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Brains, Minds + Machines Seminar Series: Feedforward and feedback processes in visual recognition

Nov 5, 2019 - 4:00 pm
Photo of Thomas Serre
Venue:  Singleton Auditorium Address:  43 Vassar Street, Cambridge MA 02139 Speaker/s:  Thomas Serre, Cognitive, Linguistic & Psychological Sciences Department, Carney Institute for Brain Science, Brown University

Title: Feedforward and feedback processes in visual recognition

Abstract: Progress in deep learning has spawned great successes in many engineering applications. As a prime example, convolutional neural networks, a type of feedforward neural networks, are now approaching – and sometimes even surpassing – human accuracy on a variety of visual recognition tasks. In this talk, however, I will show that these neural networks and their recent extensions exhibit a limited ability to solve seemingly simple visual reasoning problems involving incremental grouping, similarity and spatial relation judgments. Our group has developed a recurrent network model of classical and extra-classical receptive fields that is constrained by the anatomy and physiology of the visual cortex. The model was shown to account for diverse visual illusions providing computational evidence for a novel canonical circuit that is shared across visual modalities. I will show that this computational neuroscience model can be turned into a modern end-to-end trainable deep recurrent network architecture which addresses some of the shortcomings exhibited by state-of-the-art feedforward networks for solving complex visual reasoning tasks. This suggests that neuroscience may contribute powerful new ideas and approaches to computer science and artificial intelligence.​

Organizer:  Hector Penagos Organizer Email:  cbmm-contact@mit.edu

CBMM Special Seminar: Beyond Empirical Risk Minimization: the lessons of deep learning

Oct 28, 2019 - 4:00 pm
Photo of Mikhail Belkin
Venue:  Singleton Auditorium Address:  43 Vassar Street, Cambridge MA 02139 Speaker/s:  Mikhail Belkin, Professor, The Ohio State University - Department of Computer Science and Engineering, Department of Statistics, Center for Cognitive Science

Title: Beyond Empirical Risk Minimization: the lessons of deep learning

Abstract: "A model with zero training error is  overfit to the training data and  will typically generalize poorly"  goes statistical textbook wisdom.  Yet, in modern practice, over-parametrized deep networks with   near  perfect  fit on  training data still show excellent test performance.  This apparent  contradiction points to troubling cracks in the conceptual foundations of machine learning. While classical analyses of Empirical Risk Minimization rely on balancing the  complexity of  predictors with  training error, modern models are best described by interpolation. In that paradigm  a predictor is chosen by minimizing (explicitly or implicitly) a norm corresponding to a certain inductive bias over a space of functions that  fit the training data exactly. I will discuss the nature of the challenge to our understanding of machine learning and point the way forward to first analyses that account for the empirically observed phenomena.  Furthermore, I will show how  classical and modern models can  be unified within a single  "double descent" risk curve,  which subsumes the classical U-shaped bias-variance trade-off.

Finally, as an example of a particularly interesting inductive bias, I will show evidence that deep  over-parametrized autoencoders networks, trained with SGD, implement a form of associative memory with training examples as attractor states.

Organizer:  Jean Lawrence Organizer Email:  cbmm-contact@mit.edu

CBMM Special Seminar: Quantum Computing: Current Approaches and Future Prospects-Jack Hidary

Oct 2, 2019 - 11:00 am
Photo of Jack Hidary
Venue:  Singleton Auditorium Address:  MIT Bldg 46 Rm 3002, 43 Vassar Street, Cambridge MA 02139   Speaker/s:  Jack Hidary, Alphabet X, formerly Google X

Abstract: Jack Hidary will take us through the nascent, but promising field of quantum computing and his new book, Quantum Computing: An Applied Approach

Bio: Jack D. Hidary is a research scientist in quantum computing and in AI at Alphabet X, formerly Google X. He and his group develop and research algorithms for NISQ-regime quantum processors as well as create new software libraries for quantum computing.  In the  AI field, Jack and his  group focus on fundamental research such as the generalization of deep networks as well as applied AI technologies.

Organizer:  Kathleen Sullivan Organizer Email:  cbmm-contact@mit.edu

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