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Segmentation of sentences into phonological phrases as a function of constituent length
JOURNAL OF VERBAL LEARNING AND VERBAL BEHAVIOR
10, 226-233 (1971)
Segmentation of Sentences into Phonological Phrases as a Function of Constituent Length J. E. MARTIN, BARBARAKOLODZIEJ, AND JOSEPH GENAY The Pennsylvania State University, UniversityPark, Pennsylvania 16802
Evidence is reported which supports the frequent claims that the segmentation of sentences into phonologicalphrases is partially a function of length of utterance and the position of syntactic boundaries. It is shown that segmentation is more likely to occur at constituent boundaries rather than between them. There is a greater tendency to place segment boundaries before or after long phrases than to place them before or after short phrases. There is a tendency to minimlze the number of segments.
The first purpose of this paper is to present data concerning the parameters affecting the segmentation of utterances into phonological phrases. In this context, it will be argued that the role of syntactic surface structures in psychological processing has been widely misunderstood. It is argued that it is the phonologically interpreted readjusted surface structures, not the syntactic surface structures, which have primary psychological reahty. Chomsky and Halle (1968) argue that the phonological rules are not generally applied directly to the syntactic surface structure. They claim that the phonological rules are best viewed as applying directly to the "readjusted" surface structure formed by dividing the original syntactic surface structure into a succession of phonological phrases. They call the principles which determine the place and number of segmentations the readjustment rules. The phonological phrases so determined are the smallest phonologically independent and complete elements, and the "maximal domain(s) of the phonological process"; that is, dependencies which can be stated strictly in terms of phonology do not extend beyond the boundaries of the phonological phrases. The typical phonological phrase consists of one or more phonological words and is characterazed by having a pitch contour, and a
rhythmical structure, and by being bounded by terminal junctures (Francis, 1965; Stetson, 1951). An example of phonological phrasing would be as follows. Consider the sentence Parents were assisting the advanced teenage pupils. The sentence may be spoken with a pause after assisting and before the. In this case the sentence would be spoken as two phonological phrases, Parents were assisting and the advanced teenage pupils. The boundaries of the phonological phrases are said to depend to a degree on surface syntax, but not to be entirely determined by it (Chomsky & Halle, 1968). Rather, the factors (readjustment rules) which influence the segmentation process are viewed as pertaining to a theory of performance rather than a theory of competence. There have been other studies related to readjustment. Lipsky (1907), introspecting on the segmentation of prose into subjective phrases, noticed a tendency to place more junctures after longer syntactically defined subject phrases than after shorter ones. Bierwisch (1966) has made some suggestions concerning the determinants of segmentation. Among them is the proposal that as the rate of utterance increases, the rate of segmentation per word boundary decreases. Also, Fonagy and Magdics (1960) have reported that the 226
227
SEGMENTATIONOF SENTENCES length o f phrases, defined by the n u m b e r o f words, correlates positively with the rate o f utterance. M o r e recently, E. M a r t i n (1970) has shown that although the perceived " n a t u r a l " groupings o f words in sentences correlate with traditional constituent analysis, the correlation is n o t perfect. F o r example, he demonstrated cases where the natural grouping o f words in a sentence was such that the verb was g r o u p e d with the subject rather than the object. This, o f course, is different f r o m the grouping implied by the constituent analysis in which the verb would be grouped with the object rather t h a n the subject. E. Martin was primarily interested in the failure o f Ss to g r o u p words as predicted f r o m the constituent analysis. He did n o t show h o w the " n a t u r a l " groupings could be systematically controlled. Lipsky's observation, while somewhat casual, is o f fundamental importance for the study o f readjustment rules. In w h a t follows data will be presented which assess his claim in a m o r e careful manner. It will be seen that the p h e n o m e n o n Lipsky noticed is a reliable one and that controlled observation reveals that it is only one o f a n u m b e r o f closely related facts.
short. The short subject and object phrases were composed of single nouns with determiners. The long subject and object phrases were composed of determiners, nouns, and one or two modifiers. The short verb constituents were composed of a single verb in the present tense. The long verb constituents were composed of the same verbs plus the auxiliary had (or has) been-ing. Thus eight categories of five sentences each were constructed with the following lengths: SSS (short subject, short verb, short object), SSL (short subject, short verb, long object), SLS, SLL, LSS, LSL, LLS, LLL. The 40 sentences were then combined with 25 filler sentences and placed in random order on presentation sheets. Procedure. The Ss were instructed to read each sentence several times, until they achieved an "ideal reading," that is, Ss were instructed to read the sentences over, saying them to themselves, until they felt they had read them without error and with the proper intonation pattern. When they had achieved the ideal reading for a given sentence, Ss indicated where they felt a break in the intonation contour of the sentence. They were told that this break might be correlated with a drop in the pitch of the intonation contour and that such drops would be important cues to the breaks or pauses. The Ss indicated the position of a perceived break by drawing a perpendicular line between the two words between which they had felt the break. The Ss were told to mark as many or as few breaks as they felt necessary. In cases where they perceived no break, Ss were to draw the slash at the end of the sentence. One hundred and six undergraduate volunteers served as Ss. RESULTS
METHOD The general method used was to ask Ss to indicate their introspections as to the optimal mode of phrasing for each of a series of sentences. It was assumed that introspections concerning phonological phrases would be valid since they are necessarily a part of the primary linguistic data required for the construction of the phonological grammar. If phonological rules only apply to phonological phrases, then the primary data which the phonological grammar must explain are the contents of individual phonological phrases. It is clear that the intuition of such primary data requires the prior intuitions of the boundaries of such phrases. Therefore, the intuition of phonological phrase boundaries is at least as valid as many other phonological intuitions. Materials. Forty sentences of the subject-verb-object type were constructed. The sentences were constructed so as to vary in terms of the length of the subject, verb, or object. Each constituent could either be long or
Each response f r o m a given S for a given sentence was placed into one o f five categories. Category 11 designates those cases in which a S reported breaks between the subject phrase and the verb, and between the verb and the object phrase, and nowhere else. Category 10 designates those cases in which a S reported a break between the subject phrase and the verb, and nowhere else. Category 01 designates those cases in which a S reported a break between the verb and the object phrase, and nowhere else. Category O0 designates those cases in which a S reported no breaks at all for a sentence. Category Other designates all other cases. Analyses o f variance were c o m p u t e d for each o f the response categories with the inde-
228
MARTIN, KOLODZIEJ, AND GENAY
pendent variables being the lengths of the subject, verb, and object constituents. The analyses for the response categories 11, 10, 01, and 00 were 2 x 2 x 2 designs with repeated measures of each of the 106 Ss. The scores used in the analyses were the number of responses, out of a possible five, of a given response type, that each S made, for each of the eight experimental conditions. Analyses were also done for 01 + 00, 10 + 00, 10 + 11, and 01 + 11.
