- Email: [email protected]
Effects of word-onset cuing on picture naming in aphasia: A reconsideration
BRAIN
AND
LANGUAGE
39, 373-390 (1990)
Effects of Word-Onset
Cuing on Picture Naming in Aphasia: A Reconsideration ARTHUR WINGFIELD
Department of Psychology and Center for Complex Systems, Brandeis University, Aphasia Research Center, Department of Neurology, Boston University School of Medicine
and
AND HAROLD GOODGLASS AND KATHERINE Boston VA Medical
L. SMITH
Center and Aphasia Research Center, Department Boston University School of Medicine
of Neurology,
When an aphasic is unable to name an object, giving the patient the opening sounds of the target name will often trigger the correct response. Eighteen aphasic subjects were tested using a gating paradigm to compare word onset durations necessary to elicit correct names after an initial naming failure with those necessary for recognizing the same words when spoken in isolation with no picture present. Prerecognition errors were also examined. Results suggested that the facilitation of naming found when examiners supply word-onset sound cues may be due in part to a two-stage process consisting of stem-completion followed by matching the picture with the potential name as generated. Q 1990 Academic Press, Inc.
When an aphasic patient is unable to name an object on command, giving the patient the opening sounds of the target name will often trigger the correct response. Indeed, initial sound cues (as opposed to, for example, a rhyming word, or information about the object’s function) This work was supported in part by the Medical Research Service of the Veterans Administration and in part by PHS Grants AG 04517 and NS 06209 from the National Institutes of Health. We thank Joan Gay Snodgrass for making available originals of her stimulus pictures, Sarah Wayland and John Aberdeen for help in construction of the auditory stimuli, and Mark Silberstein for assistance with data tabulation. Address reprint requests to Arthur Wingfield, Department of Psychology, Brandeis University, Waltham, MA 02254. 373 0093-934x/90
$3.00
Copyright Q 1990 by Academic Press. Inc. All rights of reproduction in any form reserved.
374
WINGFIELD,
GOODGLASS,
AND
SMITH
are ordinarily the most effective retrieval cues for almost all aphasics (Goodglass, 1980a; Pease & Goodglass, 1978). Such findings are commonly characterized as reflecting an internal representation of the acoustic pattern (an inner “speech image”) of the intended word which can be activated, or “triggered,” by hearing its initial sound (cf. Goodglass, 1980a; Luria, 1970; Wayland, Wingfield, & Goodglass, 1989; Wingfield & Wayland, 1988). The use of word-initial phonology as a cue to an intended word is similar in many respects to the technique of gating, ordinarily associated with the study of spoken word perception (Grosjean, 1980; Cotton & Grosjean, 1984). In this technique, subjects hear increasing amounts of word-onset information until the word can be correctly identified. So, for example, the subject might hear the first 50 msec of a word, then the first 100 msec of that word, then the first 150 msec, and so on, until the word is correctly identified. Although longer gate-sizes will be required if speech quality or signal clarity is poor (cf. Grosjean, 1985; Nooteboom & Doodeman, 1984), such studies have shown that words heard within a sentence context can be recognized, on average, within as little as 200 msec of their onset, or when less than half of their full acoustic signal has been heard. Spoken words heard in isolation (i.e., without a sentence context) require, on average, only 130 msec more (Grosjean, 1980; Marslen-Wilson, 1984). Most writers using the paradigm have presumed that a word can be correctly identified before its complete acoustic signal has been heard because of the very rapid decrease in the number of possible word candidates which share the same initial sounds as the target word as progressively more of the word-onset information is heard (Grosjean, 1980; Marslen-Wilson, 1984, 1987; Tyler, 1984; Wayland et al., 1989). The role of temporal alignment of word onsets between a stimulus fragment and potential word candidates has been developed by Nooteboom and van der Vlugt (1988). In terms of neural mechanism, we have proposed that word-initial sounds may activate an internal representation of this sound pattern which, in turn, yields an unfolding representation of all words beginning with this word-onset information. Phonological sequences sharing the same initial phonology would presumably be activated in parallel, with additional acoustic information progressively increasing the activation of the target word, and simultaneously inhibiting nontargets (Wayland et al., 1989). From these considerations, we were led to wonder to what extent the facilitating effects of word initial phonology for name retrieval by aphasics may in fact be mediated, at least in part, by the recognition of the lexical entry to which the initial sound segment belongs. That is, we might speculate that the known benefits of word initial sounds to the aphasic (e.g., Goodglass, 1980a; Pease & Goodglass, 1978) may derive
NAMING IN APHASIA
375
primarily from the subjects’ ability to recognize a lexical item from hearing its stem and to provide the completion. If this is the case we would expect that patients’ responses to gated word onsets, without any pictorial cue, would account for most of their success in stem-completion. The alternative hypothesis is that aphasics’ ability to complete word stems depends on their having a response in readiness, as a result of prior effort to name a picture of the target object. For this alternative to be supported, we would expect to observe little success in stem completion unless a picture of the target had been presented. In the following experiment, asphasic subjects were tested for picture naming with a set of ordinarily easy to name outline drawings of objects (Snodgrass & Vanderwart, 1980). When a naming failure did occur, the subject heard the beginning of the correct name, followed by progressively larger amounts of the word-onset duration until the subject was able to give the correct response. Our interest was to compare the wordonset duration necessary to elicit the correct names under these circumstances with recognition times for these same words when presented in a gated format alone, without any picture present. METHOD
Subjects Eighteen aphasic patients, drawn from a variety of diagnostic categories and with varying degrees of naming ability, served as subjects. Prior clinical examination had established that all had normal ability to recognize pictures. Descriptive information for the patient group is given in Table 1. The patients’ diagnostic classifications and ratings of severity of the aphasia were determined by clinical examination and pattern of performance on the Boston Diagnostic Aphasia Examination (Goodglass & Kaplan, 1972). Localization data were obtained by neurological examination and CT scan. A comparison group of I4 normal subjects was also tested. This group was composed of 13 males and 1 female drawn from a subject pool of paid volunteers from the local community. The members of this group had no known history of neurological or psychiatric disorder. Their ages ranged from 55 to 72 years (M = 64.2 years) and they had between 10 to I7 years of formal education (M = 13.0 years). The aphasic and control groupswere equivalent in mean age, r(30) = 1.62, n.s., and in years of formal education, r(29)
Stimuli Object pictures and names. The stimuli consisted of 24 pictures taken from Snodgrass and Vanderwart (1980). These were pen and ink outline drawings rendered without background context, much in the manner of dictionary illustrations. The objects were chosen to be clearly recognizable in their pictorial form and to have high subject name agreement. Of the 24 objects, 8 had one-syllable names, 8 had two-syllable names, and 8 had threesyllable names. All of the 24 stimulus words had been used in a preliminary study of recognition times for gated words. Detail on numbers of potential sound-initial word candidates per word-onset gate size, and recognition versus cohort-size relationships, can be found in the report of that study (Wayland et al., 1989). Within each word-length, the names covered a wide range of word frequency using a standard print frequency count (Francis & K&era, 1982), although none were especially
59
71
Moderate
Moderate/Severe
Broca
Broca
Broca
Global/ Nonthrent
6
7
a
Severe
Moderate/Severe
56
56
14 years
16 years
M
M
16 years
12 years
M
M
9 years
5
M
Broca
4
61
12 years
M
69
Moderate/Severe
Broca
3
Moderate/Severe
-
2
M
16 years
43
Broca
I
Severe
Education
Sex
Broca
Age M
Severity
TABLE
1
13 years
6 years
Right
Left
CVA
CVA
CVA
10 years
II years
0.2 year
Right
Right
Right
CVA
CVA
CVA
Aneurism
CVA
Etiology
16 years
Right
7 years
2 years
Right
Right
Time postonset
PATIENTS SERVING AS SUBJECTS
Handedness
FOR 18 APHASIC
64
Diagnostic group
INFORMATION
Moderate/Severe
Patient No.
