Thursday, February 26, 2015

The Mental Tool Rack: Scripts and Schemas

I was in the middle of writing the next great American novel when my hard-drive became extremely fragmented, and it mixed up all of my sentences. Can you help me put them back in order?
  1. I cleaned up my mess and threw away my napkins, wrappers, and cup.
  2. I waited for my food to be prepared.
  3. I ate my delicious food.
  4. I paid for my food.
  5. I read the menu behind the cashier and decided what I wanted to order.
  6. I sat down.
  7. I placed my order.
  8. I opened the door and walked into the restaurant. 
  9. I left the restaurant.

How did you do? When you first started the task, was there any ambiguity that you had to resolve before putting the sentences in order? How did you decide where to put things in sequence? To see the order that I intended, check the footnotes [1].

"Line!" --Ned Nederlander in Three Amigos!

One of the emerging themes throughout this blog is that the mind craves (at least) two things: meaning and order. To make sense of the information-rich world, it helps when actions and events follow a pattern. Over many exposures to the same sequence of events, the mind assembles a script, that is, a mental representation of the expected sequence of events for that situation. You have many different scripts, like going to a restaurant, flying to another city, going to work/school, shopping for groceries, or attending a sporting event. Scripts help set expectations about what is supposed to happen, and they greatly decrease the amount of problem solving that you have to do. If you don't have a script for a given situation, then you find yourself trying to figure out what to do next. 

For example, when my wife and I bought our first car together, we went through a dealership. Neither of us had ever bought a car from a dealer, so we were pretty clueless about all the steps that stood between us and actually driving off the lot in our new (to us) car. We were particularly bewildered when, after we had test driven a couple cars and selected the one we wanted, the salesperson who had been helping us through the process had to go talk to his manager several times during the negotiation process. We now know that this was all part of a very typical script that takes place at most car dealerships: The customer looks around the showroom; a salesperson approaches the customer and tells him why the car he is interested in is ok, but why another model is even better; the customer takes the car(s) for a test drive; and then the customer, salesperson, and an unseen "manager" engage in a long and drawn out negotiation that, in stories with happy endings, results in the customer getting a reasonable deal on their car of choice.

A Schema Is Like an Organized Tool Rack

Scripts work well for organizing sequences of events. There is another mental representation, called a schema, that does essentially the same thing for information in general. In fact, you could say that a script is a type of schema that is specialized for one particular type of information (i.e., events). 

Traditionally, a schema is described as a structure with labeled slots. I think of it as a tool rack where all the tools have an outline drawn around where they should go. When an old tool is ready to be put away, you find the spot where it fits on the rack and store it there for future use. If an unfamiliar tool comes your way, you will likely look at your well-organized tool rack, see whether the new tool seems like any of the others you already have, and store it with those that are most similar to the new one. 

A good example of a mental schema comes from my hobby-level interest in cars. I love reading about the newest models and their embedded technologies. Over the years, I have built up a schema for cars. The slots in my schema include: category (e.g., sedan, coupe, sports car), make (e.g., Honda, Ford, Porsche), model (e.g., Civic, Taurus, 911), and origin (e.g., foreign or domestic).

Schemas can be violated when you encounter new information that doesn't fit into the existing organizational structure of the schema. When this happens, there are a couple of potential outcomes. One outcome is that you dismiss the new information because it does not fit into your current understanding of the world. Another outcome is that you misconstrue the true nature of the new information by trying to fit it into an existing schema where it doesn't really fit. Yet another outcome of a schema violation is that it inspires a person to modify his or her existing schema to accommodate the new information. I recently had my car schema violated when I learned about the Tesla Type S, which is a purely electric car. It has no tailpipe, spark plugs, or fuel door. In fact, it doesn't even require an oil change! To accommodate these new facts, I had to add a new slot to my car schema, which is fuel type (e.g., gas, pure electric, hybrid).

The STEM Connection

One could argue that the primary goal of education is to help students create accurate and detailed scripts and schemas. Because we live in a changing world, however, educators also need to confer upon their students the tools to notice violations and modify their representations when needed. 