case the effect was stronger in verb-object boundary than in subject-verb boundary. Long object phrases produced more junctures in the verb-object boundary than did short object phrases. Long object phrases also produced fewer junctures in the subject-verb boundaries than did short object phrases. The second effect was not as strong as the first. The subject-verb boundary was more strongly affected by the length of the subject
TABLE
1
THE MEAN NUMBER OF RESPONSES PER SUBJECT AS A FUNCTION OF CONSTITUENT LENGTH AND o92 SCORES FOR MAIN EFFECTS
Response category Treatment level
00
11
10
01
01 + 00
10 + 00
10 + 11
01 + 11
Subject Short Long to2
1.35 0.38 .10"
0.48 0.79 .02*
1.21 3.06 .26*
1.68 0.38 .21"
3.02 0.77 .39*
2.56 3.45 .06*
1.70 3.85 .34*
2.16 1.17 .09*
Verb Short Long o92
1.23 0.50 .06*
0.20 1.06 .14"
2.33 1.95 .01"
0.93 1.13 .00
2.16 1.63 .02*
3.56 2.45 .09*
2.54 3.01 .02*
1.14 2.19 .10"
Object Short Long co2
1.26 0.47 .07*
0.45 0.82 .03"
2.54 1.73 .05"
0.57 1.50 .11"
1.83 1.97 .00
3.80 2.20 .19"
2.99 2.55 .01"
1.01 2.32 .15'
*p < .001. The main effects are given in Table 1. The o~2 values, included to give a clearer picture of the results, indicate the proportion of the total variance due to differences among treatment conditions. The results show that long subject phrases produced more junctures between the subject and the verb than short subject phrases. They also show that long subject phrases tended to produce fewer junctures between the verb and the object than do short subject phrases. However, the second effect was not as strong as the first. Long verbs were more often preceded and followed by juncture than short verbs. In this
phrase than by the length of the verb. This result was entirely due to main effects as the interaction was nonsignificant. The tendencies to place junctures in the two major boundaries were not independent. The unconditional probability of placing a juncture in a major boundary was greater than the conditional probability of placing a juncture in that boundary given that a juncture had been placed in the other major boundary. This occurred for every sentence type but LLL. The unconditional probability of placing a juncture in a major boundary was less than the conditional probability of placing a juncture in that
SEGMENTATION OF SENTENCES
boundary given that a juncture had not been placed in the other boundary. This occurred for all sentence types. Categories 10, 01,00, 11 and Other appeared 43, 21, 17, 13, and 7 ~ of the time, respectively. DISCUSSION
The results clearly support the claim that the division of an utterance into phonological phrases is dependent upon the length of the total utterance and the lengths of its syntactically defined constituents. There is evidence for an upper limit on the length of phonological phrases. Furthermore there was a strong tendency to place the junctures between, rather than within, the major syntactic constituents. As a result of these two factors, it appears, there was a greater tendency to place junctures after long syntactic units than after short syntactic units. Also, apparently in anticipation of processing difficulties, there was a greater tendency to place junctures prior to long syntactic units than prior to short syntactic units. The nonindependence of junctures at the two major boundaries indicates that there is a strong tendency to minimize the number of segments a sentence is broken into. Subjects will, in response to sentence length, place a juncture at one place in the sentence. However, having done this, they then avoid, to a large extent, further segmentation of the sentence. These data must be qualified in the following ways. First, replications of the reported results indicate that instructional set is an important determinant of S's responses. If Ss are given very casual instructions, they tend to report fewer junctures than if the instructions emphasize the need for careful introspections and attention to correlated cues in order to perceive the slightest pauses. The results reported in this experiment are dependent upon instructions which stress the importance of careful introspections. Second, the great majority of pauses were at the major syntactic boundaries. Subsequent data indicate that if the long phrases had been
229
still longer they would have been broken up much more frequently. Thus while these data indicate rightly the strong tendency to pause at major boundaries, they should not obscure the fact that Ss will break up syntactic units still further if forced to by the length of those phrases. Third, as collected, the results leave open the question as to whether the crucial factor manipulated by the independent variable was length in terms of number of syllables or length in terms of the time required for processing. The arguments of Bierwisch (1966) mentioned above support the view that the number of syllables affects segmentation partly through its effect on the time required for processing. When rate increases, the number of syllables in a processed segment increases and the number of junctures per syllable decreases. Thus the number of syllables does not necessarily directly affect the number of junctures. Rather, the same number of syllables will differentially affect juncture depending on the time required to produce them. The more time required for production, the greater the tendency to introduce juncture. Time for processing, therefore, is probably a crucial determiner of the tendency to introduce junctures. There is considerable similarity between the data presented by E. Martin (1970) and those presented here. In the present case, Ss were instructed to group the words of sentences using phonological cues. In E. Martin's case Ss were instructed to place the words into "natural groups" and were allowed to group together discontinuous strings of words. In the reported cases where he found the subjects and verbs grouped together and separated from the objects, the subject phrases were short and the object phrases were long. This result corresponds exactly to the groupings Ss imposed on sentences with short subject phrases "and long object phrases in the present study. This fact suggests that similar constraints were operating in the two experiments. Note, however, that the intuition of word groupings is a primary datum for linguistic
230
MARTIN, KOLODZIEJ, AND GENAY
