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Phonological encoding by hearing children of deaf parents
Cognitive Development, 2, 169-178 (1987)
Phonological Encoding by Hearing Children of Deaf Parents Robert E. Guttentag Evelyn G. Schaefer University of Winnipeg
Eleven hearing children of deaf parents were tested on a serial recall task with pictured items to determine the form in which they encode information for shortterm recall. All children were fluent in American Sign Language (ASL) as well as spoken English. More item-ordering errors were made on lists of phonologically similar items than on lists of sign-similar or unrelated items. An examination of the children's rehearsal strategies revealed greater use of phonological than signbased rehearsal, even when the children were required to recall the list items in ASL. It was concluded that, even though the majority of the children reported that their proficiency in ASL was superior to their proficiency with spoken English, they made greater use of phonological than sign-based encoding on the serial recall task.
Research with people who are bilingual has been used to address fundamental questions of concern to students of human cognitive functioning. The hearing children of deaf parents represent a unique bilingual population because, unlike those who are fluent in two spoken languages, they are fluent in two fundamentally different language systems, sign language and spoken language, which are rooted in different sensory modalities. This study represents a first attempt to examine the possible influence of sign language fluency on the cognitive functioning of such children. The study focused specifically on information encoding for short-term serial recall. Past research with serial recall tasks has shown that normal heating adults typically perform more poorly with lists of phonologically related items than with lists of unrelated items, indicating that they encode letter and word information phonologically even when items have been presented visually (Baddeley, 1966; Conrad, 1963). A similar effect has been found with children as young as 5
This research was supported by a grant to Robert E. Guttentag from the Natural Sciences and Engineering Research Council of Canada. We wish to thank Loneta Siemens and Marni Brownell for their assistance with data collection, Bruce Koskie for helping us locate subjects, as well as Made Clarke of the Interpreter Referral Service. Correspondence and requests for reprints should be addressed to Robert E. Guttentag, Department of Psychology, University of North Carolina at Greensboro, Greensboro, NC 27412. Manuscript received September 12, 1986; revision accepted November 6, 1986
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years of age, although the magnitude of the effect increases with age during the elementary school years (Conrad, 1971; Hulme, 1984). Studies of information encoding by deaf subjects fluent in ASL have found that, when the to-be-remembered items are presented as signs, both children and adults tend to use a sign-based form of encoding (Bellugi, Klima, & Siple, 1975; Frumkin & Anisfieid, 1977; Hanson, 1982; Poizner, Bellugi, & Tweney, 1981; Shand, 1982); however, the results are less consistent when other forms of item presentation are used. For instance, whereas Shand (1982) found evidence for sign-based, but not phonological, encoding of printed words by deaf adults, a similar study by Hanson (1982) produced almost the opposite pattern of findings. Most research with deaf children suggests that they do not encode information phonologically, except in the case of deaf children who are good readers or who have good oral skills (Conrad, 1972; Hanson, Liberman, & Shankweiler, 1984; Locke & Locke, 1971). Hanson, Liberman, & Shankweiler (1984), for instance, found in a study of deaf children's encoding of letter names that the children who were good readers used both phonological and dactylic (finger spelling) encoding, whereas little evidence of either phonological or dactylic encoding was found with the poor readers. In the one study that has used pictures as stimuli, Liben and Drury (1977) found that deaf children frequently labeled the items both orally and through finger spelling, suggesting (similar to Hanson et al.'s good readers) the simultaneous use of both phonological and dactylic encoding. Notably, the subjects tested by Liben and Drury were educated with the Rochester method, which emphasizes the use of simultaneous speech and finger spelling. In contrast to the large body of research with deaf children and adults, there at present exists no data concerning the effects of sign language fluency on the encoding processes of hearing individuals. The subjects in this study were all hearing children of deaf parents, and as is typical of such children (Bonvillian, Orlansky, & Novack, 1983; Prinz & Prinz, 1979), all had acquired ASL as their first language. In addition, all children in this study used ASL on a daily basis within the home as the principle form of communication with their parents. Thus, it seems reasonable to expect that they would utilize a sign-based form of encoding on recall tasks. On the other hand, it has also been proposed that the tendency for normal-hearing subjects to encode to-be-remembered information phonologically reflects a basic superiority of phonological encoding over other forms of encoding (Krakow & Hanson, 1985; Sperling & Speelman, 1970); this hypothesis suggests that even when hearing children are fluent in ASL, they would be expected to encode to-be-remembered information phonologically. The children in this study were tested on a serial recall task for the names of pictured items. Vocal recall was required on half the trials, and recall in sign was required on the remaining trials. The study included both phonologically similar and sign-similar lists, along with sign- and phonological-control lists of unrelated items. If the children encoded the items phonologically, they would be expect to
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make more errors in their recall of phonologically similar than phonologicalcontrol lists; similarly, if the children utilized a sign-based form of encoding they would be expected to make more errors on sign-similar than on sign-control lists. In addition, because vocal rehearsal entails phonological encoding while rehearsal in sign entails sign-based encoding, the form of children's rehearsal could also be examined to provide further evidence concerning the form of their information encoding. METHOD
Subjects The subjects were 5 younger children between 6 and 8 years of age (4 females, 1 male, M = 7.6 years) and 6 older children between 12 and 16 years of age (2 females, 4 males, M = 14.1 years). In all cases both parents were deaf and the primary language of communication between parent and child was ASL. All subjects were free of identified hearing, spoken-language, learning, and emotional problems. It was reported for all subjects that they had learned sign language as infants prior to their first use of spoken language. Subjects were asked, following testing, which of their two languages they felt they were better at using and were more comfortable using. Six of the 11 subjects (including 4 of the 5 younger subjects) reported that their expressive and receptive language skills were currently better in ASL than in spoken English and that their preferred means of communication was ASL.
