Lecture: Cognition, Language & Intelligence
Lecture script · about 15–20 minutes spoken · Week 9
Opening
A nurse double-checks a quick first impression of a patient. A marketer decides whether a yogurt label should say "90% fat-free" or "10% fat." A teacher reads a test score next to everything else a student can do. Each of them is working with the same machinery: a mind that thinks fast, usually well, and sometimes wrong in ways you can predict.
That machinery is this lecture's subject. In Weeks 1 and 2, you learned to ask "how do we know?" In Week 7, you followed memory through encoding, storage, and retrieval. Week 8 pulled the first half of the course together. This week, we turn to thinking itself: how you sort the world, solve problems, make judgments, use language, and how intelligence gets measured. Next week, in Week 10, the course turns to motivation and emotion.
Here's the plan. Concepts first, then two ways to solve a problem, then the shortcuts and biases in judgment, then what gets you stuck, then language, then intelligence and the IQ scale. If you keep one sentence, keep this one: fast is not the same as right.
1. Organize what you know: concepts and prototypes
A friend texts you a photo of a fruit you've never seen. Within a second, you know it's food, it grew on a plant, and you could probably eat it. You didn't need to meet that fruit before. You put it in a category, and the category told you the rest.
That's cognition at work: the mental activities involved in knowing, which are thinking, forming categories, judging, solving problems, remembering, and using language. Categories come first. A concept is a mental category that groups objects, events, or ideas that share features, such as "bird" or "furniture," so a new example can be recognized and reasoned about. A prototype is the most typical, best example of a mental category, such as a robin for "bird"; new examples are judged by how closely they resemble it.
Here's how that plays out. A robin is small, flies, sings, and perches in trees. When someone asks "is it a bird?", a robin gets an instant yes. A chicken gets a slightly slower yes. A penguin often gets a pause. All three are birds, every bit as much. What changes is how far each one sits from the prototype, and that distance sets your speed.
Pause and try this. Is a penguin less of a bird than a robin?
Hold your answer for a moment before you read on.
Here's the answer. No; the concept decides membership, and a penguin belongs fully, while the prototype only decides how fast you recognize a member.
2. Solve problems two ways: algorithms versus heuristics
You've forgotten the code to your bike lock. It has three dials, each with the digits 0 to 9. One plan is to start at 000 and try every code in order. That's 10 times 10 times 10, which is 1,000 tries at worst, and you're guaranteed to open it eventually. The other plan is to try your birthday first, then your old locker code. That might work in three tries, or never.
Those are the two basic ways to solve a problem. An algorithm is a step-by-step procedure that guarantees a correct solution if it is followed completely, though it can be slow. A heuristic is a fast mental rule of thumb that usually leads to a good answer with little effort but can produce predictable errors.
The algorithm trades speed for certainty. The heuristic trades certainty for speed. And most of your day runs on heuristics. You don't compare every route home. You take the usual one, and it usually works. That frees your attention for the parts of life that need it.
So a heuristic isn't bad thinking. It's fast thinking. The trouble comes only because its errors are predictable, and that's what the next part is about.
Pause and try this. Trying all 1,000 lock codes in order: algorithm or heuristic?
Decide, then keep reading.
Here's the answer. It's an algorithm, because following every step in order is guaranteed to reach the right code, even though it may be slow.
3. Judge by memory and by resemblance: availability and representativeness
The week before a beach trip, you read a headline about a shark attack on a faraway coast. Suddenly the swim feels risky. The long drive there never crosses your mind. Shark attacks are rare, which is exactly why one makes the news.
In 1974, Tversky and Kahneman described this shortcut. The availability heuristic is judging how common or likely something is by how easily examples of it come to mind, so vivid, recent, or repeated events seem more frequent than they are. It's a memory effect. Remember Week 7: retrieval is easier for memories that are vivid, recent, or repeated. When an example is easy to retrieve, your mind treats that ease as a sign the event is common.
