Peter D. Eimas

Speech perception in infants.

Discriminiationi of synthetic speech sounds was studied in 1- and 4-month-old infants. The speech sounds varied along an acoustic dimension previously shown to cue phonemic distinctions among the voiced and voiceless stop consonants in adults. Discriminability was measured by an increase in conditioned response rate to a second speech sound after habituation to the first speech sound. Recovery from habituation was greater for a given acoustic difference when the two stimuli were from different adult phonemic categories than when they were from the same category. The discontinuity in discrimination at the region of the adult phonemic boundary was taken as evidence for categorical perception.

Selective adaptation of linguistic feature detectors

Abstract Using a selective adaptation procedure, evidence was obtained for the existence of linguistic feature detectors, analogous to visual feature detectors. These detectors are each sensitive to a restricted range of voice onset times, the physical continuum underlying the perceived phonetic distinctions between voiced and voiceless stop consonants. The sensitivity of a particular detector can be reduced selectively by repetitive presentation of its adequate stimulus. This results in a shift in the locus of the phonetic boundary separating the voiced and voiceless stops.

Evidence for representations of perceptually similar natural categories by 3-month-old and 4-month-old infants.

The paired-preference procedure was used in a series of experiments to explore the abilities of infants aged 3 and 4 months to categorize photographic exemplars from natural (adult-defined) basic-level categories. The question of whether the categorical representations that were evidenced excluded members of a related, perceptually similar category was also investigated. Experiments 1–3 revealed that infants could form categorical representations for dogs and cats that excluded birds. Experiment 4 showed that the representation for cats also excluded dogs, but that the representation for dogs did not exclude cats. However, a supplementary experiment showed that the representation for dogs did exclude cats when the variability of the dog exemplars was reduced to match that of the cat exemplars. The results are discussed in terms of abilities necessary for the formation of more complex categorical representations.

Auditory and phonetic coding of the cues for speech: Discrimination of the [r-l] distinction by young infants

Infants, 2 and 3 months of age, were found to discriminte stimuli along the acoustic continuum underlying the phonetic contrast [r] vs. [l] in a nearly categorical manner. For an approximately equal acoustic difference, discrimination, as measured by recovery from satiation or familiarization, was reliably better when the two stimuli were exemplars of different phonetic categories than when they were acoustic variations of the same phonetic category. Discrimination of the same acoustic information presented in a nonspeech mode was found to be continuous, that is, determined by acoustic rather than phonetic characteristics of the stimuli. The findings were discussed with reference to the nature of the mechanisms that may determine the processing of complex acoustic signals in young infants and with reference to the role of linguistic experience on the development of speech perception at the phonetic level.

Auditory and linguistic processing of cues for place of articulation by infants

Two- and 3-month-old infants were found to discriminate the acoustic cues for the phonetic feature of place of articulation in a categorical manner; that is, evidence for the discriminability of two synthetic speech patterns was present only when the stimuli signaled a change in the phonetic feature of place. No evidence of discriminability was found when two stimuli, separated by the same acoustic difference, signaled acoustic variations of the same phonetic feature. Discrimination of the same acoustic cues in a nonspeech context was found, in contrast, to be noncategorical or continuous. The results were discussed in terms of infants’ ability to process acoustic events in either an auditory or a linguistic mode.

Speech, language, and communication

L. Frazier, Issues of Representation in Psycholinguistics. C.A. Fowler, Speech Production. L.C. Nygaard and D.B. Pisoni, Speech Perception: New Directions in Research and Theory. A. Cutler, Spoken Word Recognition and Production. M.S. Seidenberg, Visual Word Recognition: An Overview. K. Bock, Sentence Production: From Mind to Mouth. M.K. Tanenhaus and J.C. Trueswell, Sentence Comprehension. P.W. Jusczyk, Language Acquisition: Speech Sounds and the Beginnings of Phonology. E.V. Clark, Language Acquisition: The Lexicon and Syntax. S.E. Blumstein, The Neurobiology of Language. H.H. Clark and B. Bly, Pragmatics and Discourse. Subject Index.

Studies on the categorization of speech by infants

Abstract It is well-known that complexities exist in the mapping between the acoustic information in the speech signal and the phonetic categories of adult language users. We investigated whether the same complexities exist in the mapping between the speech signal and the forerunners of these categories in infants. For two classes of complexity, we found that the manner in which the categorization of information for speech occurs was virtually identical in infant and adult listeners. These findings indicate that the infant possesses finely tuned linguistically-relevant perceptual abilities, which undoubtedly facilitate and shape the task of language acquisition.

Global and local processing by 3- and 4-month-old infants

In two experiments with 3- and 4-month-old infants, we used a familiarization/novelty preference procedure to assess the ability of infants to acquire information about the global and local information in a complex visual pattern. The initial experiment established that individual infants were able to acquire and remember information about both the global forms and the local forms from which the global patterns were constructed. In addition, we found that the global and local forms were of nearly equal discriminability. Using these patterns and a Stroop-like interference paradigm, in the second experiment we obtained evidence for a global precedence effect that could not, we argue, be attributed solely to a difference in discriminability favoring the global stimuli.

The Emergence of Category Representations During Infancy: Are Separate Perceptual and Conceptual Processes Required?

A long-standing issue in cognitive development concerns the manner in which the earliest, presumably perceptually based, categorical representations of young infants, become knowledge-rich categories, concepts in most theoretical descriptions, that are often interconnected and permit causal explanations of their properties. In her feature article, Mandler’s (this issue) position on this question presumes that it is wrong to posit a single form of categorical representation that is perceptually based. Although there exist perceptual categories (or schemas) that detect and compile surface features of objects useful for the recognition and identification of cats versus dogs, for example, true concepts that represent object kind information and meaning emerge from a markedly different process from that of perception, namely, perceptual analysis of the analog percept. As was true for Mandler, we discuss primarily the development of the initial categorical and later conceptual representation for animals, a global mental entity. JOURNAL OF COGNITION AND DEVELOPMENT, 2000, Volume 1, pp. 55–61 Copyright

Some properties of linguistic feature detectors

A series of experiments, using a selective adaptation procedure, investigated some of the properties of the linguistic feature detectors that mediate the perception of the voiced and voiceless stop consonants. The first experiment showed that these detectors are centrally rather than peripherally located, in that monotic presentation of the adapting stimulus and test stimuli to different ears resulted in large and reliable shifts in the locus of the phonetic boundary. The second experiment revealed that the detectors are part of the specialized speech processor, inasmuch as adaptation of a voicing detector (as measured by a shift in the phonetic boundary) occurred only when the voicing information was presented in a speech context. In the third experiment, the detector mediating perception of the voiced stops was shown to be more resistant to adaptation than the detector mediating perception of the voiceless stops.