The scientific method is perhaps one of the most successful scripts for producing new knowledge. A scientist starts with noticing something in the world that is in desperate need of an explanation. Toward that end, the scientist formulates a hypothesis and begins the arduous task of collecting data to confirm or disconfirm her hypothesis. This script works well, but it's important to teach budding scientists that they need to be willing (eager even!) to update their beliefs once the data are collected. This can be difficult, of course, but it is the best way to move the field forward. In a sense, scientists need to be flexible in constructing and updating their schemas. 

Some scientific discoveries, like penicillin, happen precisely because some piece of empirical evidence violated a scientist's schema. As the story goes, Alexander Fleming was working on a project that required him to create colonies of the Staphylococcus bacteria. Getting nowhere, he decided to take a vacation, and he left his lab in disarray. As expected, when he got back from vacation, some of his petri dishes were overrun with bacteria. What he didn't expect, however, was that some colonies were suspiciously missing. Fleming noticed that some of the bacteria were killed by a mold that was also growing in the dish. In that moment, Fleming experienced a profound schema violation.

Louis Pasteur famously said, "In the fields of observation, chance favors only the prepared mind." Given the language introduced here, we might recast Pasteur's recommendation to students to become more like Fleming: Take the time to construct a detailed schema. Then, be on the lookout for violations of your schema because they might result in important scientific advancements. 

Share and Enjoy! 

Dr. Bob

For More Information

[1] The answer is: 8, 5, 7, 4, 2, 6, 3, 1, 9

[2] Hollywood relies on schema violations to delight their audiences. The Matrix and Memento are excellent examples of movies that rely on violating our schemas to enhance the storytelling.

Thursday, February 19, 2015

The Memory Half-pipe: Primacy and Recency Effects

We have been doing a lot of memorization in this blog. So why stop now?! Here is another list of words. Do you best to memorize them all. 
  1. Slow
  2. Bridge
  3. Capital
  4. Plug
  5. Ladle
  6. Battery
  7. Keyboard
  8. Insurance
  9. Heater
  10. Shovel
  11. Bread
  12. Goggles

Without looking at the original list, write down all of the words that you remember. This demonstration may fail miserably because, at this point, you are a memory Jedi. The memorization strategies that you have in your arsenal include chunking and placing things in your memory palace

Assume, for a moment, you didn't know about all the various memory hacks we have covered in previous posts. What would you predict in terms of remembering each word? Which words would you be most likely to remember? Which words do you think you would be most likely to forget? If you introspect for a minute, what were some of the things you were doing mentally when trying to memorize the list? 

"There was food in my mouth!" —Mr. Short-term Memory Man

One of the fundamental distinctions in Cognitive Science is the split between long-term and short-term memory. In a previous post, we discussed a very simple model of memory where information enters short-term memory. If it is sufficiently processed, then that information enters long-term memory via a process called encoding. How can we increase the likelihood that information gets encoded?

Probably the most basic method to enhance encoding of information is to rehearse it over and over again. Through repetition you can increase the odds of a specific item getting into long-term memory. Sometimes, if you watch people as they try to memorize a list of words as I challenged you to do earlier, you can see them moving their lips as they rehearse the words. 

Rehearsal is effective at getting items at the top of the list encoded into long-term memory. But as you make your way further into the list, the later items (starting around items 4-9) create a bottleneck because it gets harder for you to loop through the entire list of 4+ items. So the  words in the middle of the list don't get rehearsed as much as the first items and have a harder time making it into long-term memory.

The last part of the list (e.g., items 10-12) also have a hard time making it into long-term memory, but still have a good chance of being recalled. Due to their placement at the end of the list, they can be easily crammed into short-term memory. When it comes time for you to remember the list of words, it's probably easiest for you to quickly list items from the end of the list first, purge those from your short-term memory, and then concentrate on recalling the first part of the list. 

