Predicting developmental shifts in perceptual weighting schemes

Recent models of developmental changes in speech perception suggest that the weights assigned to acoustic properties change as children gain experience with a native language. Empirical evidence supports this position, but few suggestions have been offered as to what guides this shift. These three experiments were designed to improve our ability to predict how perceptual weighting schemes change with development. The specific hypothesis explored was twofold: (1) the weight assigned by adults to any one acoustic property differs across phonetic environments according to how informative that property is in each environment; and (2) the weight assigned by children to any one acoustic property differs less across phonetic environments because children have not fully learned the patterns of covariation between phonetic informativeness and environment for each property. Experiment 1 replicated previous findings of age-related differences in the weights assigned to noise spectra and formant transitions in labeling of syllable-initial fricatives (/s/ or /[symbol: see text]/). In experiment 2 the variation in F3-onset frequency associated with place of fricative constriction was eliminated. This property differs more (i.e., is more informative) in /u/ than in /a/. Accordingly adults' transition effect was reduced more for /u/ than for /a/ from experiment 1. Children's transition effect was similarly reduced across vowel environments. In experiment 3, F3-onset frequency was appropriately manipulated for both vowels, and adults transition effect increased more for /u/ than for /a/ from experiment 2. The increase in children's transition effect was more similar across vowels. We conclude that the children had not fully learned how information provided by F3 transitions varies across /a/ and /u/ environments, and suggest that developmental weighting shifts may be guided by children learning the relation between phonetic informativeness and environment.     

Dissociations in Perceptual Learning Revealed by Adult Age Differences in Adaptation to Time-Compressed Speech.

When presented with several time-compressed sentences, young adults' performance improves with practice. Such adaptation has not been studied in older adults. To study age-related changes in perceptual learning, the authors tested young and older adults' ability to adapt to degraded speech. First, the authors showed that older adults, when equated for starting accuracy with young adults, adapted at a rate and magnitude comparable to young adults. However, unlike young adults, older adults failed to transfer this learning to a different speech rate and did not show additional benefit when practice exceeded 20 sentences. Listeners did not adapt to speech degraded by noise, indicating that adaptation to time-compressed speech was not attributable to task familiarity. Finally, both young and older adults adapted to spectrally shifted noise-vocoded speech. The authors conclude that initial perceptual learning is comparable in young and older adults but maintenance and transfer of this learning decline with age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Auditory habituation in young and older adults: The verbal transformation effect.

In 3 experiments, auditory massed repetition was used to examine age-related differences in habituation by means of the verbal transformation paradigm. Participants heard 10 words (5 high frequency and 5 low frequency), each presented 180 times, and they reported perceived changes in the repeated words (verbal transformations). In these experiments, older adults reported fewer illusory percepts than young adults. Older adults' loss of auditory acuity and slowing of processing, stimulus degradation (in young adults), and instructions biasing the report of these illusory percepts did not account for the fewer illusory percepts reported by the older adults. These findings suggest that older adults' reduced susceptibility to habituation arises from centrally located declines in the transmission of information within the word recognition pathway. The discussion focuses on the implications that these age-related declines may have on word identification during on-line speech perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The specific relation between perception and production errors for place of articulation in developmental apraxia of speech

Developmental apraxia of speech is a disorder of phonological and articulatory output processes. However, it has been suggested that perceptual deficits may contribute to the disorder. Identification and discrimination tasks offer a fine-grained assessment of central auditory and phonetic functions. Seventeen children with developmental apraxia (mean age 8:9, years:months) and 16 control children (mean age 8:0) were administered tests of identification and discrimination of resynthesized and synthesized monosyllabic words differing in place-of-articulation of the initial voiced stop consonants. The resynthetic and synthetic words differed in the intensity of the third formant, a variable potentially enlarging their clinical value. The results of the identification task showed equal slopes for both subject groups, which indicates no phonetic processing deficit in developmental apraxia of speech. The hypothesized effect of the manipulation of the intensity of the third formant of the stimuli was not substantiated. However, the children with apraxia demonstrated poorer discrimination than the control children, which suggests affected auditory processing. Furthermore, analyses of discrimination performance and articulation data per apraxic subject demonstrated a specific relation between the degree to which auditory processing is affected and the frequency of place-of-articulation substitutions in production. This indicates the interdependence of perception and production. The results also suggest that the use of perceptual tasks has significant clinical value.     

