[MUSIC, Title: "Learning without Knowing You Know: Revisiting the Procedural System"] [Barb] "If we compare non-conscious brain activity to a tower a kilometer high, the conscious mind represents merely a millimeter. The kilometer allows us to recognize a familiar face among millions of strangers, to think, to walk, to identify a heart murmer, to know from her voice in the telephone, how Mom is doing today, or to inspire a group of students." This quote, from Professor Edvin Schei of the University of Bergen and his colleagues in relation to teaching medical school students, beautifully informs us about the deep layers of the brain that process complex information without our even knowing about it. We may think that we can explain anything to students. But the reality is that those deep non-conscious layers generally can't be reached through verbal instruction. What's really extraordinary though, is that the kilometer of non-conscious processes can recognize such subtle and complex patterns that the millimeter of conscious you is oblivious to them— and these processes can operate far more quickly than you can ever consciously be aware of. [MUSIC, Title: "Declarative Versus Procedural Memory Pathways"] [Terry] As a quick review, remember that the declarative pathway makes neural links in the neocortex via the hippocampus—good old Hip. The procedural pathway, on the other hand, makes links on the neocortex through the basal ganglia. That is, in our metaphorical world, the gang of basal plants. When we explicitly explain information to a student— and the student is paying attention and not experiencing cognitive overload!— that information then flows onto the hippocampus and from there into long-term memory. Of course, this assumes the information is mostly going through the funnel of working memory. In other words, the information flows from Trinity—the Conductor— through Hip, into Neo. Hip, as we recall, whispers to Neo whenever he has a chance to help her strengthen her initially very weak sets of links. [Barb] When you're first learning something— perhaps you're doing retrieval practice— you pull recent memories from the neocortex into working memory with the help of Hip. Later, after the information is well established and consolidated, you can pull the information directly from Neo without using Hip. I tend to think of Hip as pouting about being left out in the end. You're mostly conscious of your learning through the declarative system. These declarative links often—but not always— involve special information or information about objects or concepts. [Beth] I do declare, we English teachers think of the declarative pathway as being like declarative sentences, the purpose of which is to pass information on. [Terry] But the brain is like a rocket ship that has redundant systems for essential tasks. It has a second way of getting information into long-term memory— a backup system we don't even have to think about consciously: the procedural learning system, which we introduced in our previous course. This system takes information from what we see, hear or feel, into long-term memory, through the basal ganglia and their associated structures. Interestingly, unlike the hippocampus which is no longer needed after neural links are well- consolidated in long-term memory, the basal ganglia continue to have an essential role working together with the neocortex, using the links previously laid out in long-term memory through the procedural system. [Barb] Exactly right. The basal ganglia doesn't just disappear from use once a person has practiced enough with the material, like our pouty Hip does. Instead, the basal ganglia always plays a role whenever procedural information is needed from long-term memory. To keep things simple though, for the most part, we don't show those links between Neo and the basal ganglia in our animations. [Terry] In case you're wondering, the procedural system also compacts and concentrates neural learning through processes of consolidation. Similar to the way links are consolidated in long-term memory through the declarative system. Most of the procedural consolidation also occurs during sleep, but at different times during sleep. The consolidation of procedural learning occurs during what's called rapid eye movement sleep, which begins about an hour and a half after we fall asleep. That's when the eye start darting back and forth and we start dreaming. Consolidation of declarative learning, on the other hand, occurs when we are sleeping most deeply during what's called slow-wave sleep. These slow waves cover the entire cortex and have a giant amplitude with very low frequency. This is your brain humming the "Om-mantra" to itself.
[Terry hums] [Barb] Also, in case you're wondering, it's not really possible to cram with information learned through the procedural system like you can with the hippocampal system. There are no shortcuts to practice. Attempting to cram actually hurts procedural performance. [MUSIC, Title: "Following Procedures"] [Beth] And here we are in Barb's kitchen, I've never made a homemade clay before so I looked up the procedures for how to do it. First, mix one cup cornstarch, two cups of baking soda, and 1.5 cups of water in a non-stick pot or pan. Second, heat the pot while stirring until it reaches the consistency of mashed potatoes. Third, turn off the heat as soon as the mixture pulls away from the pan. And fourth, cover it with a damp cloth and let it cool. Pretty simple, right? So, here's my question. When I followed the set of procedures for making homemade clay, was I learning how to do it declaratively or procedurally? It can be surprising, but the term "following procedures" in this case, meant following the set of declarative step-by-step rules. I was following explicit instructions! So, why do they say following PROCEDURES when they actually mean that you should be doing something you are learning explicitly? That is DECLARATIVELY? This oddity in terminology arose because educators, cognitive psychologists, and neuroscientists were all working independently from one another as they tried to better understand how the brain works. But here's the interesting thing. If you use your declarative system to follow a set of procedures enough times, those procedures also begin to develop links in the procedural system! You don't even need to look at the recipe— that is, the list of procedures. The procedures basically become a habit that you can do without even thinking about. We see this play out in the classroom all the time. We teachers explicitly teach students the procedure for entering a classroom, taking attendance, participating in classroom discussions, and more. Students learn the steps to following a procedure through their declarative pathway. Once they internalize the procedure and they don't need to even think about following it, they are acting out of their procedural pathway. We'll build further on this idea toward the end of this week. [Terry] Here's how that looks. A part of the brain called the prefrontal cortex has links that are laid down declaratively. If those declarative links start being used over and over again in sequences, guess what? The procedural system starts to also build sets of PROCEDURAL links! The procedural links are easier for the brain to access and use. You don't even need to think about them. If you've practiced a lot of times, all you need is a cue, like thinking 2 x 8 = ? in a math class, or add more of vibrato when playing the violin, or hit the line when playing tennis. Your procedural system takes over automatically and produces the appropriate response while you're thinking ahead to the next move. [Beth] I'm Beth Rogowsky [Barb] I'm Barb Oakley. [Terry] I'm Terry Sejnowski. [All] Learn it, link it, let's do it!
