Papers by Mariam Dar
Two habituation experiments tested English-learning infants to examine effects of development on ... more Two habituation experiments tested English-learning infants to examine effects of development on cross-language speech perception. In study 1, 7- and 11-month-old infants were tested on the Urdu affricates /tʃʰ/ and /tʃ/. The order of presentation was counterbalanced: Half of the infants at each age were familiarized with the aspirated affricate and tested on the unaspirated while the other half were presented with the stimuli in the reverse order. The younger group discriminated the affricate contrast; marginally significant results were obtained for the 11-month-olds. Further investigation revealed that the order of presentation of the stimuli significantly affected discrimination in the older group of infants only. Experiment 2 was conducted to further test the possible order-effect. The results clearly showed asymmetry in non-native consonant perception, but only for the 11-month-olds: Infants showed discrimination when the non-English-like aspirated affricate was presented first. This finding of an asymmetry in infant speech perception suggests that perception may be a more complex phenomenon than has generally been assumed; perceptual narrowing, generally reported for the end of the first year, was not be observed when the ordering was reversed. Further research is needed to clarify the nature and role of such asymmetries in perceptual development.
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This paper reports on the development of a lexical checklist for parents to trace vocabulary
adva... more This paper reports on the development of a lexical checklist for parents to trace vocabulary
advances in Pakistani children. Various cross-linguistic adaptations of the MacArthurBates
Communicative Development Inventory (CDI) were consulted. Pilot testing was
carried out using a sample of 17 children from middle-class homes, aged from 12 to 30
months. Cross-linguistic comparison reveals similarities between the vocabulary growth
of the Pakistani children and children learning other languages. Plans for further pilottesting
and eventual validation are discussed.
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Conference Presentations by Mariam Dar
The present study tested infants from English-speaking homes to examine effects of development on... more The present study tested infants from English-speaking homes to examine effects of development on cross-language speech perception. Werker (1981) showed that 6-8-month-old infants are able to discriminate non-native speech sounds that adults cannot discriminate, but by 10-12 months the infants were no longer able to make the discrimination. According to Kuhl (2008), this decline in discrimination is due to infants’ increase in native-language exposure, which leads to “neural commitment” to the native language at this age. Many studies have shown a decline in discriminatory abilities of infants for non-native contrasts between 6 – 12 months of age but no study to date has tested a contrast in affricates in a cross-language perception test. Also, very little attempt has been made to show whether the experimental order of presentation of stimuli affects infants’ performance. An aspirated – unaspirated contrast of Urdu /tʃ / - /tʃh/ was selected based on a pilot study with 20 English-speaking adults who were tested on a number of Urdu contrasts not found in English to identify the most difficult. Twenty-four 7- and 11-month olds were tested in a habituation procedure. Half of the infants were habituated to the voiceless aspirated affricate and tested on the contrasting voiceless unaspirated affricate while the remaining infants experienced the reverse pattern . Discrimination was assessed by comparing mean looking time during the last two habituation trials to mean looking time during the first two trials of the test phase. In agreement with the literature, the results indicated that 6-8-month-olds could discriminate the affricate pair but 11-month-olds could not. Infants presented with the non-prototypical consonant (the aspirated affricate, which does not occur in English) in the habituation phase showed better discrimination in the test phase than the infants presented with the prototypical consonant in the habituation phase.
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The MacArthur Communicative Development Inventory (CDI) is a standard checklist on which parents ... more The MacArthur Communicative Development Inventory (CDI) is a standard checklist on which parents record their children’s lexical progress. CDIs have been developed for American, British English, French, Catalan, Italian, Japanese, Spanish and Russian, among other languages, but not for Urdu or any other regional language in Pakistan. However, the multilingual situation in Pakistan makes development of a CDI for Urdu and Pashto a laborious undertaking as children in typical Pakistani households are exposed to two or more languages. Urdu and English co-exist in almost every middle-class household. Urdu is the national language and English is the official language of the country and also the medium of instruction in schools. This explains the common occurrence of English loan words in Urdu and other regional languages like Pashto. Children are exposed to cartoons and children’s books in English even before going to school. Apart from English and Urdu, at least one regional language is spoken in many homes (sometimes two, if the mother and father have different regional languages).