PATIENT
CT scan uninformative
Large L frontal, temporal, and parieta1 lesion including Broca’s area, half of Wemicke’s area. Anterior extension to middle frontal gyrus. Deep going superior extension invalving motor and sensory cortex and supramarginal gyrus L Broca’s area with deep extension including insular structures. Superior lesion extension to middle frontal gyrus: posteriorly to motor and sensory cortex and anterior temporal lobe L Broca’s area deep to the ventricle, with superior extension to the motor and sensory cortex L Broca’s area, with superior lesion extension to parietal lobe L Broca’s area, with a second lesion in the L parietal Deep going L Broca’s area lesion with some posterior subcortical extension, and deep going superior extension across motor and sensory cortex Primarily deep going lesion in L Broca’s area, with partial patchy involvement of Wemicke’s area
Lesion location
X
g
5
“5
F
8
< ? Q 2 F P
Transcortical motor
Transcortical motor
Mixed nonfluent
Wemicke
Wemicke
Anomic/ Fluent Anemic/ Fluent
Anemic/ fluent
Transcortical sensory
IO
II
12
I3
I4
I5
17
I8
I6
Global/ Nonfluent
9
Moderate/ Severe
Moderate
Moderate
Moderate
Very severe
Severe
Moderate/ Severe
Moderate
Severe
Severe
67
58
59
54
60
47
68
59
71
64
M
M
M
M
M
M
F
M
M
M
8 years
16 years
12 years
16 years
I2 years
I2 years
II years
II years
II years
13 years
Right
Right
Right
Right
Right
Right
Right
Right
Right
Right
0.1 year
6 years
3 years
0.1 year
3 years
0.2 year
5 years
7 years
0.1 year
7 years
(2)
Intracerebral hemorrhage CVA
CVA
CVA
CVA
CVA
CVA
CVA
CVA
CVA
Scattered bilateral lesions: Left, inferior and middle temporal gyri, and part of supramarginal gyrus; Right, putamen, and anterior periventricular white matter
Small lesion involving L Wemicke’s area Deep going L Wemicke’s area, with superior extension into angular gyms Lesion to middle and inferior left temporal gyrus Small deep patchy L anterior lesion, and angular gyrus lesion, with large patchy extension to high frontal-parietal region Very deep subcortical L frontal lesion, with extension to L subcortical prefrontal zone
L deep going Broca’s area, with large surface and deep superior extension Small subcortical lesion of L lateral putamen and external capsule, with small subcortical R anterior lesion Large lesion involving most of L Broca’s area and Wemicke’s area, with superior extension to parietal lobe Large lesion to most of L Broca’s area, and subcortical structures underlying Broca’s area, with superior extension to anterior parieta1 lobe
378
WINGFIELD,
GOODGLASS,
AND
SMITH
rare. The names of the objects varied in their frequency of occurrence in print from 2 per million words in print (e.g., pumpkin) to 451 per million (e.g., church). Each of the 24 stimulus pictures (plus an additional 10 pictures for practice) were individually mounted on 5 x 8 in. cards for presentation. Recording of object names. The names of each object were recorded once by a male speaker of American English, preceded by the carrier phrase, “The object is--“. Each word was spoken in citation form with natural intonation, clear enunciation, and all were matched for sound level intensity. Once the full list was recorded, each of the words was rerecorded in a series of progressively increasing word-onset durations in the following way. Recordings of the carrier phrase and the object names were digitized at a sampling rate of 22 kHz and edited using the SoundCap speech editing system on a Macintosh Plus microcomputer to produce a sequence of presentations in which the gate size of the target word from word onset began at 150 msec and then was increased by 3%msec increments until the “gate” included the full acoustic duration of the word. This was accomplished by selecting the desired gate sizes on a computer-generated visual display of the speech wave form of the carrier phrase and target word. Accuracy of selection of the target wordonset point for start of gate duration was determined visually on the wave form and then verified by auditory monitoring. As the preparation of each presentation in the gating sequence was completed it was transferred to standard cassette tape to be used as a master for preparation of individual subject stimulus tapes. The 24 object names and their spoken utterance durations as measured on their visual waveforms (in mseconds) are given in the Appendix. Also listed are the 10 practice stimuli. Phoneme discrimination test. All subjects also received a phoneme discrimination test in which subjects heard word pairs which were either the same (e.g., card-card; gategait), or which differed in their initial sounds (e.g., card-guard; gate-bait). The test was adapted from Baker, Blumstein, and Goodglass (1981), and included test of a full range of distinctive features of word initial sounds. Subjects received a total of 120 spoken word pairs, and the task was simply to indicate after each pair whether they were the same or different.
Procedures Subjects were run in two test sessions. In the first test session each of the subjects received 12 of the stimulus pictures in a picture-naming condition. The subject would be shown one of the pictures and then asked to give its name. If unable to do so, the subject then heard the first gated word-onset presentation (150 msec of word onset) and was asked to attempt the name. If the correct name was not produced the subject then heard the first 200 msec of word onset and was asked for a name. This procedure was continued with progressive 50-msec increases in word-onset gate size until the name was given correctly. A tape recorder was kept running throughout the procedure to record subjects’ responses. Subjects were encouraged to attempt to give the correct name after each presentation, and the examiner kept a verbatim record of each of these individual attempts. (The tape recording of the test session allowed later verification of the accuracy of the examiner’s transcriptions of the subjects’ responses.) Following traditional initial sound cuing procedures (e.g., Goodglass, 1980a; Pease & Goodglass, 1978), the picture remained present in front of the subject throughout the gated presentations and response attempts. In the “word only” condition, subjects heard the remaining 12 words in their spoken forms only, with no picture present. In this case subjects were told that they would hear a series of spoken object names. At first they would hear a small part of the beginning of the word (i.e., the first 150 msec of the word), then a bit more of the word beginning (the first 200 msec of the word), and so forth until they could correctly identify the spoken
NAMING IN APHASIA
379
word. As in the picture condition, subjects were encouraged to attempt a response after each presentation and these prerecognition responses were again recorded for later analysis. The particular stimuli given in the “picture naming” condition and the “word only” condition were varied between subjects. (These conditions will be referred to in subsequent discussion as the With Picture and No Picture conditions, respectively.) In the second session all subjects again received the 24 stimuli, but in this case the 12 that had been presented for picture naming in Session 1 were now presented in the name only (No Picture) condition in Session 2, and vice versa. The order of presentation of the conditions was counterbalanced between sessions and across subjects.
RESULTS Recognition
Speed
The aphasic subjects as a group were able to give the correct target word from just the gated words in the No Picture condition within an average of 368 msec of word onset, or, on average, just over 56% of word-onset duration. By contrast, the normal subjects’ mean gate size for correct recognition without a picture was 297 msec. Although significant, t(30) = 5.12, p < .OOl, the difference was clearly a small one in absolute terms, amounting to just 71 msec or an average of only 1.4 additional gates being required for word recognition by the aphasic subjects. Our primary interest, however, was the contrast between recognition times for the aphasic patients when the pictures were, or were not, present. (We do not have With Picture data for the normal subjects since there were no naming failures for that group). For this analysis we examined only word recognition data in the No Picture condition for those stimuli which were not named immediately in the With Picture condition by a given subject (i.e., that subset of stimuli for which we had gating data for both conditions). Two subjects, Patients 7 (a Broca’s aphasic) and 17 (a fluent anemic), had to be excluded from this analysis as they did not offer any instances of gating data for the same stimuli under both the No Picture and the With Picture conditions. Overall, the 16 aphasic subjects for whom we had such comparable data points produced the correct response with significantly less wordonset information when the picture was present (M = 282 msec) than when no picture was present (M = 358 msec), t(16) = 3.33, p < .005. In absolute terms, however, this mean difference in gate size was only 76 msec a difference corresponding to an average of just over an additional 1.5 gates for a correct response. Just as important, however, was the variability in gate sizes both within and between subjects. We show this in Table 2 which lists, in the first three columns, each subject’s phonemic discrimination score, the percentage of pictures named correctly in the With Picture condition without the need of any cues, and the mean recognition times for the 24 names when they were presented in the No Picture condition.
g 0
TABLE 2
Phoneme discrimination (percentage
220 175
418
2%
79.2
83.3
45.8
90
100
13. Wernicke 14. Wernicke 15. Anemic/ Fluent 16. Anemic/ Fluent 17. Anemic/ Fluent IX. Transcortical sensory
IlOllfIWll
85
434 402 368
335
309
426
79.0 91.7 37.5
95.8
loo
4.2
95 78 98
78
98
80
406
-
403
350
550 450 323
389
225
340
375
458
300 250 450 200 -
350
317
Mean gate-size in No Picture conditionfor matching stimuli
200
375 300 265
263
258
357
75.0
95
382
275
438
25.0
73
X. Global/ Nonfluent 9. Global/ Nonfluent IO. Transconical motor I I. Transcortical motor 12. Mixed
375 167 275 300 I.50
412 346 298 276 361
70.8 87.5 91.7 91.7 87.5
50 98 98 98 97
3. Broca 4. Broca 5. Broca 6. Broca 7. Broca
230 435
367
402
93
100
I. Broca
42.0
MWll gate-sizefor recognition in With Picture condition
31.5
COlTKt)
Naming ability (percentage pictures correct)
2. Broca
Aphasic subjects
Mean gate-sizefor recognition in No Picture condition
(15)
(9)
126
(16)
-
3
(1)
150
(3) (II (II)
(4)
50
175 IS0 58
(5)
6)
2
I case
3.3,2.1.1
-
3
5,4,43,2,2
6-6 3
8.6,2,2,2,2,1
6 cases
-
1.1,1.1.3
-
-
-
1 case
2,I.I
-
-
-
3X.22
3 I
-
-
5,4,2,1,1,1
4 cases
13.9.5.4.3, 3.3.3.2.2
3 cases
-
3,3,4,5,6 3.6
12 1.2.2.2.3,
1 2.2 6 5,2 -
(2) (2) (1%
(3)
1 case
2 cases
No diierence
Fewer gates for recognition with no picture present
I case I ctise -
321
(6)
(14)
5.4.4,3,3.3,
(No. of stimuli)
2,2,1,1.1 8.1.1
Fewer gates for recognition with picture present
120
117
183
-7s a3 175 -100 -
-85
87
Dierence scores (positive or tlQWiW) for matching stimuli
Casesin which recognitiontimeswere shorter, longer, or the same,when a picture was present.Numericalvalues indicatedifferencesin the numberof gatesfor eachcase
INDIVIDUAL SUBJECTDATA FOR PHONEMIC DISCRIMINATION, PICTURE-NAMING ABILITY, AND RECGGNITION TIMES (IN MILLISECONDS)FOR GATED NAME-WORDS WITH AND WITHOUT PICTURESPREL~ENT
NAMING IN APHASIA
381
