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Biomedical subjects

M A Hagen

Publications and source records attributed to M A Hagen.

12 recordsLinked to original sources
PubMed1983

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 picutres of people's 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 subjecs: 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.

Face↗
PubMed1978

A distinctive characteristic of pictorial perception: the zoom effect.

To investigate the role of flat surface information for the plane of projection in pictorial perception, three studies were designed in which varying amounts of such information were made available to adult subjects. The first study tested preferences for true or modified linear perspective under conditions of presence or absence of surface texture cues for the plane of projection. In the second and third studies, the absence of texture cues for the plane was coupled with the addition of motion parallax and binocular information respectively. It was found that adults showed a consistent preference for parallel perspective in pictures when the flat-surface information was provided either by visible texture or by motion parallax; but no consistent preference for either true or modified perspective in the absence of all three sources of flatness information or when the flat surface information was given only by binocular cues in the absence of visible surface texture of visible surface texture or head motion.

Cues↗
PubMed1978

Role of two-dimensional surface characteristics in pictorial depth perception.

The purpose of the present experiment was to test the hypothesis that flat surface information for the plane of projection is the essential difference between ordinary and pictorial perception. Adults were asked to make relative size judgments of pairs of squares and triangles placed and pictured at various distances. The conditions were: real scene controls, life-size slides and prints, and real scenes viewed through clear glass, textured glass, a screen and a 50-mm lens. The error rate was significantly lower with real scenes than with either slides or prints which did not differ. The control data for real scenes were used for comparison to test for the effects of interposed flat surfaces on size judgments of real scenes. Viewing real scenes through either a clear glass pane or a 50-mm lens increased the error rate two and one-half times that of the controls for real scenes. Neither textured glass nor a screen significantly affected error rate. Results were interpreted as supporting the hypothesis that information about a flat surface for the plane of projection is the critical variable determining the special character of picture perception.

Depth Perception↗
PubMed1977

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 distance relations. Erroneous choices available to the subject indicated errors in size judgement, 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.

Adult↗
PubMed1976

An investigation of the relationship between viewing condition and preference for true and modified linear perspective and adults.

In four experiments, pictures varying in degree of perspective convergence from linear to parallel were observed under the following conditions: at an arbitrary station point, at correct station points, and with unconstrained view. Adults were asked to rank the pictures from the most to least natural and realistic-looking picture or from the most to the least accurate drawing. Subjects nearly always chose the parallel perspective pictures as most preferred and the linear perspective pictures as least preferred. Intermediate degrees of convergence were ranked accordingly. Results were interpreted in light of an argument for a pictorial station poing independent of the correct center of projection for a picture. Since this station point was calculated to be at a distance at least 10 times as great as the object is large, its assumption for pictorial viewing was termed the "Zoom "effect.

Adult↗
PubMed1976

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. Children's 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 demension 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.

Age Factors↗
PubMedDate not supplied

The Lewis system and secretor status in autoimmune hemolytic anemia complicating infectious mononucleosis.

Two patients with acute infectious mononucleosis and associated immune hemolysis were found to be Le(a-b-). One of them had anti-Leb antibodies during the acute phase of the disease, which disappeared during convalescence. Two other patients with previous infectious mononucleosis and hemolysis were found to be Le(a-b-) and Le(a+b-) respectively. Of the four patients, three were nonsecretors and the fourth likely to be so. The Lewis status of these four patients varies significantly from that of other patients with uncomplicated infectious mononucleosis and from the known distribution of the Lewis type in the Caucasian population. The findings suggest that the Lewis status of the patient is important in the development of hemolysis in infectious mononucleosis.

Adolescent↗