Identification, discrimination, and selective adaptation of simultaneous musical intervals

Transcription

1 Perceptin & Psychphysics 1979, Vl. 26 (5), Identificatin, discriminatin, and selective adaptatin f simultaneus musical intervals ROBERT J. ZATORRE Brwn University, Prvidence, Rhde Island and ANDREA R. HALPERN Brandeis University, altham, Massachusetts Fur experiments investigated perceptin f majr and minr thirds whse cmpnent tnes were sunded simultaneusly. Effects akin t categrical perceptin f speech sunds were fund. In the first experiment, musicians demnstrated relatively sharp categry bundaries in identificatin and peaks near the bundary in discriminatin tasks f an interval cntinuum where the bttm nte was always an F and the tp nte varied frm A t A flat in seven equal lgarithmic steps. Nnmusicians shwed these effects nly t a small extent. The musicians shwed higher than predicted discriminatin perfrmance verall, and reactin time increases at categry bundaries. In the secnd experiment, musicians failed t cnsistently identify r discriminate 'thirds which varied in abslute pitch, but retained the prper interval rati. In the last tw experiments, using selective adaptatin, cnsistent shifts were fund in bth identificatin and discriminatin, similar t thse fund in speech experiments. Manipulatins f adapting and test shwed that the mechanism underlying the effect appears t be centrally mediated and cnfined t a frequency-specific level. A multistage mdel f interval perceptin, where the first stages deal nly with specific pitches may accunt fr the results. Categrical perceptin is said t ccur when signals that vary cntinuusly are assigned t a few discrete categries by a perceiver. In the mst extreme case f categrical perceptin, discriminatin is limited by identificatin, in cntrast t mre cmmn psychphysical principles which indicate that many mre stimuli can be discriminated than can be identified n an abslute basis (Miller, 1956). Typically, the ccurrence f categrical perceptin has been peratinally defined by (1) the presence f distinct labeling categries separated by a sharp bundary, (2) peaks in discriminatin near the bundary, with lw perfrmance within categries, and (3) a clse crrespndence between btained discriminatin and that predicted by the hypthesis that dis- e wish t express ur thanks and appreciatin t Dr. Peter D. Eimas fr his supprt and highly valuable advice thrughut ur wrk. Helpful cmments were als prvided by Drs. A. ingfield, S. Blumstein, and. F. Ganng. e als wish t thank Dr. A. M. Liberman fr his permissin t use the facilities at the Haskins Labratries. This research was supprted in part by NICHD Grant HD t P. D. Eimas. Sme f the results f these experiments were presented at the 97th meeting f the Acustical Sciety f America, Cambridge, Massachusetts, June Andrea R. Halpern is currently at the Psychlgy Department, Stanfrd University, Stanfrd, Califrnia Reprint requests and crrespndence may be sent t Rbert J. Zatrre, Psychlgy Department, Brwn- University, Prvidence, Rhde Island criminatin can ccur nly insfar as stimuli can be identified as different (Studdert-Kennedy, Liberman, Harris, & Cper, 1970). hen first investigated, this frm f perceptin was presumed t perate nly in the decding f cnsnants in speech (Liberman, Harris, Hffman, & Griffith, 1957). Nnspeech sunds, vwels, and speech cues such as frmant transitins in nnspeech cntexts failed t elicit categrical perceptin (Eimas, 1963; Liberman, Harris, Kinney, & Lane, 1961; Mattingly, Liberman, Syrdal, & Halwes, 1971). Subsequent investigatins have mdified riginal claims that speech perceptin invlves nly phnetic (i.e., categrical) infrmatin and that speech is the nly mde perceived categrically. An auditry (i.e., nncategrical) level f prcessing can be discerned by the use f reactin times which shw increasing latencies when there is uncertainty as t categry membership, especially as the signal appraches a phnetic bundary (Studdert-Kennedy, Liberman, & Stevens, 1963; Pisni & Tash, 1974). In additin, prcessing f the speech sunds can be interrupted by interfering with shrt-term memry stres which are thught t be auditry in nature (Pisni, 1973, 1975; Fujisaki & Kawashima, Nte 1). Use f selective adaptatin has als implicated auditry prcessing in additin t phnetic prcess- Cpyright 1979 Psychnmic Sciety, Inc $01.450

2 MUSICAL INTERVALS 385 ing in speech perceptin. Repeated presentatin f an auditry stimulus can shift the lcus f the phnetic bundary presumably because specific detectrs have been fatigued r adapted (Eimas & Crbit, 1973;Eimas, Cper, & Crbit, 1973). Adaptrs that share either phnetic (Diehl, 1975) r acustic (Sawusch, 1977) characteristics with the testing stimuli have prduced adaptatin effects, thugh mst investigatrs agree that the results can be best explained in purely auditry terms (cf. Eimas & Miller, 1978, fr a review). The claim that speech is nt the nly mde in which categrical perceptin ccurs is substantiated by demnstrating categrical perceptin fr nnlinguistic stimuli, such as rise time f sawtth waves (Cutting & Rsner, 1974; Cutting, Rsner, & Fard, 1976), tempral rder f auditry stimuli (Miller, ier, Pastre, Kelly, & Dling, 1976; Pisni, 1977), rhythmic units (Raz & Brandt, 1977), and flicker frequency f a light (Pastre, Ahrn, Baffut, Friedman, Pule, & Fink, 1977). These results imply that categrical perceptin may be a much mre general phenmenn than riginally thught. It may ccur, therefre, whenever the physical stimulus structure is nt stred in memry, the infrmatin instead being reduced t a few discrete categries. Thus, the mechanism underlying categrical perceptin may be useful fr dealing with the memry demands invlved in the rapid decding f cmplex infrmatin, such as must ccur in speech perceptin and als perhaps in sme aspects f music perceptin. In the case f musical stimuli, the relevant cues are the pitches f pure tnes and the frequency ratis between tnes. These acustic cues are nt relevant t phnemic distinctins, unlike, fr instance, the dimensin f rise time which cues the fricativeaffricate distinctin. Furthermre, musical intervals are particularly useful fr experimentatin due t their extremely simple acustic nature. Anther reasn fr studying musical interval perceptin is that the rle f experience in the develpment f ne instance f categrical perceptin can be investigated, since the degree f musical training can be cntrlled in the subject ppulatin. Lcke and Kellar (1973) cnstructed a cntinuum f three-nte chrds where the central nte varied in small steps. They fund categrical perceptin by trained musicians but cntinuus perceptin by nnmusicians. Hwever, there were sme prblems with this study, particularly with regard t their signal detectin analyses (Pastre, 1976). Blechner (Nte 2) fund similar results using simultaneus tw-nte intervals, as did Siegel and Siegel (1977a, 1977b), wh used sequential tw-nte intervals. In these studies, musically trained subjects tended t classify acustically ambiguus chrds as "majr," "minr," "diminished," etc., in much the same ways as listeners classify ambiguus speech signals as ne phneme r anther. Burns and ard (1978) extended the wrk n perceptin f sequential intervals by cnstructing cntinua f stimulus intervals whse, bttm nte varied randmly within a certain range. The tp nte, hwever, was always kept in the prper frequency relatinship fr the interval being tested. Burns and ard btained discriminatin functins very clse t thse predicted n the basis f the identificatin data (i.e., under the assumptin that stimuli can be discriminated nly insfar as they can be labeled as different). Burns, Carney, and ard (1976) have presented preliminary data n selective adaptatin f sequential intervals. Based n a single subject, they reprted bundary shifts when endpint stimuli were used as adaptrs. Adaptatin seemed als t ccur in spite f the fact that the abslute pitch f the intervals varied within a small range; this wuld imply that the adaptatin effect cannt be cmpletely auditry in rigin. Hwever, these preliminary data d nt allw a precise estimate f the nature f the effect r its lcus. T summarize: (1) Research with musical intervals seems t indicate that categrical perceptin is nt unique t speech r t speech-relevant acustic cues. (2) There is the pssibility that musical interval categries are learned, as the degree f categrical perceptin shwn by the subjects seems t vary with the amunt f musical training, and als because nn estern cultures use different musical interval systems. This series f studies was designed t explre the perceptin f simultaneus musical intervals by musicians and nnmusicians, paralleling wrk in speech perceptin. e hped t shw that analgus prcesses perate fr speech and music perceptin, thereby demnstrating that categrical perceptin is a relatively general phenmenn. The use f simultaneus (as ppsed t sequential) intervals as stimuli is reasnable; based n the principles f estern music thery, an interval is defined as the frequency rati between tw tnes. Simultaneus and sequential intervals crrespnd musically t harmnic and meldic intervals, respectively. Experiment 1 required identificatin and discriminatin f eight simultaneus intervals ranging in frequency rati between a majr and minr third. Reactin times t bth tasks were als recrded. Experiment 2 used the same tasks as Experiment 1, but emplyed stimuli whse abslute frequency varied within a small range in rder t investigate hw abstract (i.e., hw independent f the specific cmpnent pitches) the musical categries were. Experiment 3 applied selective adaptatin with ne endpint f the stimulus cntinuum t establish validity f the technique fr musical interval perceptin. Experiment 4 varied the adaptr and test stimuli in several cnditins t begin pinpinting the cntributin f auditry vs. mre abstract ("phnetic") and central vs. peripheral' cmpnents t the adaptatin effect.

