Applications of Pavlovian Learning

Pavlovian Learning: Applications Part 2

Conditioned Taste Aversion

• When an organism forms an association between a "taste" and illness, and subsequently avoids that taste.

• Garcia's work on taste aversion demonstrated key differences from other conditioning research:

  • The Conditioned Stimulus (CS) and Unconditioned Stimulus (US) occur together only once.

  • The time between the CS and the Unconditioned Response (UR) can be significantly delayed (up to 30 minutes!).

  • The responding observed is adaptive, meaning it enhances survival.

  • Organisms are biologically prepared, or predisposed, to learn certain specific associations more easily (Garcia & Koelling, 1966).

Preparedness

• Garcia & Koelling (1966) further demonstrated that the specific CSs used profoundly impacted the learning process:

  • Some CSs (e.g., taste) are highly effective for learning associations with illness.

  • Other CSs (e.g., light, sound) are more effective for learning associations with pain.

  • These types of CS-US pairings often do not overlap; a taste associated with pain, or a sound associated with illness, is less readily learned.

  • This highlights the principle of adaptive responding and biological preparedness, suggesting that evolutionary pressures have shaped which associations are easily formed.

Applications of Taste Aversion Learning

• Treatment of alcoholism: Aversion therapy using drugs like Disulfiram (Antabuse) is a direct application, creating an aversive experience when alcohol is consumed.

Conditioned Taste Aversion and Livestock Management

• This principle has practical applications in agricultural settings to protect livestock:

  • Teaching horses to avoid eating toxic locoweed.

  • Preventing cattle from consuming toxic plants.

  • Training sheep to avoid eating grapevines, allowing them to safely weed vineyards without damaging the valuable crops.

• These types of aversions are remarkably durable and can persist for several years, demonstrating their strength and adaptive value.

Advertising

• The use of Conditioned Emotional Responses in advertising is a long-standing and widespread practice.

• Conditioning is employed to create positive associations with products:

  • Pairing a beer with images and experiences of having a good time.

  • Associating a fragrance with attractiveness.

  • Linking undergarments with sexual desirability.

• Evidence indicating that conditioning influences attitude toward brands includes:

  • Studies where people preferred peanut butter from a jar with a brand name label over an identical jar without one.

  • Participants choosing a pen of the same color they had seen while listening to music they found enjoyable.

  • Students expressing a preference for a toothpaste brand after seeing it paired with positive images.

  • Our own observable buying habits often reflect these conditioned preferences.

• Simultaneous conditioning (presenting the product and the positive unconditioned stimulus together, e.g., a famous person using a product) is the foundation of most advertisements.

• Some ads use backward conditioning (e.g., famous person shown before the product name), but presenting the brand name first (simultaneous or forward conditioning) is generally more effective.

• However, conditioning is not very effective in changing preferences if a strong brand preference already exists.

Medical Applications of Pavlovian Learning

• Hearing tests in newborn infants: The conditioned eyeblink test is a classic example, where a sound (CS) is paired with a puff of air (US) to elicit an eyeblink (CR).

• Peanut Desensitization Therapy: Modern treatments for severe allergies involve gradually exposing individuals to increasing amounts of the allergen (CS) in controlled environments, aiming to extinguish the extreme immune reaction (UR) and build tolerance.

• The pioneering work in this area gave rise to Psychoneuroimmunology, an interdisciplinary field studying the interactions between psychological processes, the nervous system, and the immune system.

Robert Ader's Experiment (Birth of Psychoneuroimmunology)

• During a conditioned taste aversion experiment, Robert Ader observed an unexpected and profound outcome.

• Methodology:

  • Rats were divided into four groups, each receiving varying amounts of sweet saccharin water (CS).

  • All groups were subsequently injected with an immunosuppressive drug (US).

  • Later, the drug injections were stopped, but the rats continued to receive the saccharin solution.

• Results:

  • Not only did the rats develop an aversion to drinking the sweet solution, but a significant number of the animals died.

  • The volume of saccharin solution consumed during subsequent "probe trials" was directly predictive of the degree of avoidance shown, and, critically, it was also directly related to the mortality rate.

  • Ader found that "the more rats drank, the more likely they were to die!!!" This stunning finding indicated that a conditioned stimulus (saccharin) could trigger an immune response (or suppression) even in the absence of the actual drug.

