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December 17, 2012

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Music and movement might share a common structure

Dec. 17, 2012
Courtesy of PNAS
and World Science staff

Mu­sic and move­ment might share a com­mon struc­ture across dis­par­ate cul­tures, ac­cord­ing to a stu­dy. 

Re­search­ers Tha­lia Wheat­ley of Dart­mouth Col­lege in Han­o­ver, N.H. and col­leagues de­vel­oped a com­put­er pro­gram to gen­er­ate both sim­ple pia­no melodies and an an­i­mat­ed bounc­ing ball. 

The sci­en­tists then re­cruited 50 US col­lege stu­dents and sep­a­rat­ed them in­to two equal groups. They then asked one group to move slid­er bars on a com­put­er screen that con­trolled five melody-related qua­li­ties—rate, jit­ter, di­rec­tion, step size, and con­so­nance—to re­flect dif­fer­ent emo­tions, such as “an­gry,” “hap­py,” “peace­ful,” “sad,” and “scared.” 

The oth­er group was asked to per­form the same task, but the slid­er bars var­ied equiv­a­lent at­tributes of the bal­l’s move­ment in rela­t­ion to the same emo­tions. 

Peo­ple who used mu­sic to ex­press an emo­tion set the slid­er bars to the same po­si­tions as those who ex­pressed the same emo­tion through move­ment, the sci­en­tists found, sug­gest­ing mu­sic and move­ment might share an un­der­ly­ing struc­ture. 

When a slightly mod­i­fied ver­sion of the ex­pe­ri­ment was con­ducted among vil­lagers in L’ak, a cul­tur­ally iso­lat­ed tribe in north­east­ern Cam­bo­dia, the in­ves­ti­ga­tors found that the fea­tures of emo­tional ex­pression through mu­sic and move­ment are si­m­i­lar across cul­tures. 

Un­rav­el­ing the cul­tur­ally-u­niver­sal fea­tures of mu­sic might help re­search­ers un­cov­er why and how mu­sic orig­i­nat­ed, Wheat­ley and col­leagues ar­gued.

“By stu­dying uni­ver­sal fea­tures of mu­sic we can beg­in to map its ev­o­lu­tion­ary his­to­ry,” they wrote, re­port­ing their find­ings in this week’s early on­line is­sue of the re­search jour­nal Pro­ceed­ings of the Na­tio­n­al Aca­de­my of Sci­en­ces. “Un­der­stand­ing the cross-modal na­ture of mu­sical ex­pression may in turn help us un­der­stand why and how mu­sic came to ex­ist.”

“The shared struc­ture of emo­tional mu­sic and move­ment must be re­flected in the or­gan­iz­a­tion of the brain,” they added. They al­so cit­ed past work by Stanis­las De­haene and Lau­rent Co­hen at the Uni­vers­ity of Par­is-Sud and Uni­vers­ity of Par­is VI, who have ar­gued that soph­is­t­icated ac­ti­vi­ties like read­ing and math “re­pur­pose” brain ar­eas that orig­i­nally served for sim­pler pur­poses. Sim­i­lar­ly, mu­sic may “re­cy­cle” brain ar­eas that evolved for move­ment and speech, Wheat­ley and col­leagues pro­posed.

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Music and movement might share a common structure across disparate cultures, according to a study. Researchers Thalia Wheatley of Dartmouth College in Hanover, N.H. and colleagues developed a computer program to generate both simple piano melodies and an animated bouncing ball. The scientists then recruited 50 US college students and separated them into two equal groups. They then asked one group to move slider bars on a computer screen that controlled five piano melody-related attributes—rate, jitter, direction, step size, and consonance—to reflect different emotions, such as “angry,” “happy,” “peaceful,” “sad,” and “scared.” The other group was asked to perform the same task, but the slider bars varied equivalent attributes of the ball’s movement in relation to the same emotions. People who used music to express an emotion set the slider bars to the same positions as those who expressed the same emotion through movement, the scientists found, suggesting music and movement might share an underlying structure. When a slightly modified version of the experiment was conducted among villagers in L’ak, a culturally isolated tribe in northeastern Cambodia, the investigators found that the features of emotional expression through music and movement are similar across cultures. Unraveling the culturally-universal features of music might help researchers uncover why and how music originated, Wheatley and colleagues argued. “By studying universal features of music we can begin to map its evolutionary history,” they wrote, reporting their findings in this week’s early online issue of the research journal PNAS. “Understanding the cross-modal nature of musical expression may in turn help us understand why and how music came to exist.” “The shared structure of emotional music and movement must be reflected in the organization of the brain,” they added. They also cited past work by Stanislas Dehaene and Laurent Cohen at the University of Paris-Sud and University of Paris VI, who have argued that sophisticated activities like reading and math “repurpose” brain areas that originally served for simpler purposes. Similarly, music may “recycle” brain areas that evolved for movement and speech, Wheatley and colleagues proposed.