3 386 ZATORRE AND HALPERN EXPERIMENT 1 This experiment was designed t shw t what extent musicians and nnmusicians categrically perceive simultaneus musical intervals. Methd Subjects. A ttal f 16 Brandeis University graduate and undergraduate students served as subjects. The musicians, ne undergraduate and seven graduate music students, were students f cmpsitin, music histry, r musiclgy. Hwever, all were prficient (at least 8 years f training) n at least ne instrument. Pianists, brass, wdwind, and string players were represented by at least ne subject. N subjects reprted pssessing abslute pitch, but all had studied music thery and ear training. The nnmusicians were eight undergraduates wh had very little r n perfrming experience and had never studied music frmally. N subject reprted any speech r hearingdisrders. Stimulus materials. Stimuli cnsisted f tw simultaneusly presented pure tnes. The lwer tne was always an F (349 Hz), and the higher tne ranged frm A flat (415 Hz), which frms an interval f 300 cents (a minr third), t A natural (440 Hz), which frms an interval f 400 cents (a majr third). The tp ntes varied frm 415 t 440 Hz in seven lgarithmically equal stps (14.29 cents each) t frm a cntinuum f eight intervals. The smallest step was 3.4 Hz and the largest was 3.6 Hz. Pure tnes were generated n a Hewlett-Packard 207A audi sweep scillatr. Fine cntrl f frequency was btained by mnitring the utput f the scillatr n a Hewlett-Packard 52l2A electric digital cunter. Tnes were fed int the pulse cde mdulatin system (Cper & Mattingly, 1969) at the Haskins Labratries, where they were digitized, truncated t a duratin f 500 msec with instantaneus rise and fall times, and cmbined int the simultaneus intervals. The stimuli were cnverted back t analg frm and recrded nt magnetic tape. Tw separate randm-rder identificatin tapes were made. Fr each tape, 15 examples f each f the 8 stimuli were randmized fr a ttal f 120 stimuli. Each stimulus was fllwed by a 3-sec respnse perid. Tw discriminatin tapes were als prepared. Each stimulus was paired with the stimulus tw steps (apprximately 7 Hz) away n the cntinuum t frm pairs such as Stimuli I and 3, 2 and 4, etc. Likewise, each stimulus was paired with the stimulus three steps (apprximately 10 Hz) away n the cntinuum." One ddity triad cnsisted f tw presentatins f ne member f the pair, and a third presentatin f the ther member, all separated by I sec f silence. Each ddity triad was fllwed by a 3-sec respnse perid. The dd stimulus appeared equally ften as the first, secnd, r third interval f the triad. Each triad appeared 12 times per tape fr a ttal f 132 trials. Order f presentatin f the triads was randmized. Prcedure. Tapes were played n a Teac 3300 stere tape recrder, whse utput was fed thrugh a Sctt Steremaster 299F amplifier t bth channels f gd-quality headphnes fr binaural presentatin. Intensity f the stimuli was maintained at apprximately 73 db SPL. In rder t familiarize the subjects with the stimuli and task, they first heard examples f the cntinuum endpints. Fr musicians, these were labeled as majr r minr thirds; fr nnmusicians, they were called "I" and "2," respectively. The labels were prvided by the experimenter in bth cases. Nnmusicians were allwed t hear the endpint stimuli as ften as they wished thrughut the experiment. The identificatin task required subjects t decide whether each f the 120 stimuli sunded clser t a minr r t a majr third ("I" r "2" fr nnrnusicians). In the discriminatin task, the subjects were instructed t respnd verbally "1," "2," r "3" t indicate the psitin in the set f the dd member. Guessing was encuraged in bth tasks. The respnses were recrded n magnetic tape in rder t analyze the reactin times, which were measured by using a vice-triggered strage scillscpe. Accuracy was btained t the nearest 12 rnsec. There were tw sessins f apprximately 40 min each, and at least 3 days intervened between testing sessins. Order f task presentatin was cunterbalanced acrss subjects. All subjects were run individually. Results and Discussin Mean percentage f each stimulus labeled as minr by all eight musicians is shwn in Figure 1. The identificatin functin shws distinct categries fr majr and minr thirds, i.e., Stimuli 1, 2, and 3 are clearly cnsidered minr; 7 and 8 are classified as majr. The regin ftransitin between the tw categries is sharp and distinct. Each data pint is based n a ttal f 240 trials. Reactin times fr identificatin f each stimulus are als shwn in Figure 1. Reactin times increase fr the stimuli in the middle f the cntinuum [F(5,35) = 43.92, p <.001, fr the main effect f stimulus pair]; this indicates that reactin time, and presumably decisin time, is slwest where there exists maximum uncertainty abut the identity f the stimulus. By a Neuman-Keuls test, reactin times t Stimuli 1, 2, and 3 failed t shw a difference: respnses t 7 and 8 were als nt different. Reactin times nly increase where there is a change in certainty reflected by the identificatin functin. Nt nly was, fr example, Stimulus 3 being called minr f the time, but als the subjects were as quick t call it minr as they were fr Stimuli 1 and 2, even thugh Stimulus 3 was physically n the sharp (higher frequency) side fminr. Mean percentage crrect fr btained and predicted tw-step discriminatin as a functin f stimulus pair is shwn in Figure 2. Three-step functins are nt presented, since a ceiling effect ccurred. The btained discriminatin functin (dashed line) clearly shws an increase in perfrmance which peaks at the categry bundary. This bservatin was cnfirmed by a ne-way analysis f variance, which shws a significant effect f stimulus pair [F(5,35) = 9.58, p <.001]. Each data pint is based n 192trials. The dtted line in Figure 2 is the discriminatin functin predicted if discriminatin were strictly limited by identificatin." Musicians clearly perfrmed abve the predicted level, and this was cnfirmed in a tw-way analysis f variance which shwed an effect f btained vs. predicted functins [F(l,7) = 57.25, p <.001]. An imprtant characteristic shwn by experiments which demnstrate categrical perceptin is a gd crrespndence f peak perfrmance between btained and predicted functins. If a phnetic r symblic level f analysis is being emplyed, then best perfrmance shuld ccur when the tw stimuli being discriminated are farthest frm each ther n either side f the categry bundary. That pattern f results is shwn here, where the tw functins have