analysis (cf. Fodor & Garrett, 1966). The structural description of the surface structure is allegedly a characterization of such intuitions. Thus Fodor and Garrett assert there exists "both psychological and linguistic support for the assurance that the structural description of sentences is 'psychologically real,' and hence for understanding the task of developing a performance model as involving the construction of a device capable of converting a sentence into its structural description." [p.142] E. Martin's data and the data presented here appear to complicate matters for both linguistics and psycholinguistics. They call into question the reliability or the validity of the primary linguistic intuition and, consequently, cast doubt on Fodor and Garrett's assumptions about the goals of psycholinguistic modeling. There are at least two possible interpretations of these data. The first of these is that the conventional constituent structure analysis is not generally reliable or even valid for the average college sophomore. This is the radical interpretation E. Martin suggests for his data. He proposes this interpretation as an explanation for the great variability in the predictive success of psycholinguistic hypotheses based on the assumption of a conventional constituent analysis. The second interpretation, that of the present authors, is that E. Martin, Fodor and Garrett, and many others, have failed to take seriously the fundamentally abstract nature of syntactic surface structures. As Chomsky and Halle assert, such surface structures are not segmented, nor are they assigned phonological interpretation. It is introspectively obvious, and evident from the data presented here, that the readjusted, phonologically interpreted surface structures are objects of direct linguistic intuition. We propose, however, that it is not clear to what extent syntactic surface structures are objects of direct intuition. Both base structures and phonologically interpreted readjusted surface structures are relatively nonabstract in the sense that they are
intended to represent the objects of direct intuition. Surface structures are under less direct constraint. Linguistically, it is primarily necessary that they, in conjunction with transformation, readjustment, and phonological rules, mediate between base structures and phonologically interpreted readjusted surface structures. We are not arguing, as E. Martin seems to, that the constituent analysis is irrelevant to psychological processes. In fact, our data show that manipulation of materials in terms of the constituent analysis produces systematic effects on the intuitions of native speakers. Nor are we arguing that the surface structure is not at all an object of linguistic intuition. It may be that some intuition of the surface structure is necessary in order for the readjustment rules to be properly applied. The segmentation procedure is guided by the constituent groupings and the monitoring of those groupings may well be conscious. What we are arguing is that our data show that the phonologically interpreted readjusted surface structure is a more direct object of linguistic intuition than is the syntactic surface structure. In this view, the failure to obtain consistent experimental results in studies where the constituent analysis has been assumed is not a fault of the constituent analysis, rather it is a fault of those experimenters who have failed to realize that it is the readjusted surface structure, not the syntactic surface structure, which has primary "psychological reality." In assessing the results of past and future experiments, it will be important to determine the effects of the readjusted surface structure as well as the effects of the syntactic surface structure. Actually, the literature reveals considerable support for the view that it is the phonologically interpreted readjusted surface structure which has been largely responsible for much of the data which have allegedly confirmed the psychological reality of syntactic structures at other levels. There are several persuasive examples of this.
SEGMENTATION OF SENTENCES
First, it has been claimed that the subjective location of noise heard while attending to sentences (the click phenomenon) demonstrates the psychological reality of surface structures (Fodor & Garrett, 1966). Since the click phenomenon is affected by pausing, intonation is typically held constant and syntax is varied in an attempt to determine the effects of syntax independent of intonation. However, there is some evidence that the differences attributed to differences in syntax may have resulted more directly from differences in perceived intonational phrasing. J. G. Martin and W. Strange (1968) have reported results consistent with the view that hesitations at minor syntactic boundaries are not perceived while nonexistent pauses at major syntactic boundaries are perceived. Thus while the wave form was controlled in the click experiments, no attempt was made to control for the perceived intonation pattern. Second, Miller and Isard (1963) have shown that grammatical strings are more easily shadowed than are anomalous or ungrammatical strings. In a similar task, however, J. G. Martin (1968) has been able to reduce the superiority of the grammatical strings, primardy through suppression of the grammatical condition, by placing intervals between the to-be-shadowed words and thus by ehminating the intonation patterns. Third, Marks and Miller (1964) showed that grammatical strings were learned more easily than anomalous or ungrammatical strings. Epstein (1961) has shown a similar phenomenon using nonsense materials. On the other hand, O'Connell, Turner, and Onuska (1968) also using nonsense materials controlled for intonation and found that the facilitative effect of grammatical structure was apparent only when intonation was present. Fourth, Ammon (1968) used a probe and reaction time technique to demonstrate that the grouping of words of a sentence in short-term storage depended on the groupings entailed by the syntactic surface structure. However, these results were confounded by the fact that
231
the materials were presented in "normal intonation." Wilkes and Kennedy (1970) have reported that pauses in nonlinguistic materials have the same effect as do constituent boundaries in the Ammon study, that is, the pauses act as boundaries between groups of stored materials. Furthermore, Wilkes and Kennedy report that when pauses occur at other than constituent boundaries in linguistic materials, then the pause~ define groups even as they do in nonlinguistic materials. While we might cite other literature, these findings are not atypical. In most cases, surface structure has been directly confounded with readjusted structure and no attempt has been made to determine the effects of perceived intonation. Perhaps one of the reasons that the constituent analysis has gone so long unchallenged is that the phonological phrasing tends to correspond to the traditional syntactic analysis. For example, in the present study with systematic variation of stimuli, Category 10 was used 43 ~ of the time while Category 01 was used only 21 ~ of the time. Also, junctures usually fall at clause boundaries when sentences contain several clauses. Note also that our interpretation implies that some decisions about surface structures may have to be deduced from semantic and phonological considerations rather than intuited. This possibility suggests a reexamination of linguistic results analogous to the reexamination of psychological results proposed above. Finally, we wish to sketch some speculations about specific ways in which phonological phrases may be directly involved in the processes of production and perception. Lashley (1951) has shown that the production process must operate on hierarchically and sequentially integrated structures; that is, representations of some to-be-produced segments must be stored as units as a precondition for the production of those segments. We suggest that phonological phrases are often examples of such segments. Consider first the fact that
