Skip to main content
Global

6.3: تكييف كلاسيكي

  • Page ID
    198350
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    أهداف التعلم

    • شرح كيفية حدوث التكييف الكلاسيكي
    • لخص عمليات الاستحواذ والانقراض والتعافي التلقائي والتعميم والتمييز

    هل اسم إيفان بافلوف يرن الجرس؟ حتى لو كنت جديدًا في دراسة علم النفس، فمن المحتمل أنك سمعت عن بافلوف وكلابه الشهيرة.

    أجرى العالم الروسي بافلوف (1849-1936) بحثًا مكثفًا عن الكلاب واشتهر بتجاربه في التكييف الكلاسيكي. كما ناقشنا بإيجاز في القسم السابق، فإن التكييف الكلاسيكي هو عملية نتعلم من خلالها ربط المنبهات وبالتالي توقع الأحداث.

    صورة تظهر إيفان بافلوف.
    الشكل\(\PageIndex{1}\): أدى بحث إيفان بافلوف حول الجهاز الهضمي للكلاب بشكل غير متوقع إلى اكتشافه لعملية التعلم المعروفة الآن باسم التكييف الكلاسيكي.

    توصل بافلوف إلى استنتاجاته حول كيفية حدوث التعلم تمامًا عن طريق الصدفة. كان بافلوف عالمًا فسيولوجيًا وليس طبيبًا نفسيًا. يدرس علماء الفيزيولوجيا العمليات الحياتية للكائنات الحية، من المستوى الجزيئي إلى مستوى الخلايا وأنظمة الأعضاء والكائنات الحية بأكملها. كان مجال اهتمام بافلوف هو الجهاز الهضمي (هانت، 2007). في دراسته للكلاب، زرع بافلوف جراحيًا أنابيب داخل خدود الكلاب لجمع اللعاب. ثم قام بقياس كمية اللعاب المنتجة استجابة للأطعمة المختلفة. مع مرور الوقت، لاحظ بافلوف (1927) أن الكلاب بدأت في إفراز اللعاب ليس فقط عند تذوق الطعام، ولكن أيضًا عند رؤية الطعام، وعند رؤية وعاء طعام فارغ، وحتى على خطى مساعدي المختبر. إن إفراز اللعاب إلى الطعام في الفم هو أمر انعكاسي، لذلك لا ينطوي الأمر على أي تعلم. ومع ذلك، لا يسيل لعاب الكلاب بشكل طبيعي عند رؤية وعاء فارغ أو صوت خطى.

    أثارت هذه الاستجابات غير العادية اهتمام بافلوف، وتساءل عن سبب ما أطلق عليه «الإفرازات النفسية» للكلاب (بافلوف، 1927). لاستكشاف هذه الظاهرة بطريقة موضوعية، صمم بافلوف سلسلة من التجارب التي تم التحكم فيها بعناية لمعرفة المنبهات التي قد تتسبب في إفراز اللعاب للكلاب. كان قادرًا على تدريب الكلاب على إفراز اللعاب استجابة للمنبهات التي من الواضح أنها لا علاقة لها بالطعام، مثل صوت الجرس والضوء واللمس على الساق. من خلال تجاربه، أدرك بافلوف أن الكائن الحي لديه نوعين من الاستجابات لبيئته:

    1. الاستجابات غير المشروطة (غير المكتسبة)، أو ردود الفعل، و
    2. استجابات مشروطة (متعلمة).

    في تجارب بافلوف، كانت الكلاب تسيل اللعاب في كل مرة يتم فيها تقديم مسحوق اللحم لهم. كان مسحوق اللحم في هذه الحالة بمثابة حافز غير مشروط (UCS): حافز يثير استجابة انعكاسية في الكائن الحي. كان إفراز اللعاب لدى الكلاب استجابة غير مشروطة (UCR): رد فعل طبيعي (غير مكتسب) لمحفز معين. قبل التكييف، فكر في تحفيز الكلاب واستجابتها على النحو التالي:

    \[\text{Meat powder (UCS)} \rightarrow \text{Salivation (UCR))}\]