If you plot the probability of recall for each item in the list, you would get the standard serial position curve that you see here in yellow [1]. Items early in the list (slow, bridge, capital) have a high probability of recall. We call that the primacy effect. The items at the end of the list (shovel, bread, goggles) also have a high probability of being recalled. We call that the recency effect because they were the most recent items to cram into memory. Unfortunately, the middle of the list is going to have a low probability of recall.

But wait...there's more!

The serial position curve makes an appearance in most introductory psychology textbooks.  In other words, it is a fairly standard finding. But are there exceptions to the primacy and recency effects? Of course! We've already covered one exception. Memorization strategies can yield perfect recall, which thus negates a primacy or recency effect.

Another exception can occur thanks to an interesting feature of the memory system. Suppose I gave you the list below:
  1. apple
  2. banana
  3. orange
  4. kiwi
  5. strawberry
  6. pineapple
  7. Boeing 747
  8. blueberry
  9. mango
  10. watermelon
  11. lemon
  12. grapefruit

If you were to plot the probability of recall for the above list of items, you would not get the standard serial position curve. Instead, the word that has no business getting a 100% recall rate thanks to its location right in the middle of the list, would get recalled 100% of the time: Boeing 747. This pop-out effect (or the Von Restorff effect) demonstrates that the surrounding items in the list can set up a mental context (fruit) in which we have a very easy time remembering things that break out of that context (Boeing 747).

The STEM Connection

What does this mean for education? Does the primacy and recency effects have an implication for how to structure a lesson? It is always risky to extrapolate findings about lists of words to the complexities of a classroom. But there is a general principle at work, and it's one that journalists understand extremely well: Don't bury the lead. When teaching a lesson, don't put the most important information in the middle of the class period. Instead, either open with it or close with it. Also, you might try to think of a way to leverage the pop-out effect. In fact, maybe Monte Python always had an important contribution to education: And now for something completely different!

Share and Enjoy! 

Dr. Bob

For More Information

[1] Peterson, L. R., & Peterson, M. J. (1959). Short-term retention of individual verbal items. Journal of Experimental Psychology, 58(3), 193–198.

Thursday, February 12, 2015

Upside-down Cake: Top-down vs. Bottom-up Processing

To paraphrase the title of a great podcast, your brain is a big, fat, filthy liar [1]. Sure, it does all kinds of amazing things, but it also tricks you on a regular basis. In this post, we are going to explore some interesting, and sometimes amusing, ways your brain tricks you by convincing you to let contextual factors guide your perception. Let's start with a low-level perceptual lie.

I'm blind to the fact that I'm blind

Did you know you have a huge hole in your vision? It's always there, in both eyes, and it's called the blind spot. It is caused by the junction of a bundle of fibers in the back of the eye called the optic nerve. Instead of having a huge blank spot in your field of vision, your brain does some quick acrobatics to fill in the visual scene so it doesn't look choppy or incomplete.

You might have done this as a kid, but it still blows my mind as an adult. Look at the plus sign on the left side if the screen. Close your left eye, and look straight at the cross. Without moving your eye, move your head closer to your screen until the little person on the right disappears. Crazy, right?!

The blind spot is interesting because you don't perceive that you have a hole in your vision. Your brain takes information from the surrounding regions and integrates that to complete your visual perception. But does that type of integration happen on a level of cognition that's higher than visual perception? You bet it does! On to the next lie.

What the H?

Without any particular of context, what is this a picture of? Is it a picnic table? Is it a poorly painted parking lot?

What if I told you it was a letter? Now what do you think it is? 

Take a look at the lines in the context below. 

Notice anything strange about the lettering? The "H" in the first word is exactly the same character as the "A" in second word. When I showed you that poorly drawn character out of context, it looked like a crudely assembled set of lines. However, when I put it into context, the perception of it changes completely, depending on what's around it.

THE CAT is a nice demonstration of the mind's influence on perception at the level of higher-order symbols (e.g., letters). We call the brain's influence on perception top-down processing. An expectation, or the current context, can completely determine the perceptual experience of an ambiguous stimulus.

