High-amplitude Sucking Procedure Research Articles

Discrimination of pitch contours by neonates

With the high-amplitude sucking procedure, newborns were presented with two lists of phonetically varied Japanese words differing in pitch contour. Discrimination of the lists was found, thus indicating that newborns are able to extract pitch contour information at the word level.

High-Amplitude Sucking and Newborns: The Quest for Underlying Mechanisms

This study seeks to determine whether newborns are sensitive to an operant-conditioning task involving an unprepared relation between a response and a stimulus. The High-Amplitude Sucking procedure, which is based on such a relation by reinforcing nonnutritive sucking with auditory stimulation, was used. In order to verify that newborns learn the contingency between sucks and sounds in the HAS paradigm, three experiments were carried out. In Experiment 1, the effect of contingent versus noncontingent presentation of speech sounds on newborns’ sucking activity was investigated during the minutes following a silent baseline. In contrast to what has been reported with 2-month-old infants in HAS, contingently stimulated newborns did not differ significantly from a nonstimulated control group. Experiment 2 showed that an increase in sucking rates could be obtained after a stimulus change, when sounds were presented contingently, but not when sounds were presented noncontingently. Experiment 3 demonstrated that newborns’ sucking responses were reinforced by variation in the presented speech sounds. The results of these three experiments support the hypothesis that newborns tested under the HAS procedure are involved in an operant-learning situation. Implications for learning in neonates and possible differences with older infants are discussed.

Newborns discriminate the rhythm of multisyllabic stressed words.

Three experiments were run to test whether newborns were able to discriminate different stress patterns in multisyllabic stressed Italian words that varied both in consonants and in number of syllables. A high-amplitude sucking procedure was adopted in which the experimental group heard 2 sets of stimuli alternating minute by minute, whereas the control group heard only a single set of stimuli. The results showed that stress patterns were discriminated in 2 disyllabic phonetically unvaried words (Experiment 1), in 2 trisyliabic consonant-varied words (Experiment 2), and in 2 sets of disyllabic words varied in consonants within and between words (Experiment 3). The alternation procedure proved to be suitable for examining newborns abilities of discrimination and categorization. It also lowered the participants rejection rate compared with the classic habituation procedure. The present results suggest that newborns are sensitive to words' rhythm, as carried by stress patterns, and that this prosodic information is salient even in the presence of substantial consonant variation.

Morae and syllables: rhythmical basis of speech representations in neonates.

Are neonates sensitive to the different rhythmical units that are used in different spoken languages? And do they use these units to represent and discriminate multisyllabic words? In the present study, we used the High-Amplitude Sucking procedure to test whether 3-day-old French infants discriminate lists of Japanese words. The lists of words differed either in the number of syllabic units or in the number of sub-syllabic units such as morae. In Experiment 1, infants heard bisyllabic versus trisyllabic words (e.g.: iga vs. hekiga); in Experiment 2, they were presented with bimoraic versus trimoraic bisyllabic words (e.g.: iga vs. iNga). The results corroborate those obtained by Bijeljac-Babic, Bertoncini, and Mehler (1993), providing further evidence that neonates discriminate bisyllabic from trisyllabic words. In contrast, neonates do not appear to discriminate bisyllabic words that vary in number of sub-syllabic units. It is proposed that syllables are particularly salient units during the initial stage of speech processing, irrespective of which language and rhythmical structure is heard.

Young infants' retention of information about syllables

This study examines 2- to 3-month-olds' retention of speech information over brief delay intervals. A modified version of the high-amplitude sucking procedure, incorporating a 2-min delay period was used to test the infants' retention of information about a set of syllables to which they had been habituated. A series of four experiments was conducted to obtain information about the degree of detail present in infants' representations and to investigate factors potentially affecting the infants' encoding and retention of speech sounds. The results indicated that infants are able to retain sufficient detail about syllables over a 2-min delay period to detect changes involving a single phonetic feature. The infants were successful even when the members of the familiarization set shared no common phonetic elements. These findings are discussed in terms of their implications for understanding the acquisition of native language sound categories and the development of the mental lexicon.

Two-month-old infants' sensitivity to allophonic differences.

The present study investigated 2-month-olds' abilities to discriminate allophonic differences that are potentially useful in segmenting fluent speech. Experiment 1 investigated infants' sensitivity to the kind of distinction that may signal the presence or absence of a word boundary. When tested with the high-amplitude sucking procedure, infants discriminated pairs of items, such as "nitrate" versus "night rate" and "nikrate" versus "nike rate". By greatly reducing the potential contribution of prosodic differences to these contrasts, Experiment 2 evaluated whether the allophonic differences for /t/ and /r/ were sufficient for infants to distinguish the "nitrate" versus "night rate" pair. Infants distinguished "nitrate" from a cross-spliced version of "night rate," which differed only in the allophones for /t/ and /r/ that it included. Thus, infants appear to possess one of the prerequisite capacities (i.e., the ability to discriminate allophonic distinctions) necessary to use allophonic information in segmenting fluent speech.