    في التكييف الكلاسيكي، يتم تقديم حافز محايد مباشرة قبل التحفيز غير المشروط. كان بافلوف يصدر نغمة (مثل رنين الجرس) ثم يعطي الكلاب مسحوق اللحم. كانت النغمة هي التحفيز المحايد (NS)، وهو حافز لا يثير الاستجابة بشكل طبيعي. قبل التكييف، لم يسيل لعاب الكلاب عندما سمعت النغمة للتو لأن النغمة لم تكن مرتبطة بالكلاب. يعني هذا الاقتران بكل بساطة:

    \[\text{Tone (NS) + Meat Powder (UCS) } \rightarrow \text{Salivation (UCR))}\]

    عندما قام بافلوف بإقران النغمة بمسحوق اللحم مرارًا وتكرارًا، بدأ الحافز المحايد سابقًا (النغمة) أيضًا في إثارة اللعاب من الكلاب. وهكذا، أصبح الحافز المحايد هو الحافز المشروط (CS)، وهو حافز يثير الاستجابة بعد إقرانه بشكل متكرر بحافز غير مشروط. في النهاية، بدأت الكلاب في إفراز اللعاب بمفردها، تمامًا كما كانت في السابق تسيل لعابها على خطى المساعدين. يُطلق على السلوك الناجم عن التحفيز المشروط الاستجابة المشروطة (CR). في حالة كلاب بافلوف، تعلموا ربط النغمة (CS) بالتغذية، وبدأوا في إفراز اللعاب (CR) تحسبًا للطعام.

    \[\text{Tone (CS)} \rightarrow \text{Salivation (CR))}\]

    Two illustrations are labeled “before conditioning” and show a dog salivating over a dish of food, and a dog not salivating while a bell is rung. An illustration labeled “during conditioning” shows a dog salivating over a bowl of food while a bell is rung. An illustration labeled “after conditioning” shows a dog salivating while a bell is rung.
    Figure \(\PageIndex{2}\): Before conditioning, an unconditioned stimulus (food) produces an unconditioned response (salivation), and a neutral stimulus (bell) does not produce a response. During conditioning, the unconditioned stimulus (food) is presented repeatedly just after the presentation of the neutral stimulus (bell). After conditioning, the neutral stimulus alone produces a conditioned response (salivation), thus becoming a conditioned stimulus.

    Real World Application of Classical Conditioning

    How does classical conditioning work in the real world? Let’s say you have a cat named Tiger, who is quite spoiled. You keep her food in a separate cabinet, and you also have a special electric can opener that you use only to open cans of cat food. For every meal, Tiger hears the distinctive sound of the electric can opener (“zzhzhz”) and then gets her food. Tiger quickly learns that when she hears “zzhzhz” she is about to get fed. What do you think Tiger does when she hears the electric can opener? She will likely get excited and run to where you are preparing her food. This is an example of classical conditioning. In this case, what are the UCS, CS, UCR, and CR?

    What if the cabinet holding Tiger’s food becomes squeaky? In that case, Tiger hears “squeak” (the cabinet), “zzhzhz” (the electric can opener), and then she gets her food. Tiger will learn to get excited when she hears the “squeak” of the cabinet. Pairing a new neutral stimulus (“squeak”) with the conditioned stimulus (“zzhzhz”) is called higher-order conditioning, or second-order conditioning. This means you are using the conditioned stimulus of the can opener to condition another stimulus: the squeaky cabinet. It is hard to achieve anything above second-order conditioning. For example, if you ring a bell, open the cabinet (“squeak”), use the can opener (“zzhzhz”), and then feed Tiger, Tiger will likely never get excited when hearing the bell alone.

    A diagram is labeled “Higher-Order / Second-Order Conditioning” and has three rows. The first row shows an electric can opener labeled “conditioned stimulus” followed by a plus sign and then a dish of food labeled “unconditioned stimulus,” followed by an equal sign and a picture of a salivating cat labeled “unconditioned response.” The second row shows a squeaky cabinet door labeled “second-order stimulus” followed by a plus sign and then an electric can opener labeled “conditioned stimulus,” followed by an equal sign and a picture of a salivating cat labeled “conditioned response.” The third row shows a squeaky cabinet door labeled “second-order stimulus” followed by an equal sign and a picture of a salivating cat labeled “conditioned response.”
    Figure \(\PageIndex{3}\): In higher-order conditioning, an established conditioned stimulus is paired with a new neutral stimulus (the second-order stimulus), so that eventually the new stimulus also elicits the conditioned response, without the initial conditioned stimulus being presented.

    EVERYDAY CONNECTION: Classical Conditioning at Stingray City

    Kate and her husband Scott recently vacationed in the Cayman Islands, and booked a boat tour to Stingray City, where they could feed and swim with the southern stingrays. The boat captain explained how the normally solitary stingrays have become accustomed to interacting with humans. About \(40\) years ago, fishermen began to clean fish and conch (unconditioned stimulus) at a particular sandbar near a barrier reef, and large numbers of stingrays would swim in to eat (unconditioned response) what the fishermen threw into the water; this continued for years. By the late 1980s, word of the large group of stingrays spread among scuba divers, who then started feeding them by hand. Over time, the southern stingrays in the area were classically conditioned much like Pavlov’s dogs. When they hear the sound of a boat engine (neutral stimulus that becomes a conditioned stimulus), they know that they will get to eat (conditioned response).

    As soon as Kate and Scott reached Stingray City, over two dozen stingrays surrounded their tour boat. The couple slipped into the water with bags of squid, the stingrays’ favorite treat. The swarm of stingrays bumped and rubbed up against their legs like hungry cats. Kate and Scott were able to feed, pet, and even kiss (for luck) these amazing creatures. Then all the squid was gone, and so were the stingrays.

    A photograph shows a woman standing in the ocean holding a stingray.
    Figure \(\PageIndex{4}\): Kate holds a southern stingray at Stingray City in the Cayman Islands. These stingrays have been classically conditioned to associate the sound of a boat motor with food provided by tourists. (credit: Kathryn Dumper)

    Classical conditioning also applies to humans, even babies. For example, Sara buys formula in blue canisters for her six-month-old daughter, Angelina. Whenever Sara takes out a formula container, Angelina gets excited, tries to reach toward the food, and most likely salivates. Why does Angelina get excited when she sees the formula canister? What are the UCS, CS, UCR, and CR here?

    So far, all of the examples have involved food, but classical conditioning extends beyond the basic need to be fed. Consider our earlier example of a dog whose owners install an invisible electric dog fence. A small electrical shock (unconditioned stimulus) elicits discomfort (unconditioned response). When the unconditioned stimulus (shock) is paired with a neutral stimulus (the edge of a yard), the dog associates the discomfort (unconditioned response) with the edge of the yard (conditioned stimulus) and stays within the set boundaries. In this example, the edge of the yard elicits fear and anxiety in the dog. Fear and anxiety are the conditioned response.

    General Processes in Classical Conditioning

    Now that you know how classical conditioning works and have seen several examples, let’s take a look at some of the general processes involved. In classical conditioning, the initial period of learning is known as acquisition, when an organism learns to connect a neutral stimulus and an unconditioned stimulus. During acquisition, the neutral stimulus begins to elicit the conditioned response, and eventually the neutral stimulus becomes a conditioned stimulus capable of eliciting the conditioned response by itself. Timing is important for conditioning to occur. Typically, there should only be a brief interval between presentation of the conditioned stimulus and the unconditioned stimulus. Depending on what is being conditioned, sometimes this interval is as little as five seconds (Chance, 2009). However, with other types of conditioning, the interval can be up to several hours.

    Taste aversion is a type of conditioning in which an interval of several hours may pass between the conditioned stimulus (something ingested) and the unconditioned stimulus (nausea or illness). Here’s how it works. Between classes, you and a friend grab a quick lunch from a food cart on campus. You share a dish of chicken curry and head off to your next class. A few hours later, you feel nauseous and become ill. Although your friend is fine and you determine that you have intestinal flu (the food is not the culprit), you’ve developed a taste aversion; the next time you are at a restaurant and someone orders curry, you immediately feel ill. While the chicken dish is not what made you sick, you are experiencing taste aversion: you’ve been conditioned to be averse to a food after a single, negative experience.

