Jane E. Cottrell

Development in the understanding of perception: the decline of extramission perception beliefs

Ancient philosophers, including Plato, Euclid, and Ptolemy, believed in an extramission theory of visual perception, which held that there are emissions from the eyes during the act of vision. Three studies, comparing college and elementary school students, documented a decrease over age in the belief of emissions from the eye during the act of vision and an increase in the belief that vision involved only incoming information. Questions about hearing and smelling were less difficult than those on vision but yielded analogous age trends. The results have implications for cognitive theories of development, for education, and for understanding the childs concept of mind

The persistence of a misconception about vision after educational interventions.

Children and adults, like many ancient philosophers, believe that seeing involves emissions from the eye. Several experiments tested the strength of these “extramission” beliefs to determine whether they, like other scientific misconceptions, are resistant to educational experiences. Traditional college-level education had little impact. Presenting a simplified lesson, stressing visual input, and a lesson directly counteracting the vision misconception had an impact, but for older participants the effect was evident only on short-term tests. Despite some gain due to learning, overall the results demonstrated the robustness of extramission beliefs.

Effects of drawing on directional representations of the process of vision

Four experiments demonstrated that children and adults, when asked to represent vision schematically, have a bias to draw arrows pointing away from the eye and toward a visual referent, avoiding the response of drawing arrows to indicate visual input. The outward bias was stronger than in previous studies involving other responses and means of representation. In the present study, the outward bias was also more evident when participants were asked to draw rather than choose, in writing, between visual input and output. Conditions designed to counteract the drawing bias had weak effects, at best. The results (a) point to a possible explanation for extramission interpretations of vision, (b) generally indicate that different means of representing a scientific process can influence beliefs, and (c) have significance for education.

Testing Different Interpretations for the Mistaken Belief That Rays Exit the Eyes During Vision

Abstract Research has shown that children and adults believe that emissions from the eye occur during the act of vision. Such beliefs are similar to ancient extramission theories of perception. In Study 1, the authors tested the idea that extramission beliefs might stem from peoples thinking about what might occur during vision as opposed to what is necessary for seeing. Training participants to think about what is necessary for vision, however, had no effect on extramission responses. The results of Study 2 indicated that emphasizing the idea of visual input led to a decline in extramission responses and supported the hypothesis that extramission notions stem from the outer-oriented phenomenology of vision.