4 MUSICAL INTERVALS 387 <Jl <D <Jl Z 0 e, "' w I- 0 Z <t w U w 0 a. '" <Jl <D <Jl Z 0 a. <Jl "' I- 0 Z <t w U w 0 a. '" ~l>-----~ '"...-..j»> -- IDENTifiCATION --._... REACTION TillE lj "i!i "' "'U <Jl O~ Oz <t_ w O! 01 "'z l Ot; ~~ Figure 1. Mean percent identificatin respnses fr eight musicians frm Experiment 1 (read against left axis), and mean reactin time fr identificatin fr the same subjects (read against right axis). "REDICTEO DISC _ - -k C6TRJHED DISC --._... 'H for DISC Iii, j <D ọ.. <Jl g~ "'~ ~ 01- '" Z '" s I- U... «wq: Figure 2. Mean percent crrect predicted and btained discriminatin scres fr all eight musicians frm Experiment 1 (read against left axis), and mean reactin time fr discriminatin in the same subjects (read against right axis; nte shift in scale with respect t Figure 1). are thse fr stimulus pairs which are near r straddle the perceptual bundary as determined by the identificatin functin in Figure 1. Reactin times are highest where cmparisns invlve pair members which lie within the same symblic categries. Quick reactin times als crrespnd t best perfrmance n the task. Nte that the reactin time scales n the right-hand rdinates f Figures 1 and 2 are slightly displaced with respect t each ther. It is interesting that the lngest reactin times fr identificatin, near the bundary, crrespnd very well t the shrtest reactin times fr discriminatin, again near the bundary. This pattern implies that pairs frm different categries require nly a decisin n the symblic level (i.e., "majr" r "minr") fr discriminatin. hen this decisin cannt be made n that basis alne, then an auditry level f prcessing increases reactin time fr same-categry members. Cnversely, in identificatin, reactin times are quickest fr the "best" (i.e., clsest t the endpint) stimuli. hen the stimulus des nt match the endpints, then auditry infrmatin must be called upn, again increasing reactin times (cf. Pisni, 1973). Mean percentage f times that each stimulus was labeled "2" (minr) by all eight nnmusicians is shwn in Figure 3. The identificatin functin was nt as sharp as that fr the musicians, indicating less cnsistent use f categry labels, but the basic shape f the functin was similar t the musicians'. Mean percent crrect tw-step discriminatin is als shwn in Figure 3: discriminatin perfrmance by nnmusicians shwed a flattened curve as cmpared with the musicians. There nevertheless remained a statistically reliable peak between Stimuli 4 and 6 [F(5,35) = 3.43, p <.05], just as with the musicians. Obtained perfrmance was n better than predicted, hwever, IDENlIfICATltlN 1I---_._.--e PREDICTED D'SC _ - -Ill OBTAINED DISC essentially the same shape; the peak perfrmance is at the same stimulus pair as predicted, and there is n significant Obtained vs. Predicted by Stimulus Pair interactin [F(l,35) = 2.37, p >.10]. This latter result indicates that the hypthesized auditry infrmatin is available at all stimulus pair cmparisns, and increases perfrmance by a cnstant amunt. Since this increase seems t be independent f bundary effects, it is reasnable t prpse that it arises frm a precategrical prcessing stage. Mean reactin times t the discriminatin task fr all eight musicians are als shwn in Figure 2. As shwn, reactin times change as a functin f stimulus pair [F(5,35) = 2.59, p <.05]. The fastest times en 0 w <D en z a. 0 <Jl "' I- 0 ~ <t u ~ ~...'<, _..,t_~ <, -M-"" ~,I' ~_.. ""-- ---_., " Figure 3. Mean percent identificatin respnses fr eight nnmusicians frm Experiment 1, and mean percent crrect predicted and btained discriminatin scres in the same subjects.

5 388 ZATORRE AND HALPERN and the peak f the predicted functin did nt crrespnd with the btained peak. hen discriminatin perfrmance f the musicians and nnmusicians was cmpared, it was fund that the musicians scred much higher [F(1,14) = 23.0, p <.001], but there was n significant Subject Grup by Stimulus Pair interactin, i.e., bth grups discriminated between categry pairs better than within categries. Nevertheless, the tw functins differ in that the discriminatin peak is sharper fr the musicians, as shwn by a cmparisn f the highest between-categry t the lwest within-categry scres fr the tw grups [t(14) = 1.87, p <.05]. e shuld emphasize that there were wide individual differences here: mst nnmusicians shwed a flat discriminatin functin, while thers increased their perfrmance nticeably at categry bundaries. There were als interesting individual differences amng musicians; data fr tw f the musicians are shwn in Figures 4 and 5. Figure 4 shws data fr the subject whse perfrmance was the mst categrical. Figure 5 shws data fr a subject whse discriminatin perfrmance was near perfect at the majr end f the cntinuum. This subject's perfrmance is an extreme example f a trend present in mst musicians (see Figure 2) fr better discriminatin at the majr end than at the minr end. Of the eight musicians, three shwed a drp in discriminatin perfrmance f 1000 r less at the majr end f the cntinuum. Mrever, the majr categry was fund t be narrwer than the minr categry fr almst all subjects in identificatin (Figure I); i.e., musicians have stricter criteria fr accepting a majr third than a minr third. These facts may be due either t a learned narrwer tuning f the majr third, r t sme physical characteristic f the majr third [e.g., its place in the harmnic series, r that the majr third apprximates the bandwidth f a critical band in hearing (Scharf, 1970)]. ~... '" c z '"... ~ ~ a: I- 0 Z <t... a: CIJ,, I I. I i »>:"'~\ \\ \\\\ \'\... '\.._..."" IOEflllnCAJrclJll \!t--~------fj f'll:ed1c1eo DISC _ - -ee MSTAINEO rse Figure 4. Individual data fr ne musician frm Experiment 1: identificatin respnses and percent crrect predicted and btained discriminatin scres.... '" c 0 '" Z 0. 0 '"... <D a: I- 0 ~ <t a: ~ ~ ; , :.~_...,"'".,,i " " r.>: -j.";", '. i \'\.,.,.,.,... l! ~ ICEi'll trrcs r Ill,.. PREDICTEQ tsc c OBlRINED DISC Figure 5. Individual data fr ne musician frm Experiment 1: identificatin respnses and percent crrect predicted and btained discriminatin scres. It can be tentatively cncluded that: (1) Musicians can hear all distinctins better than nnmusicians, at least simply n ail auditry basis. Otherwise, discriminatin perfrmance, at least within categries where musicians have n symblic infrmatin t help them, wuld be equal fr the tw grups. The amunt f auditry infrmatin available (n the rder f25% imprvement ver the predicted functin) des seem t be greater than typically fund in speech experiments, perhaps because f the extreme simplicity f the steady-state stimuli used here. This added infrmatin seems t be cnstant fr all stimulus pairs." (2) Maximum difference in perfrmance between the tw grups is in the between-categry judgments. In additin t a fairly gd auditry basis fr telling the pairs apart, musicians increase their perfrmance drastically when labeling r symblic distinctins becme available t them. In physical terms, the distance between each discriminated pair is equal; nly the additinal infrmatin prvided by categrical perceptin f the intervals culd affect discriminatin in such a manner. (3) Nnmusicians als did slightly better discriminating acrss categry bundaries than between them (Figure 3). Hwever, this peak was nt well predicted by the identificatin functin. Tw f the nnmusicians shwed particularly marked peaks in discriminatin at the categry bundary. These subjects were abut 10 years lder than the ther nnmusicians and als reprted listening t music frequently. As a cnsequence, they may be in the prcess f acquiring categries similar t thse pssessed by the musicians thrugh frmal instructin. (4) The reactin time data described abve demnstrate peratin f an auditry prcessing level, reflected in the changes in reactin time at the bundaries fr the tw tasks.

