The Origins of Music: Preface - Preface

to encode and retain than equal-step scales,such advantages might be

apparent with infant listeners.

We presented infants and adults with transposed repetitions of three

ascending-descending scales:an equal-step scale that was used in previ-

ous research with adults (Shepard and Jordan 1984;Jordan and Shepard

1987),the major (unequal-step) scale,and a novel,unequal-step scale

(Trehub,Schellenberg,and Kamenetsky,in press),all of which are shown

in figure 23.4.The equal-step scale consisted of dividing the octave into

seven equal steps.In the novel,unequal-step scale,the octave was arbi-

trarily partitioned into eleven subdivisions,and a scale was constructed

with steps separated by one or two subdivisions.For each ascending-

descending scale,infants were required to detect a three/four-semitone

change in one tone;adults were required to detect a one/two-semitone

change.It was no surprise that adults performed better on the familiar

major scale than on either unfamiliar scale,but they performed no better

on the unfamiliar,unequal-step scale than on the unfamiliar,equal-step

scale.For Western adults with long-term exposure to music based on the

major scale,the ascending major scale is probably as familiar as most

tunes.Infants,for whom all scales were presumably unfamiliar,per-

formed significantly better on both unequal-step scales than on the

equal-step scale (figure 23.5). Moreover,the major scale had no

434 Sandra Trehub

Figure 23.4

Schematic illustration of major,unequal-step,and equal-step scales.Note that successive

tones in the major scale are separated by one or two semitones.Some steps in the unequal-

step scale are twice as large as other steps;step size in the equal-step scale (larger than

one semitone but smaller than two semitones) does not vary.(From Trehub,Schellenberg,

and Kamenetsky,in press.)

Fig.23.4