The Influence of Visual Texture Density Gradients on Relative Distance Judgements

A test was made of the scalability of interval-ordering judgments of distance along the median path of a plane horizontal surface. Scales were derived from different subsets of judgments. It was found that scale values were related to distance by a power function with marked individual differences in exponent, but that different subsets of judgment yielded the same mean exponent. This finding was taken as positive evidence of scalability. The individual differences in judgment were shown to be reliable over a period of 3 weeks.

supporting

confidence: 75%

The judgment of distance on a plane surface

Cook

1978

“…Differences in number of textural units, their shape, absolute size and spacing, and area of the retina involved have also been found to influence slant judgments (Eriksson, 1964;Gruber & Clark, 1956;Phillips, 1970). Newman (1971) found that relative distance judgments of the midpoint of a surface differed with varying numbers of elements in the texture, and Wohlwill (1962) reported similar findings using textures to suggest depth in pictures. All these results indicate that, despite entirely constant gradients of texture density, variations in several specifiable properties of surface texture influenced judgments of slant and distance.…”

mentioning

confidence: 57%

The influence of texture on judgments of slant and relative distance in a picture with suggested depth

Newman

Whinham

MacRae

1973

Self Cite

Six surfaces from natural environments with different visual textures were photographed at angles of 60, 65, and 70 deg from perpendicular. Measurements were taken of 24 Ss' judgments of the inferred angles of slant and inferred midpoints of the six textured surfaces represented in the photographs which were viewed in the frontoparallel plane: Judgments of both slant and relative distance within the photographs were influenced by represented angle of slant and by variations in surface texture.

“…Such cues have been studied by presenting the subject with, say, a texture gradient on a vertical or horizontal surface and having him match its apparent slant with an adjustable tilting rod (Clark, Smith, & Rabe, 1956), or compare it with the apparent slant of a neighboring textured surface (Phillips, 1970). Alternatively, the subject may be asked to set a marker at the apparent midpoint of such a gradient (Newman, 1971). It could be argued that some of these tasks have intellectual, memory, or motor components which make them less than ideal measures of the subject's immediate percept.…”

Section: Methodsmentioning

confidence: 99%

The Schröder staircase: A new perspective

Harris¹

1979

A range of variants of the Schroder staircase was generated by computer, giving quantifiable changes of perspective and the option of adding appropriate texture to the steps of the staircase. Increases in perspective and the addition of texture gradients led to increases in the proportion of viewing time during which the percept appropriate to the perspective was reported. It is suggested that this might be a useful method of studying the processing of depth information.There are several reasons for supposing that the perceptual alternations of a class of reversible figures, which includes the Necker cube, Schroder staircase, and Mach card, are linked with depth processing mechanisms. First, subjects often describe such an alternation as a reversal of the apparent depth relationships within the figure. Secondly, adding depth cues to such figures can alter both the rate of alternation and the relative durations of the various percepts. A third line of evidence is much more indirect: although the alternation rate of a number of multistable figures changes with the subjects' viewing distance, that of depth reversible figures does not (Atkinson, Campbell, Fiorentini, & Maffei, 1973).The evidence that depth cues affect reversible figures is somewhat variable in its quality, ranging from brief anecdotal reports, through incidental observations, to experiments in which attempts were made to quantify both the depth information added to the reversible figure and the resulting changes in perceptual alternation. For example, Ogle (1962) mentions that the addition of perspective to the Necker cube and Schroder staircase produces a tendency to one percept. Orbach and Zucker (1965) report that removing those edges from a Necker cube which would be hidden if it were solid has a similar effect. It was found by Howard (1961) and Virsu (1975) that adding disparity to a skeletal wire cube and Schroder staircase, respectively, increases the initial period before a perceptual reversal. In a study of the Necker cube, Cormack and Arger (1968) reported that increases in disparity up to 45 min of arc both increased the durations of the percepts appropriate to the disparity and decreased the alter-. nation rate, but that a further increase to 90 min of arc had little additional effect. This last study, if I thank the MRC for support; Nick Markovits for his programs, advice, and help, without which the study would have been impossible; Ian Low for building the timers and printer; Philip Clark for photography; and Richard Gregory, David Rose, and Priscilla Heard for helpful comments. not unique, must be one of the few investigations in which the added depth cue has been systematically varied.These studies are usually said to tell us something about perceptual multistability. But it also seems plausible to argue that they tell us something about the way in which depth information is processed by the visual system. There are some assumptions necessary for this argument, which will now be considered. The first is that the kinds of perceptua...