''The authors' style is clear, making the book accessible to newcomers, and the illustrations are excellent. There can be no doubt that this book will remain the standard work in the subject, and it will appeal to readers of all types.'' -Sir Patrick Moore in the Times Higher Education Supplement ''It will surely be the standard work on the subject for many years to come and we await with interest the outcome of further research into this fascinating subject.'' -Society for (...) the History of AstronomyFor thousands of years, one scientific puzzle has fascinated and perplexed the greatest philosophers, mathematicians, physicists, and psychologists - why do the moon and sun appear so much larger on the horizon than when high up in the sky? Now, two leading psychologists have provided a compelling account of this fascinating illusion. Taking us through the history, the characters involved, the attempts made to explain the illusion, through to modern day studies of visual perception, the book is the most comprehensive account of this puzzle so far. This is a work which will remain, for some time to come, the definitive book on a mystery that has fascinated and tested the greatest minds throughout the ages. Accessibly written, it will appeal to readers of popular science, along with those within the disciplines of psychology, mathematics, astronomy, and philosophy, from undergraduate upwards. (shrink)

Berkeley and Helmholtz proposed different indirect mechanisms for size perception: Berkeley, that size was conditioned to various cues, independently of perceived distance; Helmholtz, that it was unconsciously calculated from angular size and perceived distance. The geometrical approach cannot explain size-distance paradoxes (e.g., moon illusion). The dorsal/ventral solution is dubious for close displays and untestable for far displays.

Perceived slope varies with the viewing distance, and is consistent with the effects of foreshortening. Distant viewing makes uphill slopes appear steeper and downhill slopes flatter than does near viewing. These effects are obvious to skiers and climbers in mountainous country. They have also been measured in outdoor experiments with controlled viewing distances. There are many other sources of slope illusions.

Lehar argues that a simple Neuron Doctrine cannot explain perceptual phenomena such as size constancy but he fails to discuss existing, more complex neurological models. Size models that rely purely on scaling for distance are sparse, but several models are also concerned with other aspects of size perception such as geometrical illusions, relative size, adaptation, perceptual learning, and size discrimination.

In terms of physics, mass is the fixed attribute of an object while weight varies with the accelerative force. Neither weight nor mass are simple sensory stimuli as both involve the integration of sensory and motor information with higher cognitive processes. Studies of apparent heaviness yield only vague information about sensorimotor mechanisms.