    How does this occur—conditioning based on a single instance and involving an extended time lapse between the event and the negative stimulus? Research into taste aversion suggests that this response may be an evolutionary adaptation designed to help organisms quickly learn to avoid harmful foods (Garcia & Rusiniak, 1980; Garcia & Koelling, 1966). Not only may this contribute to species survival via natural selection, but it may also help us develop strategies for challenges such as helping cancer patients through the nausea induced by certain treatments (Holmes, 1993; Jacobsen et al., 1993; Hutton, Baracos, & Wismer, 2007; Skolin et al., 2006).

    Once we have established the connection between the unconditioned stimulus and the conditioned stimulus, how do we break that connection and get the dog, cat, or child to stop responding? In Tiger’s case, imagine what would happen if you stopped using the electric can opener for her food and began to use it only for human food. Now, Tiger would hear the can opener, but she would not get food. In classical conditioning terms, you would be giving the conditioned stimulus, but not the unconditioned stimulus. Pavlov explored this scenario in his experiments with dogs: sounding the tone without giving the dogs the meat powder. Soon the dogs stopped responding to the tone. Extinction is the decrease in the conditioned response when the unconditioned stimulus is no longer presented with the conditioned stimulus. When presented with the conditioned stimulus alone, the dog, cat, or other organism would show a weaker and weaker response, and finally no response. In classical conditioning terms, there is a gradual weakening and disappearance of the conditioned response.

    What happens when learning is not used for a while—when what was learned lies dormant? As we just discussed, Pavlov found that when he repeatedly presented the bell (conditioned stimulus) without the meat powder (unconditioned stimulus), extinction occurred; the dogs stopped salivating to the bell. However, after a couple of hours of resting from this extinction training, the dogs again began to salivate when Pavlov rang the bell. What do you think would happen with Tiger’s behavior if your electric can opener broke, and you did not use it for several months? When you finally got it fixed and started using it to open Tiger’s food again, Tiger would remember the association between the can opener and her food—she would get excited and run to the kitchen when she heard the sound. The behavior of Pavlov’s dogs and Tiger illustrates a concept Pavlov called spontaneous recovery: the return of a previously extinguished conditioned response following a rest period.

    A chart has an x-axis labeled “time” and a y-axis labeled “strength of CR;” there are four columns of graphed data. The first column is labeled “acquisition (CS + UCS) and the line rises steeply from the bottom to the top. The second column is labeled “Extinction (CS alone)” and the line drops rapidly from the top to the bottom. The third column is labeled “Pause” and has no line. The fourth column has a line that begins midway and drops sharply to the bottom. At the point where the line begins, it is labeled “Spontaneous recovery of CR”; the halfway point on the line is labeled “Extinction (CS alone).”
    Figure \(\PageIndex{5}\): This is the curve of acquisition, extinction, and spontaneous recovery. The rising curve shows the conditioned response quickly getting stronger through the repeated pairing of the conditioned stimulus and the unconditioned stimulus (acquisition). Then the curve decreases, which shows how the conditioned response weakens when only the conditioned stimulus is presented (extinction). After a break or pause from conditioning, the conditioned response reappears (spontaneous recovery).

    Of course, these processes also apply in humans. For example, let’s say that every day when you walk to campus, an ice cream truck passes your route. Day after day, you hear the truck’s music (neutral stimulus), so you finally stop and purchase a chocolate ice cream bar. You take a bite (unconditioned stimulus) and then your mouth waters (unconditioned response). This initial period of learning is known as acquisition, when you begin to connect the neutral stimulus (the sound of the truck) and the unconditioned stimulus (the taste of the chocolate ice cream in your mouth). During acquisition, the conditioned response gets stronger and stronger through repeated pairings of the conditioned stimulus and unconditioned stimulus. Several days (and ice cream bars) later, you notice that your mouth begins to water (conditioned response) as soon as you hear the truck’s musical jingle—even before you bite into the ice cream bar. Then one day you head down the street. You hear the truck’s music (conditioned stimulus), and your mouth waters (conditioned response). However, when you get to the truck, you discover that they are all out of ice cream. You leave disappointed. The next few days you pass by the truck and hear the music, but don’t stop to get an ice cream bar because you’re running late for class. You begin to salivate less and less when you hear the music, until by the end of the week, your mouth no longer waters when you hear the tune. This illustrates extinction. The conditioned response weakens when only the conditioned stimulus (the sound of the truck) is presented, without being followed by the unconditioned stimulus (chocolate ice cream in the mouth). Then the weekend comes. You don’t have to go to class, so you don’t pass the truck. Monday morning arrives and you take your usual route to campus. You round the corner and hear the truck again. What do you think happens? Your mouth begins to water again. Why? After a break from conditioning, the conditioned response reappears, which indicates spontaneous recovery.