Listening in aging adults: From discourse comprehension to psychoacoustics.

Older adults, with or without clinical hearing loss, have more trouble than younger people understanding speech in everyday life. These age-related difficulties in speech understanding may be attributed to changes in higher-level cognitive processes such as language comprehension, memory, attention, and cognitive slowing, or to lower-level sensory and perceptual processes. A complicating factor in determining how these sources might contribute to age-related declines in speech understanding is that they are highly correlated. This study describes attempts to systematically investigate sensory-cognitive interactions in controlled experimental situations. The authors looked at experimental conditions that closely approximate everyday listening, and show that older adults do indeed experience deficits in spoken language comprehension relative to younger adults in these conditions. Finally, further experiments designed to isolate more precisely the cognitive and perceptual sources of these age-related differences and how they vary with listening condition are reviewed. In large part, it was found that age-related changes in speech understanding are a consequence of auditory declines. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Second formant transitions of selected consonant-vowel combinations in the speech of deaf and normal-hearing children

Although it is well known that the speech produced by the deaf is generally of low intelligibility, the sources of this low speech intelligibility have generally been ascribed either to aberrant articulation of phonemes or inappropriate prosody. This study was designed to determine to what extent a nonsegmental aspect of speech, formant transitions, may differ in the speech of the deaf and of the normal hearing. The initial second formant transitions of the vowels /i/ and /u/ after labial and alveolar consonants (/b, d, f/) were compared in the speech of six normal-hearing and six hearing-impaired adolescents. In the speech of the hearing-impaired subjects, the second formant transitions may be reduced both in time and in frequency. At its onset, the second formant may be nearer to its eventual target frequency than in the speech of the normal subjects. Since formant transitions are important acoustic cues for the adjacent consonants, reduced F2 transitions may be an important factor in the low intelligibility of the speech of the deaf.     

Children's use of sample size and diversity information within basic-level categories

Category-based induction involves making decisions about some member(s) of a category based on information concerning other category members. Recent studies indicate that although adults make use of information concerning sample size (larger samples are a stronger basis of inference than smaller samples) and sample diversity (more diverse samples are better than more homogeneous samples) when making category-based inductive judgments, children do not do so until age 8 or 9 and even then to only a limited degree. This research however, was conducted at the superordinate level of categorization, and it is unclear if general difficulty with this category level may have masked children's ability to use size and diversity, or if these results represent a more entrenched conceptual difficulty in using this information. We therefore conducted three studies that investigate both 8- and 9-year-olds' and adults' ability to use sample size and diversity within basic level categories. Our results indicate that children's difficulty with this information is independent of category level, and may be based on preferences for other strategies concerning category membership and perceptual similarity.     

Renal and hepatic 1 alpha-hydroxylation of 25-hydroxyvitamin D3 in piglets suffering from pseudo vitamin D-deficiency rickets, type I

Research has shown that speech articulated in a clear manner is easier to understand than conversationally spoken speech in both the auditory-only (A-only) and auditory-visual (AV) domains. Because this research has been conducted using younger adults, it is unknown whether age-related changes in auditory and/or visual processing affect older adults' ability to benefit when a talker speaks clearly. The present study examined how speaking mode (clear vs conversational) and presentation mode (A-only vs AV) influenced nonsense sentence recognition by older listeners. Results showed that neither age nor hearing loss limited the amount of benefit that older adults obtained from a talker speaking clearly. However, age was inversely correlated with identification of AV (but not A-only) conversational speech, even when pure-tone thresholds were controlled statistically.     

