Katharine Graf Estes

University of California, Davis, Davis, California, United States

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Publications (15)40.09 Total impact

  • Jessica F. Hay, Katharine Graf Estes, Tianlin Wang, Jenny R. Saffran
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    ABSTRACT: Infants must develop both flexibility and constraint in their interpretation of acceptable word forms. The current experiments examined the development of infants' lexical interpretation of non-native variations in pitch contour. Fourteen-, 17-, and 19-month-olds (Experiments 1 and 2, N = 72) heard labels for two novel objects; labels contained the same syllable produced with distinct pitch contours (Mandarin lexical tones). The youngest infants learned the label–object mappings, but the older groups did not, despite being able to discriminate pitch differences in an object-free task (Experiment 3, N = 14). Results indicate that 14-month-olds remain flexible regarding what sounds make meaningful distinctions between words. By 17–19 months, experience with a nontonal native language constrains infants' interpretation of lexical tone.
    Child Development 07/2014; · 4.92 Impact Factor
  • Katharine Graf Estes
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    ABSTRACT: The current research investigated how infants apply prior knowledge of environmental regularities to support new learning. The experiments tested whether infants could exploit experience with native language (English) phonotactic patterns to facilitate associating sounds with meanings during word learning. Infants (14-month-olds) heard fluent speech that contained cues for detecting target words; the target words were embedded in sequences that occur across word boundaries. A separate group heard the target words embedded without word boundary cues. Infants then participated in an object label learning task. With the opportunity to use native language patterns to segment the target words, infants subsequently learned the labels. Without this experience, infants failed. Novice word learners can take advantage of early learning about sounds to scaffold lexical development.
    Journal of Experimental Child Psychology 06/2014; 126C:313-327. · 3.12 Impact Factor
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    Lucy C. Erickson, Erik D. Thiessen, Katharine Graf Estes
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    ABSTRACT: There is considerable evidence that infants can segment speech using syllable co-occurrence probabilities; however, relatively less is known about the nature of the representations formed during this process. The present studies tested the prediction that statistically segmented items should exhibit a specific property of real words, namely, these items should have a facilitative effect on infant categorization. During the segmentation phase, eight-month-old infants listened to a fluent speech stream that contained statistical word boundary cues. Infants were then tested on their ability to categorize drawings of an unfamiliar category when category exemplars were paired with either high-probability or low-probability labels from the segmentation phase. Infants who heard high-probability labels showed evidence of categorization. In contrast, infants who heard low-probability labels did not. A follow up experiment revealed that this effect was due to facilitation for high-probability words rather than inhibition for low-probability items. These results fit with theoretical accounts that suggest that infants treat statistically segmented units as potential words.
    Journal of Memory and Language 04/2014; 72:49–58. · 2.80 Impact Factor
  • Katharine Graf Estes
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    ABSTRACT: The current research investigated how infants apply prior knowledge of environmental regularities to support new learning. The experiments tested whether infants could exploit experience with native language (English) phonotactic patterns to facilitate associating sounds with meanings during word learning. Infants (14-month-olds) heard fluent speech that contained cues for detecting target words; the target words were embedded in sequences that occur across word boundaries. A separate group heard the target words embedded without word boundary cues. Infants then participated in an object label learning task. With the opportunity to use native language patterns to segment the target words, infants subsequently learned the labels. Without this experience, infants failed. Novice word learners can take advantage of early learning about sounds to scaffold lexical development.
    Journal of Experimental Child Psychology 01/2014; 126:313–327. · 3.12 Impact Factor
  • Katharine Graf Estes, Karinna Hurley
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    ABSTRACT: Adults typically use an exaggerated, distinctive speaking style when addressing infants. However, the effects of infant-directed (ID) speech on infants' learning is not yet well understood. This research investigates how ID speech affects how infants perform a key function in language acquisition, associating the sounds of words with their meanings. Seventeen-month-old infants were presented with two label-object pairs in a habituation-based word learning task. In Experiment 1, the labels were produced in adult-directed (AD) speech. In Experiment 2, the labels were produced in ID prosody; they had higher pitch, greater pitch variation, and longer durations than the AD labels. We found that infants failed to learn the labels in AD speech, but succeeded in learning the same labels when they were produced in ID speech. Experiment 3 investigated the role of variability in learning from ID speech. When the labels were presented in ID prosody with no variation across tokens, infants failed to learn them. Our findings indicate that ID prosody can affect how readily infants map sounds to meanings and that the variability in prosody that is characteristic of ID speech may play a key role in its effect on learning new words.
    Infancy 09/2013; 18(5). · 1.73 Impact Factor
  • Katharine Graf Estes, Sara Bowen
