Effects of Music and White Noise on Working Memory Performance in Monkeys
Synnove Carlson, Pia Rama, Denis Artchakov and Ilkka Linnankoski
NeuroReport 8, 2853-2856 (1997)
The study was done to evaluate the effects of Mozart's music, white noise, simple rhythm and silence on the delayed responses of monkeys. Mozart's music has been suggested to benefit cognitive functions, and it was later proved to only "improve spatial IQ". The working memory is processed in the prefrontal cortext, and a delayed response (DR) experiment will test the subject's ability to remember information for a short period of time. The monkeys used in the experiment were all trained to perform DR tasks, and the results of the experiment will further the researches on acoustic treatments on working memory performance. Two food bowls were shown at equal distance behind a transparent screen. A raisin is then put into one of the two bowls, and an opaque lid was then used to cover the bowls. The monkey's task was to choose the bowl with raisin in it over various delay lengths. Different monkeys had different treatments: 1) 15 minutes of the four choices (Mozart's music, white noise, simple rhythm or silence) OR 2) one choice played throughout the duration of the experiment.
The results showed a significant improvement in the white noise group. Whereas other groups of monkeys had more mistakes as the delay time increased, the white noise group did not show dramatic difference between the time-mistakes ratio. Mozart's music, on the other hand, increased the number of mistakes over all other delays except the shortest delay.
Many studies were done to prove or disprove the "Mozart Effect" and this experiment on monkeys really opened up the ambiguity of previous findings. Mozart's music was said to improve spatial IQ, however, this was not seen in the monkeys' experiment. One explanation would be that monkeys do not have the same auditory knowledge as the humans. People may not know Mozart, but they can follow the tune of a melody, notice patterns in a passage, and "feel" the emotions music express. The monkeys may hear Mozart's music as a complex auditory stimulus that disrupts attention. The white noise, on the other hand, acts like an auditory mask that blocks out distractions.
This is an interesting finding because the effects of music were supposedly "universal", but the results of human experiments were much more different than those of monkeys. Would this due to the fact that humans have a language system and music is also a language? Would that contribute to the effectiveness of music toward performance enhancement? White noises were also proven to improve sleep. It would be interesting to see if white noise can act as a "healing"property, like what people say about music therapy. One future project is to redo the experiment (maybe more complex) with human participants and see if similar results are found.