Another postgraduate and I started off by interviewing mothers from Urdu- and Pashto-speaking households in Pakistan to develop a comprehensive list of words spoken and understood by 1.5 – 3 year olds. British and American CDIs were also taken as a foundation for the set of categories and the final lists were sent to several mothers from Urdu- and Pashto-speaking homes for feedback and corrections. The Urdu and Pashto CDIs that we formulated consequently not only include English and regional equivalents of Urdu words related to everyday life but also are very much reflective of life in Pakistan, with words related to topics such as religion, traditional foods, clothing, expressions of approval/disapproval, places to visit – and power cut-offs, a regular experience in Pakistani life. The development of Pashto and Urdu CDIs will pave the way for future research, making it convenient to collect data for those working on lexical development in these languages. It should also be of interest to practitioners working in the areas of education and speech therapy, not only in Pakistan but also in places with large numbers of Pakistani emigrant families.
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Poster Presentations by Mariam Dar
The present study tested infants from English-speaking homes to examine effects of development on... more The present study tested infants from English-speaking homes to examine effects of development on cross-language speech perception. Werker (1981, 1984) showed that 6-8-month-old infants are able to discriminate non-native speech sounds that adults cannot discriminate, but by 10-12 months the infants were no longer able to make the discrimination. According to Kuhl (2004, 2008), this decline in discrimination is due to infants? increase in native-language exposure, which leads to ?neural commitment? to the native language at this age. Many studies have shown a decline in discriminatory abilities of infants for non-native contrasts between 6 - 12 months of age but no study to date has tested a contrast in affricates in a cross-language perception test. Also, very little attempt has been made to show whether the experimental order of presentation of stimuli affects infants? performance. An aspirated - unaspirated contrast of Urdu /t?/ - /t?h/ was selected based on a pilot study with 20 English-speaking adults who were tested on a number of Urdu contrasts not found in English to identify the most difficult. Twenty-four 7- and 11-month olds were tested in a habituation procedure. Half of the infants were habituated to the voiceless aspirated affricate and tested on the contrasting voiceless unaspirated affricate while the remaining infants experienced the reverse pattern. Discrimination was assessed by comparing mean looking time during the last two habituation trials to mean looking time during the first two trials of the test phase. In agreement with the literature, the results indicated that 6-8-month-olds could discriminate the affricate pair but 11-month-olds could not. Infants presented with the non-prototypical consonant (the aspirated affricate, which does not occur in English) in the habituation phase showed better discrimination in the test phase than the infants presented with the prototypical consonant in the habituation phase.
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The present study tested infants from English-speaking homes to examine effects of development on... more The present study tested infants from English-speaking homes to examine effects of development on cross-language speech perception. Werker and Tees (1984) first showed that 6-8-month-old infants are able to discriminate non-native speech sounds that adults find difficult to discriminate, but by 10-12 months infants were no longer able to make the discrimination; many studies (Best et al., 2001; Best & McRoberts, 2003; Rivera-Graxiola et al., 2005; Kuhl et al., 2006) have since shown an infant decline in discriminatory abilities for non-native contrasts between 6-12 months of age. However, no study to date has tested a contrast in affricates. Here, an aspirated – unaspirated contrast found in Urdu, /tʃ/ - /tʃh/, was selected after pilot testing with 20 English-speaking adults on a number of Urdu contrasts not found in English to identify the most difficult. Twenty-four 7- and 11-month olds were tested in a habituation procedure. Half of the infants were habituated to the aspirated affricate and tested on the contrasting unaspirated affricate while the remaining infants experienced the reverse pattern. In agreement with the other studies, the results indicated that 6-8-month-olds could discriminate the affricate pair (t = 3.015, df = 12, p < 0.05) but 11-month-olds could not (t = 1.326, df = 14, ns). More interestingly, the order of presentation of the stimuli proved to be important. In the older group, infants presented with the non-prototypical consonant (the aspirate, which does not occur in English) in the habituation phase showed better discrimination in the test phase than the infants presented with the prototypical consonant in the habituation phase (F = 0.77, df = 29, p = 0.31); there was no significant order effect in the younger infants.