232
MARTIN, KOLODZIEJ, AND GENAY
strictly phonological constraints extend to, but do not exceed, the boundaries of the phonological phrase. This indicates that phonological planning need not extend beyond the phrase boundaries and also that such planning typically extends at least that far. Second, the identification of the phonological phrase with the basic rhythm group of the language (Stetson, 1951) also indicates that the phrase is usually executed more or less as a unit. Third, the fact that pauses generally fall at major syntactic boundaries entails that, within limits, the phonological phrases tend not to break up major sense groupings. From this we may infer the possibility that the sense grouping, reflected in the surface constituent analysis, is a major determiner of phonological phrasing. It is at least reasonable to suspect that such major sense groupings might be planned as units. Concerning perception, Lashley (1951) emphasized that perceptual decisions depended on sequences of inputs, not on the individual inputs. Therefore the sequences must be stored as units as a precondition for certain perceptual decisions. We propose that perceived phonological phrases are often examples of such segments. Note first that the within phrase phonological dependencies entail that the phonological phrase would be an important perceptual unit of analysis. Within a perceived phrase, interpretations of any of a number of properties of the wave form would depend, via the phonological rules, on interpretations of other aspects of the same wave form. Second, inasmuch as the short-term storage of a temporal sequence is greatly facilitated by the perception of a rhythmical patterning in that sequence (Garner, 1970; Neisser, 1967), the perceived rhythmical structure of the phonological phrase would very hkely be exploited in the short-term storage of the phrase required for processing. Third, since the major goal of sentence perceptio'n is semantic interpretation, it is plausible to suppose that the perceptual processing of a sentence could be facilitated if the units
stored for processing corresponded to the major sense groupings within the sentence. The strong relationship between phonological phrasing and sense grouping entails that perceptual processing in terms of perceived phonological phrases would involve processing in terms of units corresponding to the major sense groups. Thus processing in terms of perceived phonological phrases might be expected to facilitate semantic as well as phonological aspects of the perceptual process. In view of the importance of short-term memory in both production and perception, it is possible that the upper bounds on segment length are partly due to limitations on the short-term memory for their representations. This possibility leads to the conjecture that one condition guiding the planned or perceived upper limit of a segment's length is that its representation be encodable as a whole into short-term storage. In summary, the segmentation of utterances into phonological phrases is viewed as an aspect of linguistic performance, rather than competence. Evidence has been reported which supports the frequent claims that the segmentation in question is partially a function of length of utterance and the position of syntactic boundaries. It was argued that the discrepancy between the subjective phrases and the traditional surface structure constituents implied that the surface structure is rather more abstract than has usually been assumed. REFERENCES AMMON,P. R. The perception of grammatical relations in sentences: A methodological exploration. Journal Verbal Learning and Verbal Behavior, 1968, 1, 869-875. BIERWISCH, M. Regeln ftir die Intonation Deutscher Satze. Studia Grammatica, 1966, 7, 99-201. CIaOMSKY,N., & HALLE,M. The sound pattern of English. New York: Harper & Row, 1968. EPSTEIN, W. The influence of syntactical structure on learning. American Journal of Psychology, 1961, 74, 80-85.
SEGMENTATION OF SENTENCES FODOR, J., & GARRETT,M. Some reflections on competence and performance. In J. Lyons & R. J. Wales (Ed.), Psycholinguistics papers. Chicago: Aldine, 1966. Pp. 135-154. FONA~Y, I., & MAGDICS, K. Speed of utterance in phrases of different lengths. Language and Speech, 1960, 3, 179-192. FRANCIS, W. N. The English language. New York: Norton, 1965. GARNER, W. R. Good patterns have few alternatives. American Scientist, 1970, 58, 34-42. LASHLEY,K. S. The problem of serial order in behavior. In L. A. Jeffress (Ed.), Cerebral mechanisms in behavior. New York: Wiley, 1951. Pp. 112-136. LIPSKY, A. Rhythm as a distinguishing characteristic of prose style. Archives of Psychology, 1970, 25 (Whole No. 4). MARKS,L. E., & MILLER, G. A. The role of semantic and syntactic constraints in the memorization of English sentences. Journal Verbal Learning and Verbal Behavior, 1964, 3, 1-5. MARTIN, E. Toward an analysis of subjective phrase structure. Psychological Bulletin, 1970, 74, 153166.
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MARTIN, J. G. Temporal word spacing and the perception of ordinary, anomalous, and scrambled strings. Journal Verbal Learning and Verbal Behavior, 1968, 1, 154-157. MARTIN,J. G., & STRANGE,W. The perception of hesitations m spontaneous speech. Perception and Psychophysics, 1968, 3, 427-438. MILLER, G. A., & IsAm~, S. Some perceptual consequences of linguistic rules. Journal VerbalLearning and VerbalBehavior, 1963, 2, 217-228. NEISSER, U. Cognitive psychology. New York: Appleton-Century-Crofts, 1967. O'CONNELL,D.C., TURNER,E. A., & ONUSKA, L. A. Intonation, grammatical structure, and contextual association in immediate recall. Journal Verbal Learning and Verbal Behavior, 1968, 7, 110-116. STETSON,R. H. Motor phonetics. Amsterdam: NorthHolland, 1951. WILKES, A. L., ~ KENNEDY,R. A. The relative accessability of list items within different pausedefined groups. Journal of Verbal Learning and Verbal Behavior, 1970, 9, 197-201. (Received August 14, 1970)
10, 226-233 (1971)
Segmentation of Sentences into Phonological Phrases as a Function of Constituent Length J. E. MARTIN, BARBARAKOLODZIEJ, AND JOSEPH GENAY The Pennsylvania State University, UniversityPark, Pennsylvania 16802
Evidence is reported which supports the frequent claims that the segmentation of sentences into phonologicalphrases is partially a function of length of utterance and the position of syntactic boundaries. It is shown that segmentation is more likely to occur at constituent boundaries rather than between them. There is a greater tendency to place segment boundaries before or after long phrases than to place them before or after short phrases. There is a tendency to minimlze the number of segments.