They described a second shortcut that works by resemblance. The representativeness heuristic is judging how likely something is by how much it resembles a typical case, often while ignoring how common each possibility actually is. Picture Lena: quiet, glasses, talks about books all evening. "She must be a librarian." But suppose her town has far more salespeople than librarians. Lena is still more likely to work in sales. That ignored piece is the base rate, which is how common a category or outcome is in the whole group being considered, before any description of one person is known.
Here's how to keep them apart. Availability asks, "How easily can I think of examples?" Representativeness asks, "How much does this look like the typical case?"
Pause and try this. Calling Lena a librarian because she fits the picture: which heuristic is that?
Say it to yourself before you read on.
Here's the answer. It's representativeness, because the judgment rests on resemblance to a typical librarian and ignores the base rate of salespeople in her town.
4. Catch three more biases: confirmation bias, framing, and overconfidence
Picture someone starting a new diet. Over the next month, they read every article that praises it and skip the ones that raise doubts. When a friend mentions a study that found no benefit, the details slip away. Nobody is lying here. Attention and memory are quietly picking sides.
That's confirmation bias: the tendency to search for, notice, and remember evidence that fits what one already believes while overlooking evidence that contradicts it.
Now back to the yogurt aisle. One label says 90% fat-free. If 90 parts out of 100 are not fat, the rest is 100 minus 90, which is 10. So the label beside it, 10% fat, says the same thing. Tversky and Kahneman showed in 1981 that wording like this changes judgments. Framing is the way a choice or fact is worded; a framing effect occurs when the same information leads to different judgments because of the wording.
The third bias is about how sure you feel. Overconfidence is the tendency to be more certain that one's judgments and answers are correct than their actual accuracy supports. Think of the group project slides that were "an hour, tops" and took all evening.
One caveat. Knowing these names doesn't switch the biases off. What helps is a habit: look for evidence against your belief, flip a framed choice into its opposite wording, and ask how often you've been right before.
Pause and try this. Do the two yogurt labels describe different amounts of fat?
Run the subtraction in your head first.
Here's the answer. No, they don't: 100 minus 90 is 10, so "90% fat-free" and "10% fat" state the same fact, and only the wording differs.
5. Get unstuck: fixation, mental set, and functional fixedness
On a camping trip, the screw on a bike seat works loose, and nobody packed a screwdriver. Everyone digs through their bags. After a long search, someone notices that a coin fits the screw's slot. The coin was in a pocket the whole time.
Being stuck isn't the same as lacking ability. Fixation is an inability to see a problem from a new angle, which keeps a person stuck on one approach that is not working. It has two common forms. Mental set is the tendency to keep using a method that worked on earlier problems, even when a different or simpler method would work better on the current one. Functional fixedness is the tendency to see an object only in its usual job, such as a coin only as money, which hides other ways it could be used to solve a problem.
Here's a way to sort them. Ask what the person is stuck on. A new office worker who totals a column by hand, while the spreadsheet in front of him could add it in one step, is stuck on a method. That's mental set. The campers were stuck on what a coin is for. That's functional fixedness.
Pause and try this. The coin finally becomes a screwdriver. Which obstacle did the campers have to get past?
Give yourself a second to name it.
Here's the answer. It's functional fixedness, because they had seen the coin only in its usual job as money.
6. Build language from small parts: phonemes, morphemes, and grammar
Say "cat," then "bat." One small change at the start, and the meaning jumps from a pet to sports gear. Now say "unbreakable." You can hear pieces inside it, and each piece adds meaning.
Language is built that way, from small parts. A phoneme is the smallest unit of sound in a language that can change a word's meaning, such as the sounds that make "cat" differ from "bat." A morpheme is the smallest unit of language that carries meaning, which may be a whole word such as "break" or a part of one such as the prefix "un" or the plural "s." Grammar is the system of rules that lets speakers combine sounds and meaning units into words and sentences others can understand. Syntax is the part of grammar that sets word order, so "the dog chased the cat" and "the cat chased the dog" mean different things.
Take "unbreakable" apart. "Break" is the root. "Un" means not. "Able" means can be. That's three morphemes.