Materials The to-be-remembered pictures were each drawn on separate pieces of white cardboard 20 cm x 30 cm in size. Eight 5-item lists of line drawing pictures were generated for use in the experiment (see Appendix). A professional ASL interpreter assisted with the selection of list items to ensure that there was a commonly known ASL sign for each item. Two of the lists contained sign-similar items while two others contained phonologically similar items. In addition, there were two sign-control lists that contained unrelated items matched in word frequency (Thorndike & Lorge, 1972) to the items from the sign-similar lists and two phonological-control lists that contained unrelated items matched in word frequency to the phonologically similar list items. The items within each signsimilar list differed from each other in terms of only one of the three basic formational attributes of signs, n For instance, the signs for all the items on signn Signs in ASL are formed from a limited set of component elements that recur across signs and that serve to contrast minimally different signs along one of three basic formational parameters: configuration of the hand or hands, location of the hands relative to the body, and movementof the hands in making the sign (Stokoe, Casterline. & Cronberg. C., 1965). Deaf subjects fluent in ASL encode signs in terms of their basic formational components(Bellugi, Klima, & Siple, 1975;Poizner, 1981).
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similar List 2 are made with the same hand configuration (using both hands, with each hand having the middle and index finger together extended straight and the third and fourth fingers curled in the palm), and in the same location (in the center front of the body), but with different motions (e.g., the sign for salt involves tapping the extended fingers of one hand on top of the extended fingers of the other, while the sign for knife involves rubbing the fingers of one hand along the fingers of the other). Four sets of lists were generated using the 8 lists of items. For the older subjects, each of the 8 lists was presented once within each set. Lists were randomly ordered within each set with the restriction that each of the 4 types of lists was presented once within each half of each set. The ordering of types of lists within sets was counterbalanced across the 4 sets. The items within each list were presented in a different predetermined random order within each set. For the younger subjects there were 6 rather than 8 lists of items within each set, including 2 'sign-similar lists, 2 phonologically similar lists, and 1 of each type of control list. The lists for the younger subjects contained 4, rather than 5, items. To generate the lists for the younger subjects, one item was randomly eliminated from each 5-item sign-similar and phonologically similar list, while new 4-item phonological- and sign-control lists were generated by selecting 2 items from each of the 2 corresponding 5-item lists used with older subjects. The 4 sets of lists were then generated following the same procedure that was used to construct the sets for the older subjects. One warm-up list, containing items not included on any of the experimental-trial lists, was presented as the first list in each set for both younger and older subjects. Procedure Subjects were tested individually in a single session lasting approximately 40 minutes. The entire session was videotaped. Subjects were first shown all of the pictures that would be used in the experiment, and were asked to label each picture vocally and in sign. Although efforts were made to select items for which there was a commonly known ASL sign, only one subject knew the ASL sign for all items. The subjects reporting greater fluency in ASL than spoken language did not know the accepted sign for an average of 7.6% of the items, while the remaining subjects did not know the accepted ASL sign for an average of 13.4% of the signs. In cases where a sign was not known, subjects frequently reported using a different sign at home than the one demonstrated, or using finger spelling for that particular item. When a sign was not known, the correct sign was demonstrated for the subject who practiced making the sign; the subject's memory for the sign was again tested prior to the presentation of the first list. Subjects were encouraged to use the accepted ASL sign during sign recall. In the small number of cases in which an alternative sign was used during sign recall, the response was counted as correct. Subjects were then presented 4 blocks of trials; 1 set of lists was presented in
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each block. Mode of recall was constant for all lists within a block; subjects recalled in sign for all lists within 2 of the blocks and recalled items vocally for all lists within the other 2 blocks. Recall form alternated across blocks for each subject; 6 of the 11 subjects responded vocally during their first block of trials. The pictures within each list were presented sequentially at a 5-second rate. A blank card presented 5 seconds after the final list item served as the signal to begin recall. An interpreter for the deaf was present throughout the testing, and subjects were instructed to direct their recall to her during both sign-recall and vocal-recall blocks of trials. Subjects were instructed to try to recall the items in the same sequence in which the items were presented, but were told not to withold an item just because they were unsure of its position within the list. Subjects were interviewed about their use of phonological and sign-based rehearsal after the task was completed. RESULTS Recall was first scored for number of items correctly recalled, regardless of order (see Table 1). An analysis of variance was conducted involving the within subject factors of mode of recall (vocal or ASL), list-type (phonological or sign), and item-similarity (similar-item or control lists). Although the analysis revealed a significant main effect of list-type, F ( I , 10) = 8.15, p < .01, this finding by itself has no relevance to the issue of the form in which information was encoded. The primary data of interest involved the effects of item similarity on recall; however, the analysis revealed that neither the main effect of item-similarity nor any of the interactions involving item-similarity was significant for number of items recalled. Most studies manipulating item-similarity have found effects on ordered recall performance rather than on levels of absolute recall. To examine the influence of item similarity on ordered recall, we measured the number of times that all items recalled for each particular list were recalled in their correct sequence. That is, regardless of the number of items actually recalled, each list was scored as containing an ordering error only if the recalled items were not recalled in their correct sequence. The percentage of lists in each condition that contained recall Table 1.
Percentage of Items Recalled by the Younger and Older Subjects Type of List Phonologically Similar
Subjects Younger Older
76 91
PhonologicalControl
79 92
SignSimilar
SignControl
93 99
88 95
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ordering errors is presented in Table 2. A repeated measures analysis of variance on the number of ordering errors revealed a significant List-Type × Item-Similarity interaction, F(I,10) = 6.48, p < .05. Simple effects tests revealed that subjects made significantly more ordering errors on phonologically similar lists than on phonological-control lists, F(I, 10) = 7.67, p < .05, whereas there was no significant difference in error rate between the sign-similar lists and the signcontrol lists. Thus, the analysis of ordering errors provides evidence for the use of phonological, but not sign-based, encoding. Liben and Drury (1977) found that the deaf children in their study frequently vocalized and/or finger-spelled the names of pictured items, behaviors that were assumed to reflect the form in which items were encoded. Accordingly, in this study we scored the videotapes for evidence of overt signing and/or vocalizing of item names during list presentation. In addition, because subjects were observed to frequently vocalize item names even during sign recall, we scored the tapes for evidence of vocal naming during sign recall and signing during vocal recall. The videotapes were scored by a hearing assistant with knowledge of ASL. Table 3 presents the percentage of trials on which evidence of overt vocal and/or sign rehearsal was observed for each subject. It may be seen that, overall, subjects exhibited much more vocal than sign rehearsal, even on sign recall trials. The analysis of the videotapes also revealed that all but 2 of the subjects vocalized item names on a majority of sign recall trials; the two exceptions were subjects 7 and 8. No evidence of signing during vocal recall was observed. The analysis of the posttest interviews adds further evidence that subjects engaged in more phonological than sign-based rehearsal. Four of the subjects reported rehearsing phonologically on both vocal and sign recall trials (subjects 5,6,9, and 10), and two more reported rehearsing phonologically but did not indicate clearly if their rehearsal was limited to vocal recall trials or if they rehearsed in this manner on sign-recall trials as well (subjects 1 and 4). Subjects 2 and 3 gave no evidence that they were aware whether they rehearsed or not. Subject 7 reported using both forms of rehearsal simultaneously with both forms of recall, subject 8 reported rehearsing phonologically on vocal recall trials and using sign-based rehearsal on sign-recall trials, while subject 11 (through a procedural error) was not asked about his strategy use. Table 2.
Percentage of Each Type of List Containing an Ordering Error
Type of List
Subjects Younger Older
Phonologically Similar
PhonologicalControl
SignSimilar
SignControl
25% 31
13 13
13 10
10 17
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Table 3. Percentage of Trials for each Subject on Which Rehearsal of Each Form Was Observed Mode of Recall Vocal
Subject
More Fluent Language
ASL Form of Rehearsal
Vocal
Sign
Both
ASL ASL ASL ASL Spoken
58 75 75 0 0
0 0 0 0 0
0 25 0 0 0
ASL ASL Equal Spoken Spoken Spoken
75 25 38 0 69 0
0 0 0 0 31 0
0 38 0 0 0 0
Vocal
Sign
Both
33 0 92 0 33
0 33 0 0 0
0 67 0 0 0
06 31 25 0 100 0
0 0 0 0 0 0
0 31 0 0 0 0
Younger
I. 2. 3. 4. 5. Older
6. 7. 8. 9. 10. I 1.
To summarize the rehearsal data, phonological rehearsal was observed on at least 25% of the trials for 7 o f the subjects on vocal recall trials and 6 o f the subjects on sign recall trials, while 3 additional subjects who did not overtly rehearse phonologically reported in the posttest interview that they had rehearsed phonologically (subjects 4, 5, and 9). Three subjects were observed rehearsing in sign on some vocal recall trials and 2 subjects on sign recall trials. However, sign-based rehearsal in the absence of simultaneous phonological rehearsal was observed with only l subject with each form of recall. In addition, subject 8 reported rehearsing in sign on sign-recall trials. Finally, all subjects vocalized item names during recall on at least one-quarter of the sign-recall trials, and all but two did so on at least two-thirds of the sign-recall trials.
DISCUSSION Subjects in this study were tested on a serial recall task with lists o f sign-similar and phonologically similar items. Overall, there was no effect of list-item similarity on the absolute number of items recalled. However, when the order in which items were recalled was taken into account, it was found that subjects made more ordering errors on lists containing phonologically similar items than on control lists of unrelated items, whereas no effect o f sign-similarity on ordered recall was observed. This finding suggests that subjects primarily encoded the list items phonologically, even though the list items were presented as pic-
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tures and even when recall was required in ASL. The lack of an effect of itemsimilarity on levels of absolute recall is consistent with the view that phonological encoding may play its principle role in the retention of item-order, rather than on item-identity, information (Krakow & Hanson, 1985). The rehearsal findings lend further support to the conclusion that subjects primarily encoded the items phonologically. Overall, subjects made greater use of vocal/phonological rehearsal than sign-based rehearsal, and all but 2 subjects consistently "supported" their recall in sign with simultaneous vocalization of item names. On the other hand, the rehearsal findings suggest that some use of sign-based encoding was made by 4 of the subjects. Thus, even hearing subjects may make some use of sign-based encoding if they are fluent in ASL. Interesting!y, most of the evidence for sign-based encoding occurred with subjects reporting equal or greater fluency in ASL than in spoken English, tentatively suggesting that, even for subjects fluent in both spoken langauge and ASL, the form in which information is encoded for short-term recall may be related to relative fluency in the two languages. The overall bias toward phonological encoding occurred despite the fact that ASL was the first language acquired by each of the subjects and despite the majority of subjects reporting greater fluency in ASL than in spoken English. Moreover, there were no significant age differences found in the pattern of recall ordering errors or rehearsal strategy use. Thus, these findings suggest that, even for hearing children of deaf parents, a bias toward the use of phonological encoding for serial recall may generally be present by the early elementary school years. Although only 4 of the 11 subjects reported greater fluency in spoken language than in sign language, only 1 subject knew the ASL sign for all items, and on the average subjects did not know the signs for approximately 10% of the items. This finding raises the possibility that the subjects may actually have been more proficient in spoken language than in ASL (their subjective reports of language fluency notwithstanding). Thus, it is possible that the results found here would not generalize to subjects with truly equivalent or superior proficiency in sign, as compared to spoken, language. On the other hand, the fact that subjects knew more spoken than signed item names may simply reflect the more limited context (primarily the home and family environment) within which they use ASL, without necessarily reflecting a lower level of general fluency or proficiency in sign than spoken language. In any case, there was no reason for subjects to misrepresent their self-perceived relative language fluency, and it is of interest that although the majority of subjects considered themselves more fluent in ASL than in spoken language, a bias toward phonological encoding was found with this task. A second factor that may limit the generalizability of the present findings is the nature of the testing environment. Although subjects directed their recall to an interpreter for the deaf, the experimenter communicated with the subjects
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primarily through spoken language, a feature of the testing environment that may have biased subjects toward a spoken-language mode of thought. It should be noted, however, that for this to be the case, the effect of the testing context must have been sufficiently potent to bias subjects toward phonological encoding even during blocks of trials when they were required to recall items in sign. Shand (1982) argued, on the basis of his work on sign-based encoding by deaf subjects, that there is nothing inherently special about phonological encoding. Instead, he suggested that subjects tend to encode information for short-term recall linguistically, and the exact form of such encoding is simply a function of the form of their dominant language system. Thus, according to Shand, the tendency of hearing subjects to encode phonologically results from the phonological nature of their language system. Similarly, deaf subjects fluent in ASL would be expected to encode information in STM using a sign-based code. A strong version of Shand's "encoding equality" hypothesis is called into question by the finding that the performance of deaf subjects fluent in ASL is inferior to that of normal-hearing subjects on short-term serial recall tasks (Krakow & Hanson, 1985). The present findings provide perhaps the most direct evidence against the strong version of Shand's hypothesis, since a bias toward phonological encoding was found even with subjects fluent in both ASL and spoken language, and even when subjects were required to recall the information in sign. The bias toward the use of phonological encoding for serial recall found here may reflect some fundamental difference between phonological and sign-based encoding that makes phonological encoding superior for short-term serial recall (Krakow & Hanson, 1985). For instance, phonological codes may be more rapidly produced and repeated than are sign-based codes, thus making the use of phonological encoding particularly advantageous for serial rehearsal. Further research with subjects fluent in both AL and spoken language may hold the key to answering this and other important questions.
REFERENCES
Baddeley, A. D. (1966). Short-termmemoryfor word sequences as a function of acoustic, semantic, and formal similarity. Quarterly Journal of Experimental Psychology, 18, 362-365. Bellugi, U., Klima, E. S., & Siple, P. (1975). Rememberingin signs. Cognition, 3, 93-125. Bonvillian, J. D., Orlansky, M. D., & Novack, L. L. (1983). Developmentalmilestones: Sign language acquisition and motor development. Child Development, 54, 1435-1445. Conrad, R. (1963). Acoustic confusions and memory span for words. Nature, 197, 1029-1030. Conrad, R. (1971). The chronologyof the developmentof covert speech in children. Developmental Psychology, 5, 398-405. Conrad, R. (1972). Short-term memory in the deaf: A test for speech coding. British Journal of Psychology, 63, 173-180. Frumkin, B., & Anisfield, M. (1977), Semantic and surface codes in the memoryof deaf children. Cognitive Psychology, 9, 475-493. Hanson, V. (1982). Short-termrecall by deaf signers of American Sign Language: Implicationsof
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encoding strategy for order recall. Journal of Experimental Psychology: Learning, Memory, and Cognition, 8, 572-583. Hanson, V., Liberman, 1. Y., & Shankweiler, D. (1984). Linguistic coding by deaf children in relation to beginning to read. Journal of Experimental Child Psychology, 37, 378-393. Hulme, C. (1984). Developmental differences in the effects of acoustic similarity on memory span. Developmental Psychology, 20, 650-652. Krakow, R.A.,& Hanson, V. (1985). Deaf signers and serial recall in the visual modality: Memory for signs, fingerspelling, and print. Memo~. & Cognition, 13, 265-272. Liben, L. S., & Drury, A. M. (1977). Short-term memory in deaf and hearing children in relation to stimulus characteristics. Journal of Experimental Child Psychology, 24, 60-73. Locke, J. L., & Locke, V. L. (1971). Deaf children's phonetic, visual, and dactylic coding in a grapheme recall task. Journal of Experimental Psychology, 89, 142-146. Poizner, H. (1981). Visual and "phonetic" coding of movement: Evidence from American Sign Language. Science, 212, 691-693. Poizner, H., Bellugi, U., & Tweney, R. (1981). Processing of forrnational, semantic and iconic information in ASL. Journal of Experimental Psychology: Human Perception and Performance, 7, 1146-1159. Prinz, P. M., & Prinz, E. A. (1979). Simultaneous acquisition of ASL and spoken English in a hearing child of a deaf mother and hearing father: Phase l--Early lexical development. Sign Language Studies, 25, 282-296. Shand, M. A. (1982). Sign-based short-term coding of ASL signs and printed English words by congenitally deaf signers. Cognitive Psychology, 14. 1-12. Sperling, G., & Speelman, R. G. (1970). Acoustic similarity and auditory short-term memory experiments and a model. In D. A. Norman (Ed.), Models of human memory. New York: Academic. Stokoe, W. C., Casterline, D. C., & Croneberg, C. G. (1965), A dictionary of American Sign Language. Washington, DC: Gallaudet College Press. Thomdike, E. L., & Lorge, 1. (1972). The teacher's word book of 30,000 words. New York: Columbia University Press.