6 MUSICAL INTERVALS 389 EXPERIMENT 2 Experiment 1 demnstrated categrical-like perceptin by musicians fr tw-nte intervals where the bttm nte remained cnstant, and the frequency ratis were changed by varying nly the frequency f the tp nte. Experiment 2 utilized majr and minr thirds where the bttm as well as the tp nte varied; since intervals are defined by the frequency rati between cmpnent tnes, changing the frequency f the tnes des nt alter the interval. It was pssible that in Experiment I subjects were basing the discriminatin in part n the tp nte differences (in additin t interval size), thereby inflating perfrmance. Thus, by randmizing the abslute psitin f the interval, subjects wuld be frced t listen t the interval infrmatin nly. Methd Subjects. The subjects were six Brwn University undergraduate music students. All had had at least 14 years' experience in playing at least ne instrument. They had all had at least ne cllegelevel music curse which included ear training, and all were currently active in music. Stimulus materials. The stimuli were similar t thse in Experiment I, except that tw mre majr-minr cntinua were cnstructed: ne whse bttm nte was always F sharp (370 Hz) and whse tp ntes varied frm A (440 Hz) t A sharp (466 Hz) in seven lgarithmically equal steps, and anther whse bttm nte was always G (392 Hz) and whse tp ntes varied frm B flat (466 Hz) t B natural (493 Hz). Each cntinuum thus had eight stimuli, the tp nte varying in cent steps, but always spanning the intervals frm 300 t 400 cents. All ther aspects f the stimuli were as in Experiment I. Tw identificatin tapes were cnstructed by presenting 5 repetitins f each f the 24 stimuli in tw different randm rders, thus making a ttal f 120per tape. Other details f the stimuli were as in Experiment I. The discriminatin tape was prepared, again by pairing members f a cntinuum tw steps away t frm ddity triads; hwever, each stimulus in the triad came frm a different cntinuum, ne frm each f the three cntinua described abve. Therefre, in rder t chse the crrect respnse, the subject wuld have t listen fr the interval size (i.e., frequency rati) and ignre the abslute pitches f the stimuli. The members f the three cntinua appeared in each psitin f the triads equally ften; in additin, the dd stimulus als appeared equally ften in each psitin. Tw randm rders f 72 trials each were prepared; ther details f presentatin were as in Experiment I. Prcedure. The tapes were played n a Crwn SX 822 tape recrder channeled thrugh an Ampex tape recrder and then thrugh bth channels f Grasn-Stadler TDH-39 headphnes. The identificatin task was similar t Experiment I except that the subjects recrded their respnses n answer sheets and were run in small grups. The discriminatin task was als run in cnditins similar t thse f Experiment I. The subjects were tld befrehand that the stimuli wuld differ in abslute pitch, and that they were t select the stimulus different in interval size frm the ther tw presented (i.e., different in degree f majr r minr). They were als allwed t hear all three cntinua in rder befre they started the experiment. Results and Discussin Five f the six subjects shwed highly incnsistent labeling data and chance r near chance discriminatin perfrmance. Only ne listener (the mst highly trained musician in the grup) shwed any evidence f being able t perfrm the task. Mst subjects seemed t be misled int respnding "minr" t the lwer-pitched intervals, regardless f the size f the interval. Even fr the ne subject wh respnded with sme cnsistency, there was little evidence fr categrical perceptin, since labeling data did nt shw well-defined categries (endpints were nt even at identificatin) and discriminatin was near chance. Since the subjects used here were different frm thse in Experiment 1, we wanted t insure that the lack f cnsistency was nt due t the selectin f subjects. Therefre, the six peple were run n the same tapes frm Experiment 1. The results were almst identical t thse presented in Figure I, s task and nt subject variables are implicated. These results are smewhat surprising in view f Burns and ard's (1978) findings f gd perfrmance with intervals randmized with respect t abslute pitch. Thugh ur discriminatin task is smewhat mre difficult than Burns and ard's, we expected at least the identificatin data t be cnsistent. The inability f ur subjects t ignre the abslute pitch f the intervals suggests that simultaneus intervals are prcessed differently frm sequential intervals. In ne sense, these results are nt cmpletely unexpected, given the high degree f stimulus uncertainty in this task. Nevertheless, the difference between sequential and simultaneus intervals remains t be explained. It is als apparent that there is a great deal f cntextual dependence with these stimuli; i.e., the relative size f the interval cannt be judged independently f the abslute pitches f the cmpnent tnes. e had expected t demnstrate, in this experiment, a ttal dependence n the symblic level (a mre abstract level where interval infrmatin and nt abslute pitches are prcessed) fr the discriminatin task, since the acustic characteristics f each stimulus in the triad were different. e did nt succeed, hwever, as this manipulatin made the task essentially impssible t perfrm. Nevertheless, we believe that there exists a symblic level because f the discriminatin peaks at categry bundaries. Our next step, therefre, was aimed at explring the symblic level by means f the selective adaptatin paradigm. EXPERIMENT 3 Selective adaptatin in speech usually invlves the repetitin f a stimulus sund related either phnetically r acustically t the test cntinuum. A shift in the pattern f perceptin after adaptatin may indicate that the adapting sund has fatigued units at that lcus f prcessing. If the bundary is thught f as the pint at which tw channels

7 390 ZATORRE AND HALPERN have similar activatin levels, then a shift can be predicted when the activity f ne unit is reduced thrugh adaptatin. The directin f the shift is always tward the adap.ted categry, since there will be relatively mre identificatins f ambiguus stimuli as members f the unadapted categry. This experiment used an adaptr which was bth acustically and symblically related t the test series in rder t determine if these basic adaptatin results culd be btained fr musical interval perceptin. Methd Subjects. Fur musicians frm Experiment I and an additinal undergraduate music student served as subjects. Stimulus materials. Identificatin and discriminatin tapes frm Experiment I were used. In additin, tape lps were cnstructed cntaining repeated presentatins f the endpint majr third stimulus (FA: 400 cents), each fllwed by 500 msec f silence. Prcedure. The apparatus was identical t that in Experiment I; the adaptatin lps were played n a Sny tape recrder which fed int the amplifier. Timing was by stpwatch and the subjects were run individually r in pairs. The subjects first heard the cntinuum endpints fr practice, then an identificatin tape and a discriminatin tape were presented as in Experiment I. After a shrt break, the adapting lp was presented fr 2 min (120 presentatins f the adaptr) fllwed by 10 trials f either identificatin r discriminatin. One minute f adaptatin was interspersed after every 10 trials thereafter. A different randm rder was used fr preadaptatin testing fr each task. Order f task presentatin was cunterbalanced acrss subjects. Results and Discussin Mean percent identificatin befre and after adaptatin are shwn in Figure 6. It is clear that there is a cnsistent shift in the bundary twards the adapted categry, similar t that reprted in speech