How do 4-day-old infants categorize multisyllabic utterances?

Three experiments, using the high-amplitude sucking procedure, tested whether 4-day-old infants discriminate multisyllabic utterances on the basis of number of syllables or number of phonemes. Experiment 1 showed that infants discriminate 2 large sets of phonetically variable utterances composed of 2- vs. 3-CV (consonant-vowel) syllables. Experiment 2 was run to assess whether infants discriminated the 2 sets on the basis of duration differences between the 2- and 3-CV stimuli. Results indicate that reducing the duration differences does not affect infants'discrimination. Finally, Experiment 3 investigated whether infants discriminate 4- vs. 6-phoneme bisyllabic utterances. The results provide no evidence that infants are sensitive to such a change in number of phonemic constituents

Could temporal order differences underlie 2-month-olds' discrimination of English voicing contrasts?

Previous studies have shown that infants discriminate voice onset time (VOT) differences for certain speech contrasts categorically. In addition, investigations of nonspeech processing by infants also yield evidence of categorical discrimination of temporal-order differences. These findings have led some researchers to argue that common auditory mechanisms underlie the infant's discrimination of timing differences in speech and nonspeech contrasts [e.g., Jusczyk et al., J. Acoust. Soc. Am. 67, 262-270 (1980)]. Nevertheless, some discrepancies in the location of the infant's category boundaries for different kinds of contrasts have been noted [e.g., Eilers et al. (1980)]. Because different procedures were used to study the different kinds of contrasts, interpretation of the discrepancies between the studies has been difficult. In the present study, three different continua were examined: [ba]-[pa] stimuli, which differed in VOT; [du]-[tu] stimuli, which differed in VOT but which lacked format transitions; nonspeech formant onset time (FOT) stimuli that varied in the time that lower harmonics increased in amplitude. An experiment with adults indicated a close match between the perceptual boundaries for the three series. Similarly, tests with 2-month-old infants using high amplitude sucking procedure yielded estimates of perceptual category boundaries at between 20 and 40 ms for all three stimulus series.

Syllabic pitch perception in 2- to 3-month-old infants.

The pitch patterns present in speech addressed to infants may play an important role in perceptual processing by infants. In this study, the high-amplitude sucking procedure was used to assess discrimination by 2- to 3-month-old infants of rising versus falling pitch patterns in 400-msec synthetic [ra] and [la] tokens. The syllables' intonation contour was modeled on infant-directed speech, and covered a range characteristic of an adult female speaker (180-300 Hz). Group data indicated that the 2- to 3-month-old infants discriminated the pitch contour for both stimuli. Results are discussed with reference to previous studies of syllabic pitch perception.

An investigation of young infants' perceptual representations of speech sounds.

The present study examined the ability of newborns and 2-month-olds to detect phonetic differences between syllables. By relying on the modified high-amplitude sucking procedure, which did not permit the infants to use a simple same-different response, the present experiments tapped the perceptual representations of the speech sounds. Infants as young as a few days old displayed some capacity to represent differences in a set of syllables varying in their phonetic composition, although there was no convincing evidence that their representations were structured in terms of phonetic segments. Finally, evidence of developmental changes in speech processing were noted for the first time with infants in this age range. The change noted was a tendency from global toward more specific representations on the part of the older infants.

Discrimination of polysyllabic sequences by one- to four-month-old infants

The goal of this research was to ascertain the effects of suprasegmental parameters (fundamental frequency, amplitude, and duration) on discrimination of polysyllabic sequences by 1- to 4-month-old infants. A high-amplitude sucking procedure, with synthesized female speech, was used. Results indicate that young infants can discriminate the three-syllable sequences [ma ra na] versus [ma la na] when suprasegmental characteristics typical of infant-directed speech emphasize the middle syllable. However, infants failed to demonstrate discrimination when adult-directed suprasegmentals were used and in several other experimental conditions in which prosodic parameters were manipulated. The pattern of results obtained in the six experiments suggests that the exaggerated suprasegmentals of infant-directed speech may function as a perceptual catalyst, facilitating discrimination by focusing the infant's attention on a distinctive syllable within polysyllabic sequences.

Organization in the perception of segmental and suprasegmental information by infants

In this study, we investigated whether infants are capable of discriminating not only differences in pitch and syllable-initial consonants but also the manner in which these components are combined. Using a modification of the high-amplitude sucking procedure, we found that three- and four-month-old infants were able to recognize rearrangements of these components, which, together with earlier findings, indicates that the infant's speech processing system is sensitive to the organization in the basic elements of human language.

Infant Behavioral State and Speech Sound Discrimination

In order to investigate the interaction between infant state and speech sound discrimination, records of state were obtained from infants participating in 3 speech sound discrimination experiments which employed the high amplitude sucking procedure. A total of 94 individual records were rated for state by 2 independent scorers. When treated as an independent variable, state interacted with responsivity to sound change as measured by sucking rate increases. Infants in the more alert states demonstrated significantly higher rates of sucking following sound change. Treating state as a dependent variable revealed that state was not significantly affected by a change in stimulus conditions.