APPENDIX Items on Each of the Four Types of Lists
Phonologically Similar Lists 1. rake, rain, plane, piate, race 2. boat, bat, coat, cake, bank Phonological-Control Lists 1. lamp, bread, eye, axe, hat 2. tree, cup, bed, doll, pen Sign-Similar Lists 1. girl, fruit, cat, gum, Indian 2. chair, knife, train, egg, salt Sign-Control Lists 1. plant, frog, ring, car, shoe 2. watch, king, star, door, flag
Phonological Encoding by Hearing Children of Deaf Parents Robert E. Guttentag Evelyn G. Schaefer University of Winnipeg
Eleven hearing children of deaf parents were tested on a serial recall task with pictured items to determine the form in which they encode information for shortterm recall. All children were fluent in American Sign Language (ASL) as well as spoken English. More item-ordering errors were made on lists of phonologically similar items than on lists of sign-similar or unrelated items. An examination of the children's rehearsal strategies revealed greater use of phonological than signbased rehearsal, even when the children were required to recall the list items in ASL. It was concluded that, even though the majority of the children reported that their proficiency in ASL was superior to their proficiency with spoken English, they made greater use of phonological than sign-based encoding on the serial recall task.
Research with people who are bilingual has been used to address fundamental questions of concern to students of human cognitive functioning. The hearing children of deaf parents represent a unique bilingual population because, unlike those who are fluent in two spoken languages, they are fluent in two fundamentally different language systems, sign language and spoken language, which are rooted in different sensory modalities. This study represents a first attempt to examine the possible influence of sign language fluency on the cognitive functioning of such children. The study focused specifically on information encoding for short-term serial recall. Past research with serial recall tasks has shown that normal heating adults typically perform more poorly with lists of phonologically related items than with lists of unrelated items, indicating that they encode letter and word information phonologically even when items have been presented visually (Baddeley, 1966; Conrad, 1963). A similar effect has been found with children as young as 5
This research was supported by a grant to Robert E. Guttentag from the Natural Sciences and Engineering Research Council of Canada. We wish to thank Loneta Siemens and Marni Brownell for their assistance with data collection, Bruce Koskie for helping us locate subjects, as well as Made Clarke of the Interpreter Referral Service. Correspondence and requests for reprints should be addressed to Robert E. Guttentag, Department of Psychology, University of North Carolina at Greensboro, Greensboro, NC 27412. Manuscript received September 12, 1986; revision accepted November 6, 1986
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years of age, although the magnitude of the effect increases with age during the elementary school years (Conrad, 1971; Hulme, 1984). Studies of information encoding by deaf subjects fluent in ASL have found that, when the to-be-remembered items are presented as signs, both children and adults tend to use a sign-based form of encoding (Bellugi, Klima, & Siple, 1975; Frumkin & Anisfieid, 1977; Hanson, 1982; Poizner, Bellugi, & Tweney, 1981; Shand, 1982); however, the results are less consistent when other forms of item presentation are used. For instance, whereas Shand (1982) found evidence for sign-based, but not phonological, encoding of printed words by deaf adults, a similar study by Hanson (1982) produced almost the opposite pattern of findings. Most research with deaf children suggests that they do not encode information phonologically, except in the case of deaf children who are good readers or who have good oral skills (Conrad, 1972; Hanson, Liberman, & Shankweiler, 1984; Locke & Locke, 1971). Hanson, Liberman, & Shankweiler (1984), for instance, found in a study of deaf children's encoding of letter names that the children who were good readers used both phonological and dactylic (finger spelling) encoding, whereas little evidence of either phonological or dactylic encoding was found with the poor readers. In the one study that has used pictures as stimuli, Liben and Drury (1977) found that deaf children frequently labeled the items both orally and through finger spelling, suggesting (similar to Hanson et al.'s good readers) the simultaneous use of both phonological and dactylic encoding. Notably, the subjects tested by Liben and Drury were educated with the Rochester method, which emphasizes the use of simultaneous speech and finger spelling. In contrast to the large body of research with deaf children and adults, there at present exists no data concerning the effects of sign language fluency on the encoding processes of hearing individuals. The subjects in this study were all hearing children of deaf parents, and as is typical of such children (Bonvillian, Orlansky, & Novack, 1983; Prinz & Prinz, 1979), all had acquired ASL as their first language. In addition, all children in this study used ASL on a daily basis within the home as the principle form of communication with their parents. Thus, it seems reasonable to expect that they would utilize a sign-based form of encoding on recall tasks. On the other hand, it has also been proposed that the tendency for normal-hearing subjects to encode to-be-remembered information phonologically reflects a basic superiority of phonological encoding over other forms of encoding (Krakow & Hanson, 1985; Sperling & Speelman, 1970); this hypothesis suggests that even when hearing children are fluent in ASL, they would be expected to encode to-be-remembered information phonologically. The children in this study were tested on a serial recall task for the names of pictured items. Vocal recall was required on half the trials, and recall in sign was required on the remaining trials. The study included both phonologically similar and sign-similar lists, along with sign- and phonological-control lists of unrelated items. If the children encoded the items phonologically, they would be expect to
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make more errors in their recall of phonologically similar than phonologicalcontrol lists; similarly, if the children utilized a sign-based form of encoding they would be expected to make more errors on sign-similar than on sign-control lists. In addition, because vocal rehearsal entails phonological encoding while rehearsal in sign entails sign-based encoding, the form of children's rehearsal could also be examined to provide further evidence concerning the form of their information encoding. METHOD
Subjects The subjects were 5 younger children between 6 and 8 years of age (4 females, 1 male, M = 7.6 years) and 6 older children between 12 and 16 years of age (2 females, 4 males, M = 14.1 years). In all cases both parents were deaf and the primary language of communication between parent and child was ASL. All subjects were free of identified hearing, spoken-language, learning, and emotional problems. It was reported for all subjects that they had learned sign language as infants prior to their first use of spoken language. Subjects were asked, following testing, which of their two languages they felt they were better at using and were more comfortable using. Six of the 11 subjects (including 4 of the 5 younger subjects) reported that their expressive and receptive language skills were currently better in ASL than in spoken English and that their preferred means of communication was ASL.