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    ABSTRACT: This research investigates how early learning about native language sound structure affects how infants associate sounds with meanings during word learning. Infants (19-month-olds) were presented with bisyllabic labels with high or low phonotactic probability (i.e., sequences of frequent or infrequent phonemes in English). The labels were produced with the predominant English trochaic (strong/weak) stress pattern or the less common iambic (weak/strong) pattern. Using the habituation-based Switch Task to test label learning, we found that infants readily learned high probability trochaic labels. However, they failed to learn low probability labels, regardless of stress, and failed to learn iambic labels, regardless of phonotactics. Thus, infants required support from both common phoneme sequences and a common stress pattern to map the labels to objects. These findings demonstrate that early word learning is shaped by prior knowledge of native language phonological regularities and provide support for the role of statistical learning in language acquisition.
    Journal of Experimental Child Psychology 11/2012; · 3.12 Impact Factor
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    Katharine Graf Estes
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    ABSTRACT: The acoustic variation in language presents learners with a substantial challenge. To learn by tracking statistical regularities in speech, infants must recognize words across tokens that differ based on characteristics such as the speaker's voice, affect, or the sentence context. Previous statistical learning studies have not investigated how these types of non-phonemic surface form variation affect learning. The present experiments used tasks tailored to two distinct developmental levels to investigate the robustness of statistical learning to variation. Experiment 1 examined statistical word segmentation in 11-month-olds and found that infants can recognize statistically segmented words across a change in the speaker's voice from segmentation to testing. The direction of infants' preferences suggests that recognizing words across a voice change is more difficult than recognizing them in a consistent voice. Experiment 2 tested whether 17-month-olds can generalize the output of statistical learning across variation to support word learning. The infants were successful in their generalization; they associated referents with statistically defined words despite a change in voice from segmentation to label learning. Infants' learning patterns also indicate that they formed representations of across word syllable sequences during segmentation. Thus, low probability sequences can act as object labels in some conditions. The findings of these experiments suggest that the units that emerge during statistical learning are not perceptually constrained, but rather are robust to naturalistic acoustic variation.
    Frontiers in Psychology 01/2012; 3:447. · 2.80 Impact Factor
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    Jessica F Hay, Bruna Pelucchi, Katharine Graf Estes, Jenny R Saffran
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    ABSTRACT: The processes of infant word segmentation and infant word learning have largely been studied separately. However, the ease with which potential word forms are segmented from fluent speech seems likely to influence subsequent mappings between words and their referents. To explore this process, we tested the link between the statistical coherence of sequences presented in fluent speech and infants' subsequent use of those sequences as labels for novel objects. Notably, the materials were drawn from a natural language unfamiliar to the infants (Italian). The results of three experiments suggest that there is a close relationship between the statistics of the speech stream and subsequent mapping of labels to referents. Mapping was facilitated when the labels contained high transitional probabilities in the forward and/or backward direction (Experiment 1). When no transitional probability information was available (Experiment 2), or when the internal transitional probabilities of the labels were low in both directions (Experiment 3), infants failed to link the labels to their referents. Word learning appears to be strongly influenced by infants' prior experience with the distribution of sounds that make up words in natural languages.
    Cognitive Psychology 09/2011; 63(2):93-106. · 4.05 Impact Factor
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    Katharine Graf Estes, Jan Edwards, Jenny R Saffran
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    ABSTRACT: How do infants use their knowledge of native language sound patterns when learning words? There is ample evidence of infants' precocious acquisition of native language sound structure during the first years of life, but much less evidence concerning how they apply this knowledge to the task of associating sounds with meanings in word learning. To address this question, 18-month-olds were presented with two phonotactically legal object labels (containing sound sequences that occur frequently in English) or two phonotactically illegal object labels (containing sound sequences that never occur in English), paired with novel objects. Infants were then tested using a looking-while-listening measure. The results revealed that infants looked at the correct objects after hearing the legal labels, but not the illegal labels. Furthermore, vocabulary size was related to performance. Infants with larger receptive vocabularies displayed greater differences between learning of legal and illegal labels than infants with smaller vocabularies. These findings provide evidence that infants' knowledge of native language sound patterns influences their word learning.
    Infancy 01/2011; 16(2):180-197. · 1.73 Impact Factor
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    Daniel Mirman, Katharine Graf Estes, James S. Magnuson
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    ABSTRACT: Statistical learning mechanisms play an important role in theories of language acquisition and processing. Recurrent neural network models have provided important insights into how these mechanisms might operate. We examined whether such networks capture two key findings in human statistical learning. In Simulation 1, a simple recurrent network (SRN) performed much like human learners: it was sensitive to both transitional probability and frequency, with frequency dominating early in learning and probability emerging as the dominant cue later in learning. In Simulation 2, an SRN captured links between statistical segmentation and word learning in infants and adults, and suggested that these links arise because phonological representations are more distinctive for syllables with higher transitional probability. Beyond simply simulating general phenomena, these models provide new insights into underlying mechanisms and generate novel behavioral predictions.
