A mathematical theory of semantic development in deep neural networks
An extensive body of empirical research has revealed remarkable regularities in the acquisition, organization, deployment, and neural representation of human semantic knowledge, thereby raising a fundamental conceptual question: what are the theoretical principles governing the ability of neural networks to acquire, organize, and deploy abstract knowledge by integrating across many individual experiences? I will describe work addressing this question by mathematically analyzing the nonlinear dynamics of learning in deep linear networks. We find exact solutions to this learning dynamics that yield a conceptual explanation for the prevalence of many disparate phenomena in semantic cognition, including the hierarchical differentiation of concepts through rapid developmental transitions, the ubiquity of semantic illusions between such transitions, the emergence of item typicality and category coherence as factors controlling the speed of semantic processing, changing patterns of inductive projection over development, and the conservation of semantic similarity in neural representations across species. Furthermore, I will show that many of these phenomena only arise in deep but not shallow networks. Thus, surprisingly, this simple neural model qualitatively recapitulates many diverse regularities underlying semantic development, while providing analytic insight into how the statistical structure of an environment can interact with nonlinear deep learning dynamics to give rise to these regularities.
Date:
22 October 2019, 15:00 (Tuesday, 2nd week, Michaelmas 2019)
Venue:
New Radcliffe House, Walton Street OX2 6NW
Venue Details:
Room 20.05 Seminar Room 2
Speaker:
Dr Andrew Saxe (Harvard)
Organising department:
Department of Experimental Psychology
Organisers:
Yaling Hsiao (University of Oxford ),
Dr Karla Holmboe (Department of Experimental Psychology, University of Oxford)
Organiser contact email address:
yaling.hsiao@psy.ox.ac.uk
Part of:
Department of Experimental Psychology - Language & Development Seminars
Booking required?:
Not required
Audience:
Public
Editor:
Yaling Hsiao