To the extent that phonemic discrimination scores reflect phonological processing ability, some degree of the gating performance seems partially related to this ability. The correlation between the mean number of gates for word recognition in the No Picture condition and the subject’s phonemic discrimination score was significant, ~(16) = - .51, p < .05, although the regression accounted for only just under 26% of the variance. We then calculated a correlation between the subjects’ discrimination scores and mean gate size to producing the correct name in the With Picture condition when gated presentations were required for a correct response. Although in the right direction, in this case the correlation was not significant, r(15) = -.30, II.S. That phonemic discrimination skill predicts gating times to a significant but small degree would be reasonable to the extent that word recognition ability rests in part on recognizing the phonemic information present in the gated segment. This would be the part of the task accounted for by the correlation with phoneme discrimination score. The full task, however, rests also in part on the subject’s ability to match that detected input with the potential word initial sound cohort. When the picture is present to give additional input, phonemic discrimination scores no longer show a significant correlation with mean gate size to producing the correct name. This would be expected if the presence of the object constrained stimulus or response possibilities. (The control subjects were close to perfect on auditory discrimination, scoring a mean of 99.7% correct on phoneme discrimination.) Correlations between overall naming ability (percentage of correct scores for correct first-time naming in the With Picture condition) and gating were also what one might expect. The correlation between picture naming ability without a cue and gating recognition speeds in the No Picture condition was significant, r(16) = - .58, p < .02. This might simply mean that the more intact the subject is the better we can expect their gating performance to be, which is reasonable. The correlation between naming performance and mean gate size in the With Picture condition (all cases in the With Picture condition where gates were needed), however, did not reach significance, r(l5) = -.45, n.s. In seeking an account for the difference between the significant correlation in the No Picture condition and the lack of a significant correlation in the With Picture condition, we note that the latter was computed only from the gate sizes for pictures that could not be named without the provision of the initial phonology. It is plausible that the subject’s ability to name the picture is an indication that its phonology is latently more available to interact with the gated signal for an early completion of the word. Hence, we recomputed the correlation between success in naming and gate-size to completion in the No Picture condition, but this time only for those items that were named on presentation in the With
382
WINGFIELD,
GOODGLASS,
AND
SMITH
Picture condition. This procedure, however, raised the correlation only slightly, r(16) = - .65, p < .Ol. Table 2 also shows subjects’ mean gate sizes to word recognition in the With Picture condition (for those cases where gated presentations were needed for correct naming), and the mean recognition times for these same words in the No Picture condition. (This is an important control, as these figures relate only to gate sizes for the same stimuli.) As can be seen in Table 2, the numbers of these cases vary widely depending on how many pictures were not named without cues. For example, Subject 1, whose naming ability was poor, had a mean gate size based on 15 data points, versus Subjects 14 and 16 who each had only a single comparable point. The difference scores column in Table 2 shows the difference (positive or negative) between mean gate sizes for matching stimuli in the With Picture and No Picture conditions. We can see that three subjects in the Broca’s group had smaller mean gate sizes without a picture present than with (Patients 2, 3, and 6). We can also see, however, that the variability across subjects is great. These differences between subjects, furthermore, do not seem to be distinguished by diagnostic category. We compared With Picture versus No Picture recognition times for the nonfluent versus fluent aphasics in our subject group (i.e., roughly, anterior versus posterior speech area lesions). The nonfluent subjects were Patients 1 through 7, and 9 through 11, all of whom were described as having nonfluent, telegraphic speech, and all of whom had ratings of between 5 and 7 on the Word Finding scale of the BDAE, a rating of the availability of substantive words in proportion to the fluency of speech output. The fluent aphasics were Patients 13 through 18, all of whom were described as having fluent and grammatical output in conversation and who had received ratings of between 1 and 3.5 on the Word Finding scale of the BDAE, indicating relative underrepresentation of substantive words in relation to general fluency. (We excluded from this analysis Patient 12, a mixed nonfluent who was not clearly categorizable as fluent or nonfluent, and Patient 8, a global aphasic who had too little verbal output for scoring on a BDAE.) Analysis of variance confirmed a significant effect on gated word recognition of having the picture present, F(1, 14) = 20.08, p < .OOl, but no effect of diagnostic category, F(1, 14) < 1. There was also no presence of picture x diagnostic category interaction, F(1, 14) < 1. Of special interest are the three final columns in Table 2 which show the actual instances of stimuli where fewer gates were needed with the picture present, where there was no difference, and, finally, cases where subjects actually required fewer gates when the picture was not present. (The numbers indicate the magnitude of the differences in numbers of gates. Note also that these data are given only for matched cases where
NAMING IN APHASIA
383
data was available for the same stimulus words in both the With Picture and No Picture conditions.) Error Analysis
and Response Sequences
Prerecognition responses. In this analysis we examined subjects’ responses on the last presentation gate prior to the subject giving the correct target word in all cases in the No Picture condition and for those cases in the With Picture condition in which the subject failed to name the picture correctly on first presentation and thus received gated presentations. These responses were categorized. (1) No attempt prior to correct response: In these cases the subjects made no attempt to give any spoken response on the presentation prior to the presentation on which the correct response was given; (2) Veridical fragment: These were productions of nonwords that corresponded exactly to the segment heard by the subject at that particular gating interval; (3) Shorter word from cohort: These were real words that were possible completions of the fragment heard, but which were shorter than the target because the disambiguating element had not yet been heard (e.g., producing “cat” after hearing the initial /kae/ from camel); (4) Other word from cohort: These responses were real words that were equal in length or longer than the target word, and could have been possible completions of the segment heard to that point (e.g., saying “cactus” or “catamaran” after hearing the opening /kae/ from camel; (5) Partial mismatch of phonology: These were any responses that partially honored the phonological content of the gated segment presented but which also contained one or more phonemes that conflicted with it; (6) Complete mismatch of phonology: These were responses that contained none of the consonants of the gated segment. Figure 1 shows the overall percentage of prerecognition responses in the six response categories for the aphasic subjects in the With Picture and No Picture conditions, and for the No Picture condition for the normal subjects. Two features are of special note. The first is that the distribution of error responses for the aphasic subjects in the No Picture condition is very similar to the profile for the normal controls. This supports our earlier observation that the aphasic subjects in this experiment responded to gated stimuli in a manner similar to that of the agematched normal subjects. The exception is that the normal subjects tended to show a greater proportion of responses that were classed as other words from the cohort than did the aphasics. The normal subjects also had fewer phonological mismatches with the word onset than did the aphasics. The second point comes from a comparison of error profiles in the With Picture and No Picture conditions for the aphasic subjects. Although there was some individual variability, the aphasic subjects in the With Picture condition generally tended to make fewer overt response attempts
384
WINGFIELD,
Aphasic
Subjects
GOODGLASS, AND SMITH
Normal
SubleaS
NoPicture NoPicture FIG. 1. Percentage of prerecognition responses to gated stimuli in each of six response categories for aphasic subjects when the object picture was present (With Picture condition) and when no picture was present during gated presentations of the object names (No Picture condition). Normal subjects received only the No Picture condition. With
Picture
on the presentation prior to the correct response than in the No Picture condition when just the gated word alone was presented. These greater numbers of attempts in the No Picture condition tended to be represented by a relative increase in other words from the sound initial cohort that were of the same or longer length than the stimulus word, and responses that were either complete or partial phonological mismatches. (The error category profile shown for the No Picture condition for the aphasic subjects was virtually identical whether one included all stimuli in the analysis, as shown here, or just those stimuli for which there was also error data in the With Picture condition.) Response sequences. Another way to look at the effect of having or not having a picture present as gated words are being presented is to examine the sequence of individual prerecognition responses as more and more of a gated word is being presented. We categorized each response sequence as falling into one of five categories. (1) No attempt sequence prior to correct response: In these cases subjects made no attempt to give any response to presentations prior to the one producing the correct response. Also included were a small number of cases in which subjects gave only a single response; (2) Continuous improvement, with success: These were cases leading to successful production of the name in which the responses given to the successive gated presentations contained no instances in which a phonemic error or deletion was introduced that brought a response farther from the target than a prior response; (3) Continuous improvement, without success: These were sequences which also showed no phonemic errors or deletions in successive responses that brought a response farther from the target than
NAMING IN APHASIA
82
385
60
B i! 5 ..z El &
60
40
z h
E 8 ii 0.
20
0 With Picture
No picture
No picture
2. Classification of sequences of prerecognition responses as word onset durations of gated stimuli were progressively increased in the With Picture and No Picture conditions for aphasic subjects, and for the No Picture condition for the normal subjects. FIG.
