A Continued study of Existing Hypothesis
Xinran Wei
PSYC 182
Reading Group 12
Moon Illusion: A Continued study of Existing Hypothesis
One of the most extraordinary optical illusions in nature, the moon illusion has attracted attention from generations of scientists. It seemed that despite of the distance between earth and moon did not change, the size of the moon appeared larger in the horizon but smaller at zenith. The debate of explanation behind this illusion had never stopped. Starting from as early as 330 B.C, Aristotle had discussed the moon illusion and explained it as effect of atmospheric phenomenon occurred close to the horizon (J. T. Enright, 1975). Later advocate of this reasoning stated …show more content…
As presented in their paper The Moon Illusion, II, they argued that with the help of a new technique enabling subjects to view an artificial moon set on different position of the sky, experiment was able to be conducted allowing people to compare moon at different position of sky without physically moving their head and changing angles. The result of the experiment disproved the previous experiment. Even though the factor of perception angle was eliminated, the illusion still existed. People still perceived the artificial moon posed at the horizontal position in the sky as larger. Built upon the analysis of their precedent in the topic, Rock and Kaufman proposed an alternative explanation – the apparent distance hypothesis. Rock and Kaufman performed an extensive experiments described in their paper Moon Illusion, II, arguing that change in the pattern of distance cues may be what cause the illusion to happen. They explained that the buildings and trees on the extended terrain presented with the moon oriented near horizon indicated the moon to be far away. The zenith moon, however, do not have these cues present as reference, therefore perceived as closer. When the visual angles of perceiving two objects were identical, but distance judged to be different by the observer, the less distant object would be considered to be the …show more content…
If the relative size hypothesis is true, the effect of moon illusion should be somewhat attenuated when no references objects appeared at horizon or lots of detailed reference objects appeared close to zenith moon as illustrated by the experiments conducted by Bilderback et al. However the experiment described in essay Distance Perception in Darkness is not thorough in that it only considered situation in the complete darkness. The hypothesis depended not on light and darkness; therefore it should work under light condition as well. Thus, hypothesis could be made that when no reference objects are present near the horizon and zenith, the moon illusion would be greatly attenuated and perceived difference should be smaller even under condition within light up