The first purpose of this paper is to present data concerning the parameters affecting the segmentation of utterances into phonological phrases. In this context, it will be argued that the role of syntactic surface structures in psychological processing has been widely misunderstood. It is argued that it is the phonologically interpreted readjusted surface structures, not the syntactic surface structures, which have primary psychological reahty. Chomsky and Halle (1968) argue that the phonological rules are not generally applied directly to the syntactic surface structure. They claim that the phonological rules are best viewed as applying directly to the "readjusted" surface structure formed by dividing the original syntactic surface structure into a succession of phonological phrases. They call the principles which determine the place and number of segmentations the readjustment rules. The phonological phrases so determined are the smallest phonologically independent and complete elements, and the "maximal domain(s) of the phonological process"; that is, dependencies which can be stated strictly in terms of phonology do not extend beyond the boundaries of the phonological phrases. The typical phonological phrase consists of one or more phonological words and is characterazed by having a pitch contour, and a
rhythmical structure, and by being bounded by terminal junctures (Francis, 1965; Stetson, 1951). An example of phonological phrasing would be as follows. Consider the sentence Parents were assisting the advanced teenage pupils. The sentence may be spoken with a pause after assisting and before the. In this case the sentence would be spoken as two phonological phrases, Parents were assisting and the advanced teenage pupils. The boundaries of the phonological phrases are said to depend to a degree on surface syntax, but not to be entirely determined by it (Chomsky & Halle, 1968). Rather, the factors (readjustment rules) which influence the segmentation process are viewed as pertaining to a theory of performance rather than a theory of competence. There have been other studies related to readjustment. Lipsky (1907), introspecting on the segmentation of prose into subjective phrases, noticed a tendency to place more junctures after longer syntactically defined subject phrases than after shorter ones. Bierwisch (1966) has made some suggestions concerning the determinants of segmentation. Among them is the proposal that as the rate of utterance increases, the rate of segmentation per word boundary decreases. Also, Fonagy and Magdics (1960) have reported that the 226
227
SEGMENTATIONOF SENTENCES length o f phrases, defined by the n u m b e r o f words, correlates positively with the rate o f utterance. M o r e recently, E. M a r t i n (1970) has shown that although the perceived " n a t u r a l " groupings o f words in sentences correlate with traditional constituent analysis, the correlation is n o t perfect. F o r example, he demonstrated cases where the natural grouping o f words in a sentence was such that the verb was g r o u p e d with the subject rather than the object. This, o f course, is different f r o m the grouping implied by the constituent analysis in which the verb would be grouped with the object rather t h a n the subject. E. Martin was primarily interested in the failure o f Ss to g r o u p words as predicted f r o m the constituent analysis. He did n o t show h o w the " n a t u r a l " groupings could be systematically controlled. Lipsky's observation, while somewhat casual, is o f fundamental importance for the study o f readjustment rules. In w h a t follows data will be presented which assess his claim in a m o r e careful manner. It will be seen that the p h e n o m e n o n Lipsky noticed is a reliable one and that controlled observation reveals that it is only one o f a n u m b e r o f closely related facts.
short. The short subject and object phrases were composed of single nouns with determiners. The long subject and object phrases were composed of determiners, nouns, and one or two modifiers. The short verb constituents were composed of a single verb in the present tense. The long verb constituents were composed of the same verbs plus the auxiliary had (or has) been-ing. Thus eight categories of five sentences each were constructed with the following lengths: SSS (short subject, short verb, short object), SSL (short subject, short verb, long object), SLS, SLL, LSS, LSL, LLS, LLL. The 40 sentences were then combined with 25 filler sentences and placed in random order on presentation sheets. Procedure. The Ss were instructed to read each sentence several times, until they achieved an "ideal reading," that is, Ss were instructed to read the sentences over, saying them to themselves, until they felt they had read them without error and with the proper intonation pattern. When they had achieved the ideal reading for a given sentence, Ss indicated where they felt a break in the intonation contour of the sentence. They were told that this break might be correlated with a drop in the pitch of the intonation contour and that such drops would be important cues to the breaks or pauses. The Ss indicated the position of a perceived break by drawing a perpendicular line between the two words between which they had felt the break. The Ss were told to mark as many or as few breaks as they felt necessary. In cases where they perceived no break, Ss were to draw the slash at the end of the sentence. One hundred and six undergraduate volunteers served as Ss. RESULTS
METHOD The general method used was to ask Ss to indicate their introspections as to the optimal mode of phrasing for each of a series of sentences. It was assumed that introspections concerning phonological phrases would be valid since they are necessarily a part of the primary linguistic data required for the construction of the phonological grammar. If phonological rules only apply to phonological phrases, then the primary data which the phonological grammar must explain are the contents of individual phonological phrases. It is clear that the intuition of such primary data requires the prior intuitions of the boundaries of such phrases. Therefore, the intuition of phonological phrase boundaries is at least as valid as many other phonological intuitions. Materials. Forty sentences of the subject-verb-object type were constructed. The sentences were constructed so as to vary in terms of the length of the subject, verb, or object. Each constituent could either be long or
Each response f r o m a given S for a given sentence was placed into one o f five categories. Category 11 designates those cases in which a S reported breaks between the subject phrase and the verb, and between the verb and the object phrase, and nowhere else. Category 10 designates those cases in which a S reported a break between the subject phrase and the verb, and nowhere else. Category 01 designates those cases in which a S reported a break between the verb and the object phrase, and nowhere else. Category O0 designates those cases in which a S reported no breaks at all for a sentence. Category Other designates all other cases. Analyses o f variance were c o m p u t e d for each o f the response categories with the inde-
228
MARTIN, KOLODZIEJ, AND GENAY
pendent variables being the lengths of the subject, verb, and object constituents. The analyses for the response categories 11, 10, 01, and 00 were 2 x 2 x 2 designs with repeated measures of each of the 106 Ss. The scores used in the analyses were the number of responses, out of a possible five, of a given response type, that each S made, for each of the eight experimental conditions. Analyses were also done for 01 + 00, 10 + 00, 10 + 11, and 01 + 11.