a prior response. In these cases, however, the subject never succeeded in giving the correct word, even when the gate eventually included the entire word; (4) Toward and away from correct response: These cases were represented by sequences in which phonological errors were introduced in a response sequence that were not present in prior responses, such that the sequence moved away from the target at some point; (5) Perseveration: These cases were sequences in’which there was persistence of a phonological error across more than two successive gated presentations. The overall percentage of response sequences falling into each of these categories are shown in Fig. 2 for the With Picture and No Picture conditions for the aphasic subjects, and for the No Picture condition for the Normal subjects. As previously indicated, one major effect of having the picture present was to inhibit incorrect response attempts prior to giving the correct name. When the picture was present, in 49% of the cases subjects made no overt incorrect attempts prior to success, as contrasted with 28% of cases when subjects heard only the gated word alone. (These figures also include 5% of responses in the With Picture condition, and 1% of responses in the No Picture condition, in which only a single response attempt was offered. There were no such cases for the normal subjects in their No Picture condition.) Further indications of constraints operating when the picture was present can be seen in the second category shown: With no picture present subjects tended in 54% of the cases to give a sequence of overt improving responses leading to the correct response. When the picture was present this category of responding occurred in only 29% of the cases. (The error
386
WINGFIELD,
GOODGLASS,
AND
SMITH
category profile for the No Picture condition was again virtually identical whether one included all of the stimuli, as shown here, or just those for which there was also error data for the With Picture condition.) Figure 2 also shows that the general pattern of responses in these sequence categories in the No Picture condition are similar for the aphasic and normal subjects. This is consistent with our gate-size to recognition data which suggested that the aphasic subjects in this experiment responded to gated presentations for spoken word recognition in a similar manner as did the normal subject group. DISCUSSION
The impetus for the present study came from observations of normal lexical retrieval that appeared to challenge a common assumption as to the mechanism for phonemic priming in aphasics. Aphasic patients who fail to retrieve the name for a pictured object commonly succeed in accessing the full name-word when provided with the initial sound. This is also true for normal speakers and has been particularly noted in the case of normal aging (Goodglass, 1980b). The assumption has been that subjects in such cases had retrieved a portion of the target phonology, but insufficiently so to bring the response to the threshold for utterance of the word. The priming stimulus of the beginning sounds of the word was assumed to serve only as a facilitator, either to tip the subthreshold word response over threshold, or perhaps to trigger a blocked response. Prior work on gating (Grosjean, 1980; Marslen-Wilson, 1984, 1987; Tyler, 1984; Wayland et al., 1989) can be seen as placing the role of phonemic priming in a different light. Using the gating technique, it appears from these studies that, in normal subjects, an average of as little as 250 to 300 msec of the word-onset phonology is sufficient to elicit a correct completion of a target word even without any other pictorial or semantic input. Applying this finding to aphasics, we asked whether these subjects’ success in phonemic priming might be overwhelmingly a completion phenomenon, in which prior semantically based subthreshold activation played a negligible role. Our results appear to support this latter view. To be sure, the role of semantically based activation provided by the presence of the picture is real and significant, averaging 76 msec across subjects. (The amount of additional phonological information contained in 76 msec will depend not only on the particular utterance, but on the position of the increment within the word. This issue is treated in detail by Wayland et al., 1989.) However, although statistically significant, 76 msec represents a comparatively small increment in word-onset information needed for completing the target word when there is no picture present-i.e., no prior semantic activation. Further, by considering only the average, important variations in the data are obscured. In addition to a number of instances
NAMING IN APHASIA
387
in which gate-sizes to recognition were the same in the With Picture and No Picture conditions, half of the subjects had instances in which they did better without seeing the object picture than when they had already attempted to name it. Three subjects had shorter mean gate sizes on No Picture trials than on With Picture trials. The most notable effect of having the picture available while listening to gated opening segments was in constraining the number of errors and the types of errors made before the full word was accessed. In the No Picture condition there also tended to be more partial or complete phonological mismatches with the stimulus word onset than when the picture was present. A smaller effect was noted for production of shorter or other words from the soundinitial cohort. Relatively few were produced in either case, but their numbers were slightly higher when no picture was present (6.5% vs. 10.5%). It was to be expected that success on the phonemic discrimination test would predict success in using gated segments for word completion, and this was clearly the case in the No Picture condition. Hpwever, in the With Picture condition there was no longer a correlation observed between phonemic discrimination and success in correctly completing gated segments. This observation may be accounted for by the markedly reduced incidence of phonological mismatches with the target. It seems likely that having the target picture available suppressed the utterance of phonologically incompatible attempts. This effect could be expected to have its greatest impact on responses from subjects who had misperceived the gated segment and hence offered phonologically off-target response when there was no constraining picture. Alternatively, converging information from the picture’s semantic input and the gated phonological input could be seen as activating the phonological output system more completely than did either source alone. The first of these alternatives interprets the gating paradigm as entailing two discrete steps: one of recognition of an item in the phonological lexicon and one of repeating that activated item. This is inherent in the position of Marslen-Wilson (1984, 1987) and consistent with an application of Morton’s (1969) ‘logogen’ model to this paradigm. The second interpretation dispenses with the role of the phonological lexicon and views the gating paradigm, at least in the present experimental context, as operating entirely within the word production system. The occurrence of nonword responses, which occurred even among the normal control subjects, could be an argument against a model that assumes repetition of a previously recognized item in the phonological lexicon. In offering the second alternative interpretation, we recognize that normal subjects are certainly capable of briefly storing nonwords and then repeating them from a phonological store. This account, however, could only apply to the very small proportion of responses that were
388
WINGFIELD,
GOODGLASS,
AND
SMITH
classified as veridical fragments. We prefer to interpret other responses, both correct and incorrect, as the product of a mechanism of phonological activation and assembly which is automatically initiated by the arrival of word-onset information. This latter view would be consistent with a model of word retrieval in object naming in which the phonology for the naming of a picture is assembled anew upon its activation by the concept of the recognized object. In this model, word-initial phonology would play a powerful role in activating sequences that have been previously learned. This model requires also that the semantics of the pictured object act to selectively reinforce developing phonological activity that carries congruent semantic associations, and to inhibit phonological activity that does not. The failures of such semantically mediated interaction would then account for paraphasic errors in aphasic speech. In the present experiment, however, the No Picture condition placed both normal subjects and aphasics under pressure to produce completions without the possibility of semantically mediated suppression of off-target responses. We suggest then that normals, in producing off-target responses, are behaving like aphasics who have a defective semantic component in their phonological retrieval mechanism. Word-initial sound cues clearly are a valuable trigger for a correct response in aphasic naming. As we have noted, the data on this are strong (cf. Goodglass, 1980a; Pease & Goodglass, 1978). On the other hand, our present data are equally unambiguous in showing that wordinitial sounds can be effective in yielding correct target responses for aphasic subjects even in the absence of a picture. In these cases, the sound cue alone is enough to suggest the correct response, with the picture functioning to confirm the hypothesis. This circumstance, in other words, will transform what might appear to an observer as an aided word retrieval task (a task known to be difficult for aphasics) to a different and far easier task: the confirmation of an incipient utterance against the recognized picture. Such a name-picture matching task is in fact a process aphasics typically perform quite well in. In conclusion, we suggest that the facilitation of naming so often found when examiners supply word-onset sound cues following an aphasic naming failure may well be accounted for by this two-stage process: stem-completion followed by matching the picture with the name so generated. We recognize that this will be true only to the degree that each of the described component abilities for successful word completion from gated segments remain intact for any given patient or lesion site. This caution also suggests a productive direction for future research.
389
NAMING IN APHASIA
APPENDIX Object Names and Spoken Utterance Durations (in msec) Duration (msec)
Name
Duration (msec)
540 660 560 700 808 740 540 640 630 700 670 680
Pumpkin Ring Spoon Sun Table Thumb Tomato Turtle Umbrella Violin Whistle Window
700 620 780 620 570 720 590 500 660 880 400 650
Banana Bicycle Camel Church Cigarette Elephant Fish Guitar Iron Nose Pipe Potato
Note. Practice stimuli: Anchor, Football, Heart, Kangaroo, Pencil, Pineapple, Sandwich, Screwdriver, Skunk, Toothbrush.
REFERENCES Baker, E., Blumstein, S., & Goodglass, H. 1981. Interaction between phonological and semantic factors in auditory comprehension. Neuropsychologia, 19, 1-15. Cotton, S., & Grosjean, F. 1984. The gating paradigm: A comparison of successive and individual presentation formats. Perception and Psychophysics, 35, 41-48. Francis, W. N., & KuCera, H. 1982. Frequency analysis of English usage: Lexicon and grammar. Boston: Houghton Mifllin. Goodglass, H. 1980a. Disorders of naming following brain injury. American Scientist, 68, 647-655. Goodglass, H. 1980b. Naming disorders in aphasia and aging. In L. K. Obler & M. L. Albert (Eds.), Languge and communication in the elderly. Lexington, MA: Lexington Books. Goodglass, H., & Kaplan, E. 1972. The assessment of aphasia and related disorders. Philadelphia: Lea & Febiger. Grosjean, F. 1980. Spoken word recognition processes and the gating paradigm. Perception and Psychophysics,
28, 267-283.
Grosjean, F. 1985. The recognition of words after their acoustic offset: Evidence and implications. Perception and Psychophysics, 38, 299-310. Luria, A. R. 1970. Traumatic aphasia. The Hague: Mouton. Marslen-Wilson, W. D. 1984. Function and process in spoken word recognition. In H. Bouma & D. G. Bouwhuis (Eds.), Attenrion and performance X. Hillsdale, NJ: Erlbaum. Marslen-Wilson, W. D. 1987.Functional parallelism in spoken word recognition. Cognition, 25, 71-102. Morton, J. 1969. Interaction of information in word recognition. Psychological Review, 76, 165-178. Nooteboom, S. G., & Doodeman, G. J. N. 1984. Speech quality and the gating paradigm. In M. P. R. van den Broeke & A. Cohen (Eds.), Proceedings of the Tenth International Congress of Phonetic Sciences. Dordrecht: Foris.
390
WINGFIELD,
GOODGLASS, AND SMITH
Nooteboom, S. G., & van der Vlugt, M. J. 1988. A search for a word-beginning superiority effect. Journal of the Acoustical Society of America, 84, 2018-2032. Pease, D. M., & Goodglass, H. 1978. The effects of cuing on picture naming in aphasia. Cortex,
14, 178- 189.
Tyler, L. 1984. Structure of the initial cohort: Evidence from gating. Perception Psychophysics,
and
36, 417-427.
Snodgrass, J. G., & Vanderwart, M. 1980. A standardized set of 260 pictures: Norms for name agreement, image agreement, familiarity, and visual complexity. Journal of Experimental Psychology: Human Learning and Memory, 6, 174-215. Wayland, S. C., Wingfield, A., & Goodglass, H. 1989. Recognition of isolated words: The dynamics of cohort reduction. Applied Psycholinguistics 10, 475-487. Wingfield, A., & Wayland, S. C. (1988). Object-naming in aphasia: Word-initial phonology and response activation. Aphasiology, 2, 423-425.
