Lab 1: Robot Charades

Purpose of the lab

The purpose of this lab is to engage in a type of psychology. In particular, you will perform synthetic psychology (the psychology of artificial or synthetic systems). Remember that a major goal of the psychology you study is to "reverse-engineer" the principles of the human mind or brain. Like many areas of science, we do not know the correct answer when we start out and so careful experiments and crafty theories (i.e., the scientific method) are necessary to make progress. However, in synthetic psychology, the operation of the robot is designed by a human. Thus, when you attempt to reverse engineer the robot's program we can check to see if you conclusions about the psychology of the robot are correct.

Think back to your math classes... Often you do many exercise problems to help sharpen your skills so you can tackle real problems on the final test, or in your job. This lab is like a practice exercise in psychology where you can check your answer at the end!


This lab consists of a couple steps:

Pretty simple, eh? Let's go.

Step 1: Wire up the brain

To start with, check out that your servo wheel have been calibrated and are connected properly. We will do this as a preliminary robot-building exercise in class. Next you will wire up the brain of your robot! On the top of the robot on the BOEbot shield there is a patch of white plastic called a bread-board or protoboard/plugboard. Inside it are about 100 tiny holes.

These holes are places where you can stick wires, resistors, sensors, etc... to wire up electrical circuits. The advantage of the breadboard is that you don't have to solder any parts together and everything is temporary (so you can build an reconfigure things easily).

This breadboard has 17 rows of sockets. In each row, there are two five-socket groups separated by a trench in the middle. All the sockets in a 5-socket group are connected together underneath with a conductive metal clip. So, two wires plugged into the same 5-socket group make electrical contact. This is how you will connect components, such as an LED and resistor, to build circuits. Two wires in the same row on opposite sides of the center trench will not be connected.

The prototyping area also has black sockets along the top, bottom, and left

Don't worry if not all of this makes sense to you yet... It will by the end of the semester!

Here's an example of a wired up circuit on the protoboard. You just plug the right components in to create the circuit. You can ignore the details on this one... it is just for illustration.

Ok, so the brain that you are going to wire up is going to be secret. I'm not going to tell you how it works just yet and try to leave a bit of mystery. If you already know a lot about electronics this may not work, but if you don't know the difference between a resistor and a capacitor (or what they do) that is GOOD! You'll be able to do the psychology without being confused by all the electronics.

Ok, so for your brain you need to identify six components and pull out a couple short wires (you should have a bundle in your robot kit). The six components are created by getting two copies of everything you see in this picture:

From top to bottom:

and you want to wire it up to look like this:

(ignore the big round disk, the green wire, and the shortest black wire for now). Also you might move things so that the two copied circuits are further apart on the breadboard.

Don't be afraid to ask questions. When you think you have it set up, continue to part 2.

Step 2: Allow me to brainwash your robot

When you are confident your robot is wired correctly bring it to me. I will give you batteries, check the circuit, and load up a program in the brain of your robot. When you have my approval you can proceed to step 3.

Step 3: Figure out what your robot is doing!

Now is where the real lab begins!

Your job is to perform experiments to figure out what your robot is doing. What rules is it following (if any). This is the game of charades.

Step 4: Answer some questions

In your group, answer the following questions:

Q4.1: Describe at a high level the overall behavior of your robot. Is it random? Is there some particular pattern to the behavior that you notice?

Q4.2: Think of a couple ways the robot might possibly be programmed to achieve the behavior you described in the previous answer. What code do you think I put in the robot?s mind? Come up with at least two plausible alternatives.

Possibility 1:

Possibility 2:

Possibility 3:

Any others?

Q4.3: Given the alternative hypotheses about the underlying rules of the robot's behavior that you just wrote down, describe empirical tests (i.e., experiments) you could perform to decide which is right. How you test which idea about the function of the robot is correct? You should work with your group member to design and run the test. At this stage please do not change the wiring of the robot!! Pretend it is a subject in a psychology experiment. What experiment can you design to test how it?s brain works? Describe at least two experiment designs and the results our your tests.

Q4.4: What stimuli does the robot seem sensitive to in the environment? What do you think the robot's sensors are measuring?

Q4.5: How does the activity of the sensors affect the speed at which the wheels of the robot turn? (Hint: If you are not sure, and didn't try this in your experiments, try moving your hand hear the sensor while holding the robot in your hand and see what happens to the wheels.

Q4.6: Brain surgery! Set the switch to position 0 (only power to the brain) and then unplug your robot from the battery pack. Try brain surgery... a useful way to figure out how a brain works but unethical for trying on people! In particular, switch the pins circled below (the resistor plugged into pin 6 should plug into pin 8 and vice versa). BE VERY CAREFUL WITH THIS... IF THEY TWO RESISTORS TOUCH IT WILL SHORT THEM OUT. IT IS CRITICAL THAT YOU SWITCH THEM WITHOUT LETTING THEM TOUCH EACH OTHER OR ANYTHING ELSE ON THE BOARD!!! DONT KILL THE PATIENT!

After you've CAREFULLY switched the cable, reconnect the battery pack and power up the servos. What has changed about the overall behavior of the robot (i.e., the description you provided in Q3.1)? How would you describe the robot now?

Step 5: Read

Please read the assigned sections from the "Vehicles" books posted on the course website over the weekend.

Step 6: Answer some more questions

Q6.1: Think about how the ideas that Braitenberg describes relate to how you thought about how your robot worked. Do you think your robot is a Braitenburg machine? Which number?

Q6.2: Think about these idea in relation to the Rodney Brooks article from earlier in the week. Is it right to think of intelligence as existing in the mind? Brooks argued that intelligent agents could ?use the world as it's own model? (or representation). Do you think it is possible that your robot operates according to a similar principal?

Q6.3: Were the ideas in the Braitenburg book surprising to you? Did they make you think differently about your robot, or what it means to be intelligent?

Q6.4: In the previous sections you were encouraged to think about the FUNCTION of the robot (the behavior it does... a high level description). In addition you were asked to think about the MECHANISM by which the robots does those functions. How are those to levels of explanation related to the study of the human mind? If you know how something works (i.e., the mechanism) is there any need for the other type of explanation (i.e., functional)?

Copyright © 2013 Todd Gureckis, Diagrams and schematics of the Parallax robot come from the Parallax website.