Another great example of top-down processing is to look at something you absolutely know the color of in the broad daylight. For example, you know that a vine-ripe tomato is a brilliant shade of red; however, when the sun has set, go back outside and look at your tomatoes again. Are they still bright red? Your brain says "yes," but it is lying to you. If you didn't know you were looking at your tomatoes in the dark, you would see those plump little fruits as dark red, or even black [2].

Fun stuff also starts to happen when the brain attempts to integrate across different senses. 

A McGurk Says What?

A really mind-bending demonstration of the integrative power of the brain is called the McGurk Effect. Instead of my trying to explain what it is, take a look at this short video and experience it for yourself (see especially seconds 0:30 - 1:30).

When you think about it, your brain has to do something fairly tricky to pull off this lie. It has to pick out a noise-producing event from the visual system and bind it to the thing that's actually causing the sound. The McGurk Effect is interesting because the visual information comes into direct conflict with the auditory information. To resolve the difference, the brain has to do something. It resolves the discrepancy by giving superiority to the visual information and tweaks what it thinks it hears; hence, you hear "fah" instead of "bah" when the lips form the visual cues of "fah."

The STEM Connection

One STEM application of top-down processing relates to "the philosophy of science" and the importance of collecting data to help us learn about the world around us. Given that our brains lie to us on a regular basis, it is important to be open to the possibility that what we see in the world around us is NOT the truth, the whole truth, and nothing but the truth. Science is all about discovery, and to make new discoveries we need to make careful observations and find ways to test whether the world is really as it appears to be, according to what are brains are telling us. 

To demonstrate the impact of top-down processing on scientific discoveries, suppose it is 1473, and you are looking up at the stars. You have been taught, like many generations before you, that the Earth is firmly planted in the center of the universe, and all of the stars rotate around us. In fact, that makes perfect sense because, when you look at the heavens above, the stars spin and we stay put. How could it be any other way? 

Then comes along Nicolaus Copernicus, with Galileo Galilei not far behind. These astronomers had the audacity to suggest that the Earth is, in fact, not the center of the universe. Instead, they suggested that sun could be at the center of our own solar system, and that the Earth rotates around that. Sacrilege! Based on their extensive documentation of planetary movement in the night skies, they concluded that the data simply did not conform to the theory that the Earth was the center of the universe. Given how entrenched people were in the prior worldview, however, it took hundreds of years for the ideas proposed by Copernicus and Galileo to be embraced as the new truth. 

When introducing students to the idea of the scientific method, illustrating the influence of top-down processing on our perception and understanding of the world around us might help convince them that collecting and analyzing data is not just something you make them do to kill time between lunch and study hall. To really get them fired up about the need to collect data to advance science, have them discuss questions like these: 

  • Is it possible for a scientist to be an "impartial" observer? 
  • What sorts of cognitive biases does the observer need to be aware of? 
  • How can he or she overcome (or at least minimize) them?

In closing, your mind is constantly pulling off some really complicated tricks. As we discussed, the brain fills in missing information with each movement of the eye, in real time. That strikes me as a computationally heavy task, in a minimal amount of time. In other words, perception is nothing short of amazing, even when the results happen to be a lie.

Share and Enjoy! 

Dr. Bob

For More Information

[1] "Your Memory Is a Filthy Liar" - Cracked Podcast.

[2] This is called the Purkinje Effect, and even knowing about the illusion doesn't make it any less powerful. You have to reduce the effects of top-down processing by eliminating any of the surrounding context. One way is by looking through a paper roll tube and just look at the object of interest. Then, you can start to appreciate that the colors have indeed shifted. 

[3] An interesting math problem would be to calculate the distance between the fovea, which is the center of your vision, and your blind spot. The retina contains the highest density of light-sensitive photoreceptors at the fovea, and the blind spot, naturally, has the fewest. So you could set this up as a nice application of using the Pythagorean Theorem to calculate distances that you can't measure directly (in other words, you can't have students sticking rulers in their eyes). 

