Indirect systems and semi-indirect systems with high-density reflectors produced the best results for sustaining clear seeing among the artificial lighting systems tested¶

Claim · All claims
Evidence · 1 study · causal r1 · q3
Currency · newest study 1917 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q3 i? Considerable loss of visual efficiency resulted from semi-indirect reflectors of low and medium density and from direct reflectors of medium and shallow depth. → C. E. Ferree and Gertrude Rand 1917

Evidence¶

C. E. Ferree and Gertrude Rand 1917¶

C. E. Ferree and Gertrude Rand. (1917). The Power of the Eye to Sustain Clear Seeing Under Different Conditions of Lighting. The Journal of Educational Psychology. https://doi.org/10.1037/h0072369

q3 · i? · causal · r1

Test results for the semi-indirect and direct installations. The authors add that with low and medium density reflectors at ordinary working intensities, the brightness of the source has not been sufficiently reduced to give much relief to the eye.

"A great deal of loss of visual efficiency has been found to result, however, from the use of semi-indirect reflectors of low and medium density and from direct reflectors of medium and shallow depth."

Discussion¶

Related Claims¶

• Across all conditions tested, a lighting condition's tendency to cause loss of visual efficiency correlates closely with its tendency to produce ocular discomfort — related
• When light is well distributed and diffuse with no extremes of surface brightness, the eye is practically independent of illumination intensity within ordinary lighting ranges — related
• Too much light is being used in ordinary work for the comfort and welfare of the eye with reflectors that introduce harmful brilliancies — possibly the same claim (merge candidate)
• Extremes of surface brightness in the field of vision are the most important causes of eye discomfort and loss of efficiency in contemporary lighting systems — a broader claim this one bears on
• The loss of efficiency sustained by the eye in an unfavorable lighting situation is muscular, not retinal — related