The experiment was replicated with the older group of infants when they reached 15 months of age, with essentially the same results as at 11 months. This leaves it unclear at what age the order effect ceases to support contrast discrimination in English speakers. As part of an on-going effort to better understand these results, studies are in progress to determine whether the same order effect will be obtained with adult English listeners. Furthermore, an order effect has also been tentatively found in Urdu infants and adults tested on English /w/ vs. /v/ (this distinction is allophonic in Urdu; the phoneme [v] is realized as /w/ in certain contexts, but only rarely). Discrimination is proving to be better, for both adults and infants, when /w/, the less frequently occurring variant, is played first. Data from both English and Urdu adult listeners will be analyzed and presented at the conference; the data on Urdu infants will be reported if available.
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There is ample evidence to show that infants are born with listening abilities that allow them to... more There is ample evidence to show that infants are born with listening abilities that allow them to successfully discriminate most of the phonetic units of the world’s languages. This ability is not maintained into adulthood, however; exposure to the ambient language results in a developmental decline in discrimination of contrasts that has been demonstrated by numerous studies using a range of non-native contrasts . Werker et al. (1981) were the first to attempt to trace the time-course of this perceptual decline from infancy to adulthood. Werker and her colleagues (1981, 1984) showed that whereas 6-8-month-old infants are able to discriminate non-native speech sounds that adults cannot discriminate, by 10-12 months the infants are no longer able to make the discrimination. Since then many studies (Werker et al., 1981; Werker & Tees, 1983; Kuhl et al., 1992; Werker & Tees 2002; Best & McRoberts, 2003; Riveria et al., 2005; Kuhl et al., 2006) have shown a decline in infants’ ability to discriminate non-native contrasts in the second half of the first year. The current study was conducted to further explore this developmental change in the perceptual abilities of infants at the end of the first year using an Urdu aspirated – unaspirated contrast, /tʃ/ - /tʃʰ/, which had not so far been tested on English infants. Fricatives have rarely been used in discrimination tests, perhaps because several early studies with young infants failed to provide evidence of discrimination between fricatives (Vihman, 1996).
Infants from English-speaking homes were tested on the Urdu affricate pair to attempt to trace the expected change in their ability to discriminate these sounds over the first year. We hypothesized that younger infants would successfully discriminate the stimuli but the older group would have difficulty with it. Twenty-four 7- and 11-month olds were tested in a habituation procedure. Half of the infants were habituated to the aspirated and tested on the contrasting unaspirated affricate while the remaining infants experienced the reverse pattern of exposure. Discrimination was assessed by comparing mean looking time during the last two habituation trials (pre-shift phase) to mean looking time during the first two trials of the test phase (post-shift phase). A significant increase in mean looking time during the post-shift relative to the pre-shift phase was taken as evidence that the infant had detected the stimulus change. The point of no discrimination was set at 0.5 – in other words, equal looking in the two phases. In agreement with the other studies, the results indicated that 6-8-month-olds could discriminate the affricate pair but 11-month-olds had only a marginally significant difference in looking to the changed stimulus . Upon closer inspection, it was found that this effect in the older group was due to differences in the performance of the two subgroups, who experienced different orders of presentation of stimuli. Infants showed better performance when the aspirated stimulus /tʃʰ/ was presented first, yielding significant results for this order of presentation. The experiment was replicated with the older group of infants when they reached 15 months of age, with essentially the same result.
Both studies provide clear confirmation of an order effect, which is not in line with previous reports of a developmental decline. These findings can be explained through the perceptual magnet effect previously observed in within-category vowel discrimination by infants and adults, where more native-like vowels act as perceptual magnets (Kuhl, 2004). Further investigation revealed that the voicing lag for English /tʃ/ (+83) is very close to that of the Urdu voiceless unaspirated affricate (+80) but is half the duration of the Urdu voiceless aspirated affricate /tʃʰ/ (+140). When the English-like affricate /tʃ/ is presented first, the following consonant /tʃʰ/ is assimilated to the more familiar sound; on the other hand, the presentation of the unfamiliar (‘non-prototypical’) aspirated affricate /tʃʰ/ first hinders assimilation, making discrimination possible. Studies currently in progress to establish whether the same order effect obtains with adult English listeners will be completed before the conference. The implications of these studies for infant consonant processing more generally, and for the course of development from infant to adult, will be discussed.
