The “Introduction to Neural Networks” Lesson

Editor’s note: On November 1st of this year, David Silver (Program Lead for Udacity’s Self-Driving Car Engineer Nanodegree program) made a pledge to write a new post for each of the 67 lessons currently in the program. We check in with him today as he introduces us to Lesson 4!

The 4th lesson of the Udacity Self-Driving Car Engineer Nanodegree Program introduces students to neural networks, a powerful machine learning tool.

This is a fast lesson that covers the basic mechanics of machine learning and how neural networks operate. We save a lot of the details for later lessons.

My colleague Luis Serrano starts with a quick overview of how regression and gradient descent work. These are foundational machine learning concepts that almost any machine learning tool builds from.

Luis is great at this stuff. I love Mt. Errorest.

Moving on from these lessons, Luis goes deeper into the distinction between linear and logistic regression and then explores how these concepts can reveal the principles behind a basic neural network.

See the slash between the red and green colors there? If you ever meet Luis in person, ask him to sing you the forward-slash-backward-slash alphabet song. It’s amazing.

From here we introduce perceptrons, which historically were the precursor to the “artificial neurons” that make up a neural network.

As we string together lots of these perceptrons, or “artificial neurons”, my colleague Mat Leonard shows that we can take advantage of a process called backpropagation, that helps train the network to perform a task.

And that’s basically what a neural network is: a machine learning tool built from layers of artificial neurons, which takes an input and produces an output, trained via backpropagation.

This lesson has 23 concepts (pages), so there’s a lot more to it than the 3 videos I posted here. If some of this looks confusing, don’t worry! There’s a lot more detail in the lesson, as well as lots of quizzes to help make sure you get it.

If you find neural networks interesting in their own right, perhaps you should sign up for Udacity’s Deep Learning Nanodegree Foundation Program. And if you find them interesting for how they can help us build a self-driving car, then of course you should apply to join the Udacity Self-Driving Car Nanodegree Program!