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  • So if the name Ivan Pavlov rings a bell, it’s because his experiments are among the most

  • famous in the history of psychology.

  • His work contributed to the foundation of the behaviorist school of thought that viewed

  • psychology as an empirically rigorous science focused on observable behaviors and not unobservable

  • internal mental processes. Even though today we view psychology as the

  • science of both behavior AND mental processes, Pavlov’s influence was tremendous. His research

  • helped pave the path for more experimental rigor in behavioral research, right up to

  • the present day. Born in 1849 in Russia, Pavlov was never much

  • for psychology. After giving up on his original aspirations to become a Russian Orthodox priest

  • like his father, he instead earned a medical degree and spent nearly twenty years studying

  • the digestive system, earning Russia’s first Nobel Prize in his mid-50s for his research

  • expanding our understanding of how stomachs worked.

  • He didn’t study human stomachs though...cause the procedures were terrible and cruel...he

  • studied dog stomachs.

  • And while researching those dogs, he noticed how the animals would salivate at a mere whiff

  • of their dinner.

  • At first he found all that slobber annoying, but soon started to suspect that this behavior

  • was actually a simple but important form of learning.

  • For us scholars of psychology, we can define learning as the process of acquiring, through

  • experience, new and relatively enduring information or behaviors.

  • Whether through association, observation, or just plain thinking, learning is what allows

  • us to adapt to our environments and to survive. And as Pavlov began to discover, it wasn’t

  • only humans who learned.

  • Soon enough he was turning out his famous series of experiments, in which he paired

  • the presence of meat powder - yummy - which got the dogs to drooling, with lots of different

  • neutral stimuli -- things that wouldn’t normally make you drool, like a certain sound,

  • a shining light, or a touch on the leg. Then Pavlov observed, after several of these

  • pairings, a dog would start to drool just at the sound or the light or the touch, even

  • if there wasn’t any slobber-inducing meat powder around.

  • Animals, he found, can exhibit associative learning. That’s when a subject links certain

  • events, behaviors, or stimuli together in the process of conditioning.

  • This may be the most elemental, basic form of learning a brain can do. But that doesn’t

  • mean that the processes behind conditioning are, or ever were, obvious. Or, for that matter,

  • simple.

  • In fact, the research that’s gone into how were conditioned by our environments has

  • helped shape the science of psychology, from a still-kinda-subjective-thought-exercise

  • into the more rigorous discipline we know today.

  • And it also starred some of psychology’s most notable, and often controversial, figures,

  • including Pavlov, B. F. Skinner -- aaaand that guy who trained kids to be terrified

  • of furry animals... [INTRO]

  • OK, I’m not a licensed dog-trainer - do they license dog trainers? But I can break

  • down for you the sequence of steps in Pavlov’s famous experiment, to help you get a sense

  • of how conditioning works: First, before conditioning, the dog just drools

  • when it smells food. That smell is the unconditioned stimulus, and the slobbering, the unconditioned,

  • or natural response. The ringing sound, which at this point means nothing to the dog, is

  • the neutral stimulus, and it produces no drooling. During conditioning, the unconditioned stimulus

  • -- that food smell -- is paired with the neutral stimulus -- the bell sound -- and results

  • in drooling. This is repeated many times until the association between the two stimuli is

  • made, in a stage called acquisition. By the time you get to the after-conditioning

  • phase, that old neutral stimulus has become a conditioned stimulus, because it now elicits

  • the conditioned response of drooling. Sounds super simple, right? If you have a

  • dog, youve probably seen it tapdance at the sight of a leash, but in Pavlov’s day,

  • this whole series of steps hadn’t really been studied in a lab setting, or thought

  • about in scientific terms. Pavlov’s work suggested that classical conditioning

  • -- as this kind of learning came to be known -- could be an adaptive form of learning that

  • helps an animal survive by changing its behavior to better suit its environment. In this case,

  • a bell means food, and food means survival. So get ready!

