This article investigates the optics conceptions of 228 Thai high school students in grades 10-12 when they attempted to explain how an object can be seen both in general and in a completely dark room. To elicit students' conceptions precisely, their confidence in giving reasons for the final two diagnostic questions is also considered. The study…

Human visual perception is a fundamentally relational process: Lightness perception depends on luminance ratios, and depth perception depends on occlusion (difference of depth) cues. Neurons in low-level visual cortex are sensitive to the difference (but not the value itself) of signals, and these differences have to be used to reconstruct the…

Replies to comments mad by Howe et al. on the current author's original article. The double-anchoring theory of lightness (P. Bressan, 2006b) assumes that any given region belongs to a set of frameworks, created by Gestalt grouping principles, and receives a provisional lightness within each of them; the region's final lightness is a weighted…

The relationship between luminance (i.e., the photometric intensity of light) and its perception (i.e., sensations of lightness or brightness) has long been a puzzle. In addition to the mystery of why these perceptual qualities do not scale with luminance in any simple way, "illusions" such as simultaneous brightness contrast, Mach bands,…

Shows that the perceived shade of gray depends on the luminance relationship between surfaces perceived to be in the same plane and not between surfaces that are merely adjacent in the retinal image. This implies that lateral inhibition cannot explain lightness constancy. (MLH)

What shade of gray a surface appears is related to the perceived distribution of light and shadow, which in turn depends on the perceived spatial relation between the surface and its neighbors. (Author/ BB)

Children and adults were tested on their beliefs about whether visual processes involved intromissions (visual input) or extramissions (visual output) across a variety of situations. Results were inconsistent with the idea that simple experiences increase or reinforce a coherent theory of vision and have implications for understanding the nature…

An effective way to teach the concept of image is to give students a model of human vision which incorporates a simple mechanism of depth perception. In this study two almost identical versions of a curriculum in geometrical optics were created. One used a mechanistic, interpretive eye model, and in the other the eye was modeled as a passive,…

Summarizes the anatomical, physiological, and psychological evidence related to the primate visual system. States that comparison of perceptual abilities with the electrophysiological properties of neurons may help deduce functions of visual areas. (RT)