Color therapists themselves disagree about why and how color acts as they believe it does. Mr. Birren, who has concentrated on the psychological effects of color, said he does not believe those effects are directly physiological. As designers and interior decorators have discovered, color sets a mood; this in turn, Mr. Birren said, affects health because as many as half of modern man's diseases may have a psychosomatic component.
But Alexander Schauss, director of the American Institute for Biosocial Research, said color had a direct physiological impact. The electromagnetic energy of color, he said, interacts in some still unknown way with the pituitary and pineal glands and the hypothalamus, deep in the brain, These organs regulate the endocrine system, which controls many basic body functions and emotional responses, such as aggression.
''Color very definitely has a physiological effect,'' said Harold Wohlfarth, who is president of the German Academy of Color Science and a photobiologist at the University of Alberta. In an experiment at the Elves Memorial Child Development Centre, a private school for handicapped children in Edmonton, Alberta, he found that light had the ''identical'' impact on the blood pressure, pulse and respiration rates of two blind children as on seven students with normal sight.
In the study, reported in the International Journal of Biosocial Research (Volume 3, No. 1), the walls of the schoolroom were changed from orange and white to royal and light blue. A gray carpet was installed in place of an orange rug. Finally, the fluorescent lights and diffuser panels were replaced with full-spectrum lighting.
As a result, Professor Wohlfarth reported, the children's mean systolic blood pressure dropped from 120 to 100, or nearly 17 percent, The children were also better behaved and more attentive and less fidgety and aggressive, according to the teachers and independent observers. When the room was returned to its original design, however, the readings gradually increased and the children once again became rowdy, he said.
Professor Wohlfarth said the minute amounts of electromagnetic energy that compose light affect one or more of the brain's neurotransmitters, chemicals that carry messages from nerve to nerve and from nerve to muscle. Several experiments on rats and other small mammals already have provided evidence, he said, that light striking the retina influences the pineal gland's synthesis of melatonin, a hormone that has been found to help determine the body's output of serotonin, a neurotransmitter. The precise role of the hormone, however, remains to be established.
As part of a $500,000 study of the effect of light on pupils in four schools in Edmonton, Professor Wohlfarth is trying to identify which of the brain's thousands of neurotransmitters, besides serotonin, is affected by electromagnetic energy.
''Perhaps these are new beginnings,'' concluded Mr. Birren. ''The magical properties of light and color, granted by men since the earliest of times, accepted, renounced and accepted again through the ages, have forever held fascination. It would be delightful, of course, if a thing of such psychological beauty - color - also held a mundane role in human physiological well-being.''
Illustrations: diagram of the color scheme of a room