experiments. Bundaries were calculated by cnverting respnses in the bundary regin t z scres and then finding the pint by linear interplatin. The average bundary change, frm t cents is significant by a crrelated means ne-tailed t test [t(4) = 2.21, p <.05]. The discriminatin data befre and after adaptatin are shwn in Figure 7. Obtained perfrmance was significantly better than predicted n the basis f identificatin respnses, as in Experiment 1. This was true fr preadaptatin [F(l,4) = 30.28, p <.001] as well as fr pstadaptatin [F(l,4) = 171.0, p <.001]. The peak in the discriminatin als shifted after adaptatin. There was n interactin f predicted by btained functins either pre- r pstadaptatin, indicating a gd fit f the tw functins. These data are very similar t thse btained in speech experiments using the selective adaptatin paradigm (e.g., Eimas & Crbit, 1973). That the adaptatin effect is nt simply a respnse bias is shwn by the change in the discriminatin functins. The discriminatin task des nt depend explicitly n relative judgments f the categry t which members f the ddity triad belng. The change in discriminatin respnse after adaptatin, therefre, mre likely 0 0" ",, if> ~, \ w, if>, z 0 \ c. 0,,, if> w "'I \ -. 0:, f- Z <t, \ <J 0: w, w c, 2 ' \ 0 L ---==~~.- - -, " \ 10 PAEAOkPl '" PC'STAOAP' Figure 6. Mean percent identificatin respnses befre and after adaptatin with majr third (400 cent) stimulus fr five musicians frm Experiment 3. 0" 0.---"'-.. if> c»: w if> Z, 0 c. 0 if> '"..j 0: f- a z e <J 0: c, a N a "" DISC DlSC PREADAPT POSTAQRP' Figure 7. Mean percent btained discriminatin scres befre and after adaptatin with majr third (400 cent) stimulus fr five musicians frm Experiment 3. represents a true change in perceptual categries, as ppsed t respnse bias. Althugh the results frm many selective adaptatin experiments have been used as evidence fr feature detectr theries f perceptin, parsimny des nt permit any similar frmulatin in the case f musical intervals. Neither d we believe that the effect takes place at a level f respnse rganizatin." Instead, it seems likely that we are affecting the utput f sme channel f analysis. e d nt knw frm these data the lcus f the adaptatin effect, nr can we describe the stimulus characteristics t which the adapted channel is sensitive. The mst bvius way t investigate these questins is by varying the adaptr and measuring the adaptatin effect. This was undertaken in the next experiment. EXPERIMENT 4 An imprtant questin raised by Experiment 3 is

8 MUSICALINTERVALS 391 whether the adapted channels are respnding t interval infrmatin independently frm abslute frequency. T answer this questin, a set f adaptrs was cnstructed in which the pitches were different frm the test cntinuum. Adaptrs where the pitches were the same (as in Experiment 3) were als used. Naturally, the intervals were always majr r minr thirds (endpints f cntinua), thus maintaining the interval infrmatin cnstant. In additin, single nte adaptrs were used t see if the adapted channel was sensitive t a single tne, as ppsed t an interval. Finally, interaural transfer f the adaptatin effect was tested t determine the lcus f the effect. Methd Subjects. The subjects frm Experiment 2 were used, alng with an additinal five musicians frm the Prvidence area wh met the criteria stated abve. Stimulus materials. The identificatin tapes frm Experiment 1 (FA-FA flat cntinuum) were used as the test stimuli in all cnditins. In Cnditins 1-6, adaptrs were always endpint stimuli frm ne f tw cntinua: FA (majr third lw pitch), FA flat (minr third lw pitch), GB (majr third high pitch), and GB flat (minr third high pitch). In Cnditins 7 and 8, the adaptr was the single tne A flat (415 Hz), which is the tp nte f the lwpitch minr interval. Other details f the stimuli were as in Experiment 3. Prcedure. The apparatus used was identical t that in Experiment 2. Adapting stimuli were played n the Ampex tape recrder, test stimuli were played n the Crwn. On each day, the subject was given a preadaptatin identificatin test fllwed by an adaptatin run (see Experiment 3 fr details f adaptatin presentatin). Only ne adaptr (i.e., ne cnditin) per day was used. In Cnditins 1 and 2, the minr adaptrs (FA flat and GB flat) were used. Since the test stimuli were taken frm the lw-pitch (FA t FA flat) cntinuum, Cnditin I cnstitutes a replicatin f the identificatin task f Experiment 3. The GB flat interval is the same frequency rati (300 cents) as FA flat, but it is transpsed upward by a full tne (200 cents), s neither f the individual tnes is the same as the tnes in the test series. Cnditins 3 and 4 used the same adaptrs as Cnditins I and 2, but the adapting stimuli were presented mnaurally, left ear nly fr all subjects, and the test stimuli always t the right ear. Preadaptatin tests were als dne mnaurally (right ear nly) fr these cnditins. Cnditins 5 and 6 used the tw majr (400-cent) adaptrs (FA and GB) frm bth lw- and high-pitch cntinua, i.e., the ppsite endpints frm the adaptrs used in Cnditins I and 2. Cnditins 7 and 8 used the single tne A flat as the adaptr; in Cnditin 7, presentatin was binaural; in Cnditin 8, the adaptr was presented t the left ear, the test series t the right ear. Order f presentatin was cunterbalanced acrss subjects fr each pair f cnditins. Results and Discussin Bundaries befre and after adaptatin were determined as in Experiment 3. The amunt f shift (preadaptatin bundary minus pstadaptatin bundary) fr each cnditin is shwn in Table 1. In spite f cnsiderable between-subject variatin, the shifts were in the predicted directin fr all subjects in the cnditins where the adaptr came frm the same frequency cntinuum as the test series (Cnditins 1, 3, and 5). Nte that the shifts were apprximately f equal size fr each endpint adaptr (i.e., majr and minr adaptrs had equally strng effects). There was n significant effect when the adaptr preserved the prper frequency rati but was pitched higher than the test cntinuum (Cnditins 2, 4, and 6). In additin, when adaptr and test were presented t different ears (i.e., cmparing Cnditins 1 and 3), the amunt f shift was statistically unchanged with respect t binaural presentatin. Finally, when the tp nte f the lw minr interval (A flat) was presented alne, the adaptatin effect was just as great as when the entire interval was presented. This effect, t, shwed interaural transfer." The fact that there was n significant effect in the cnditins where the adaptrs shared the apprpriate frequency rati with the test cntinuum but nt the abslute pitches (Cnditins 2, 4, and 6) is quite imprtant. This finding implies that the symblic level f analysis (i.e., where the decisin majr r minr is made) is nt being tapped by the adaptatin technique. Mrever, it implies that whatever is being adapted is frequency specific. The result frm the single-nte cnditin (7) indicates that the adapted level is sensitive t single tnes and nt t ratis. Perhaps the adapted level is where single-tne extractin takes place, befre the rati is cmputed. It was als fund that 100% interaural transfer ccurred (in Cnditins 3 and 8). This result implies that the effect is perating centrally. Since transfer was als btained in the single-nte cnditin (8), it seems safe t cnclude that the effect f the inter- Table 1 Amuntf BundaryShift, in Cents, fr Varius AdaptingCnditinsin Experiment 4 Cnditin SUbject 1 (FAb) 2 (GBb) 3 (FAb) 4 (GBb) 5 (FA) 6 (GB) 7 (Ab) 8 (Ab) L.M M.S L.N.* J.B K.F M.R Mean p<.005 n.s,.005 n.s..025 n.s t Nte-Adaptr and test were presented t separate ears in Cnditins 3, 4, and 8. [See text, Ftnte 4. "This subject failed t cmplete all cnditins.

