After listening for 10 minutes to a tape of Mozart's Sonata for Two Pianos in D Major (K.488), college students in that earlier experiment scored about 9 points higher in IQ test of abstract spatial reasoning than subjects exposed to 10 minutes of silence or a meditation tape. Spatial reasoning tasks, which are general processed by the brain's right hemisphere, involve the orientation of shapes in space. Such tasks are relevant to a wide range of endeavors, from high mathematics and geometry to architecture, engineering, drawing and playing chess.

One of the experiments reported yesterday replicated and extended the "Mozart effect" findings. Among 84 undergraduates in the subsequent study, those who listened to the same Mozart piece and then had to solve visual puzzles involving folded cut-out shapes scored much higher than others exposed to 10 minutes of silence, although the "silence" group caught up on successive days. Interestingly, listening to other types of music - the monotonous repeating harmonies of a Philip Glass composition - Music with Changing Parts - or the thumping rhythms of electronic British-style "trance" music, which Rausher calls "technopop" - did not enhance subjects' spatial test scores. Neither Mozart nor the other music had any effect on subjects' ability to perform tests of short-term memory, which was consistent with the researchers' prediction about how the brain processed certain kinds of musical and spatial input. The researchers believe that listening to Mozart's music, with its complex patterns of evolving musical themes, somehow primes some of the same neural circuits that the brain employs for complex visual spatial tasks. They base their ideas on a "neural network" theory of music perception developed in 1990 by Gordon L. Shaw and Xiaodan Leng of UC-Irvine and Eric Wright of the Irvine Conservatory of Music. "In a nutshell, you have these neural pathways throughout your cortex,"the higher brain centers involved in perception and thought, Rausher explained. "The theory is when you experience something or learn something, these connections become stronger."

The psychologist cautioned that the "Mozart effect" does not imply that pop music is toxic to the brain. "That has been a huge point of misunderstanding." Rausher said. "When the first study cane out, people got the idea that if Mozart would have this enhancing effect, heavy metal rock'n'roll would have the opposite. I got a lot of backlash from that, including death threats from heavy-metal musicians calling me at home. We're not saying that heavy metal is going to burn out your brain."

The UC-Irvine group believes that other kinds of music would enhance spatial reasoning as long as it shares with Mozart patterns of symmetry and evolving musical themes. That might include some kinds of rock 'n' roll, Indian music and improvisational jazz. As provocative as the "Mozart effect' studies are, the researchers found that the effect is short-lived, 15 minutes at most. After that, Mozart listeners do no better on spatial test than others. To determine if music can have more lasting benefits for spatial learning, the California researchers studied a group of 3-year-olds enrolled in a Los Angeles public pre-school program. Of the 33 children, 22 received eight months of special music training - daily group singing lessons, weekly private lessons on electronic keyboards and daily keyboard practice and play. When tested on a spatial reasoning task - assembling pictures out of puzzle pieces - "the children's scores dramatically improved after they received music lessons."