  • Not only that, but methodologically, classical conditioning shows how a process like learning

  • can actually be studied through direct observation of behavior, in real time, without all those

  • messy feelings and emotions. This was something Pavlov especially appreciated

  • given his disdain formentalisticconcepts like consciousness and introspection championed

  • by Freud. Behaviorist psychologists, like Pavlov’s

  • younger American analogues B.F. Skinner and John B. Watson, also embraced the notion that

  • psychology was all about objective, observable behavior.

  • In his 1930 book Behaviorism, he argued that given a dozen healthy infants he could train

  • any one of them to be a doctor, artist, lawyer, or even a thief, regardless of their talents,

  • tendencies, or ancestry.

  • Whoa there, Watson! Thankfully no one gave him any infants.

  • In his most famous and, yes, controversial experiment, Watson conditioned a young child,

  • dubbedLittle Albert,” to fear a white rat. Maybe that doesn’t sound so bad, but

  • he accomplished this by pairing the rat with a loud, scary noise, over and over and then

  • demonstrated that the child’s terror could branch out and be generalized to include other

  • furry, white objectslike bunnies, dogs, or even fur coats.

  • So yeah, that’d never fly today, obviously, but Watson’s research did make other psychologists

  • wonder whether adults, too, were just holding tanks of conditioned emotions -- and if so,

  • whether new conditioning could be used to undo old conditioning. Like, if youre terrified

  • of roller coasters, but you made yourself ride one ten times a day for two weeks, would

  • your fears fade? For the record, recent exploration has revealed

  • that the boy known at Little Albert sadly died a few years after these experiments,

  • while Watson eventually left academia and got into advertising, where he put all that

  • associative learning to lucrative use.

  • So that’s classical conditioning. But weve also got another kind of associative learning:

  • operant conditioning. If classical conditioning is all about forming

  • associations between stimuli, operant conditioning involves associating our own behavior with

  • consequences. The kid who gets a cookie for saying please, or the aquarium seal that gets

  • a sardine for balancing a ball on its nose, theyve both been trained with operant conditioning.

  • The basic premise here is that behaviors increase when followed by a reinforcement, or reward,

  • but they decrease when followed by a punishment. And the most well-known champion of operant

  • conditioning is American behaviorist B.F. Skinner. He designed the famous operant chamber,

  • orSkinner Box”--a confined space containing a lever or button that an animal could touch

  • to get some sort of reward, typically food, along with a device that keeps track of its

  • responses. Okay, time for a debunking break!

  • Other than maybe Freud, no other figure in psychology seems to be as shrouded in lore

  • and misinformation as B. F. Skinner. So I’m just going to tell you straight that, no,

  • Skinner never put any kids in this box. And no, he didn’t raise his children without

  • love or affection, and his daughter didn’t hate his guts until the day she committed

  • suicide. Deborah Skinner is alive and well, and she loved her dad plenty.

  • Skinner DID, however, invent something called an air crib--a climate controlled box with

  • a window on the front that was meant to keep babies warm and safe while moms ran around

  • doing their 1950’s-lady thang. It’s not exactly where I’d like to spend the night,

  • but it wasn’t remotely the same as the Skinner Box.

  • No one knows where all of these myths came from, but being a somewhat controversial guy,

  • Skinner had a lot of haters, some of whom were probably happy to perpetuate misinformation.

  • But back to the rat in the box. Basically, the box provided an observable stage to demonstrate

  • Skinner’s concept of reinforcement, which is anything that increases the behavior that

  • it follows. In other words, you push the lever, you get a snack, and then you want to keep

  • pushing the lever. But most rats aren’t going to push a lever

  • for no reason. I mean, there aren’t food-dispensing levers in a natural environment, so operant-conditioning

  • behavior requires shaping.

  • Maybe you give the rat a nibble of food each time it gets closer to the bar, then only

  • when it touches the bar, until little by little, in a series of successive approximations to

  • the desired behavior, you only reward them only when they do what youre trying to

  • shape them to do. In everyday life, were all continually

  • reinforcing, shaping, and refining each other’s behaviors, both intentionally and accidentally.