9 392 ZATORRE AND HALPERN val adaptrs (Cnditins 1, 3, and 5) can be mst parsimniusly accunted fr by the presence f the tp nte in the adaptr.7 GENERAL DISCUSSION These experiments have shwn that a phenmenn similar t categrical perceptin f speech sunds exists fr perceptin f simultaneus musical intervals. That is t say, trained musicians have internalized the cncepts f majr and minr third t such an extent that sunds they can label differently are mre discriminable than sunds given the same name. But, while Burns and ard (1978), Siegel and Siegel (1977a, 1977b), and Blechner (Nte 2) have virtually duplicated with musical stimuli results fund fr the perceptin f cnsnants, in this study we fund limits t the categricalness f perceptin, at least fr simultaneus majr and minr thirds. There is an a priri reasn t expect categrical perceptin f musical intervals by musicians. An interval, like a speech sund, cnveys invariant infrmatin despite being made up f varying physical signals. Fr example, in a majr third, the higher nte is placed int a frequency rati f 1.26:1 with the bttm nte (i.e., 400 cents), regardless f the abslute frequency f the individual ntes. In estern music thery, frequency ratis perfrm the same harmnic and meldic functin in any key (i.e., withut regard t any specified abslute frequency). In agreement with this argument, Siegel and Siegel (1977b) fund cnsistent perfrmance n a magnitude estimatin task and a labeling task using successive intervals, even when the bttm nte f the intervals was varied amng the seven diatnic tnes frm the C majr scale. Burns and ard (1978) cnstructed intervals whse abslute frequency varied within a range f 360 cents, and fund categrical perceptin with cnsistent labeling and discriminatin perfrmance n higher than predicted n the basis f identificatin. There is even evidence that interval infrmatin is stred in memry as an abstract entity (nt as particular ntes) frm the interference data gathered by Deutsch (1978; Deutsch & Rll, 1974). These studies reinfrce the idea that the theretical invariance f the interval (in music) extends t perceptual invariance, as is the case with acustically different, but perceptually identical, cnsnantal speech sunds. Hwever, using simultaneus intervals in tasks very similar t thse used by Burns and ard, we fund, in Experiment 2, that ur musicians were unable t successfully apply the cncept f majr and minr thirds when abslute pitch was randmized. Mrever, these results were cnfirmed in Experiment 4, where adaptatin by an interval which shared symblic, but nt acustic, similarities with the test series failed t shift the categry bundary. e must, then, cnclude that there is a fundamental difference between prcessing successive and simultaneus intervals. In simultaneus intervals, listeners must first islate the cmpnent tnes and then analyze their frequency relatinship. This perceptual islatin is accmplished in successive intervals by the tempral separatin between cmpnent tnes. Categrical perceptin can nly be emplyed by the listener if this frequency rati has been abstracted. Perhaps the perceptual cmplexity f simultaneus intervals frces analysis t ccur nly at a frequencyspecific level, especially in the rigrus tasks we presented t the subjects. Mst cntemprary mdels f pitch perceptin (Gldstein, 1973; ightman, 1973a, 1973b) invlve a tw-stage mechanism which is relevant t sme f ur results. In the first stage, the incming cmplex acustic wavefrm is subjected t a Furier transfrm which cmputes the spectral characteristics f the signal. Frm this, the individual cmpnents f the cmplex culd be identified. This stage wuld naturally be frequency specific. The secnd stage is typically viewed as a pattern recgnitin r template match that searches ut the best fitting fundamental fr the given harmnics. In the case f musical intervals, subjects are nt listening fr a peridicity pitch arising frm the tw tnes, but rather t the interval infrmatin; it is therefre reasnable t prpse that the utput f the pitch extractr culd feed int a third stage that cmputes ratis. B Thus, discriminatin peaks and reactin time increases at categry bundaries, such as were fund in ur first experiment, culd perhaps arise frm the peratin f this third stage, since it is here that particular interval infrmatin wuld be stred. This stage wuld mst likely be set up t accept a range f particular ratis as exemplars f prttype intervals n the basis f learning, and thus wuld be assciated with lngterm memry strage. e cannt cmpletely rule ut the pssibility, hwever, that there culd exist sme natural prpensity f the auditry system n which the tuning fr the learned intervals wuld be superimpsed (e.g., a prpensity fr small-integer ratis). Only individual nte infrmatin (i.e., pitches f the cmpnents) wuld be stred at the pitch extractin stages. The availability f this auditry, analg infrmatin wuld explain the higher than predicted discriminatin perfrmance in Experiment 1, because the differences between the tp ntes f the intervals culd be cmpared t each ther. This scheme wuld als explain the adaptatin effects. Since single-nte adaptrs were effective, we must assume that adaptatin fatigues the single-nte analyzers. Further evidence that is cnsistent with this mdel cmes frm the fact that ur adaptatin effects all appear t be centrally mediated, as d the effects assciated with cmplex tne perceptin (Hutsma & Gldstein, 1972).