AND
LANGUAGE
39, 373-390 (1990)
Effects of Word-Onset
Cuing on Picture Naming in Aphasia: A Reconsideration ARTHUR WINGFIELD
Department of Psychology and Center for Complex Systems, Brandeis University, Aphasia Research Center, Department of Neurology, Boston University School of Medicine
and
AND HAROLD GOODGLASS AND KATHERINE Boston VA Medical
L. SMITH
Center and Aphasia Research Center, Department Boston University School of Medicine
of Neurology,
When an aphasic is unable to name an object, giving the patient the opening sounds of the target name will often trigger the correct response. Eighteen aphasic subjects were tested using a gating paradigm to compare word onset durations necessary to elicit correct names after an initial naming failure with those necessary for recognizing the same words when spoken in isolation with no picture present. Prerecognition errors were also examined. Results suggested that the facilitation of naming found when examiners supply word-onset sound cues may be due in part to a two-stage process consisting of stem-completion followed by matching the picture with the potential name as generated. Q 1990 Academic Press, Inc.
When an aphasic patient is unable to name an object on command, giving the patient the opening sounds of the target name will often trigger the correct response. Indeed, initial sound cues (as opposed to, for example, a rhyming word, or information about the object’s function) This work was supported in part by the Medical Research Service of the Veterans Administration and in part by PHS Grants AG 04517 and NS 06209 from the National Institutes of Health. We thank Joan Gay Snodgrass for making available originals of her stimulus pictures, Sarah Wayland and John Aberdeen for help in construction of the auditory stimuli, and Mark Silberstein for assistance with data tabulation. Address reprint requests to Arthur Wingfield, Department of Psychology, Brandeis University, Waltham, MA 02254. 373 0093-934x/90
$3.00
Copyright Q 1990 by Academic Press. Inc. All rights of reproduction in any form reserved.
374
WINGFIELD,
GOODGLASS,
AND
SMITH
are ordinarily the most effective retrieval cues for almost all aphasics (Goodglass, 1980a; Pease & Goodglass, 1978). Such findings are commonly characterized as reflecting an internal representation of the acoustic pattern (an inner “speech image”) of the intended word which can be activated, or “triggered,” by hearing its initial sound (cf. Goodglass, 1980a; Luria, 1970; Wayland, Wingfield, & Goodglass, 1989; Wingfield & Wayland, 1988). The use of word-initial phonology as a cue to an intended word is similar in many respects to the technique of gating, ordinarily associated with the study of spoken word perception (Grosjean, 1980; Cotton & Grosjean, 1984). In this technique, subjects hear increasing amounts of word-onset information until the word can be correctly identified. So, for example, the subject might hear the first 50 msec of a word, then the first 100 msec of that word, then the first 150 msec, and so on, until the word is correctly identified. Although longer gate-sizes will be required if speech quality or signal clarity is poor (cf. Grosjean, 1985; Nooteboom & Doodeman, 1984), such studies have shown that words heard within a sentence context can be recognized, on average, within as little as 200 msec of their onset, or when less than half of their full acoustic signal has been heard. Spoken words heard in isolation (i.e., without a sentence context) require, on average, only 130 msec more (Grosjean, 1980; Marslen-Wilson, 1984). Most writers using the paradigm have presumed that a word can be correctly identified before its complete acoustic signal has been heard because of the very rapid decrease in the number of possible word candidates which share the same initial sounds as the target word as progressively more of the word-onset information is heard (Grosjean, 1980; Marslen-Wilson, 1984, 1987; Tyler, 1984; Wayland et al., 1989). The role of temporal alignment of word onsets between a stimulus fragment and potential word candidates has been developed by Nooteboom and van der Vlugt (1988). In terms of neural mechanism, we have proposed that word-initial sounds may activate an internal representation of this sound pattern which, in turn, yields an unfolding representation of all words beginning with this word-onset information. Phonological sequences sharing the same initial phonology would presumably be activated in parallel, with additional acoustic information progressively increasing the activation of the target word, and simultaneously inhibiting nontargets (Wayland et al., 1989). From these considerations, we were led to wonder to what extent the facilitating effects of word initial phonology for name retrieval by aphasics may in fact be mediated, at least in part, by the recognition of the lexical entry to which the initial sound segment belongs. That is, we might speculate that the known benefits of word initial sounds to the aphasic (e.g., Goodglass, 1980a; Pease & Goodglass, 1978) may derive
NAMING IN APHASIA
375
primarily from the subjects’ ability to recognize a lexical item from hearing its stem and to provide the completion. If this is the case we would expect that patients’ responses to gated word onsets, without any pictorial cue, would account for most of their success in stem-completion. The alternative hypothesis is that aphasics’ ability to complete word stems depends on their having a response in readiness, as a result of prior effort to name a picture of the target object. For this alternative to be supported, we would expect to observe little success in stem completion unless a picture of the target had been presented. In the following experiment, asphasic subjects were tested for picture naming with a set of ordinarily easy to name outline drawings of objects (Snodgrass & Vanderwart, 1980). When a naming failure did occur, the subject heard the beginning of the correct name, followed by progressively larger amounts of the word-onset duration until the subject was able to give the correct response. Our interest was to compare the wordonset duration necessary to elicit the correct names under these circumstances with recognition times for these same words when presented in a gated format alone, without any picture present. METHOD
Subjects Eighteen aphasic patients, drawn from a variety of diagnostic categories and with varying degrees of naming ability, served as subjects. Prior clinical examination had established that all had normal ability to recognize pictures. Descriptive information for the patient group is given in Table 1. The patients’ diagnostic classifications and ratings of severity of the aphasia were determined by clinical examination and pattern of performance on the Boston Diagnostic Aphasia Examination (Goodglass & Kaplan, 1972). Localization data were obtained by neurological examination and CT scan. A comparison group of I4 normal subjects was also tested. This group was composed of 13 males and 1 female drawn from a subject pool of paid volunteers from the local community. The members of this group had no known history of neurological or psychiatric disorder. Their ages ranged from 55 to 72 years (M = 64.2 years) and they had between 10 to I7 years of formal education (M = 13.0 years). The aphasic and control groupswere equivalent in mean age, r(30) = 1.62, n.s., and in years of formal education, r(29)
Stimuli Object pictures and names. The stimuli consisted of 24 pictures taken from Snodgrass and Vanderwart (1980). These were pen and ink outline drawings rendered without background context, much in the manner of dictionary illustrations. The objects were chosen to be clearly recognizable in their pictorial form and to have high subject name agreement. Of the 24 objects, 8 had one-syllable names, 8 had two-syllable names, and 8 had threesyllable names. All of the 24 stimulus words had been used in a preliminary study of recognition times for gated words. Detail on numbers of potential sound-initial word candidates per word-onset gate size, and recognition versus cohort-size relationships, can be found in the report of that study (Wayland et al., 1989). Within each word-length, the names covered a wide range of word frequency using a standard print frequency count (Francis & K&era, 1982), although none were especially
59
71
Moderate
Moderate/Severe
Broca
Broca
Broca
Global/ Nonthrent
6
7
a
Severe
Moderate/Severe
56
56
14 years
16 years
M
M
16 years
12 years
M
M
9 years
5
M
Broca
4
61
12 years
M
69
Moderate/Severe
Broca
3
Moderate/Severe
-
2
M
16 years
43
Broca
I
Severe
Education
Sex
Broca
Age M
Severity
TABLE
1
13 years
6 years
Right
Left
CVA
CVA
CVA
10 years
II years
0.2 year
Right
Right
Right
CVA
CVA
CVA
Aneurism
CVA
Etiology
16 years
Right
7 years
2 years
Right
Right
Time postonset
PATIENTS SERVING AS SUBJECTS
Handedness
FOR 18 APHASIC
64
Diagnostic group
INFORMATION
Moderate/Severe
Patient No.
