Effects of Motion Parallax and Perspective Cues on Perceived Size and Distance

Abstract

In three experiments we examined the relative effectiveness of motion parallax and two perspective cues for the perception of size and distance. The experimental stimuli consisted of two ellipses (a standard and a comparison) and a horizontal line that indicated the horizon. The subject's task was to report the apparent size and distance of the comparison stimulus relative to the standard stimulus. Two perspective cues were given by the relative heights of the two stimuli and the absolute height of the standard stimulus below the horizon. Motion parallax was defined by both the ratio and the difference in angular velocities between the two stimuli on the display. In experiment 1 we examined the effects of the two perspective cues and the motion parallax. In experiment 2 we eliminated the horizon line, and examined the role of the horizon in size and distance perception. In experiment 3 we separately evaluated the effects of motion parallax and the relative height cues. The results from the three experiments showed that the effect of motion parallax and the two perspective cues were different in three ways. First, the relative effectiveness of motion parallax and the two perspective cues differed for size and distance estimates. For size estimates, the motion parallax was more effective than the perspective cues (experiments 1 and 3). For distance estimates, the motion parallax was as effective as the two perspective cues (experiments 1 and 3). Second, the role of the horizon differed for size and distance estimates. The size estimates were strongly affected by the horizon, while the distance estimates were not affected much by the horizon (experiment 2). Third, the effective perspective cues differed for the size estimates and the distance estimates: size estimates were affected by the perspective cues as a combination of the horizon and relative height; distance estimates were affected by the perspective cues as an interaction between the absolute and relative heights without the horizon line.

Height Perception Influenced by Texture Gradient

“…Based on these explanations of Gibson (1950), we can account for the current result showing that height cues differ from distance cues. Many previous researchers have reported that size perception was specified by the cue that was irrelevant to distance (eg Burbeck 1987;Humphrey and Morgan 1965;Tozawa and Oyama 2006).…”

Efeitos da perspectiva na amplificação dos tamanhos de objetos que interceptam a linha do horizonte

“…Outra possível explicação está relacionada com a Hipótese da Invariância Tamanho-Distância (HITD), que es-tabelece que se o tamanho angular de um objeto for mantido constante, o tamanho percebido será propor-cional à distância percebida (Holway & Boring, 1941;Tozawa & Oyama, 2006). Esse efeito pode ser facilmente comprovado em uma situação em que dois objetos de mesmo tamanho são posicionados em diferentes pontos do gradiente de textura.…”

“…O julgamento de tamanho de objetos é modulado por distintas informações presentes em arranjos ópticos, tais como informações pictóricas de profundidade provenientes de gradientes de textura (Aks & Enns, 1996;Torro-Alves & Fukusima, 2007;Williams & Enns, 1996) e a linha do horizonte (Bennett & Warren, 2002;Bertamini, Yang, & Proffitt, 1998;Bingham, 1993;Dixon, Wraga, Proffitt, & Williams, 2000;Rogers, 1996;Sedgwick, 1980;Wraga, 1999). É reconhecida há décadas a importância do gradiente de textura como condição suficiente para a percepção de distância (Gibson, 1979), o que repercute sobre a percepção de tamanho, já que esta requer o conhecimento sobre a distância percebida do objeto, especialmente em condições com limitações visuais (O'Brien & Johnston, 2000;Tozawa & Oyama, 2006).…”

Effects of Shape, Size, and Chromaticity of Stimuli on Estimated Size in Normally Sighted, Severely Myopic, and Visually Impaired Students

“…However, Rulence-Paques and Mullet (1998) suggested that participants used the information concerning height and width of the size and then integrated these two items by additive or multiplicative operations. Therefore, the area estimated might be affected by a combination of cues taken from both the horizon line and the relative height (Tozawa & Oyama, 2006). It may be that participants need to estimate both height and width of square stimuli to judge the stimulus area, but that they need only estimate the diameter of a circle to judge its area.…”