    Acquisition and extinction involve the strengthening and weakening, respectively, of a learned association. Two other learning processes—stimulus discrimination and stimulus generalization—are involved in distinguishing which stimuli will trigger the learned association. Animals (including humans) need to distinguish between stimuli—for example, between sounds that predict a threatening event and sounds that do not—so that they can respond appropriately (such as running away if the sound is threatening). When an organism learns to respond differently to various stimuli that are similar, it is called stimulus discrimination. In classical conditioning terms, the organism demonstrates the conditioned response only to the conditioned stimulus. Pavlov’s dogs discriminated between the basic tone that sounded before they were fed and other tones (e.g., the doorbell), because the other sounds did not predict the arrival of food. Similarly, Tiger, the cat, discriminated between the sound of the can opener and the sound of the electric mixer. When the electric mixer is going, Tiger is not about to be fed, so she does not come running to the kitchen looking for food.

    On the other hand, when an organism demonstrates the conditioned response to stimuli that are similar to the condition stimulus, it is called stimulus generalization, the opposite of stimulus discrimination. The more similar a stimulus is to the condition stimulus, the more likely the organism is to give the conditioned response. For instance, if the electric mixer sounds very similar to the electric can opener, Tiger may come running after hearing its sound. But if you do not feed her following the electric mixer sound, and you continue to feed her consistently after the electric can opener sound, she will quickly learn to discriminate between the two sounds (provided they are sufficiently dissimilar that she can tell them apart).

    Sometimes, classical conditioning can lead to habituation. Habituation occurs when we learn not to respond to a stimulus that is presented repeatedly without change. As the stimulus occurs over and over, we learn not to focus our attention on it. For example, imagine that your neighbor or roommate constantly has the television blaring. This background noise is distracting and makes it difficult for you to focus when you’re studying. However, over time, you become accustomed to the stimulus of the television noise, and eventually you hardly notice it any longer.

    Behaviorism

    John B. Watson, shown in Figure \(\PageIndex{6}\), is considered the founder of behaviorism. Behaviorism is a school of thought that arose during the first part of the 20th century, which incorporates elements of Pavlov’s classical conditioning (Hunt, 2007). In stark contrast with Freud, who considered the reasons for behavior to be hidden in the unconscious, Watson championed the idea that all behavior can be studied as a simple stimulus-response reaction, without regard for internal processes. Watson argued that in order for psychology to become a legitimate science, it must shift its concern away from internal mental processes because mental processes cannot be seen or measured. Instead, he asserted that psychology must focus on outward observable behavior that can be measured.

    A photograph shows John B. Watson.
    Figure \(\PageIndex{6}\): John B. Watson used the principles of classical conditioning in the study of human emotion.

    Watson’s ideas were influenced by Pavlov’s work. According to Watson, human behavior, just like animal behavior, is primarily the result of conditioned responses. Whereas Pavlov’s work with dogs involved the conditioning of reflexes, Watson believed the same principles could be extended to the conditioning of human emotions (Watson, 1919). Thus began Watson’s work with his graduate student Rosalie Rayner and a baby called Little Albert. Through their experiments with Little Albert, Watson and Rayner (1920) demonstrated how fears can be conditioned.