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Colloquium Talk by Mariam Dar
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Papers by Mariam Dar
advances in Pakistani children. Various cross-linguistic adaptations of the MacArthurBates
Communicative Development Inventory (CDI) were consulted. Pilot testing was
carried out using a sample of 17 children from middle-class homes, aged from 12 to 30
months. Cross-linguistic comparison reveals similarities between the vocabulary growth
of the Pakistani children and children learning other languages. Plans for further pilottesting
and eventual validation are discussed.
Conference Presentations by Mariam Dar
Another postgraduate and I started off by interviewing mothers from Urdu- and Pashto-speaking households in Pakistan to develop a comprehensive list of words spoken and understood by 1.5 – 3 year olds. British and American CDIs were also taken as a foundation for the set of categories and the final lists were sent to several mothers from Urdu- and Pashto-speaking homes for feedback and corrections. The Urdu and Pashto CDIs that we formulated consequently not only include English and regional equivalents of Urdu words related to everyday life but also are very much reflective of life in Pakistan, with words related to topics such as religion, traditional foods, clothing, expressions of approval/disapproval, places to visit – and power cut-offs, a regular experience in Pakistani life. The development of Pashto and Urdu CDIs will pave the way for future research, making it convenient to collect data for those working on lexical development in these languages. It should also be of interest to practitioners working in the areas of education and speech therapy, not only in Pakistan but also in places with large numbers of Pakistani emigrant families.
Poster Presentations by Mariam Dar
The experiment was replicated with the older group of infants when they reached 15 months of age, with essentially the same results as at 11 months. This leaves it unclear at what age the order effect ceases to support contrast discrimination in English speakers. As part of an on-going effort to better understand these results, studies are in progress to determine whether the same order effect will be obtained with adult English listeners. Furthermore, an order effect has also been tentatively found in Urdu infants and adults tested on English /w/ vs. /v/ (this distinction is allophonic in Urdu; the phoneme [v] is realized as /w/ in certain contexts, but only rarely). Discrimination is proving to be better, for both adults and infants, when /w/, the less frequently occurring variant, is played first. Data from both English and Urdu adult listeners will be analyzed and presented at the conference; the data on Urdu infants will be reported if available.
Infants from English-speaking homes were tested on the Urdu affricate pair to attempt to trace the expected change in their ability to discriminate these sounds over the first year. We hypothesized that younger infants would successfully discriminate the stimuli but the older group would have difficulty with it. Twenty-four 7- and 11-month olds were tested in a habituation procedure. Half of the infants were habituated to the aspirated and tested on the contrasting unaspirated affricate while the remaining infants experienced the reverse pattern of exposure. Discrimination was assessed by comparing mean looking time during the last two habituation trials (pre-shift phase) to mean looking time during the first two trials of the test phase (post-shift phase). A significant increase in mean looking time during the post-shift relative to the pre-shift phase was taken as evidence that the infant had detected the stimulus change. The point of no discrimination was set at 0.5 – in other words, equal looking in the two phases. In agreement with the other studies, the results indicated that 6-8-month-olds could discriminate the affricate pair but 11-month-olds had only a marginally significant difference in looking to the changed stimulus . Upon closer inspection, it was found that this effect in the older group was due to differences in the performance of the two subgroups, who experienced different orders of presentation of stimuli. Infants showed better performance when the aspirated stimulus /tʃʰ/ was presented first, yielding significant results for this order of presentation. The experiment was replicated with the older group of infants when they reached 15 months of age, with essentially the same result.
Both studies provide clear confirmation of an order effect, which is not in line with previous reports of a developmental decline. These findings can be explained through the perceptual magnet effect previously observed in within-category vowel discrimination by infants and adults, where more native-like vowels act as perceptual magnets (Kuhl, 2004). Further investigation revealed that the voicing lag for English /tʃ/ (+83) is very close to that of the Urdu voiceless unaspirated affricate (+80) but is half the duration of the Urdu voiceless aspirated affricate /tʃʰ/ (+140). When the English-like affricate /tʃ/ is presented first, the following consonant /tʃʰ/ is assimilated to the more familiar sound; on the other hand, the presentation of the unfamiliar (‘non-prototypical’) aspirated affricate /tʃʰ/ first hinders assimilation, making discrimination possible. Studies currently in progress to establish whether the same order effect obtains with adult English listeners will be completed before the conference. The implications of these studies for infant consonant processing more generally, and for the course of development from infant to adult, will be discussed.
