This book is clearly dated science, but much of the science it purports has not changed dramatically. Some of the experiments were particularly interesting (such as the apparent electromagnetic effect of color on blindfolded humans whose arms are drawn closer or further apart depending on which side of the color spectrum is the color placed in front of them). One note toward the end I found laughable was the scientific study Birren references that the sex of an offspring can be affected well into the third trimester simply by exposing the mother to colored light. Haha. What we know now...
The impact of color on the human organism...that's pretty interesting. I was definitely intrigued by the practice of altering perception with color, to be sure. I mean, most of us already knew color had an impact on the psyche when we learned the so-called reasoning that fast food chains painted themselves red or orange (to give the impression of speed and to speed up patron's use of the space), or that hospitals are painted blue (to create a sensation of serenity). So it's pretty reasonable (or at least sociologically accepted) that color has a great impact on the observer. I found this book very interesting, to be sure.