PATIENT
CT scan uninformative
Large L frontal, temporal, and parieta1 lesion including Broca’s area, half of Wemicke’s area. Anterior extension to middle frontal gyrus. Deep going superior extension invalving motor and sensory cortex and supramarginal gyrus L Broca’s area with deep extension including insular structures. Superior lesion extension to middle frontal gyrus: posteriorly to motor and sensory cortex and anterior temporal lobe L Broca’s area deep to the ventricle, with superior extension to the motor and sensory cortex L Broca’s area, with superior lesion extension to parietal lobe L Broca’s area, with a second lesion in the L parietal Deep going L Broca’s area lesion with some posterior subcortical extension, and deep going superior extension across motor and sensory cortex Primarily deep going lesion in L Broca’s area, with partial patchy involvement of Wemicke’s area
Lesion location
X
g
5
“5
F
8
< ? Q 2 F P
Transcortical motor
Transcortical motor
Mixed nonfluent
Wemicke
Wemicke
Anomic/ Fluent Anemic/ Fluent
Anemic/ fluent
Transcortical sensory
IO
II
12
I3
I4
I5
17
I8
I6
Global/ Nonfluent
9
Moderate/ Severe
Moderate
Moderate
Moderate
Very severe
Severe
Moderate/ Severe
Moderate
Severe
Severe
67
58
59
54
60
47
68
59
71
64
M
M
M
M
M
M
F
M
M
M
8 years
16 years
12 years
16 years
I2 years
I2 years
II years
II years
II years
13 years
Right
Right
Right
Right
Right
Right
Right
Right
Right
Right
0.1 year
6 years
3 years
0.1 year
3 years
0.2 year
5 years
7 years
0.1 year
7 years
(2)
Intracerebral hemorrhage CVA
CVA
CVA
CVA
CVA
CVA
CVA
CVA
CVA
Scattered bilateral lesions: Left, inferior and middle temporal gyri, and part of supramarginal gyrus; Right, putamen, and anterior periventricular white matter
Small lesion involving L Wemicke’s area Deep going L Wemicke’s area, with superior extension into angular gyms Lesion to middle and inferior left temporal gyrus Small deep patchy L anterior lesion, and angular gyrus lesion, with large patchy extension to high frontal-parietal region Very deep subcortical L frontal lesion, with extension to L subcortical prefrontal zone
L deep going Broca’s area, with large surface and deep superior extension Small subcortical lesion of L lateral putamen and external capsule, with small subcortical R anterior lesion Large lesion involving most of L Broca’s area and Wemicke’s area, with superior extension to parietal lobe Large lesion to most of L Broca’s area, and subcortical structures underlying Broca’s area, with superior extension to anterior parieta1 lobe
378
WINGFIELD,
GOODGLASS,
AND
SMITH
rare. The names of the objects varied in their frequency of occurrence in print from 2 per million words in print (e.g., pumpkin) to 451 per million (e.g., church). Each of the 24 stimulus pictures (plus an additional 10 pictures for practice) were individually mounted on 5 x 8 in. cards for presentation. Recording of object names. The names of each object were recorded once by a male speaker of American English, preceded by the carrier phrase, “The object is--“. Each word was spoken in citation form with natural intonation, clear enunciation, and all were matched for sound level intensity. Once the full list was recorded, each of the words was rerecorded in a series of progressively increasing word-onset durations in the following way. Recordings of the carrier phrase and the object names were digitized at a sampling rate of 22 kHz and edited using the SoundCap speech editing system on a Macintosh Plus microcomputer to produce a sequence of presentations in which the gate size of the target word from word onset began at 150 msec and then was increased by 3%msec increments until the “gate” included the full acoustic duration of the word. This was accomplished by selecting the desired gate sizes on a computer-generated visual display of the speech wave form of the carrier phrase and target word. Accuracy of selection of the target wordonset point for start of gate duration was determined visually on the wave form and then verified by auditory monitoring. As the preparation of each presentation in the gating sequence was completed it was transferred to standard cassette tape to be used as a master for preparation of individual subject stimulus tapes. The 24 object names and their spoken utterance durations as measured on their visual waveforms (in mseconds) are given in the Appendix. Also listed are the 10 practice stimuli. Phoneme discrimination test. All subjects also received a phoneme discrimination test in which subjects heard word pairs which were either the same (e.g., card-card; gategait), or which differed in their initial sounds (e.g., card-guard; gate-bait). The test was adapted from Baker, Blumstein, and Goodglass (1981), and included test of a full range of distinctive features of word initial sounds. Subjects received a total of 120 spoken word pairs, and the task was simply to indicate after each pair whether they were the same or different.
Procedures Subjects were run in two test sessions. In the first test session each of the subjects received 12 of the stimulus pictures in a picture-naming condition. The subject would be shown one of the pictures and then asked to give its name. If unable to do so, the subject then heard the first gated word-onset presentation (150 msec of word onset) and was asked to attempt the name. If the correct name was not produced the subject then heard the first 200 msec of word onset and was asked for a name. This procedure was continued with progressive 50-msec increases in word-onset gate size until the name was given correctly. A tape recorder was kept running throughout the procedure to record subjects’ responses. Subjects were encouraged to attempt to give the correct name after each presentation, and the examiner kept a verbatim record of each of these individual attempts. (The tape recording of the test session allowed later verification of the accuracy of the examiner’s transcriptions of the subjects’ responses.) Following traditional initial sound cuing procedures (e.g., Goodglass, 1980a; Pease & Goodglass, 1978), the picture remained present in front of the subject throughout the gated presentations and response attempts. In the “word only” condition, subjects heard the remaining 12 words in their spoken forms only, with no picture present. In this case subjects were told that they would hear a series of spoken object names. At first they would hear a small part of the beginning of the word (i.e., the first 150 msec of the word), then a bit more of the word beginning (the first 200 msec of the word), and so forth until they could correctly identify the spoken
NAMING IN APHASIA
379
word. As in the picture condition, subjects were encouraged to attempt a response after each presentation and these prerecognition responses were again recorded for later analysis. The particular stimuli given in the “picture naming” condition and the “word only” condition were varied between subjects. (These conditions will be referred to in subsequent discussion as the With Picture and No Picture conditions, respectively.) In the second session all subjects again received the 24 stimuli, but in this case the 12 that had been presented for picture naming in Session 1 were now presented in the name only (No Picture) condition in Session 2, and vice versa. The order of presentation of the conditions was counterbalanced between sessions and across subjects.
RESULTS Recognition
Speed
The aphasic subjects as a group were able to give the correct target word from just the gated words in the No Picture condition within an average of 368 msec of word onset, or, on average, just over 56% of word-onset duration. By contrast, the normal subjects’ mean gate size for correct recognition without a picture was 297 msec. Although significant, t(30) = 5.12, p < .OOl, the difference was clearly a small one in absolute terms, amounting to just 71 msec or an average of only 1.4 additional gates being required for word recognition by the aphasic subjects. Our primary interest, however, was the contrast between recognition times for the aphasic patients when the pictures were, or were not, present. (We do not have With Picture data for the normal subjects since there were no naming failures for that group). For this analysis we examined only word recognition data in the No Picture condition for those stimuli which were not named immediately in the With Picture condition by a given subject (i.e., that subset of stimuli for which we had gating data for both conditions). Two subjects, Patients 7 (a Broca’s aphasic) and 17 (a fluent anemic), had to be excluded from this analysis as they did not offer any instances of gating data for the same stimuli under both the No Picture and the With Picture conditions. Overall, the 16 aphasic subjects for whom we had such comparable data points produced the correct response with significantly less wordonset information when the picture was present (M = 282 msec) than when no picture was present (M = 358 msec), t(16) = 3.33, p < .005. In absolute terms, however, this mean difference in gate size was only 76 msec a difference corresponding to an average of just over an additional 1.5 gates for a correct response. Just as important, however, was the variability in gate sizes both within and between subjects. We show this in Table 2 which lists, in the first three columns, each subject’s phonemic discrimination score, the percentage of pictures named correctly in the With Picture condition without the need of any cues, and the mean recognition times for the 24 names when they were presented in the No Picture condition.
g 0
TABLE 2
Phoneme discrimination (percentage
220 175
418
2%
79.2
83.3
45.8
90
100
13. Wernicke 14. Wernicke 15. Anemic/ Fluent 16. Anemic/ Fluent 17. Anemic/ Fluent IX. Transcortical sensory
IlOllfIWll
85
434 402 368
335
309
426
79.0 91.7 37.5
95.8
loo
4.2
95 78 98
78
98
80
406
-
403
350
550 450 323
389
225
340
375
458
300 250 450 200 -
350
317
Mean gate-size in No Picture conditionfor matching stimuli
200
375 300 265
263
258
357
75.0
95
382
275
438
25.0
73
X. Global/ Nonfluent 9. Global/ Nonfluent IO. Transconical motor I I. Transcortical motor 12. Mixed
375 167 275 300 I.50
412 346 298 276 361
70.8 87.5 91.7 91.7 87.5
50 98 98 98 97
3. Broca 4. Broca 5. Broca 6. Broca 7. Broca
230 435
367
402
93
100
I. Broca
42.0
MWll gate-sizefor recognition in With Picture condition
31.5
COlTKt)
Naming ability (percentage pictures correct)
2. Broca
Aphasic subjects
Mean gate-sizefor recognition in No Picture condition
(15)
(9)
126
(16)
-
3
(1)
150
(3) (II (II)
(4)
50
175 IS0 58
(5)
6)
2
I case
3.3,2.1.1
-
3
5,4,43,2,2
6-6 3
8.6,2,2,2,2,1
6 cases
-
1.1,1.1.3
-
-
-
1 case
2,I.I
-
-
-
3X.22
3 I
-
-
5,4,2,1,1,1
4 cases
13.9.5.4.3, 3.3.3.2.2
3 cases
-
3,3,4,5,6 3.6
12 1.2.2.2.3,
1 2.2 6 5,2 -
(2) (2) (1%
(3)
1 case
2 cases
No diierence
Fewer gates for recognition with no picture present
I case I ctise -
321
(6)
(14)
5.4.4,3,3.3,
(No. of stimuli)
2,2,1,1.1 8.1.1
Fewer gates for recognition with picture present
120
117
183
-7s a3 175 -100 -
-85
87
Dierence scores (positive or tlQWiW) for matching stimuli
Casesin which recognitiontimeswere shorter, longer, or the same,when a picture was present.Numericalvalues indicatedifferencesin the numberof gatesfor eachcase
INDIVIDUAL SUBJECTDATA FOR PHONEMIC DISCRIMINATION, PICTURE-NAMING ABILITY, AND RECGGNITION TIMES (IN MILLISECONDS)FOR GATED NAME-WORDS WITH AND WITHOUT PICTURESPREL~ENT
NAMING IN APHASIA
381
