Computational models of associative learning in the acquisition of speech imitation, acoustic word models, and word-meaning mappings

Heikki Rasilo

Research output: ThesisDoctoral ThesisCollection of Articles

Abstract

Human infants manage to learn their native language from noisy and ambiguous language input, but the exact mechanisms underlying language learning are not known. Recent decades of research have shown that so-called statistical learning mechanisms provide a possible way to learn linguistic patterns from sensory signals, either within auditory input or as consistent relations between different perceptual domains. Statistical learning is especially powerful in situations where relevant patterns in different sensory streams do not occur in a one-to-one fashion, enabling the learning of associations that still occur at above-chance level. In this thesis, the potential role of associative statistical learning is studied in the context of three aspects of language learning: learning to imitate the speech of human caregivers, learning words and their segmentation from continuous speech, and learning word-to-meaning mappings. The three tasks are investigated with computational models of human-like learning in ambiguous learning situations. The first learning task considers the existing hypothesis that infants have to learn to imitate the speech of their parents, rather than the imitation skill being innate. It is hypothesized that infants can use statistical relations between their vocalic babble and caregivers' imitative responses to learn correspondences between the two. In this thesis, a mechanism for the learning of vocal imitation with ambiguous babble-response type input is introduced, and tested using human participants acting as caregivers to a virtual infant. It is also investigated how ambiguous visual information about possible word meanings can be used to bootstrap the learning of acoustic word models and word segmentation in continuous speech. Finally, it is studied what kind of cognitive constraints could explain human behaviour in so-called cross-situational learning experiments, where the subjects need to infer correct word-to-meaning mappings from ambiguous pairings of audiovisual stimuli. The findings of this thesis indicate that statistical associative learning can be successfully used in several tasks related to language learning, and that highly specialized innate mechanisms related to speech may not be necessary in order for speech learning to take place. The findings and the computational algorithms introduced in this thesis may be of technological use in the implementation of autonomous robots able to learn from their environment, while also offer insight into what learning mechanisms may exist in the human brain and what kinds of stimuli are beneficial in order to facilitate human speech learning.
Translated title of the contributionAssosiatiivisen oppimisen laskennallinen mallinnus puheen matkimisen, sanamallien ja sana-merkitysparien oppimisessa
Original languageEnglish
QualificationDoctor's degree
Awarding Institution
  • Aalto University
Supervisors/Advisors
  • Laine, Unto K. , Supervising Professor
  • Alku, Paavo, Supervising Professor
  • de Boer, Bart, Supervising Professor, External person
  • Räsänen, Okko, Thesis Advisor
Publisher
Print ISBNs978-952-60-7659-1
Electronic ISBNs978-952-60-7658-4
Publication statusPublished - 2017
MoE publication typeG5 Doctoral dissertation (article)

Keywords

  • language acquisition
  • speech imitation
  • articulation
  • weakly supervised learning
  • associative learning
  • word recognition
  • segmentation

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