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W02. Movement 01

Welcome to the first lecture of the Movement module. When we think of movement, we often think of output in terms of muscles, motors, or other force-producing devices. However, movement by intelligent creatures (from viruses to humans) is usually purpose-driven in some way. If we think about what it means to be alive, there seems to be some kind of purpose-driven action involved (i.e., eating for the purpose of self-perpetuation, self-replication, etc.). To be purpose-driven in any way, some kind of sensation is required, since you need to not just act, but act in a way that moves you closer to some kind of eventual goal.

As we will always do in this class, we use computation as a model to understand sensation. Of course, sensation in biology is very diverse and complex, but having a clear model of the mechanisms involved is helpful in understanding the minimum requirements for sensation.

This lecture introduces the basic analog-to-digital sensing circuit as exemplified by potentiometers and photoresistors. Most basic sensors can be conceptually modelled with the potentiometer circuit. An electronic photocell functionally mimics the rod photocell in our eyes, even though the mechanism by which it operates is significantly different.

Pre-readings and Videos​

These are good, solid reference and how-to videos for using potentiometers and photo resistors. You can and should look up other videos in this series if you’re ever confused about a lab component. You will eventually be responsible for knowing how everything in photoresistor and potentiometer video works and being able to recreate it, e.g., on a test, however you will have plenty of time to practice before that happens (and, trust me, it's actually way easier than it looks right now).

The Searle reading is a good, classic, short reading on whether machines can actually "think" the way we understand thinking. It's a rare argument against the hype that we see in AI right now. However, it also poses interesting engineering problems, i.e., what about the meat stuff makes it the only stuff that Searle thinks can think?

Resistors​

Before getting into potentiometers, it's helpful to have a basic understanding of resistors, since a potentiometer is basically a variable resistor.

Potentiometer​

Our model sensor is the potentiometer. If you're ever trying to understand the logic of another simple sensor, try to translate it to what a poteniometer does.

Photocell​

A photocell is also called a photoresistor. A photoresistor changes its resistance based on the presence of light.

Sensory Pathways​

Our brains have sensory pathways, starting from sensory neurons that interact with the real world, translate that interaction into a neuronal signal, and transmit the signal to the brain.

Can Computers Think?​

John Searle is one of the most well-known philosophers who deal with computation. In this essay, he makes an argument against programs themselves being able to think, and advances the idea that a machine that thinks must be at least as causally powerful as a brain. Link.

Summary of the Day​

Learning Goals​

  1. Learn how a variable resistor is the most basic model of an analog sensing circuit, and use it for foundational understanding of sensation.
  2. Be able to wire sensing circuits using the potentiometer as a model.
  3. Learn about the agent-world loop and compare to it to Arduino parts/computational hierarchy/body organization.