To the extent that phonemic discrimination scores reflect phonological processing ability, some degree of the gating performance seems partially related to this ability. The correlation between the mean number of gates for word recognition in the No Picture condition and the subject’s phonemic discrimination score was significant, ~(16) = - .51, p < .05, although the regression accounted for only just under 26% of the variance. We then calculated a correlation between the subjects’ discrimination scores and mean gate size to producing the correct name in the With Picture condition when gated presentations were required for a correct response. Although in the right direction, in this case the correlation was not significant, r(15) = -.30, II.S. That phonemic discrimination skill predicts gating times to a significant but small degree would be reasonable to the extent that word recognition ability rests in part on recognizing the phonemic information present in the gated segment. This would be the part of the task accounted for by the correlation with phoneme discrimination score. The full task, however, rests also in part on the subject’s ability to match that detected input with the potential word initial sound cohort. When the picture is present to give additional input, phonemic discrimination scores no longer show a significant correlation with mean gate size to producing the correct name. This would be expected if the presence of the object constrained stimulus or response possibilities. (The control subjects were close to perfect on auditory discrimination, scoring a mean of 99.7% correct on phoneme discrimination.) Correlations between overall naming ability (percentage of correct scores for correct first-time naming in the With Picture condition) and gating were also what one might expect. The correlation between picture naming ability without a cue and gating recognition speeds in the No Picture condition was significant, r(16) = - .58, p < .02. This might simply mean that the more intact the subject is the better we can expect their gating performance to be, which is reasonable. The correlation between naming performance and mean gate size in the With Picture condition (all cases in the With Picture condition where gates were needed), however, did not reach significance, r(l5) = -.45, n.s. In seeking an account for the difference between the significant correlation in the No Picture condition and the lack of a significant correlation in the With Picture condition, we note that the latter was computed only from the gate sizes for pictures that could not be named without the provision of the initial phonology. It is plausible that the subject’s ability to name the picture is an indication that its phonology is latently more available to interact with the gated signal for an early completion of the word. Hence, we recomputed the correlation between success in naming and gate-size to completion in the No Picture condition, but this time only for those items that were named on presentation in the With
382
WINGFIELD,
GOODGLASS,
AND
SMITH
Picture condition. This procedure, however, raised the correlation only slightly, r(16) = - .65, p < .Ol. Table 2 also shows subjects’ mean gate sizes to word recognition in the With Picture condition (for those cases where gated presentations were needed for correct naming), and the mean recognition times for these same words in the No Picture condition. (This is an important control, as these figures relate only to gate sizes for the same stimuli.) As can be seen in Table 2, the numbers of these cases vary widely depending on how many pictures were not named without cues. For example, Subject 1, whose naming ability was poor, had a mean gate size based on 15 data points, versus Subjects 14 and 16 who each had only a single comparable point. The difference scores column in Table 2 shows the difference (positive or negative) between mean gate sizes for matching stimuli in the With Picture and No Picture conditions. We can see that three subjects in the Broca’s group had smaller mean gate sizes without a picture present than with (Patients 2, 3, and 6). We can also see, however, that the variability across subjects is great. These differences between subjects, furthermore, do not seem to be distinguished by diagnostic category. We compared With Picture versus No Picture recognition times for the nonfluent versus fluent aphasics in our subject group (i.e., roughly, anterior versus posterior speech area lesions). The nonfluent subjects were Patients 1 through 7, and 9 through 11, all of whom were described as having nonfluent, telegraphic speech, and all of whom had ratings of between 5 and 7 on the Word Finding scale of the BDAE, a rating of the availability of substantive words in proportion to the fluency of speech output. The fluent aphasics were Patients 13 through 18, all of whom were described as having fluent and grammatical output in conversation and who had received ratings of between 1 and 3.5 on the Word Finding scale of the BDAE, indicating relative underrepresentation of substantive words in relation to general fluency. (We excluded from this analysis Patient 12, a mixed nonfluent who was not clearly categorizable as fluent or nonfluent, and Patient 8, a global aphasic who had too little verbal output for scoring on a BDAE.) Analysis of variance confirmed a significant effect on gated word recognition of having the picture present, F(1, 14) = 20.08, p < .OOl, but no effect of diagnostic category, F(1, 14) < 1. There was also no presence of picture x diagnostic category interaction, F(1, 14) < 1. Of special interest are the three final columns in Table 2 which show the actual instances of stimuli where fewer gates were needed with the picture present, where there was no difference, and, finally, cases where subjects actually required fewer gates when the picture was not present. (The numbers indicate the magnitude of the differences in numbers of gates. Note also that these data are given only for matched cases where
NAMING IN APHASIA
383
data was available for the same stimulus words in both the With Picture and No Picture conditions.) Error Analysis
and Response Sequences
Prerecognition responses. In this analysis we examined subjects’ responses on the last presentation gate prior to the subject giving the correct target word in all cases in the No Picture condition and for those cases in the With Picture condition in which the subject failed to name the picture correctly on first presentation and thus received gated presentations. These responses were categorized. (1) No attempt prior to correct response: In these cases the subjects made no attempt to give any spoken response on the presentation prior to the presentation on which the correct response was given; (2) Veridical fragment: These were productions of nonwords that corresponded exactly to the segment heard by the subject at that particular gating interval; (3) Shorter word from cohort: These were real words that were possible completions of the fragment heard, but which were shorter than the target because the disambiguating element had not yet been heard (e.g., producing “cat” after hearing the initial /kae/ from camel); (4) Other word from cohort: These responses were real words that were equal in length or longer than the target word, and could have been possible completions of the segment heard to that point (e.g., saying “cactus” or “catamaran” after hearing the opening /kae/ from camel; (5) Partial mismatch of phonology: These were any responses that partially honored the phonological content of the gated segment presented but which also contained one or more phonemes that conflicted with it; (6) Complete mismatch of phonology: These were responses that contained none of the consonants of the gated segment. Figure 1 shows the overall percentage of prerecognition responses in the six response categories for the aphasic subjects in the With Picture and No Picture conditions, and for the No Picture condition for the normal subjects. Two features are of special note. The first is that the distribution of error responses for the aphasic subjects in the No Picture condition is very similar to the profile for the normal controls. This supports our earlier observation that the aphasic subjects in this experiment responded to gated stimuli in a manner similar to that of the agematched normal subjects. The exception is that the normal subjects tended to show a greater proportion of responses that were classed as other words from the cohort than did the aphasics. The normal subjects also had fewer phonological mismatches with the word onset than did the aphasics. The second point comes from a comparison of error profiles in the With Picture and No Picture conditions for the aphasic subjects. Although there was some individual variability, the aphasic subjects in the With Picture condition generally tended to make fewer overt response attempts
384
WINGFIELD,
Aphasic
Subjects
GOODGLASS, AND SMITH
Normal
SubleaS
NoPicture NoPicture FIG. 1. Percentage of prerecognition responses to gated stimuli in each of six response categories for aphasic subjects when the object picture was present (With Picture condition) and when no picture was present during gated presentations of the object names (No Picture condition). Normal subjects received only the No Picture condition. With
Picture
on the presentation prior to the correct response than in the No Picture condition when just the gated word alone was presented. These greater numbers of attempts in the No Picture condition tended to be represented by a relative increase in other words from the sound initial cohort that were of the same or longer length than the stimulus word, and responses that were either complete or partial phonological mismatches. (The error category profile shown for the No Picture condition for the aphasic subjects was virtually identical whether one included all stimuli in the analysis, as shown here, or just those stimuli for which there was also error data in the With Picture condition.) Response sequences. Another way to look at the effect of having or not having a picture present as gated words are being presented is to examine the sequence of individual prerecognition responses as more and more of a gated word is being presented. We categorized each response sequence as falling into one of five categories. (1) No attempt sequence prior to correct response: In these cases subjects made no attempt to give any response to presentations prior to the one producing the correct response. Also included were a small number of cases in which subjects gave only a single response; (2) Continuous improvement, with success: These were cases leading to successful production of the name in which the responses given to the successive gated presentations contained no instances in which a phonemic error or deletion was introduced that brought a response farther from the target than a prior response; (3) Continuous improvement, without success: These were sequences which also showed no phonemic errors or deletions in successive responses that brought a response farther from the target than
NAMING IN APHASIA
82
385
60
B i! 5 ..z El &
60
40
z h
E 8 ii 0.
20
0 With Picture
No picture
No picture
2. Classification of sequences of prerecognition responses as word onset durations of gated stimuli were progressively increased in the With Picture and No Picture conditions for aphasic subjects, and for the No Picture condition for the normal subjects. FIG.