Conditioned Immune Responses

• The findings from Ader's work and subsequent studies in this area have led to extensive research examining the utility of conditioning in:

  • Treatment of autoimmune disease: Potentially using conditioned cues to suppress inappropriate immune responses.

  • Treatment of cancer: Exploring whether conditioned stimuli can enhance the effectiveness of chemotherapy or radiation by priming the immune system or reducing side effects.

• This phenomenon might also partially explain the Placebo effect, where expectations and conditioned cues (e.g., taking a pill) can elicit real physiological changes in the absence of an active drug.

Drug Addiction (Siegel)

• Siegel's experiments with heroin conclusively demonstrated that substance use and its related phenomena are substantially impacted by Pavlovian processes.

• The concept of Conditioned Compensatory Responding (CCR) is central to understanding addiction:

  • The High: The drug (US) inherently produces the high (UR). However, any environmental cues or rituals associated with drug use (CSs) can become conditioned to elicit a conditioned compensatory response (CR).

  • Tolerance: The CR in this context is often a compensatory physiological response that counteracts the effects of the drug. When the drug is taken in the usual environment (where CSs are present), the body begins to prepare for the drug's effects before the drug takes full effect, leading to a need for higher doses to achieve the same "high." This explains tolerance.

  • Withdrawal and Craving: These challenging experiences can be understood as the equivalent of CS probe trials. When addicts encounter drug-associated cues (CSs) in the absence of the drug, these cues trigger the conditioned compensatory responses, leading to physiological symptoms resembling withdrawal and intense cravings.

Drug Withdrawal (MacRae & Siegel, 1997)

• Later work by Siegel further demonstrated that symptoms of withdrawal could be profoundly accounted for by conditioning processes.

• Experiment: Rats were divided into groups:

  • SA-M (self-administered morphine): Rats pressed a lever (Y) to receive morphine.

  • Y-M (yoked morphine): These rats received the same morphine doses at the same time as the SA-M rats, but their drug delivery was contingent on the SA-M rat's lever presses (they had no control).

  • Y-R (yoked saline): These rats received saline when the SA-M rats pressed the lever.

• Results: Although rats in both the SA-M and Y-M groups received identical drug doses at identical times, the SA-M rats (who had actively self-administered the drug and formed stronger context-drug associations) exhibited significantly more pronounced withdrawal symptoms compared to the Y-M rats.

• This finding powerfully illustrates that the predictive cues and the active engagement in drug seeking and administration strengthen the conditioning, leading to more severe withdrawal when those cues are present and the drug is absent.

Treatment of Substance Use Disorders

• Many modern pharmacological treatments for Substance Use Disorders are grounded in principles derived from Classical Conditioning:

  • Extinction: Strategies that aim to break the association between drug cues (CSs) and the drug's effects (US) or the subsequent CRs.

  • Opioid Antagonists and Agonists:

    • Agonists (e.g., Methadone): A medication that binds to the opioid receptor, producing a similar but controlled response to the drug of abuse, thereby reducing craving and withdrawal without producing the same high.

    • Antagonists (e.g., Suboxone): A medication that binds to the receptor (either at the primary site or another site), which partially or completely blocks the receptor from producing a response. This prevents the illicit drug from having its full effect, making it less rewarding.

  • Aversion Therapy:

    • Antabuse (Disulfiram): A drug that blocks the breakdown of alcohol in the body, leading to a build-up of toxic byproducts (acetaldehyde). Drinking alcohol while taking this medication results in severe illness (nausea, vomiting, headache, etc.), creating a strong aversive state.

  • Exposure Therapy: A behavioral therapy technique aiming to reduce the power of conditioned cues.

    • This is often difficult to implement "in vivo" (in real-life situations) due to safety and ethical concerns.

    • Recent efforts are directed towards the use of Virtual Reality Exposure Therapy (VRET), which allows for controlled exposure to drug-related cues in a simulated environment, facilitating extinction learning.

Conclusions

• Classical Conditioning Procedures have a vast array of practical applications across various fields.

• While we have reviewed the most prominent uses, the fundamental principle is that anything that can be considered an innate or reflexive response can be manipulated and influenced using these conditioning processes.