reliability of the diverse perceptual phenomena that have served as domains of research enterprise for all of the perceptual theories so far described, and that resolves the apparent opposition among them by subsumption of each into a more descriptively adequate general theory of perception.

Pictorial Perspective: Perception of Size, Linear, and Texture Perspective in Children and Adults

Perception of size, linear, and texture perspective was investigated in third-grade and sixth-grade children and in college adults in three separate studies. A matching task required the observer to choose from a set of four alternative real scenes the correct match for the test stimulus, which was either a picture or a real scene. Correct performance required that the subject utilize perspective information for both size and distance relations. Erroneous choices available to the subject indicated errors in size judgment, in distance judgment, or in both simultaneously. View was either restricted at the correct station point or was free, with head motion. There were no significant effects of grade level. For all three groups, mean percent correct was nearly 100% with the real-scene test stimuli, and significantly below the chance level with the picture test stimuli. Errors in size judgment occurred most frequently, indicating that the geometrically correct rate of perspective convergence was too rapid to be seen by the subjects as perceptually acceptable. With size-perspective information alone, the number of size plus distance errors also increased significantly. There was no significant effect of viewing condition.