Materials The to-be-remembered pictures were each drawn on separate pieces of white cardboard 20 cm x 30 cm in size. Eight 5-item lists of line drawing pictures were generated for use in the experiment (see Appendix). A professional ASL interpreter assisted with the selection of list items to ensure that there was a commonly known ASL sign for each item. Two of the lists contained sign-similar items while two others contained phonologically similar items. In addition, there were two sign-control lists that contained unrelated items matched in word frequency (Thorndike & Lorge, 1972) to the items from the sign-similar lists and two phonological-control lists that contained unrelated items matched in word frequency to the phonologically similar list items. The items within each signsimilar list differed from each other in terms of only one of the three basic formational attributes of signs, n For instance, the signs for all the items on signn Signs in ASL are formed from a limited set of component elements that recur across signs and that serve to contrast minimally different signs along one of three basic formational parameters: configuration of the hand or hands, location of the hands relative to the body, and movementof the hands in making the sign (Stokoe, Casterline. & Cronberg. C., 1965). Deaf subjects fluent in ASL encode signs in terms of their basic formational components(Bellugi, Klima, & Siple, 1975;Poizner, 1981).
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similar List 2 are made with the same hand configuration (using both hands, with each hand having the middle and index finger together extended straight and the third and fourth fingers curled in the palm), and in the same location (in the center front of the body), but with different motions (e.g., the sign for salt involves tapping the extended fingers of one hand on top of the extended fingers of the other, while the sign for knife involves rubbing the fingers of one hand along the fingers of the other). Four sets of lists were generated using the 8 lists of items. For the older subjects, each of the 8 lists was presented once within each set. Lists were randomly ordered within each set with the restriction that each of the 4 types of lists was presented once within each half of each set. The ordering of types of lists within sets was counterbalanced across the 4 sets. The items within each list were presented in a different predetermined random order within each set. For the younger subjects there were 6 rather than 8 lists of items within each set, including 2 'sign-similar lists, 2 phonologically similar lists, and 1 of each type of control list. The lists for the younger subjects contained 4, rather than 5, items. To generate the lists for the younger subjects, one item was randomly eliminated from each 5-item sign-similar and phonologically similar list, while new 4-item phonological- and sign-control lists were generated by selecting 2 items from each of the 2 corresponding 5-item lists used with older subjects. The 4 sets of lists were then generated following the same procedure that was used to construct the sets for the older subjects. One warm-up list, containing items not included on any of the experimental-trial lists, was presented as the first list in each set for both younger and older subjects. Procedure Subjects were tested individually in a single session lasting approximately 40 minutes. The entire session was videotaped. Subjects were first shown all of the pictures that would be used in the experiment, and were asked to label each picture vocally and in sign. Although efforts were made to select items for which there was a commonly known ASL sign, only one subject knew the ASL sign for all items. The subjects reporting greater fluency in ASL than spoken language did not know the accepted sign for an average of 7.6% of the items, while the remaining subjects did not know the accepted ASL sign for an average of 13.4% of the signs. In cases where a sign was not known, subjects frequently reported using a different sign at home than the one demonstrated, or using finger spelling for that particular item. When a sign was not known, the correct sign was demonstrated for the subject who practiced making the sign; the subject's memory for the sign was again tested prior to the presentation of the first list. Subjects were encouraged to use the accepted ASL sign during sign recall. In the small number of cases in which an alternative sign was used during sign recall, the response was counted as correct. Subjects were then presented 4 blocks of trials; 1 set of lists was presented in
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each block. Mode of recall was constant for all lists within a block; subjects recalled in sign for all lists within 2 of the blocks and recalled items vocally for all lists within the other 2 blocks. Recall form alternated across blocks for each subject; 6 of the 11 subjects responded vocally during their first block of trials. The pictures within each list were presented sequentially at a 5-second rate. A blank card presented 5 seconds after the final list item served as the signal to begin recall. An interpreter for the deaf was present throughout the testing, and subjects were instructed to direct their recall to her during both sign-recall and vocal-recall blocks of trials. Subjects were instructed to try to recall the items in the same sequence in which the items were presented, but were told not to withold an item just because they were unsure of its position within the list. Subjects were interviewed about their use of phonological and sign-based rehearsal after the task was completed. RESULTS Recall was first scored for number of items correctly recalled, regardless of order (see Table 1). An analysis of variance was conducted involving the within subject factors of mode of recall (vocal or ASL), list-type (phonological or sign), and item-similarity (similar-item or control lists). Although the analysis revealed a significant main effect of list-type, F ( I , 10) = 8.15, p < .01, this finding by itself has no relevance to the issue of the form in which information was encoded. The primary data of interest involved the effects of item similarity on recall; however, the analysis revealed that neither the main effect of item-similarity nor any of the interactions involving item-similarity was significant for number of items recalled. Most studies manipulating item-similarity have found effects on ordered recall performance rather than on levels of absolute recall. To examine the influence of item similarity on ordered recall, we measured the number of times that all items recalled for each particular list were recalled in their correct sequence. That is, regardless of the number of items actually recalled, each list was scored as containing an ordering error only if the recalled items were not recalled in their correct sequence. The percentage of lists in each condition that contained recall Table 1.
