L3: Extra reading Flashcards
instrumental conditioning and addiction intervention
Higgins et al. (1966)
The effectiveness of voucher-based abstinence reinforcement is illustrated by a study with methadone patients who injected drugs and continued to use cocaine during methadone treatment (Silverman, Higgins, Brooner, Montoya, Cone, Schuster, and Preston, 1996b). After a 5-week baseline period, participants in that study were randomly assigned to an abstinence reinforcement group or to a yoked control group. Participants in the abstinence reinforcement group could earn up to $1,155 in vouchers for providing cocaine-free urine samples every Monday, Wednesday, and Friday for 12 weeks. The value of the vouchers increased as the number of consecutive cocaine-free urine samples increased. If a participant ever provided a cocaine-positive urine sample or failed to provide a scheduled sample, the participant did not receive a voucher and the value of the next voucher earned was reset to the initial low value. Control participants received vouchers on a noncontingent basis, yoked in pattern and amount to vouchers received by participants in the abstinence reinforcement group. The voucher-based abstinence reinforcement intervention significantly increased the longest duration of cocaine abstinence that participants achieved during the 12-week period in which the voucher intervention was in effect. Half of the participants in the abstinence reinforcement group achieved between 7 and 12 weeks of sustained cocaine abstinence, but only one participant in the control group achieved more than 2 weeks of sustained abstinence. This study showed clearly that the voucher-based abstinence reinforcement intervention was effective in promoting cocaine abstinence in about half of the participants.
the overjustification effect
Levy et al. (2018)
“One potential limitation of instrumental conditioning, particularly in the use of positive reinforcement, is the overjustification effect. This effect suggests that providing external rewards for a behavior that is already intrinsically motivating may lead to a reduction in intrinsic motivation once the reward is removed. For instance, children who enjoy drawing may draw less if they begin to associate the activity with receiving a prize. This challenges the long-term effectiveness of reinforcement strategies and raises concerns about reward dependency. However, it is important to note that this effect tends to occur in cases where intrinsic motivation is already high. In contexts such as addiction treatment, where intrinsic motivation for abstinence may be low, external reinforcement (as in voucher-based interventions) can be highly effective without undermining intrinsic motivation.”
Here’s where it gets spicy. Instrumental conditioning predicts that adding a reward strengthens behavior—more food, more lever presses. Overjustification flips that: adding a reward can weaken the behavior’s intrinsic pull, especially long-term. If the reward stops, you might ditch the task entirely, unlike a purely conditioned response where you’d expect gradual extinction. This suggests instrumental conditioning oversimplifies motivation—it doesn’t account for the interplay between internal drives and external incentives. Cognitive theories (e.g., Deci’s self-determination theory) jump in here, arguing that rewards can undermine autonomy, which Skinner’s model doesn’t really wrestle with.
Another challenging instrumental conditioning
While instrumental conditioning highlights the power of external reinforcers in shaping behavior, Self-Determination Theory (Deci & Ryan) offers a complementary and sometimes critical perspective. It suggests that human motivation is influenced not just by rewards and punishments, but by the satisfaction of innate psychological needs — autonomy, competence, and relatedness. External rewards that support these needs can enhance motivation, but those that feel controlling may undermine it, potentially leading to effects like the overjustification phenomenon. This broader framework encourages a more holistic understanding of behavior and highlights the limitations of relying solely on extrinsic reinforcement
the reward prediction error?
Reward prediction errors consist of the differences between received and predicted rewards. They are crucial for basic forms of learning about rewards and make us strive for more rewards—an evolutionary beneficial trait. Most dopamine neurons in the midbrain of humans, monkeys, and rodents signal a reward prediction error; they are activated by more reward than predicted (positive prediction error), remain at baseline activity for fully predicted rewards, and show depressed activity with less reward than predicted (negative prediction error). The dopamine signal increases nonlinearly with reward value and codes formal economic utility. Drugs of addiction generate, hijack, and amplify the dopamine reward signal and induce exaggerated, uncontrolled dopamine effects on neuronal plasticity. The striatum, amygdala, and frontal cortex also show reward prediction error coding, but only in subpopulations of neurons. Thus, the important concept of reward prediction errors is implemented in neuronal hardware.
“Recent neuroscientific research has provided strong support for the mechanisms underlying instrumental conditioning. The concept of reward prediction error (RPE), where the brain compares expected versus actual rewards, has been identified as a key driver of learning. Dopamine neurons in the midbrain are activated when rewards are better than expected, remain neutral for expected rewards, and are suppressed when rewards are worse than expected. This dopamine-based feedback loop reinforces behaviors that lead to greater-than-expected outcomes, aligning closely with Skinner’s principle of positive reinforcement. Furthermore, addictive substances like cocaine or heroin exploit this reward system by artificially increasing dopamine activity, leading to compulsive behavior patterns. These findings offer a biological explanation for reinforcement learning and suggest that the principles of instrumental conditioning are embedded in neural circuitry.”