The issue of negative evidence: Adult responses to children's language errors.

This study was designed to assess one of the major assumptions of current language learning theories: Adults ignore children's speech errors. We observed both parents (n?=?16) and nonparent adults (n?=?13) conversing with children and examined the conversations for evidence of adults' differential responding to the children's syntactic, phonological, and semantic errors. Results indicated that adults were more likely to repeat verbatim a well-formed sentence than an ill-formed sentence. In contrast, adults were more likely to repeat with changes, or request clarification of, a sentence containing syntactic or phonological errors than well-formed sentences. Adults also more frequently used the correct syntactic or phonological form in the immediately subsequent sentence if the child's preceding sentence contained only one syntactic or phonological error rather than multiple errors. Overall, the results indicate that all adults tend to respond differentially to children's language mistakes, with parents showing greater sensitivity than adults who are not parents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The aging decision maker: Cognitive aging and the adaptive selection of decision strategies.

Are older adults' decision abilities fundamentally compromised by age-related cognitive decline? Or can they adaptively select decision strategies? One study (N = 163) investigated the impact of cognitive aging on the ability to select decision strategies as a function of environment structure. Participants made decisions in either an environment that favored the use of information-intensive strategies or one favoring the use of simple, information-frugal strategies. Older adults tended to (a) look up less information and take longer to process it and (b) use simpler, less cognitively demanding strategies. In accordance with the idea that age-related cognitive decline leads to reliance on simpler strategies, measures of fluid intelligence explained age-related differences in information search and strategy selection. Nevertheless, both young and older adults seem to be equally adapted decision makers in that they adjust their information search and strategy selection as a function of environment structure, suggesting that the aging decision maker is an adaptive one. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stripes do not a zebra make, or do they? Conceptual and perceptual information in inductive inference.

Four-year-olds' and adults' inferences based on shared conceptual properties, category labels, and perceptual information were assessed in 4 experiments. Stimuli included novel animals (Studies 1, 3, and 4) and familiar animals (Study 2). Experiments suggest that both category membership information and similarity (in the form of conceptual information and perceptually provided information) affect inferences. Furthermore, conceptual attribute information and category membership information were used differently by adults but not by children. It is concluded that the inferential behavior of children and adults is influenced by perceptual information, conceptual attribute information, and category membership information, as well as by hypotheses about how these kinds of information relate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pupillometry as a measure of visual sensitivity among infants, young children, and adults.

Proposes pupillometry as an objective measure of visual sensitivity for infants, young children, and adults. To study the possible close relationship between pupillary contraction and perceived brightness for infants and young children, photopic pupillary sensitivity was measured for 5 1-yr-olds, 5 3-yr-olds, and 5 adults. Results support the utility of pupillometry as a sensitivity measure for infants and children, based on the demonstrated close agreement between the children's and adults' data in the study and adult data obtained by more traditional psychophysical techniques. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Moral education and domains in the classroom: Is nothing as practical as a good theory?

Reviews the book, Education in the moral domain by L. P. Nucci (see record 2001-06857-000). In his book Education in the Moral Domain, Nucci summarizes more than two decades of developmental research indicating that it is impossible to ignore children's active understanding of sociomoral rules in search of simple "habit formation." Instead, he argues, children routinely form complex conceptions of both sociomoral events and adults' legitimate roles in those events and if adults ignore these conceptions it will only undermine their attempts at moral education. In the past, ideas like these were seen as damaging because they suggested that children should "question authority." By contrast, the recent developmental research reviewed in this book indicates that, although children and adolescents do sometimes "question authority," there is a surprising amount of consensus in children's and adults' sociomoral understanding and behavior. This book provides an intellectually compelling summary of recent developmental research on children's sociomoral development with a clear eye on the implications of that work for classroom moral education and the larger moral climate of schools. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Assessing knowledge conveyed in gesture: Do teachers have the upper hand?