a prior response. In these cases, however, the subject never succeeded in giving the correct word, even when the gate eventually included the entire word; (4) Toward and away from correct response: These cases were represented by sequences in which phonological errors were introduced in a response sequence that were not present in prior responses, such that the sequence moved away from the target at some point; (5) Perseveration: These cases were sequences in’which there was persistence of a phonological error across more than two successive gated presentations. The overall percentage of response sequences falling into each of these categories are shown in Fig. 2 for the With Picture and No Picture conditions for the aphasic subjects, and for the No Picture condition for the Normal subjects. As previously indicated, one major effect of having the picture present was to inhibit incorrect response attempts prior to giving the correct name. When the picture was present, in 49% of the cases subjects made no overt incorrect attempts prior to success, as contrasted with 28% of cases when subjects heard only the gated word alone. (These figures also include 5% of responses in the With Picture condition, and 1% of responses in the No Picture condition, in which only a single response attempt was offered. There were no such cases for the normal subjects in their No Picture condition.) Further indications of constraints operating when the picture was present can be seen in the second category shown: With no picture present subjects tended in 54% of the cases to give a sequence of overt improving responses leading to the correct response. When the picture was present this category of responding occurred in only 29% of the cases. (The error
386
WINGFIELD,
GOODGLASS,
AND
SMITH
category profile for the No Picture condition was again virtually identical whether one included all of the stimuli, as shown here, or just those for which there was also error data for the With Picture condition.) Figure 2 also shows that the general pattern of responses in these sequence categories in the No Picture condition are similar for the aphasic and normal subjects. This is consistent with our gate-size to recognition data which suggested that the aphasic subjects in this experiment responded to gated presentations for spoken word recognition in a similar manner as did the normal subject group. DISCUSSION
The impetus for the present study came from observations of normal lexical retrieval that appeared to challenge a common assumption as to the mechanism for phonemic priming in aphasics. Aphasic patients who fail to retrieve the name for a pictured object commonly succeed in accessing the full name-word when provided with the initial sound. This is also true for normal speakers and has been particularly noted in the case of normal aging (Goodglass, 1980b). The assumption has been that subjects in such cases had retrieved a portion of the target phonology, but insufficiently so to bring the response to the threshold for utterance of the word. The priming stimulus of the beginning sounds of the word was assumed to serve only as a facilitator, either to tip the subthreshold word response over threshold, or perhaps to trigger a blocked response. Prior work on gating (Grosjean, 1980; Marslen-Wilson, 1984, 1987; Tyler, 1984; Wayland et al., 1989) can be seen as placing the role of phonemic priming in a different light. Using the gating technique, it appears from these studies that, in normal subjects, an average of as little as 250 to 300 msec of the word-onset phonology is sufficient to elicit a correct completion of a target word even without any other pictorial or semantic input. Applying this finding to aphasics, we asked whether these subjects’ success in phonemic priming might be overwhelmingly a completion phenomenon, in which prior semantically based subthreshold activation played a negligible role. Our results appear to support this latter view. To be sure, the role of semantically based activation provided by the presence of the picture is real and significant, averaging 76 msec across subjects. (The amount of additional phonological information contained in 76 msec will depend not only on the particular utterance, but on the position of the increment within the word. This issue is treated in detail by Wayland et al., 1989.) However, although statistically significant, 76 msec represents a comparatively small increment in word-onset information needed for completing the target word when there is no picture present-i.e., no prior semantic activation. Further, by considering only the average, important variations in the data are obscured. In addition to a number of instances
NAMING IN APHASIA
387
in which gate-sizes to recognition were the same in the With Picture and No Picture conditions, half of the subjects had instances in which they did better without seeing the object picture than when they had already attempted to name it. Three subjects had shorter mean gate sizes on No Picture trials than on With Picture trials. The most notable effect of having the picture available while listening to gated opening segments was in constraining the number of errors and the types of errors made before the full word was accessed. In the No Picture condition there also tended to be more partial or complete phonological mismatches with the stimulus word onset than when the picture was present. A smaller effect was noted for production of shorter or other words from the soundinitial cohort. Relatively few were produced in either case, but their numbers were slightly higher when no picture was present (6.5% vs. 10.5%). It was to be expected that success on the phonemic discrimination test would predict success in using gated segments for word completion, and this was clearly the case in the No Picture condition. Hpwever, in the With Picture condition there was no longer a correlation observed between phonemic discrimination and success in correctly completing gated segments. This observation may be accounted for by the markedly reduced incidence of phonological mismatches with the target. It seems likely that having the target picture available suppressed the utterance of phonologically incompatible attempts. This effect could be expected to have its greatest impact on responses from subjects who had misperceived the gated segment and hence offered phonologically off-target response when there was no constraining picture. Alternatively, converging information from the picture’s semantic input and the gated phonological input could be seen as activating the phonological output system more completely than did either source alone. The first of these alternatives interprets the gating paradigm as entailing two discrete steps: one of recognition of an item in the phonological lexicon and one of repeating that activated item. This is inherent in the position of Marslen-Wilson (1984, 1987) and consistent with an application of Morton’s (1969) ‘logogen’ model to this paradigm. The second interpretation dispenses with the role of the phonological lexicon and views the gating paradigm, at least in the present experimental context, as operating entirely within the word production system. The occurrence of nonword responses, which occurred even among the normal control subjects, could be an argument against a model that assumes repetition of a previously recognized item in the phonological lexicon. In offering the second alternative interpretation, we recognize that normal subjects are certainly capable of briefly storing nonwords and then repeating them from a phonological store. This account, however, could only apply to the very small proportion of responses that were
388
WINGFIELD,
GOODGLASS,
AND
SMITH
classified as veridical fragments. We prefer to interpret other responses, both correct and incorrect, as the product of a mechanism of phonological activation and assembly which is automatically initiated by the arrival of word-onset information. This latter view would be consistent with a model of word retrieval in object naming in which the phonology for the naming of a picture is assembled anew upon its activation by the concept of the recognized object. In this model, word-initial phonology would play a powerful role in activating sequences that have been previously learned. This model requires also that the semantics of the pictured object act to selectively reinforce developing phonological activity that carries congruent semantic associations, and to inhibit phonological activity that does not. The failures of such semantically mediated interaction would then account for paraphasic errors in aphasic speech. In the present experiment, however, the No Picture condition placed both normal subjects and aphasics under pressure to produce completions without the possibility of semantically mediated suppression of off-target responses. We suggest then that normals, in producing off-target responses, are behaving like aphasics who have a defective semantic component in their phonological retrieval mechanism. Word-initial sound cues clearly are a valuable trigger for a correct response in aphasic naming. As we have noted, the data on this are strong (cf. Goodglass, 1980a; Pease & Goodglass, 1978). On the other hand, our present data are equally unambiguous in showing that wordinitial sounds can be effective in yielding correct target responses for aphasic subjects even in the absence of a picture. In these cases, the sound cue alone is enough to suggest the correct response, with the picture functioning to confirm the hypothesis. This circumstance, in other words, will transform what might appear to an observer as an aided word retrieval task (a task known to be difficult for aphasics) to a different and far easier task: the confirmation of an incipient utterance against the recognized picture. Such a name-picture matching task is in fact a process aphasics typically perform quite well in. In conclusion, we suggest that the facilitation of naming so often found when examiners supply word-onset sound cues following an aphasic naming failure may well be accounted for by this two-stage process: stem-completion followed by matching the picture with the name so generated. We recognize that this will be true only to the degree that each of the described component abilities for successful word completion from gated segments remain intact for any given patient or lesion site. This caution also suggests a productive direction for future research.
389
NAMING IN APHASIA
APPENDIX Object Names and Spoken Utterance Durations (in msec) Duration (msec)
Name
Duration (msec)
540 660 560 700 808 740 540 640 630 700 670 680
Pumpkin Ring Spoon Sun Table Thumb Tomato Turtle Umbrella Violin Whistle Window
700 620 780 620 570 720 590 500 660 880 400 650
Banana Bicycle Camel Church Cigarette Elephant Fish Guitar Iron Nose Pipe Potato
Note. Practice stimuli: Anchor, Football, Heart, Kangaroo, Pencil, Pineapple, Sandwich, Screwdriver, Skunk, Toothbrush.
REFERENCES Baker, E., Blumstein, S., & Goodglass, H. 1981. Interaction between phonological and semantic factors in auditory comprehension. Neuropsychologia, 19, 1-15. Cotton, S., & Grosjean, F. 1984. The gating paradigm: A comparison of successive and individual presentation formats. Perception and Psychophysics, 35, 41-48. Francis, W. N., & KuCera, H. 1982. Frequency analysis of English usage: Lexicon and grammar. Boston: Houghton Mifllin. Goodglass, H. 1980a. Disorders of naming following brain injury. American Scientist, 68, 647-655. Goodglass, H. 1980b. Naming disorders in aphasia and aging. In L. K. Obler & M. L. Albert (Eds.), Languge and communication in the elderly. Lexington, MA: Lexington Books. Goodglass, H., & Kaplan, E. 1972. The assessment of aphasia and related disorders. Philadelphia: Lea & Febiger. Grosjean, F. 1980. Spoken word recognition processes and the gating paradigm. Perception and Psychophysics,
28, 267-283.
Grosjean, F. 1985. The recognition of words after their acoustic offset: Evidence and implications. Perception and Psychophysics, 38, 299-310. Luria, A. R. 1970. Traumatic aphasia. The Hague: Mouton. Marslen-Wilson, W. D. 1984. Function and process in spoken word recognition. In H. Bouma & D. G. Bouwhuis (Eds.), Attenrion and performance X. Hillsdale, NJ: Erlbaum. Marslen-Wilson, W. D. 1987.Functional parallelism in spoken word recognition. Cognition, 25, 71-102. Morton, J. 1969. Interaction of information in word recognition. Psychological Review, 76, 165-178. Nooteboom, S. G., & Doodeman, G. J. N. 1984. Speech quality and the gating paradigm. In M. P. R. van den Broeke & A. Cohen (Eds.), Proceedings of the Tenth International Congress of Phonetic Sciences. Dordrecht: Foris.
390
WINGFIELD,
GOODGLASS, AND SMITH
Nooteboom, S. G., & van der Vlugt, M. J. 1988. A search for a word-beginning superiority effect. Journal of the Acoustical Society of America, 84, 2018-2032. Pease, D. M., & Goodglass, H. 1978. The effects of cuing on picture naming in aphasia. Cortex,
14, 178- 189.
Tyler, L. 1984. Structure of the initial cohort: Evidence from gating. Perception Psychophysics,
and
36, 417-427.
Snodgrass, J. G., & Vanderwart, M. 1980. A standardized set of 260 pictures: Norms for name agreement, image agreement, familiarity, and visual complexity. Journal of Experimental Psychology: Human Learning and Memory, 6, 174-215. Wayland, S. C., Wingfield, A., & Goodglass, H. 1989. Recognition of isolated words: The dynamics of cohort reduction. Applied Psycholinguistics 10, 475-487. Wingfield, A., & Wayland, S. C. (1988). Object-naming in aphasia: Word-initial phonology and response activation. Aphasiology, 2, 423-425.