Children typically build language in the same order. First comes babbling, the stage in which an infant produces strings of speech sounds, like "ba-ba-ba," that are not yet words. Then single words, like "ball." Then pairs, like "more juice." Then telegraphic speech, short mostly noun-and-verb sentences that leave out small words, like "want more milk."
Pause and try this. Is a morpheme the same thing as a syllable?
Think of the word "cats" before you answer.
Here's the answer. No; "cats" is one syllable but two morphemes, cat and the plural s, because a morpheme is defined by meaning, not by sound.
7. Compare three views of intelligence: g, multiple intelligences, and the triarchic theory
Think of three people you know. One aces every exam. One can fix an engine by ear. One can calm a tense room. Are they all intelligent, and in the same way?
Intelligence is the mental ability to learn from experience, solve problems, and use knowledge to adapt to new situations. Three theories disagree about how many kinds there are.
Charles Spearman noticed that a person's scores on very different tests tend to rise and fall together. He proposed general intelligence, often written as the single letter g, a single broad ability under many kinds of mental tests. Howard Gardner looked at people with uneven gifts and proposed multiple intelligences, several relatively independent kinds, such as musical, spatial, and interpersonal ability. Robert Sternberg's triarchic theory says intelligence has three parts: analytical intelligence for academic problems, creative intelligence for new situations, and practical intelligence for everyday tasks.
Here's one person through all three. A nurse aces written exams, invents a better way to organize the supply room, and is the one coworkers ask about a difficult family. Spearman would see high g showing up everywhere. Gardner would point to interpersonal and spatial intelligence. Sternberg would call those analytical, creative, and practical intelligence.
Pause and try this. Did Gardner's theory prove that general intelligence doesn't exist?
Weigh it before you read on.
Here's the answer. No; g explains why scores on different tests move together, the other theories explain what one score misses, and the debate is still open.
8. Read the IQ scale: what a score says and what it does not
Two cousins compare report cards from different schools. One has an 88, the other a B plus. Which is better? You can't tell until you know how each school grades. An IQ score has the same problem, and testers solve it with a reference group.
An intelligence quotient, or IQ, is a score on a standardized intelligence test, scaled so that the average score is 100 and about 68 percent of people score between 85 and 115. Standardization is giving a test in the same way to a large, representative sample and using that group's scores as the yardstick for everyone after.
Here's the scale, step by step. The mean is 100, and 15 points mark one step of spread. So the lower edge of the average band is 100 minus 15, which is 85. The upper edge is 100 plus 15, which is 115. About 68 percent of people land in that band, roughly two in three. That leaves 100 minus 68, which is 32 percent, outside it, some above and some below.
A good test is also reliable, giving about the same score on a retest, and valid, measuring intelligence and not something else. And the Flynn effect, the rise in average test performance from one generation to the next, means tests must be re-standardized from time to time.
Here's the limit worth saying out loud. An IQ score is one measured slice of a mind. It says nothing direct about kindness, effort, or creativity. It is not a measure of a person's worth.
Pause and try this. What does a score of 100 tell you about a person?
Answer in one sentence before you read on.
Here's the answer. It tells you the person did as well as the average person in the standardization sample, on that test, on that day, and nothing about the person's worth.
Closing
Let me pull it together in the order we built it. A concept is a mental category, and its prototype is the best example. An algorithm guarantees a solution; a heuristic is fast but can mislead. Availability judges frequency by how easily examples come to mind, and representativeness judges by resemblance while ignoring the base rate. Confirmation bias, framing, and overconfidence bend judgments in predictable ways, and the two yogurt labels prove framing with one subtraction. Fixation, mental set, and functional fixedness are how capable people get stuck. Language builds phonemes into morphemes and morphemes into sentences by grammar. Spearman, Gardner, and Sternberg offer three views of intelligence, and an IQ score places a person on a scale with a mean of 100, where about 68 percent score between 85 and 115.
Next in this module come the slide deck, the Readings & Resources page, the lecture tutorial, the practice set, and the quiz, then the discussion, the assignment, and the Analysis Workshop. Next week, in Week 10, Motivation & Emotion, the course asks what moves you to act and how you feel.
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