Colloquium Talk by Mariam Dar
advances in Pakistani children. Various cross-linguistic adaptations of the MacArthurBates
Communicative Development Inventory (CDI) were consulted. Pilot testing was
carried out using a sample of 17 children from middle-class homes, aged from 12 to 30
months. Cross-linguistic comparison reveals similarities between the vocabulary growth
of the Pakistani children and children learning other languages. Plans for further pilottesting
and eventual validation are discussed.
Another postgraduate and I started off by interviewing mothers from Urdu- and Pashto-speaking households in Pakistan to develop a comprehensive list of words spoken and understood by 1.5 – 3 year olds. British and American CDIs were also taken as a foundation for the set of categories and the final lists were sent to several mothers from Urdu- and Pashto-speaking homes for feedback and corrections. The Urdu and Pashto CDIs that we formulated consequently not only include English and regional equivalents of Urdu words related to everyday life but also are very much reflective of life in Pakistan, with words related to topics such as religion, traditional foods, clothing, expressions of approval/disapproval, places to visit – and power cut-offs, a regular experience in Pakistani life. The development of Pashto and Urdu CDIs will pave the way for future research, making it convenient to collect data for those working on lexical development in these languages. It should also be of interest to practitioners working in the areas of education and speech therapy, not only in Pakistan but also in places with large numbers of Pakistani emigrant families.
The experiment was replicated with the older group of infants when they reached 15 months of age, with essentially the same results as at 11 months. This leaves it unclear at what age the order effect ceases to support contrast discrimination in English speakers. As part of an on-going effort to better understand these results, studies are in progress to determine whether the same order effect will be obtained with adult English listeners. Furthermore, an order effect has also been tentatively found in Urdu infants and adults tested on English /w/ vs. /v/ (this distinction is allophonic in Urdu; the phoneme [v] is realized as /w/ in certain contexts, but only rarely). Discrimination is proving to be better, for both adults and infants, when /w/, the less frequently occurring variant, is played first. Data from both English and Urdu adult listeners will be analyzed and presented at the conference; the data on Urdu infants will be reported if available.
Infants from English-speaking homes were tested on the Urdu affricate pair to attempt to trace the expected change in their ability to discriminate these sounds over the first year. We hypothesized that younger infants would successfully discriminate the stimuli but the older group would have difficulty with it. Twenty-four 7- and 11-month olds were tested in a habituation procedure. Half of the infants were habituated to the aspirated and tested on the contrasting unaspirated affricate while the remaining infants experienced the reverse pattern of exposure. Discrimination was assessed by comparing mean looking time during the last two habituation trials (pre-shift phase) to mean looking time during the first two trials of the test phase (post-shift phase). A significant increase in mean looking time during the post-shift relative to the pre-shift phase was taken as evidence that the infant had detected the stimulus change. The point of no discrimination was set at 0.5 – in other words, equal looking in the two phases. In agreement with the other studies, the results indicated that 6-8-month-olds could discriminate the affricate pair but 11-month-olds had only a marginally significant difference in looking to the changed stimulus . Upon closer inspection, it was found that this effect in the older group was due to differences in the performance of the two subgroups, who experienced different orders of presentation of stimuli. Infants showed better performance when the aspirated stimulus /tʃʰ/ was presented first, yielding significant results for this order of presentation. The experiment was replicated with the older group of infants when they reached 15 months of age, with essentially the same result.
Both studies provide clear confirmation of an order effect, which is not in line with previous reports of a developmental decline. These findings can be explained through the perceptual magnet effect previously observed in within-category vowel discrimination by infants and adults, where more native-like vowels act as perceptual magnets (Kuhl, 2004). Further investigation revealed that the voicing lag for English /tʃ/ (+83) is very close to that of the Urdu voiceless unaspirated affricate (+80) but is half the duration of the Urdu voiceless aspirated affricate /tʃʰ/ (+140). When the English-like affricate /tʃ/ is presented first, the following consonant /tʃʰ/ is assimilated to the more familiar sound; on the other hand, the presentation of the unfamiliar (‘non-prototypical’) aspirated affricate /tʃʰ/ first hinders assimilation, making discrimination possible. Studies currently in progress to establish whether the same order effect obtains with adult English listeners will be completed before the conference. The implications of these studies for infant consonant processing more generally, and for the course of development from infant to adult, will be discussed.