Children's gestures can reveal important information about their problem-solving strategies. This study investigated whether the information children express only in gesture is accessible to adults not trained in gesture coding. Twenty teachers and 20 undergraduates viewed videotaped vignettes of 12 children explaining their solutions to equations. Six children expressed the same strategy in speech and gesture, and 6 expressed different strategies. After each vignette, adults described the child's reasoning. For children who expressed different strategies in speech and gesture, both teachers and undergraduates frequently described strategies that children had not expressed in speech. These additional strategies could often be traced to the children's gestures. Sensitivity to gesture was comparable for teachers and undergraduates. Thus, even without training, adults glean information, not only from children's words but also from their hands. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the perceptual organization of speech.

A general account of auditory perceptual organization has developed in the past 2 decades. It relies on primitive devices akin to the Gestalt principles of organization to assign sensory elements to probable groupings and involves secondary schematic processes to confirm or to repair the possible organization. Although this conceptualization is intended to apply universally, the variety and arrangement of acoustic constituents of speech violate Gestalt principles at numerous junctures, cohering perceptually, nonetheless. Three experiments are reported on organization in phonetic perception, using sine wave synthesis to evade the Gesalt rules and the schematic processes alike. These findings falsify a general auditory account, showing that phonetic perceptual organization is achieved by specific sensitivity to the acoustic modulations characteristic of speech signals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Natural and artifactual kinds: Are children realists or relativists about categories?

Research in cognitive development has highlighted important differences between conceptions of natural kinds and artifacts. One interpretation of the distinction is that natural kinds are categories one discovers, whereas artifactual kinds are invented. Four studies assessed whether children and adults saw categorization decisions as objective matters of fact or as invented conventions. Preschool-age children treated basic-level categories of animals and human-made artifacts as objective. At the superordinate level, kinds of animals were treated as more objective than were kinds of artifacts. In general, adults' judgments were similar to children's. Both children and adults have reliable and differentiated intuitions regarding category objectivity. The results from these studies are discussed in terms of their implications for structural and theory-based accounts of category naturalness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The frequency of two-base tracts in eukaryotic genomes

The mismatch negativity event-related potential (MMN) was elicited in normal school-age children in response to just perceptibly different variants of the speech phoneme /da/. A significant MMN was measured in each subject tested. Child and adult MMNs were similar with respect to peak latency and duration. Measures of MMN magnitude (peak-to-peak amplitude and area) were significantly larger in children than in adults. The results of the present study indicate that the MMN can be elicited in response to minimal acoustic stimulus differences in complex speech signals in school-age children. The results support the feasibility of using the MMN as a tool in the study of deficient auditory perception in children.     

The costs of doing two things at once for young and older adults: Talking while walking, finger tapping, and ignoring speech of noise.

Young and older adults provided language samples in response to questions while walking, finger tapping, and ignoring speech or noise. The language samples were scored on 3 dimensions: fluency, complexity, and content. The hypothesis that working memory limitations affect speech production by older adults was tested by comparing baseline samples with those produced while the participants were performing the concurrent tasks. There were baseline differences: Older adults' speech was less fluent and less complex than young adults' speech. Young adults adopted a different strategy in response to the dual-task demands than older adults: They reduced sentence length and grammatical complexity. In contrast, older adults shifted to a reduced speech rate in the dual-task conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Self-monitoring in children: A differential approach to social development.

A new measure, the Junior Self-Monitoring scale, was developed and related to individual differences in children's tendencies to engage in social comparison when making decisions. Snyder's work on self-monitoring in adults provided the theoretical framework for a developmental extension of this construct. As predicted, children scoring high in self-monitoring were more likely to attend to the decisions of other children, and to do so for a longer period of time, than were low self-monitoring children. The scale may be useful for exploring the origins and developmental processes leading to adult individual differences in self-monitoring. Results were discussed in terms of the need for research on the ontogeny of individual differences in patterns of social behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)