Percentage of Items Recalled by the Younger and Older Subjects Type of List Phonologically Similar
Subjects Younger Older
76 91
PhonologicalControl
79 92
SignSimilar
SignControl
93 99
88 95
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ordering errors is presented in Table 2. A repeated measures analysis of variance on the number of ordering errors revealed a significant List-Type × Item-Similarity interaction, F(I,10) = 6.48, p < .05. Simple effects tests revealed that subjects made significantly more ordering errors on phonologically similar lists than on phonological-control lists, F(I, 10) = 7.67, p < .05, whereas there was no significant difference in error rate between the sign-similar lists and the signcontrol lists. Thus, the analysis of ordering errors provides evidence for the use of phonological, but not sign-based, encoding. Liben and Drury (1977) found that the deaf children in their study frequently vocalized and/or finger-spelled the names of pictured items, behaviors that were assumed to reflect the form in which items were encoded. Accordingly, in this study we scored the videotapes for evidence of overt signing and/or vocalizing of item names during list presentation. In addition, because subjects were observed to frequently vocalize item names even during sign recall, we scored the tapes for evidence of vocal naming during sign recall and signing during vocal recall. The videotapes were scored by a hearing assistant with knowledge of ASL. Table 3 presents the percentage of trials on which evidence of overt vocal and/or sign rehearsal was observed for each subject. It may be seen that, overall, subjects exhibited much more vocal than sign rehearsal, even on sign recall trials. The analysis of the videotapes also revealed that all but 2 of the subjects vocalized item names on a majority of sign recall trials; the two exceptions were subjects 7 and 8. No evidence of signing during vocal recall was observed. The analysis of the posttest interviews adds further evidence that subjects engaged in more phonological than sign-based rehearsal. Four of the subjects reported rehearsing phonologically on both vocal and sign recall trials (subjects 5,6,9, and 10), and two more reported rehearsing phonologically but did not indicate clearly if their rehearsal was limited to vocal recall trials or if they rehearsed in this manner on sign-recall trials as well (subjects 1 and 4). Subjects 2 and 3 gave no evidence that they were aware whether they rehearsed or not. Subject 7 reported using both forms of rehearsal simultaneously with both forms of recall, subject 8 reported rehearsing phonologically on vocal recall trials and using sign-based rehearsal on sign-recall trials, while subject 11 (through a procedural error) was not asked about his strategy use. Table 2.
Percentage of Each Type of List Containing an Ordering Error
Type of List
Subjects Younger Older
Phonologically Similar
PhonologicalControl
SignSimilar
SignControl
25% 31
13 13
13 10
10 17
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Table 3. Percentage of Trials for each Subject on Which Rehearsal of Each Form Was Observed Mode of Recall Vocal
Subject
More Fluent Language
ASL Form of Rehearsal
Vocal
Sign
Both
ASL ASL ASL ASL Spoken
58 75 75 0 0
0 0 0 0 0
0 25 0 0 0
ASL ASL Equal Spoken Spoken Spoken
75 25 38 0 69 0
0 0 0 0 31 0
0 38 0 0 0 0
Vocal
Sign
Both
33 0 92 0 33
0 33 0 0 0
0 67 0 0 0
06 31 25 0 100 0
0 0 0 0 0 0
0 31 0 0 0 0
Younger
I. 2. 3. 4. 5. Older
6. 7. 8. 9. 10. I 1.
To summarize the rehearsal data, phonological rehearsal was observed on at least 25% of the trials for 7 o f the subjects on vocal recall trials and 6 o f the subjects on sign recall trials, while 3 additional subjects who did not overtly rehearse phonologically reported in the posttest interview that they had rehearsed phonologically (subjects 4, 5, and 9). Three subjects were observed rehearsing in sign on some vocal recall trials and 2 subjects on sign recall trials. However, sign-based rehearsal in the absence of simultaneous phonological rehearsal was observed with only l subject with each form of recall. In addition, subject 8 reported rehearsing in sign on sign-recall trials. Finally, all subjects vocalized item names during recall on at least one-quarter of the sign-recall trials, and all but two did so on at least two-thirds of the sign-recall trials.
DISCUSSION Subjects in this study were tested on a serial recall task with lists o f sign-similar and phonologically similar items. Overall, there was no effect of list-item similarity on the absolute number of items recalled. However, when the order in which items were recalled was taken into account, it was found that subjects made more ordering errors on lists containing phonologically similar items than on control lists of unrelated items, whereas no effect o f sign-similarity on ordered recall was observed. This finding suggests that subjects primarily encoded the list items phonologically, even though the list items were presented as pic-
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tures and even when recall was required in ASL. The lack of an effect of itemsimilarity on levels of absolute recall is consistent with the view that phonological encoding may play its principle role in the retention of item-order, rather than on item-identity, information (Krakow & Hanson, 1985). The rehearsal findings lend further support to the conclusion that subjects primarily encoded the items phonologically. Overall, subjects made greater use of vocal/phonological rehearsal than sign-based rehearsal, and all but 2 subjects consistently "supported" their recall in sign with simultaneous vocalization of item names. On the other hand, the rehearsal findings suggest that some use of sign-based encoding was made by 4 of the subjects. Thus, even hearing subjects may make some use of sign-based encoding if they are fluent in ASL. Interesting!y, most of the evidence for sign-based encoding occurred with subjects reporting equal or greater fluency in ASL than in spoken English, tentatively suggesting that, even for subjects fluent in both spoken langauge and ASL, the form in which information is encoded for short-term recall may be related to relative fluency in the two languages. The overall bias toward phonological encoding occurred despite the fact that ASL was the first language acquired by each of the subjects and despite the majority of subjects reporting greater fluency in ASL than in spoken English. Moreover, there were no significant age differences found in the pattern of recall ordering errors or rehearsal strategy use. Thus, these findings suggest that, even for hearing children of deaf parents, a bias toward the use of phonological encoding for serial recall may generally be present by the early elementary school years. Although only 4 of the 11 subjects reported greater fluency in spoken language than in sign language, only 1 subject knew the ASL sign for all items, and on the average subjects