    In 1920, Watson was the chair of the psychology department at Johns Hopkins University. Through his position at the university he came to meet Little Albert’s mother, Arvilla Merritte, who worked at a campus hospital (DeAngelis, 2010). Watson offered her a dollar to allow her son to be the subject of his experiments in classical conditioning. Through these experiments, Little Albert was exposed to and conditioned to fear certain things. Initially he was presented with various neutral stimuli, including a rabbit, a dog, a monkey, masks, cotton wool, and a white rat. He was not afraid of any of these things. Then Watson, with the help of Rayner, conditioned Little Albert to associate these stimuli with an emotion—fear. For example, Watson handed Little Albert the white rat, and Little Albert enjoyed playing with it. Then Watson made a loud sound, by striking a hammer against a metal bar hanging behind Little Albert’s head, each time Little Albert touched the rat. Little Albert was frightened by the sound—demonstrating a reflexive fear of sudden loud noises—and began to cry. Watson repeatedly paired the loud sound with the white rat. Soon Little Albert became frightened by the white rat alone. In this case, what are the UCS, CS, UCR, and CR? Days later, Little Albert demonstrated stimulus generalization—he became afraid of other furry things: a rabbit, a furry coat, and even a Santa Claus mask. Watson had succeeded in conditioning a fear response in Little Albert, thus demonstrating that emotions could become conditioned responses. It had been Watson’s intention to produce a phobia—a persistent, excessive fear of a specific object or situation— through conditioning alone, thus countering Freud’s view that phobias are caused by deep, hidden conflicts in the mind. However, there is no evidence that Little Albert experienced phobias in later years. Little Albert’s mother moved away, ending the experiment, and Little Albert himself died a few years later of unrelated causes. While Watson’s research provided new insight into conditioning, it would be considered unethical by today’s standards.

    A photograph shows a man wearing a mask with a white beard; his face is close to a baby who is crawling away. A caption reads, “Now he fears even Santa Claus.”
    Figure \(\PageIndex{7}\): Through stimulus generalization, Little Albert came to fear furry things, including Watson in a Santa Claus mask.

    EVERYDAY CONNECTION: Advertising and Associative Learning

    Advertising executives are pros at applying the principles of associative learning. Think about the car commercials you have seen on television. Many of them feature an attractive model. By associating the model with the car being advertised, you come to see the car as being desirable (Cialdini, 2008). You may be asking yourself, does this advertising technique actually work? According to Cialdini (2008), men who viewed a car commercial that included an attractive model later rated the car as being faster, more appealing, and better designed than did men who viewed an advertisement for the same car minus the model.

    Have you ever noticed how quickly advertisers cancel contracts with a famous athlete following a scandal? As far as the advertiser is concerned, that athlete is no longer associated with positive feelings; therefore, the athlete cannot be used as an unconditioned stimulus to condition the public to associate positive feelings (the unconditioned response) with their product (the conditioned stimulus).

    Now that you are aware of how associative learning works, see if you can find examples of these types of advertisements on television, in magazines, or on the Internet.

    Summary

    Pavlov’s pioneering work with dogs contributed greatly to what we know about learning. His experiments explored the type of associative learning we now call classical conditioning. In classical conditioning, organisms learn to associate events that repeatedly happen together, and researchers study how a reflexive response to a stimulus can be mapped to a different stimulus—by training an association between the two stimuli. Pavlov’s experiments show how stimulus-response bonds are formed. Watson, the founder of behaviorism, was greatly influenced by Pavlov’s work. He tested humans by conditioning fear in an infant known as Little Albert. His findings suggest that classical conditioning can explain how some fears develop.

    Glossary

    acquisition
    period of initial learning in classical conditioning in which a human or an animal begins to connect a neutral stimulus and an unconditioned stimulus so that the neutral stimulus will begin to elicit the conditioned response
    classical conditioning
    learning in which the stimulus or experience occurs before the behavior and then gets paired or associated with the behavior
    conditioned response (CR)
    response caused by the conditioned stimulus
    conditioned stimulus (CS)
    stimulus that elicits a response due to its being paired with an unconditioned stimulus
    extinction
    decrease in the conditioned response when the unconditioned stimulus is no longer paired with the conditioned stimulus
    habituation
    when we learn not to respond to a stimulus that is presented repeatedly without change
    higher-order conditioning
    (also, second-order conditioning) using a conditioned stimulus to condition a neutral stimulus
    neutral stimulus (NS)
    stimulus that does not initially elicit a response
    spontaneous recovery
    return of a previously extinguished conditioned response
    stimulus discrimination
    ability to respond differently to similar stimuli
    stimulus generalization
    demonstrating the conditioned response to stimuli that are similar to the conditioned stimulus
    unconditioned response (UCR)
    natural (unlearned) behavior to a given stimulus
    unconditioned stimulus (UCS)
    stimulus that elicits a reflexive response