case the effect was stronger in verb-object boundary than in subject-verb boundary. Long object phrases produced more junctures in the verb-object boundary than did short object phrases. Long object phrases also produced fewer junctures in the subject-verb boundaries than did short object phrases. The second effect was not as strong as the first. The subject-verb boundary was more strongly affected by the length of the subject
TABLE
1
THE MEAN NUMBER OF RESPONSES PER SUBJECT AS A FUNCTION OF CONSTITUENT LENGTH AND o92 SCORES FOR MAIN EFFECTS
Response category Treatment level
00
11
10
01
01 + 00
10 + 00
10 + 11
01 + 11
Subject Short Long to2
1.35 0.38 .10"
0.48 0.79 .02*
1.21 3.06 .26*
1.68 0.38 .21"
3.02 0.77 .39*
2.56 3.45 .06*
1.70 3.85 .34*
2.16 1.17 .09*
Verb Short Long o92
1.23 0.50 .06*
0.20 1.06 .14"
2.33 1.95 .01"
0.93 1.13 .00
2.16 1.63 .02*
3.56 2.45 .09*
2.54 3.01 .02*
1.14 2.19 .10"
Object Short Long co2
1.26 0.47 .07*
0.45 0.82 .03"
2.54 1.73 .05"
0.57 1.50 .11"
1.83 1.97 .00
3.80 2.20 .19"
2.99 2.55 .01"
1.01 2.32 .15'
*p < .001. The main effects are given in Table 1. The o~2 values, included to give a clearer picture of the results, indicate the proportion of the total variance due to differences among treatment conditions. The results show that long subject phrases produced more junctures between the subject and the verb than short subject phrases. They also show that long subject phrases tended to produce fewer junctures between the verb and the object than do short subject phrases. However, the second effect was not as strong as the first. Long verbs were more often preceded and followed by juncture than short verbs. In this
phrase than by the length of the verb. This result was entirely due to main effects as the interaction was nonsignificant. The tendencies to place junctures in the two major boundaries were not independent. The unconditional probability of placing a juncture in a major boundary was greater than the conditional probability of placing a juncture in that boundary given that a juncture had been placed in the other major boundary. This occurred for every sentence type but LLL. The unconditional probability of placing a juncture in a major boundary was less than the conditional probability of placing a juncture in that
SEGMENTATION OF SENTENCES
boundary given that a juncture had not been placed in the other boundary. This occurred for all sentence types. Categories 10, 01,00, 11 and Other appeared 43, 21, 17, 13, and 7 ~ of the time, respectively. DISCUSSION
The results clearly support the claim that the division of an utterance into phonological phrases is dependent upon the length of the total utterance and the lengths of its syntactically defined constituents. There is evidence for an upper limit on the length of phonological phrases. Furthermore there was a strong tendency to place the junctures between, rather than within, the major syntactic constituents. As a result of these two factors, it appears, there was a greater tendency to place junctures after long syntactic units than after short syntactic units. Also, apparently in anticipation of processing difficulties, there was a greater tendency to place junctures prior to long syntactic units than prior to short syntactic units. The nonindependence of junctures at the two major boundaries indicates that there is a strong tendency to minimize the number of segments a sentence is broken into. Subjects will, in response to sentence length, place a juncture at one place in the sentence. However, having done this, they then avoid, to a large extent, further segmentation of the sentence. These data must be qualified in the following ways. First, replications of the reported results indicate that instructional set is an important determinant of S's responses. If Ss are given very casual instructions, they tend to report fewer junctures than if the instructions emphasize the need for careful introspections and attention to correlated cues in order to perceive the slightest pauses. The results reported in this experiment are dependent upon instructions which stress the importance of careful introspections. Second, the great majority of pauses were at the major syntactic boundaries. Subsequent data indicate that if the long phrases had been
229
still longer they would have been broken up much more frequently. Thus while these data indicate rightly the strong tendency to pause at major boundaries, they should not obscure the fact that Ss will break up syntactic units still further if forced to by the length of those phrases. Third, as collected, the results leave open the question as to whether the crucial factor manipulated by the independent variable was length in terms of number of syllables or length in terms of the time required for processing. The arguments of Bierwisch (1966) mentioned above support the view that the number of syllables affects segmentation partly through its effect on the time required for processing. When rate increases, the number of syllables in a processed segment increases and the number of junctures per syllable decreases. Thus the number of syllables does not necessarily directly affect the number of junctures. Rather, the same number of syllables will differentially affect juncture depending on the time required to produce them. The more time required for production, the greater the tendency to introduce juncture. Time for processing, therefore, is probably a crucial determiner of the tendency to introduce junctures. There is considerable similarity between the data presented by E. Martin (1970) and those presented here. In the present case, Ss were instructed to group the words of sentences using phonological cues. In E. Martin's case Ss were instructed to place the words into "natural groups" and were allowed to group together discontinuous strings of words. In the reported cases where he found the subjects and verbs grouped together and separated from the objects, the subject phrases were short and the object phrases were long. This result corresponds exactly to the groupings Ss imposed on sentences with short subject phrases "and long object phrases in the present study. This fact suggests that similar constraints were operating in the two experiments. Note, however, that the intuition of word groupings is a primary datum for linguistic
230
MARTIN, KOLODZIEJ, AND GENAY