did not know the signs for approximately 10% of the items. This finding raises the possibility that the subjects may actually have been more proficient in spoken language than in ASL (their subjective reports of language fluency notwithstanding). Thus, it is possible that the results found here would not generalize to subjects with truly equivalent or superior proficiency in sign, as compared to spoken, language. On the other hand, the fact that subjects knew more spoken than signed item names may simply reflect the more limited context (primarily the home and family environment) within which they use ASL, without necessarily reflecting a lower level of general fluency or proficiency in sign than spoken language. In any case, there was no reason for subjects to misrepresent their self-perceived relative language fluency, and it is of interest that although the majority of subjects considered themselves more fluent in ASL than in spoken language, a bias toward phonological encoding was found with this task. A second factor that may limit the generalizability of the present findings is the nature of the testing environment. Although subjects directed their recall to an interpreter for the deaf, the experimenter communicated with the subjects
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primarily through spoken language, a feature of the testing environment that may have biased subjects toward a spoken-language mode of thought. It should be noted, however, that for this to be the case, the effect of the testing context must have been sufficiently potent to bias subjects toward phonological encoding even during blocks of trials when they were required to recall items in sign. Shand (1982) argued, on the basis of his work on sign-based encoding by deaf subjects, that there is nothing inherently special about phonological encoding. Instead, he suggested that subjects tend to encode information for short-term recall linguistically, and the exact form of such encoding is simply a function of the form of their dominant language system. Thus, according to Shand, the tendency of hearing subjects to encode phonologically results from the phonological nature of their language system. Similarly, deaf subjects fluent in ASL would be expected to encode information in STM using a sign-based code. A strong version of Shand's "encoding equality" hypothesis is called into question by the finding that the performance of deaf subjects fluent in ASL is inferior to that of normal-hearing subjects on short-term serial recall tasks (Krakow & Hanson, 1985). The present findings provide perhaps the most direct evidence against the strong version of Shand's hypothesis, since a bias toward phonological encoding was found even with subjects fluent in both ASL and spoken language, and even when subjects were required to recall the information in sign. The bias toward the use of phonological encoding for serial recall found here may reflect some fundamental difference between phonological and sign-based encoding that makes phonological encoding superior for short-term serial recall (Krakow & Hanson, 1985). For instance, phonological codes may be more rapidly produced and repeated than are sign-based codes, thus making the use of phonological encoding particularly advantageous for serial rehearsal. Further research with subjects fluent in both AL and spoken language may hold the key to answering this and other important questions.
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Baddeley, A. D. (1966). Short-termmemoryfor word sequences as a function of acoustic, semantic, and formal similarity. Quarterly Journal of Experimental Psychology, 18, 362-365. Bellugi, U., Klima, E. S., & Siple, P. (1975). Rememberingin signs. Cognition, 3, 93-125. Bonvillian, J. D., Orlansky, M. D., & Novack, L. L. (1983). Developmentalmilestones: Sign language acquisition and motor development. Child Development, 54, 1435-1445. Conrad, R. (1963). Acoustic confusions and memory span for words. Nature, 197, 1029-1030. Conrad, R. (1971). The chronologyof the developmentof covert speech in children. Developmental Psychology, 5, 398-405. Conrad, R. (1972). Short-term memory in the deaf: A test for speech coding. British Journal of Psychology, 63, 173-180. Frumkin, B., & Anisfield, M. (1977), Semantic and surface codes in the memoryof deaf children. Cognitive Psychology, 9, 475-493. Hanson, V. (1982). Short-termrecall by deaf signers of American Sign Language: Implicationsof
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encoding strategy for order recall. Journal of Experimental Psychology: Learning, Memory, and Cognition, 8, 572-583. Hanson, V., Liberman, 1. Y., & Shankweiler, D. (1984). Linguistic coding by deaf children in relation to beginning to read. Journal of Experimental Child Psychology, 37, 378-393. Hulme, C. (1984). Developmental differences in the effects of acoustic similarity on memory span. Developmental Psychology, 20, 650-652. Krakow, R.A.,& Hanson, V. (1985). Deaf signers and serial recall in the visual modality: Memory for signs, fingerspelling, and print. Memo~. & Cognition, 13, 265-272. Liben, L. S., & Drury, A. M. (1977). Short-term memory in deaf and hearing children in relation to stimulus characteristics. Journal of Experimental Child Psychology, 24, 60-73. Locke, J. L., & Locke, V. L. (1971). Deaf children's phonetic, visual, and dactylic coding in a grapheme recall task. Journal of Experimental Psychology, 89, 142-146. Poizner, H. (1981). Visual and "phonetic" coding of movement: Evidence from American Sign Language. Science, 212, 691-693. Poizner, H., Bellugi, U., & Tweney, R. (1981). Processing of forrnational, semantic and iconic information in ASL. Journal of Experimental Psychology: Human Perception and Performance, 7, 1146-1159. Prinz, P. M., & Prinz, E. A. (1979). Simultaneous acquisition of ASL and spoken English in a hearing child of a deaf mother and hearing father: Phase l--Early lexical development. Sign Language Studies, 25, 282-296. Shand, M. A. (1982). Sign-based short-term coding of ASL signs and printed English words by congenitally deaf signers. Cognitive Psychology, 14. 1-12. Sperling, G., & Speelman, R. G. (1970). Acoustic similarity and auditory short-term memory experiments and a model. In D. A. Norman (Ed.), Models of human memory. New York: Academic. Stokoe, W. C., Casterline, D. C., & Croneberg, C. G. (1965), A dictionary of American Sign Language. Washington, DC: Gallaudet College Press. Thomdike, E. L., & Lorge, 1. (1972). The teacher's word book of 30,000 words. New York: Columbia University Press.
APPENDIX Items on Each of the Four Types of Lists
Phonologically Similar Lists 1. rake, rain, plane, piate, race 2. boat, bat, coat, cake, bank Phonological-Control Lists 1. lamp, bread, eye, axe, hat 2. tree, cup, bed, doll, pen Sign-Similar Lists 1. girl, fruit, cat, gum, Indian 2. chair, knife, train, egg, salt Sign-Control Lists 1. plant, frog, ring, car, shoe 2. watch, king, star, door, flag