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The identification of words and their meanings in the transition into language
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THE IDENTIFICATION OF WORDS AND THEIR MEANINGS IN THE TRANSITION INTO LANGUAGE Catharine H. Echols Department of Psychology, University of Texas, 330 Mezes Hall, Austin, TX 78712 The research reported here contributes to an understanding of two fundamental tasks of the beginning of language development, the segmentation of words from the speech stream and the discovery of word meaning. Though these two areas of language development tend to be investigated in distinct lines of research, it will be argued that they share certain broad commonalties. Specifically, both appear to rely on a developing sensitivity to properties of the native language. There is now a body of research showing that, during the latter half of the first year, Englishhearing infants have identified certain properties of the native language that are useful for word-level segmentation: In English, a sequence consisting of a stressed followed by an unstressed syllable (i.e., a trochaic disyllable) frequently corresponds to a word. By 7 l/2 to 9 months, infants have discovered this property of English and can use that knowledge to segment words from the speech stream (Echols et al., 1997; Jusczyk et al., 1993; Newsome & Jusczyk, 1995). One account for the origin of a rhythmically-based segmentation strategy is as follows: Infants start out attending to stressed and final syllables because they are perceptually salient. Stress is penultimate in English, which will mean that an infant who extracts a stressed and final syllable frequently will have extracted a trochaic sequence. After extracting a number of such sequences, the infant may determine that a trochaic disyllable is a common English word-type. Recent research supports this account: We have shown that 9-month infants attend both to stress and to rhythmicallydefined units, whereas 7-month olds are less attentive to trochaic sequences. Our most recent findings indicate that infants also attend to final syllables. In these studies, 7- and 9-month old infants were familiarized to three-syllable nonsense sequences that closely approximated English words. In one variant of the study, stress was in initial position and in another it was in medial position. After familiarization, infants were tested with three test items. In the initial stress variant, for example, if the target item were Za’rbrsltar, the test items might include a change in the medial unstressed syllable (e.g., l&p&or), a change in the final unstressed syllable (e.g., Idrbrsdar) and a no-ch &lge control; in this variant, infants listened longer for the change in the final syllable than for the nonfinal change, suggesting that they represented final syllables more accurately than unstressed nonfinal syllables. The results of several studies using variants on this procedure support the proposal that languagespecific cues (e.g., trochaic rhythm) may derive from general cues (e.g., stress, final position).. The identification of word meaning also may reflect a developing sensitivity to languagespecific cues. For example, infants may come to recognize that, in English, nouns often follow a or the and verbs may precede -ed or -ing. Our recent findings suggest that 13-month olds may distinguish the frames that indicate nouns versus verbs, thus demonstrating some sensitivity to these language-specific cues. However, this tendency is fragile and it takes the form that a verb-frame disrupts a tendency to associate language to an object; there is little evidence that a verb-frame actually directs infants’ attention to a motion. Specifically, infants were familiarized to a novel word embedded either in a noun- or a verb-frame (e.g., it’s a gep versus it’s gepping). Infants hearing the noun frame subsequently looked longer to the object seen during familiarization than toward the action when asked to look at the gep; infants in the verb-labeled condition showed no such preference. Thus, at 13 months, infants’ sensitivities may be relatively general: Infants notice that a verb-frame differs from a noun-frame, so do not seek to associate the word embedded in the verbframe to an object, but they are unaware of the specific function of the verb frame. By 18 months, infants can use the verb frame to associate a novel word to an action, reflecting greater knowledge of language-specific cues. In summary, the results of these two lines of research, on the identification of words and on the discovery of word meanings, both provide evidence of developing sensitivities to properties of the native language. An important next step will be to examine more direct interrelationships between these two aspects of language development.
THE IDENTIFICATION OF WORDS AND THEIR MEANINGS IN THE TRANSITION INTO LANGUAGE Catharine H. Echols Department of Psychology, University of Texas, 330 Mezes Hall, Austin, TX 78712 The research reported here contributes to an understanding of two fundamental tasks of the beginning of language development, the segmentation of words from the speech stream and the discovery of word meaning. Though these two areas of language development tend to be investigated in distinct lines of research, it will be argued that they share certain broad commonalties. Specifically, both appear to rely on a developing sensitivity to properties of the native language. There is now a body of research showing that, during the latter half of the first year, Englishhearing infants have identified certain properties of the native language that are useful for word-level segmentation: In English, a sequence consisting of a stressed followed by an unstressed syllable (i.e., a trochaic disyllable) frequently corresponds to a word. By 7 l/2 to 9 months, infants have discovered this property of English and can use that knowledge to segment words from the speech stream (Echols et al., 1997; Jusczyk et al., 1993; Newsome & Jusczyk, 1995). One account for the origin of a rhythmically-based segmentation strategy is as follows: Infants start out attending to stressed and final syllables because they are perceptually salient. Stress is penultimate in English, which will mean that an infant who extracts a stressed and final syllable frequently will have extracted a trochaic sequence. After extracting a number of such sequences, the infant may determine that a trochaic disyllable is a common English word-type. Recent research supports this account: We have shown that 9-month infants attend both to stress and to rhythmicallydefined units, whereas 7-month olds are less attentive to trochaic sequences. Our most recent findings indicate that infants also attend to final syllables. In these studies, 7- and 9-month old infants were familiarized to three-syllable nonsense sequences that closely approximated English words. In one variant of the study, stress was in initial position and in another it was in medial position. After familiarization, infants were tested with three test items. In the initial stress variant, for example, if the target item were Za’rbrsltar, the test items might include a change in the medial unstressed syllable (e.g., l&p&or), a change in the final unstressed syllable (e.g., Idrbrsdar) and a no-ch &lge control; in this variant, infants listened longer for the change in the final syllable than for the nonfinal change, suggesting that they represented final syllables more accurately than unstressed nonfinal syllables. The results of several studies using variants on this procedure support the proposal that languagespecific cues (e.g., trochaic rhythm) may derive from general cues (e.g., stress, final position).. The identification of word meaning also may reflect a developing sensitivity to languagespecific cues. For example, infants may come to recognize that, in English, nouns often follow a or the and verbs may precede -ed or -ing. Our recent findings suggest that 13-month olds may distinguish the frames that indicate nouns versus verbs, thus demonstrating some sensitivity to these language-specific cues. However, this tendency is fragile and it takes the form that a verb-frame disrupts a tendency to associate language to an object; there is little evidence that a verb-frame actually directs infants’ attention to a motion. Specifically, infants were familiarized to a novel word embedded either in a noun- or a verb-frame (e.g., it’s a gep versus it’s gepping). Infants hearing the noun frame subsequently looked longer to the object seen during familiarization than toward the action when asked to look at the gep; infants in the verb-labeled condition showed no such preference. Thus, at 13 months, infants’ sensitivities may be relatively general: Infants notice that a verb-frame differs from a noun-frame, so do not seek to associate the word embedded in the verbframe to an object, but they are unaware of the specific function of the verb frame. By 18 months, infants can use the verb frame to associate a novel word to an action, reflecting greater knowledge of language-specific cues. In summary, the results of these two lines of research, on the identification of words and on the discovery of word meanings, both provide evidence of developing sensitivities to properties of the native language. An important next step will be to examine more direct interrelationships between these two aspects of language development.