Thursday, February 5, 2015

Memory Hacks: The Memory Palace

Here is today's mission. Suppose you need to memorize a long list of words. Before you start, think about what strategy you might use. How would you go about committing the list to memory? Okay, now that you have a strategy in mind, here are the words: 
  • Toy
  • Fish
  • Airplane
  • Temple
  • Bells
  • Day
  • Garbage
  • Cranberry
  • Hole
  • Nail
  • Beach
  • Radio

Because the list includes more than 7±2 items, it is going to overwhelm our verbal working memory; therefore, we need a strategy –a "memory hack" if you will– to memorize the entire list. For inspiration, let us turn our attention to antiquity, as the ancient Greeks  already figured out a highly effective memory hack for missions such as these.  

The Best Exotic Marigold Memory Palace

As the story goes, Greekguy was hosting party at his fraternity house. He stepped out for a breath of fresh air, and just as he left the house, the whole edifice came crashing down. Tragically, everyone at the party was killed. When the campus police arrived, they asked Greekguy to name the people who were in the house at the time. Amazingly, he was able to name every partygoer. He accomplished this amazing feat of memory by visualizing the house, mentally moving from room to room, and naming each person who was in each the room. He used each person's physical location (e.g., Hercules was on the couch, Athena was standing next to fireplace) as a memory aid [1]. In other words, Greekguy created a memory palace to help recall the enormous amount of information. 

Because our brains are probably organized in the same way as Greekguy's, the same memory hack is available to you and me. Let's give it a try. Think about a place you know extremely well. This might be your place of residence, or it might be the building where you work. Now, look back at the above list of words and physically place those items around your memory palace. You're lucky in the sense that I chose a bunch of words that are concrete nouns. For more abstract words, like "freedom" or "devious," we would need a way of representing those symbolically. For example, "freedom" could be represented by picturing an open window. 

Time to get (redundantly) organized.

How or why does the memory palace work? This goes back to a contradiction that I raised in a previous post, in that sometimes adding information can make it easier, as opposed to harder, to commit something to memory. I think the simple explanation for why this is true is that the mind craves order. It is constantly trying to detect patterns and make sense of the world. If we can supply a strategy for bringing order to the world, then the brain is happy to cooperate. 

Another explanation is that our memory system enjoys redundancy. It helps to have multiple routes to the same item in long-term memory. If I try to brute-force the list of 12 items into long-term memory, then I have precisely one route to access that information. If instead I hang each item on a memory that already resides in long-term memory, then I have another route to rely on. Another way to say this is that the memory palace creates a memory cue, which can then help trigger recall. Cognitive psychologists call this "cued recall" (as opposed to "free recall," which refers to the brute-force approach).

If the hypothesis that "the brain craves order and redundancy" is true, then we might speculate that creating a narrative around the list is yet another way to hack memory. That is, instead of just placing the items around your memory palace, you could also take those items and create a little story about them. For example, you might start the story with, "The toy fish flew an airplane to the temple to ring the bells." Voila! You have already encoded the first five items merely by establishing a main character and the setting.

The STEM Connection

How is the memory palace useful in the educational arena? There are many applications. For example, suppose you are teaching an anatomy class and you want your students to learn all the bones in the hand and wrist. Or, you are teaching chemistry and you are covering the noble gases. How can you help them hack their memory? The first step is to have each student identify a memory palace that consists of a place that they can easily visualize. It could be their room at home or the classroom itself. Then, have them go through the process of mentally placing each bone around the room. Have them visualize each bone in its very own spot, as well as place bones that are physically connected in the body close to each other in their memory palace. The main idea is to add multiple routes to items that they want to store in long-term memory, and contextualizing the bones in a setting that they know well provides more opportunities for cued recall later on. 

Share and Enjoy! 

Dr. Bob

For More Information

[1] By the way, this isn't how the official story goes. It's a modern rendition on the old tale

[2] If you think hacking memory is interesting, take a look at Moonwalking with Einstein. The author decides to win a memory competition. To do so, he trains himself to memorize random things, like decks of cards, very quickly. One of the methods that he talks about is the memory palace. Also, the author's TED talk is a good way to learn more about this topic.