Even if you’ve never taken a psychology course, you’re likely at least marginally familiar with B.F. Skinner. The American psychologist is most famous for his theory of the principle of reinforcement, or operant conditioning. Anyone who has ever trained an animal or worked with a child knows this principle well – the more you reward certain behavior, the more the child or animal will repeat that behavior in the future. To further study the principle of reinforcement, Skinner invented the operant conditioning chamber, also known as the Skinner box. Skinner placed rats into the chamber, which contained a lever. When pressed, the lever would dispense food into the chamber; quickly, the rats learned to associate the lever with rewards, and would go straight to it as soon as they were placed into the box.
That’s the Skinner box at its most basic, but it has undergone many iterations, created both by Skinner and psychologists after him, to perform various experiments in both positive and negative reinforcement. Dr. Rogelio Escobar, Professor of Psychology at the National Autonomous University of Mexico, teaches several courses on animal learning and behavior. Skinner’s experiments are central to the curriculum, but without the means to perform the experiments themselves and see the principles at work with live subjects, Dr. Escobar believes that the students cannot fully understand the theories.
“Although it was recognized since the early 1950s that laboratory courses must be an integral part of courses on operant conditioning, these courses are now a rarity in Universities around the world,” Dr. Escobar tells 3DPrint.com. “One reason is the high cost of laboratory equipment. This problem is particularly acute in third-world countries in which resources in Universities are severely limited. In some cases, even accessing laboratories with computers is restricted.”
So he decided to build the components for his own laboratory, which in this case meant the construction of a fully functional operant conditioning chamber for rats. The chamber, once completed, would include a lever that, when pressed, would deliver a small drop of water to the rat subject as a reward. Additional stimuli such as lights and tones were included to further influence the rats’ behavior. To start, he needed to design and program the electronics required for the operant conditioning chambers to function. The full process of this stage of the project was documented in a peer-reviewed research paper by Dr. Escobar and one of his students, which you can find here.
Then it was time to build the chambers themselves, which is where 3D printing comes in. Using 123D Design, Dr. Escobar designed the chambers’ structural parts and printed them with a RoBo 3D printer he purchased using a grant from the university.
“Aside from the 3D printed parts, the chambers were built with laser-cut transparent acrylic panels, and 8 mm steel rods for the floor grid,” Dr. Escobar tells us. “I use a servo motor to retract and extend the metal lever, and a peristaltic pump to deliver the drop of water into a tray. All the devices in the chamber are controlled using a keypad connected to an Arduino board.”
The chamber’s control system was designed to give the students complete control over the experiments, by having them present stimuli to the rats using the keypad. This kept them fully engaged, and, according to Dr. Escobar, they were full of questions that wouldn’t have occurred to them during a lecture, which reinforced his theory that hands-on experimentation is critical for learning.
“There has been an increasing demand of applied behavior analysis (ABA) therapists in recent years,” he continues. “The principles that were once discovered in operant-conditioning chambers are now important in treatments for problem behaviors associated with autism, health and exercise issues, repetitive habits, substance abuse, language acquisition, etc. As part of training, students learn to identify the relations between behavior and environmental events, and learn about schedules of reinforcement. Laboratory courses using operant-conditioning chambers are not only important to show first-hand the principles of behavior but could be useful also to emphasize the relation between basic research and the development of interventions.”
This brings us to the larger goal of Dr. Escobar’s project, which is to help other psychology educators without access to laboratory space and tools to set up their own labs; in particular, to build their own operant conditioning chambers. He set up a website, and will soon be uploading all of the files he used and making them available for free download and modification. Discuss this story in the 3D Printed Psychological Laboratory Forum Thread on 3DPB.com. Here’s another look at Dr. Escobar’s students at work with their animal subjects: