ERIC Number: ED040579
Record Type: RIE
Publication Date: 1968
Reference Count: N/A
The Effects of Visual Angle, Brightness, and Contrast on the Visibility of Projected Material.
Metcalf, Richard Maddox
A study was conducted with three eighth grade students to determine the separate and joint effects of image size, image brightness, and image contrast on the visibility of projected materials. Twenty-five hundred slides were presented, representing 20 slides each of all possible combinations of values of the independent variables. Telegraph keys were wired to a timer and used to indicate both the accuracy and speed of the subject's response. Results showed that both visual angle and contrast affected both reaction time and the number of correct responses. It was concluded that: (1) letter size should subtend a minimum of 16.32 minutes of visual angle for adequate visibility, (2) if the room cannot be sufficiently darkened, materials must be increased in size for adequate visibility, and (3) for materials of a minimum size, contrast must be relatively high for adequate visibility to occur. (JY)
Descriptors: Audiovisual Aids, Educational Media, Lighting, Slides, Visual Perception, Visual Stimuli
University Microfilms, 300 North Zeeb Road, Ann Arbor, Mich. 48106 (Order No. 69-6756, MF $3.00, Xerography $4.20)
Publication Type: N/A
Education Level: N/A
Authoring Institution: Indiana Univ., Bloomington. School of Education.
Note: Thesis submitted to the School of Education of the University of Indiana, Bloomington, Indiana