analysis (cf. Fodor & Garrett, 1966). The structural description of the surface structure is allegedly a characterization of such intuitions. Thus Fodor and Garrett assert there exists "both psychological and linguistic support for the assurance that the structural description of sentences is 'psychologically real,' and hence for understanding the task of developing a performance model as involving the construction of a device capable of converting a sentence into its structural description." [p.142] E. Martin's data and the data presented here appear to complicate matters for both linguistics and psycholinguistics. They call into question the reliability or the validity of the primary linguistic intuition and, consequently, cast doubt on Fodor and Garrett's assumptions about the goals of psycholinguistic modeling. There are at least two possible interpretations of these data. The first of these is that the conventional constituent structure analysis is not generally reliable or even valid for the average college sophomore. This is the radical interpretation E. Martin suggests for his data. He proposes this interpretation as an explanation for the great variability in the predictive success of psycholinguistic hypotheses based on the assumption of a conventional constituent analysis. The second interpretation, that of the present authors, is that E. Martin, Fodor and Garrett, and many others, have failed to take seriously the fundamentally abstract nature of syntactic surface structures. As Chomsky and Halle assert, such surface structures are not segmented, nor are they assigned phonological interpretation. It is introspectively obvious, and evident from the data presented here, that the readjusted, phonologically interpreted surface structures are objects of direct linguistic intuition. We propose, however, that it is not clear to what extent syntactic surface structures are objects of direct intuition. Both base structures and phonologically interpreted readjusted surface structures are relatively nonabstract in the sense that they are
intended to represent the objects of direct intuition. Surface structures are under less direct constraint. Linguistically, it is primarily necessary that they, in conjunction with transformation, readjustment, and phonological rules, mediate between base structures and phonologically interpreted readjusted surface structures. We are not arguing, as E. Martin seems to, that the constituent analysis is irrelevant to psychological processes. In fact, our data show that manipulation of materials in terms of the constituent analysis produces systematic effects on the intuitions of native speakers. Nor are we arguing that the surface structure is not at all an object of linguistic intuition. It may be that some intuition of the surface structure is necessary in order for the readjustment rules to be properly applied. The segmentation procedure is guided by the constituent groupings and the monitoring of those groupings may well be conscious. What we are arguing is that our data show that the phonologically interpreted readjusted surface structure is a more direct object of linguistic intuition than is the syntactic surface structure. In this view, the failure to obtain consistent experimental results in studies where the constituent analysis has been assumed is not a fault of the constituent analysis, rather it is a fault of those experimenters who have failed to realize that it is the readjusted surface structure, not the syntactic surface structure, which has primary "psychological reality." In assessing the results of past and future experiments, it will be important to determine the effects of the readjusted surface structure as well as the effects of the syntactic surface structure. Actually, the literature reveals considerable support for the view that it is the phonologically interpreted readjusted surface structure which has been largely responsible for much of the data which have allegedly confirmed the psychological reality of syntactic structures at other levels. There are several persuasive examples of this.
SEGMENTATION OF SENTENCES
First, it has been claimed that the subjective location of noise heard while attending to sentences (the click phenomenon) demonstrates the psychological reality of surface structures (Fodor & Garrett, 1966). Since the click phenomenon is affected by pausing, intonation is typically held constant and syntax is varied in an attempt to determine the effects of syntax independent of intonation. However, there is some evidence that the differences attributed to differences in syntax may have resulted more directly from differences in perceived intonational phrasing. J. G. Martin and W. Strange (1968) have reported results consistent with the view that hesitations at minor syntactic boundaries are not perceived while nonexistent pauses at major syntactic boundaries are perceived. Thus while the wave form was controlled in the click experiments, no attempt was made to control for the perceived intonation pattern. Second, Miller and Isard (1963) have shown that grammatical strings are more easily shadowed than are anomalous or ungrammatical strings. In a similar task, however, J. G. Martin (1968) has been able to reduce the superiority of the grammatical strings, primardy through suppression of the grammatical condition, by placing intervals between the to-be-shadowed words and thus by ehminating the intonation patterns. Third, Marks and Miller (1964) showed that grammatical strings were learned more easily than anomalous or ungrammatical strings. Epstein (1961) has shown a similar phenomenon using nonsense materials. On the other hand, O'Connell, Turner, and Onuska (1968) also using nonsense materials controlled for intonation and found that the facilitative effect of grammatical structure was apparent only when intonation was present. Fourth, Ammon (1968) used a probe and reaction time technique to demonstrate that the grouping of words of a sentence in short-term storage depended on the groupings entailed by the syntactic surface structure. However, these results were confounded by the fact that
231
the materials were presented in "normal intonation." Wilkes and Kennedy (1970) have reported that pauses in nonlinguistic materials have the same effect as do constituent boundaries in the Ammon study, that is, the pauses act as boundaries between groups of stored materials. Furthermore, Wilkes and Kennedy report that when pauses occur at other than constituent boundaries in linguistic materials, then the pause~ define groups even as they do in nonlinguistic materials. While we might cite other literature, these findings are not atypical. In most cases, surface structure has been directly confounded with readjusted structure and no attempt has been made to determine the effects of perceived intonation. Perhaps one of the reasons that the constituent analysis has gone so long unchallenged is that the phonological phrasing tends to correspond to the traditional syntactic analysis. For example, in the present study with systematic variation of stimuli, Category 10 was used 43 ~ of the time while Category 01 was used only 21 ~ of the time. Also, junctures usually fall at clause boundaries when sentences contain several clauses. Note also that our interpretation implies that some decisions about surface structures may have to be deduced from semantic and phonological considerations rather than intuited. This possibility suggests a reexamination of linguistic results analogous to the reexamination of psychological results proposed above. Finally, we wish to sketch some speculations about specific ways in which phonological phrases may be directly involved in the processes of production and perception. Lashley (1951) has shown that the production process must operate on hierarchically and sequentially integrated structures; that is, representations of some to-be-produced segments must be stored as units as a precondition for the production of those segments. We suggest that phonological phrases are often examples of such segments. Consider first the fact that