10 MUSICALINTERVALS 393 Blechner (Nte 2) als reprted higher than predicted discriminatin fr sme f his musicians in tasks very similar t urs. It is interesting that he fund that when subjects were given nly a singlente cntinuum (ur tp nte), their discriminatin functins did nt shw the peak characteristic f categrical perceptin. It seems clear, then, that althugh the auditry, nncategrical infrmatin may increase discriminatin perfrmance, it cannt be the sle basis fr it. As fr the results f the secnd experiment, which used intervals randmized with respect t abslute frequency, it seems that the task did nt successfully engage the rati analysis stage. Rather, the system may have been verladed at sme pint (t many stimuli, t shrt presentatin duratins, etc.), and mst subjects fell back n using a simpler (and incrrect) strategy f relying n the abslute frequency f the stimuli. The mdel utlined here bears a strng resemblance t a mdel fr interval recgnitin discussed by Deutsch (1969, 1975). In her frmulatin, there is a primary array where individual nte infrmatin is stred (e.g., F r A). This stage is cnnected t a specific interval stage, where interval infrmatin at specific pitches is stred (e.g., FA r GB flat). The infrmatin frm this secnd stage then cnverges nt a third, whereabstract (i.e., frequency-independent) interval infrmatin is prcessed. Clearly, this mdel is in basic agreement with ur data. Deutsch's mdel ffers anther explanatin f the data frm Experiment 2. If that paradigm nly tapped a frequencyspecific interval stage, the subjects wuld have been unable t successfully cmparestimuli frm different cntinua, as these wuld have been cded accrding t interval size and abslute frequency, rather than the abstract interval. In ther wrds, a true majr third whse bttm nte was F wuld nt have been cded as equivalent t ne whse bttm nte was G. Anther effect which we fund here that has nt been reprted by ther studies in this field was the generally better discriminatin (in Experiment 1) f stimuli frm the majr end f the cntinuum than frm the minr end. This effect is prbably als related t the narrwer categry in identificatin fr majr stimuli in Experiment 1. As mentined abve, this special nature f the majr third may be due t sme special acustical characteristics f this particular interval, r it may be due t the majr third having a special place in the estern musical system. One pint which wuld argue against the frmer interpretatin is that the better within-categry discriminatin f majr than f minr intervals was cmpletely absent fr the nnmusicians (Figure 3). e wish nw t bring up the questin f hw relevant these findings are fr the perceptin f real music. Neither tasks nr stimuli used here resemble thse nrmally fund in music. Even s, it stands t reasn that categrical perceptin wuld be even mre advantageus in the cncert hall than in the labratry. ard (1970) has cited data shwing that in real perfrmances there is much variance in the frequency f the ntes being played, but that it is nt usually nticed by listeners. Categrical perceptin results when a listener ignres small pitch irregularities and thereby pays mre attentin t mre imprtant aspects f the music. Hwever, a truly ut f tune perfrmance is bviusly detectable t mst listeners. This phenmenn shws up in the labratry in the appearance f the auditry cmpnent (i.e., higher than predicted results) in the discriminatin task. Als, recall that in Experiment 1 we fund unifrmly gd perfrmance even within categries fr the discriminatin task with three steps (43 cents) between stimuli. Further, the principal result frm Experiment 2, i.e., that intervals culd nt be judged cnsistently when the abslute frequency f the cmpnent tnes was varied, culd be interpreted in terms f real-life musical systems as ne reasn fr the establishment f such devices as key centers and tnalities. A key center prvides a framewrk fr tnes in a scale such that sme tnes are mre imprtant than thers; chrds built n these tnes gravitate away frm and back t these mre imprtant tnes (e.g., in a majr diatnic scale, the harmnic rts f chrds mve twards the first, third, and fifth scale degrees). Thus, the tnal centers prvide a cntext fr the interpretatin f individual harmnic intervals, withut which the intervals might nt be judged crrectly. e have n dubt that in real music there are many such higher rder cnstraints n prcessing the basic acustic infrmatin, perhaps analgus t the syntactic and semantic cnstraints that apply t language. The mdel that we have discussed bviusly remains preliminary and smewhat vague. There remain many issues t be explained; specificially, a precise descriptin f the mechanism underlying the adaptatin effect has nt been given. Als, sufficient data t distinguish between a frequency-specific interval stage and an abstract interval stage is lacking, and an adequate descriptin f the characteristics f these higher rder stages has nt yet been given. Finally, the issue f hw experience affects categrical perceptin is unclear-it is nt knwn if training results in the phenmena we have seen, r if there are natural differences between listeners such that thse wh prcess musical stimuli in a certain way are als thse wh seek ut training and thus becme musicians. REFERENCE NOTES 1. Fujisaki, H., & Kawashima, T. Sme experiments n speech perceptin and a mdel fr the perceptual mechanism. Annual Reprt f the Engineering Research Institute, University f Tky, 1970,29,

11 394 ZATORRE AND HALPERN 2. Blechner, M. J. Musical skill and the categrical perceptin fharmnic mde. Haskins Labratries Status Reprt n Speech Perceptin, 1977, SR-5152, REFERENCES BURNS, E. M., CARNEY, A. E., & ARD,. D. Balancing the scales fr music and speech. Jurnal f the Acustical Sciety famerica, 1976,60, S94(A). BURNS, E. M., & ARD,. D. Categrical perceptin-phenmenn r epiphenmenn: Evidence frm experiments in the perceptin f meldic musical intervals. Jurnal f the Acustical Sciety famerica, 1978,63, COOPER, F. S., & MATTINGLY, I. G. A cmputer-cntrlled PCM system fr the investigatin f dichtic speech perceptin. Jurnal fthe AcusticalSciety famerica, 1969,46, 115(A). CUTTING, J. E., & ROSNER, B. S. Categries and bundaries in speech and music. Perceptin & Psychphysics, 1974, 16, CUTTING, J. E., ROSNER, B. S., & FOARD, C. F. Perceptual categries fr musiclike sunds: Implicatins fr theries f speech perceptin. Quarterly Jurnal fexperimental Psychlgy, 1976,28, DEUTSCH, D. Music recgnitin. Psychlgical Review, 1969, 76, DEUTSCH, D. The rganizatin f shrt-term memry fr a single acustic attribute. In D. Deutsch & J. A. Deutsch (Eds.), Shrtterm memry. New Yrk: Academic Press, DEUTSCH, D. Interactive effects in memry fr harmnic intervals. Perceptin & Psychphysics, 1978,24,7-10. DEUTSCH, D., & ROLL, P. L. Errr patterns in delayed pitch cmparisns as a functin f relatinal cntext. Jurnal f Experimental Psychlgy, 1974, 103, DIEHL, R. L. The effect f selective adaptatin n the identificatin f speech sunds. Perceptin & Psychphysics, 1975, 17, DIEHL, R. L., ELMAN, J. L., & MCCUSKER, S. B. Cntrast effects n stp cnsnant identificatin. Jurnal fexperimental Psychlgy: Human Perceptin and Perfrmance, 1978, 4, EIMAS, P. D. The relatin between identificatin and discriminatin alng speech and nnspeech cntinua. Language & Speech, 1963,6, EIMAS, P. D., & CORBIT, J. D. Selective adaptatin f linguistic feature detectrs. Cgnitive Psychlgy, 1973,4, EIMAS, P. D., COOPER,. E., & CORBIT, J. D. Sme