  • We do this with both positive and negative reinforcement.

  • Positive reinforcement obviously strengthens responses by giving rewards after a desired

  • event, like the rat snack after a lever push, or getting a cookie when you say please.

  • Negative reinforcement is a little trickier. It’s what increases a behavior by taking

  • away an aversive or upsetting stimulus. Like, say, you get in your car and it does that

  • infernal beeping thing until you fasten your seatbelt. The car is reinforcing your seatbelt-wearing

  • by getting rid of that horrible beeping. And it’s good, because you should wear your

  • seatbelt. It’s important to recognize here that negative

  • reinforcement is NOT the same as punishment.

  • Punishment decreases a behavior either positively, by say, giving a speeding ticket, or negatively,

  • by taking away a driver’s license. But negative reinforcement removes the punishing

  • event to increase a behavior. So, painkillers negatively reinforce the behavior of swallowing

  • them by ending the headache.

  • So by now hopefully youre getting the picture. There are things that we want and things that

  • we don’t want, and we can be taught by way of those impulses to behave certain ways.

  • But it’s worth pointing out that conditioning is way more complex than just the cookie and

  • the beeping car. For one thing ending annoyance or getting

  • a cookie, are types of primary reinforcers--you don’t have to learn that, they just make

  • innate biological sense. Beeping is annoying, cookies are delicious.

  • But there are other kinds of reinforcers that we only recognize after we learn to associate

  • them with primary reinforcers. Like, a paycheck is a conditioned reinforcer--we want money

  • because we need food and shelter, which are still the primary drivers.

  • Plus, just as there are different kinds of reinforcers, so are there various reinforcement

  • schedules. Like, those boxed rats were getting continuous reinforcement when they got a treat

  • every single time they hit that lever, so they picked it up pretty quickly.

  • But if one day the rat chow doesn’t come, that connection quickly dwindles, and the

  • rat stops hitting the lever. This is a process called extinction.

  • And it is important, because that’s how real life works. Outside of a Skinner box,

  • youre not gonna get continuous reinforcement. All of life is a series of partial, or intermittent

  • reinforcements, that occur only sometimes. Learning under these conditions takes longer,

  • but it holds up better in the long run and is less susceptible to that extinction.

  • So, say a cafe gives out a free cup of coffee for every ten you buy, while another shop

  • pours a free double shots every Tuesday morning, and yet another has a free-coffee lottery

  • that customers win at random. These are all different kinds of intermittent reinforcement

  • techniques that get customers coming back for more.

  • Now, Pavlov, Watson, and Skinner’s ideas were definitely controversial -- as well as

  • the whole scary-rat experiments. Plenty of folks disagreed with their insistence that

  • only external influences, and not internal thoughts and feelings, shaped behavior.

  • It was clear to many of the behavioristsrivals that our cognitive processes - our

  • thoughts, perceptions, feelings, memories - also influence the way we learn.

  • Were going talk about how these other things factor into learning next week when we look

  • more at conditioning, cognition and observational learning -- and yeah, also watch kids beat

  • the face iff blow-up dolls. Today you learned about how associative learning

  • works, the essentials of behaviorist theory, the basic components of classical and operant

  • conditioning, including positive and negative reinforcement, and reinforcement scheduling.

  • Thanks for watching this, especially to all of our Subbable subscribers, who make this

  • whole channel possible. If you’d like to sponsor an episode of Crash Course, or get

  • a special Laptop Decal, or even be animated into an upcoming episode, just go to Subbable.com.

  • This episode was written by Kathleen Yale, edited by Blake de Pastino, and our consultant

  • is Dr. Ranjit Bhagwat. Our director and editor is Nicholas Jenkins, the script supervisor

  • is Michael Aranda, who is also our sound designer, and the graphics team is Thought Café.

So if the name Ivan Pavlov rings a bell, it’s because his experiments are among the most

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如何訓練大腦--心理學速成班 #11 (How to Train a Brain - Crash Course Psychology #11)

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    稲葉白兎 發佈於 2021 年 01 月 14 日
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