232
MARTIN, KOLODZIEJ, AND GENAY
strictly phonological constraints extend to, but do not exceed, the boundaries of the phonological phrase. This indicates that phonological planning need not extend beyond the phrase boundaries and also that such planning typically extends at least that far. Second, the identification of the phonological phrase with the basic rhythm group of the language (Stetson, 1951) also indicates that the phrase is usually executed more or less as a unit. Third, the fact that pauses generally fall at major syntactic boundaries entails that, within limits, the phonological phrases tend not to break up major sense groupings. From this we may infer the possibility that the sense grouping, reflected in the surface constituent analysis, is a major determiner of phonological phrasing. It is at least reasonable to suspect that such major sense groupings might be planned as units. Concerning perception, Lashley (1951) emphasized that perceptual decisions depended on sequences of inputs, not on the individual inputs. Therefore the sequences must be stored as units as a precondition for certain perceptual decisions. We propose that perceived phonological phrases are often examples of such segments. Note first that the within phrase phonological dependencies entail that the phonological phrase would be an important perceptual unit of analysis. Within a perceived phrase, interpretations of any of a number of properties of the wave form would depend, via the phonological rules, on interpretations of other aspects of the same wave form. Second, inasmuch as the short-term storage of a temporal sequence is greatly facilitated by the perception of a rhythmical patterning in that sequence (Garner, 1970; Neisser, 1967), the perceived rhythmical structure of the phonological phrase would very hkely be exploited in the short-term storage of the phrase required for processing. Third, since the major goal of sentence perceptio'n is semantic interpretation, it is plausible to suppose that the perceptual processing of a sentence could be facilitated if the units
stored for processing corresponded to the major sense groupings within the sentence. The strong relationship between phonological phrasing and sense grouping entails that perceptual processing in terms of perceived phonological phrases would involve processing in terms of units corresponding to the major sense groups. Thus processing in terms of perceived phonological phrases might be expected to facilitate semantic as well as phonological aspects of the perceptual process. In view of the importance of short-term memory in both production and perception, it is possible that the upper bounds on segment length are partly due to limitations on the short-term memory for their representations. This possibility leads to the conjecture that one condition guiding the planned or perceived upper limit of a segment's length is that its representation be encodable as a whole into short-term storage. In summary, the segmentation of utterances into phonological phrases is viewed as an aspect of linguistic performance, rather than competence. Evidence has been reported which supports the frequent claims that the segmentation in question is partially a function of length of utterance and the position of syntactic boundaries. It was argued that the discrepancy between the subjective phrases and the traditional surface structure constituents implied that the surface structure is rather more abstract than has usually been assumed. REFERENCES AMMON,P. R. The perception of grammatical relations in sentences: A methodological exploration. Journal Verbal Learning and Verbal Behavior, 1968, 1, 869-875. BIERWISCH, M. Regeln ftir die Intonation Deutscher Satze. Studia Grammatica, 1966, 7, 99-201. CIaOMSKY,N., & HALLE,M. The sound pattern of English. New York: Harper & Row, 1968. EPSTEIN, W. The influence of syntactical structure on learning. American Journal of Psychology, 1961, 74, 80-85.
SEGMENTATION OF SENTENCES FODOR, J., & GARRETT,M. Some reflections on competence and performance. In J. Lyons & R. J. Wales (Ed.), Psycholinguistics papers. Chicago: Aldine, 1966. Pp. 135-154. FONA~Y, I., & MAGDICS, K. Speed of utterance in phrases of different lengths. Language and Speech, 1960, 3, 179-192. FRANCIS, W. N. The English language. New York: Norton, 1965. GARNER, W. R. Good patterns have few alternatives. American Scientist, 1970, 58, 34-42. LASHLEY,K. S. The problem of serial order in behavior. In L. A. Jeffress (Ed.), Cerebral mechanisms in behavior. New York: Wiley, 1951. Pp. 112-136. LIPSKY, A. Rhythm as a distinguishing characteristic of prose style. Archives of Psychology, 1970, 25 (Whole No. 4). MARKS,L. E., & MILLER, G. A. The role of semantic and syntactic constraints in the memorization of English sentences. Journal Verbal Learning and Verbal Behavior, 1964, 3, 1-5. MARTIN, E. Toward an analysis of subjective phrase structure. Psychological Bulletin, 1970, 74, 153166.
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MARTIN, J. G. Temporal word spacing and the perception of ordinary, anomalous, and scrambled strings. Journal Verbal Learning and Verbal Behavior, 1968, 1, 154-157. MARTIN,J. G., & STRANGE,W. The perception of hesitations m spontaneous speech. Perception and Psychophysics, 1968, 3, 427-438. MILLER, G. A., & IsAm~, S. Some perceptual consequences of linguistic rules. Journal VerbalLearning and VerbalBehavior, 1963, 2, 217-228. NEISSER, U. Cognitive psychology. New York: Appleton-Century-Crofts, 1967. O'CONNELL,D.C., TURNER,E. A., & ONUSKA, L. A. Intonation, grammatical structure, and contextual association in immediate recall. Journal Verbal Learning and Verbal Behavior, 1968, 7, 110-116. STETSON,R. H. Motor phonetics. Amsterdam: NorthHolland, 1951. WILKES, A. L., ~ KENNEDY,R. A. The relative accessability of list items within different pausedefined groups. Journal of Verbal Learning and Verbal Behavior, 1970, 9, 197-201. (Received August 14, 1970)