    Infancy 08/2010; 15(5):471 - 486. · 1.73 Impact Factor
  • Katharine Graf Estes
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    ABSTRACT: By age 1, infants display remarkable sensitivity to the sound structure of their native language. Statistical learning, the process of detecting structure in the environment by tracking patterns in the input, is hypothesized to contribute to infants’ early learning about sound. The present paper explores how infants’ ability to track distributional information in the speech signal contributes to a fundamental aspect of language development, linking sounds with meanings in word learning. Previous research has demonstrated that infants detect several cues that mark where words begin and end in the fluent stream of speech (e.g., transitional probability, phonotactic regularities). Tracking such patterns may allow infants to isolate individual words, making them available to be associated with referents. Even very early in vocabulary development, statistical learning about which sound sequences are likely or unlikely to occur within words in the native language may also shape word learning. We propose that early experience with sound sequence regularities provides infants with a foundation for lexical acquisition.
    Language and Linguistics Compass 01/2009; 3:1379-1389.
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    Daniel Mirman, James S Magnuson, Katharine Graf Estes, James A Dixon
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    ABSTRACT: Many studies have shown that listeners can segment words from running speech based on conditional probabilities of syllable transitions, suggesting that this statistical learning could be a foundational component of language learning. However, few studies have shown a direct link between statistical segmentation and word learning. We examined this possible link in adults by following a statistical segmentation exposure phase with an artificial lexicon learning phase. Participants were able to learn all novel object-label pairings, but pairings were learned faster when labels contained high probability (word-like) or non-occurring syllable transitions from the statistical segmentation phase than when they contained low probability (boundary-straddling) syllable transitions. This suggests that, for adults, labels inconsistent with expectations based on statistical learning are harder to learn than consistent or neutral labels. In contrast, a previous study found that infants learn consistent labels, but not inconsistent or neutral labels.
    Cognition 08/2008; 108(1):271-80. · 3.63 Impact Factor
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    ABSTRACT: The present experiments investigated how the process of statistically segmenting words from fluent speech is linked to the process of mapping meanings to words. Seventeen-month-old infants first participated in a statistical word segmentation task, which was immediately followed by an object-label-learning task. Infants presented with labels that were words in the fluent speech used in the segmentation task were able to learn the object labels. However, infants presented with labels consisting of novel syllable sequences (nonwords; Experiment 1) or familiar sequences with low internal probabilities (part-words; Experiment 2) did not learn the labels. Thus, prior segmentation opportunities, but not mere frequency of exposure, facilitated infants' learning of object labels. This work provides the first demonstration that exposure to word forms in a statistical word segmentation task facilitates subsequent word learning.
    Psychological Science 04/2007; 18(3):254-60. · 4.43 Impact Factor
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    Katharine Graf Estes, Julia L Evans, Nicole M Else-Quest
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    ABSTRACT: This study presents a meta-analysis of the difference in nonword repetition performance between children with and without specific language impairment (SLI). The authors investigated variability in the effect sizes (i.e., the magnitude of the difference between children with and without SLI) across studies and its relation to several factors: type of nonword repetition task, age of SLI sample, and nonword length. The authors searched computerized databases and reference sections and requested unpublished data to find reports of nonword repetition tasks comparing children with and without SLI. Children with SLI exhibited very large impairments in nonword repetition, performing an average (across 23 studies) of 1.27 standard deviations below children without SLI. A moderator analysis revealed that different versions of the nonword repetition task yielded significantly different effect sizes, indicating that the measures are not interchangeable. The second moderator analysis found no association between effect size and the age of children with SLI. Finally, an exploratory meta-analysis found that children with SLI displayed difficulty repeating even short nonwords, with greater difficulty for long nonwords. These findings have potential to affect how nonword repetition tasks are used and interpreted, and suggest several directions for future research.
    Journal of Speech Language and Hearing Research 03/2007; 50(1):177-95. · 1.97 Impact Factor
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    Jenny R Saffran, Katharine Graf Estes
    Advances in child development and behavior 02/2006; 34:1-38. · 0.95 Impact Factor

Publication Stats

267 Citations
40.09 Total Impact Points

Institutions

  • 2008–2014
    • University of California, Davis
      • Department of Psychology
      Davis, California, United States
  • 2011
    • The University of Tennessee Medical Center at Knoxville
      Knoxville, Tennessee, United States
  • 2006–2007
    • University of Wisconsin, Madison
      • Department of Psychology
      Madison, MS, United States