In 1991 Dr. D. B. Harmon studied about 160,000 school children and learned that about half of these suffered detrimental effects from classroom lighting. Good lighting provides a compensatory remedy. In 1999, Vuontella and others studied the effects of color on learning by comparing verbal cues for recall with color cues. Learners invariably did better using color. NASA scientists have discovered that the presence of plants in a room seems to stimulate learning not merely because of their green color but because of their ability to increase negative ions in the air and remove pollutants.
Some house plants are more effective than others.
Studies reveal that learners have divergent preferences. Studies have shown that extraneous noise is detrimental to most learners, but music is a more controversial issue. A number of workers have tried to relate use of various types of background music to increased learning. The olfactory senses stimulate the brain, and optimal learning environments may come with distinctive smells. Basil, lemon, cinnamon and rosemary seem to have a similar stimulating effect, while other odors elicit relaxation.