prperties f linguistic feature detectrs. Perceptin & Psychphysics, 1973,13, EIMAS, P. D., & MILLER, J. L. Effects f selective adaptatin n the perceptin f speech and visual patterns: Evidence fr feature detectrs. In H. L. Pick & R. D. alk (Eds.), Perceptin and experience. New Yrk: Plenum, GOLDSTEIN, J. L. An ptimum prcessr thery fr the central frmatin f the pitch f cmplex tnes. Jurnal f the AcusticalSciety famerica, 1973,54, HOUTSMA, A. J. M., & GOLDSTEIN, J. L. The central rigin f the pitch f cmplex tnes. Jurnal f the Acustical Sciety famerica, 1972,51, JESTEAD,., & BILGER, R. C. Intensity and frequency discriminatin I: One- and tw-interval paradigms. Jurnal f the AcusticalSciety famerica, 1974,55, LIBERMAN, A. L., HARRIS, K. S., HOFFMAN, H. S., & GRIFFITH, B. S. The discriminatin f speech sunds within and acrss phneme bundaries. Jurnal f Experimental Psychlgy, 1957,54, LIBERMAN, A. L., HARRIS, K. S., KINNEY, J. A., & LANE, H. The discriminatin f relative nset time f the cmpnents f certain speech and nnspeech patterns. Jurnal fexperimental Psychlgy, 1961,61, LOCKE, S., & KELLAR, L. Categrical perceptin in a nnlinguistic mde. Crtex, 1973,9, MACMILLAN, N. A., KAPLAN, H. L., & CREELMAN, C. D. The psychphysics f categrical perceptin. Psychlgical Review, 1977, 84, MATTINGLY, I. G., LIBERMAN, A. L., SYRDAL, A., & HALES, T. Discriminatin in speech and nnspeech mdes. Cgnitive Psychlgy, 1971,2, MILLER, G. A. The magical number seven plus r minus tw: Sme limits n ur capacity fr prcessing infrmatin. Psychlgical Review, 1956,63, MILLER, J. D., IER, C. C., PASTORE, R. E., KELLY,. J., & DOOLING, R. J. Discriminatin and labeling f nise-buzz sequences with varying nise-lead times. Jurnal f the Acustical Sciety famerica, 1976,60, PASTORE, R. E. Categrical perceptin: A critical reevaluatin. In S. K. Hirsh, D. H. Eldredge, I. J. Hirsh, & S. R. Silverman (Eds.), Hearing and Davis: Essays hnring Hallwell Davis. St. Luis, M: ashingtn University Press, PASTORE, R. E., AHROON,. A., BAFFUTO, K. J., FREIDMAN, C., PULEO, J. S., & FINK, E. A. Cmmn factr mdel f categrical perceptin. Jurnal f Experimental Psychlgy: Human Perceptin and Perfrmance, 1977,3, PISONI, D. B. Auditry and phnetic memry cdes in the discriminatin f cnsnants and vwels. Perceptin & Psychphysics, 1973, 13, PISONI, D. B. Auditry shrt term memry and vwel perceptin. Memry & Cgnitin, 1975,3,7-18. PISONI, D. B. Identificatin and discriminatin f the relative nset time f tw cmpnent tnes: Implicatins fr vicing perceptin in stps. Jurnal f the Acustical Sciety f America, 1977,61, PISONI, D. B., & TASH, J. Reactin times t cmparisns within and acrss phnetic categries. Perceptin & Psychphysics, 1974, IS, RAZ, I., & BRANDT, J. F. Categrical perceptin f nnspeech stimuli by musicians and nnmusicians. Jurnal f the Acustical Sciety famerica, 1977,62, S60(A). SAUSCH, J. R. Peripheral and central prcesses in selective adaptatin f place f articulatin in stp cnsnants. Jurnal fthe AcusticalSciety famerica, 1977,62, SCHARF, B. Critical bands. In J. V. Tbias (Ed.), Fundatins f mdern auditry thery (Vl. I). New Yrk: Academic Press, SHOER, E. G., & BIDDULPH, R. Differential pitch sensitivity f the ear. Jurnal fthe Acustical Sciety famerica, 1931, 3, SIEGEL, J. A., & SIEGEL,. Abslute identificatin f ntes and intervals by musicians. Perceptin & Psychphysics, 1977, 21, (a) SIEGEL, J. A., & SIEGEL,. Categrical perceptin f tnal intervals: Musicians can't tell sharp frm flat. Perceptin & Psychphysics, 1977,21, (b) SIMON, H. J., & STUDDERT-KENNEDY, M. Selective anchring and adaptatin f phnetic and nn phnetic cntinua. Jurnal fthe Acustical Sciety famerica, 1978,64, STUDDERT-KENNEDY, M., LIBERMAN, A. M., HARRIS, K. S., & COOPER, F. S. Mtr thery f speech perceptin: A reply t Lane's critical review. Psychlgical Review, 1970,77, STUDDERT-KENNEDY, M., LIBERMAN, A. M., & STEVENS, K. N. Reactin time t synthetic stp cnsnants and vwels at phneme centers and at phneme bundaries. Jurnal f the AcusticalSciety famerica, 1963,35, 1900(A). ARD,. D. Musical perceptin. In J. V. Tbias (Ed.), Fundatins fmdern auditry thery (Vl. I). New Yrk: Academic Press, IGHTMAN, F. L. Pitch and stimulus fine structure. Jurnal f the Acustical Sciety famerica, 1973,54, (a) IGHTMAN, F. L. The pattern-transfrmatin mdel f pitch. Jurnal f the Acustical Sciety f America, 1973, 54, (b)

12 MUSICAL INTERVALS 395 NOTES I. By peripheral and central, we simply mean prcessing stages befre and after infrmatin frm the tw ears is cmbined, respectively. 2. The difference threshld fr frequency discriminatin varies cnsiderably depending n the methds used, ludness and frequency f the tnes, etc., but within the frequency range we are using here, the DL is typically n the rder f 2-4 Hz (Jestead & Bilger, 1974; Shwer & Biddulph, 1931). Thus, we are wrking well abve threshld. 3. The frmula we are using is cmmnly used in speech research: P(crr) = (13)[1 +2(PI-PI ')2), where PI is the prbability f assigning ne member f a pair t a categry, and PI' is the prbability f assigning the ther member t that categry. 4. This claim must be made very cautiusly since we have n unbiased estimate f discriminatry sensitivity fr each stimulus cmparisn (cf. Macmillan, Kaplan, & Creelman, 1977). 5. Recent accunts f adaptatin experiments have emphasized sensry cntrast and anchring rather than sensry fatigue (Diehl, Elman, & McCusker, 1978; Simn & Studdert-Kennedy, 1978). e cannt at present rule ut such influences in ur results. It is interesting that Siegel and Siegel (1977a), using sequential intervals with musicians, failed t find any cntrast effects. It will be interesting t see if the same hlds true fr simultaneus intervals..6. This effect did nt achieve significance with the riginal five subjects; hwever, it seemed t be mainly due t a single deviant scre, that f a subject wh later admitted nt paying attentin during the task. T be certain that there was interaural transfer in this cnditin, five new subjects were run in Cnditins 7 and 8 f Experiment 4. The results shwed significant adaptatin in bth cnditins in the predicted directin. 7. This might als explain the lack f effect in the cnditins where the adaptr did nt cme frm the same cntinuum as the test series. In Cnditin 2, fr example, the adaptr is GB flat; the critical tnes in the test series g frm A t A flat, and since B flat is 100 cents abve A and G is 100 cents belw A flat, it is pssible that they had a mutually cancelling effect. At this pint, hwever, we d nt knw the tuning functins assciated with the adaptatin effect, s we cannt be certain that adaptatin wuld result when a single tne adaptr is as much as 100 cents away frm the endpint f the test series. 8. If the tw tnes that make up the interval were harmnic cmplexes (with r withut fundamentals) rather than sinusids, then the tne extractin stage wuld be slightly mre invlved, as tw different spectral pattern matches wuld have t be made in rder t determine the tw fundamentals. The particulars f this prcess are necessarily cmplicated, but they need nt cncern us here; the end result f this prcessing stage wuld still be tw pitch percepts frm which the musical interval culd be cmputed. e assume, then, that the mdel described wuld be valid fr cmplex tnes as well as fr pure tnes, thugh we plan t test this assumptin empirically in future wrk. (Received fr publicatin March 8, 1979; revisin accepted August 17, 1979.)