In this British study, 38 people (20 adults between the ages of 18 and 32 and 18 adolescents between the ages of 12 and 17) participated. They received 5 pounds (about $6.20) for participating, plus anywhere from zero to 10 pounds ($12.40) based on their performance in the task. They viewed pairs of abstract items (the Agathodaimon alphabet). As shown in Figure 8.8, their choices were either rewarded (happy smiley and +1 point) or punished (unhappy smiley and −1 point).
Figure 8.8Research Protocol for Studying the Effects of Reward and Punishment.
Participants viewed these slides in order. First, they fixated on the cross. Next, they see both figures and select one. Finally, they receive feedback in the form of a smiley and point total (in this case, our participant was correct).
Source: S. Palminteri, E. J. Kilford, G. Coricelli, & S.-J. Blakemore (2016). “The Computational Development of Reinforcement Learning During Adolescence.” PLoS Computational Biology, 12(6), e1004953.
Although the topic of punishment might make it sound like this study raises more than the typical ethical concerns about research, facing an unhappy smiley and failing to earn 10 pounds ($12.40) are unlikely to cause the participants significant distress. The “risks” of the study would be spelled out for prospective participants in an informed consent process. The participation of adolescents would require parent or guardian approval plus participant assent. In other words, adolescents can’t be forced to participate by their parents, but they cannot participate without parental approval.
The adults learned equally well from punishment and reinforcement. In contrast, the adolescents were more likely to learn from reinforcement than from punishment. In other words, the adolescents were more likely to seek rewards than to try to avoid punishments.
This research demonstrated that decision making based on the probabilities of reward and punishment continues to develop through adolescence into young adulthood. Unlike the adults, who were as likely to seek rewards as they were to try to avoid punishments, the adolescents appeared to pay more attention to rewards.
Among the many implications of this study, we might conclude that using positive feedback to support learning in adolescents is likely to produce more benefits that using negative feedback. In other words, teens might learn more at school about what they’re doing correctly than what they’re doing incorrectly. College students, in contrast, are likely to benefit from both types of feedback.
8-4bSchedules of Reinforcement
Reinforcing a behavior every time it occurs is known as continuous reinforcement. Although it is highly desirable to use continuous reinforcement when a new behavior is being learned, it is inconvenient to do so forever. Dog owners want their dogs to walk with a loose leash, but once this skill is learned, the owners don’t want to carry dog treats for reinforcement whenever they walk their dogs. Once we deviate from continuous reinforcement, however, the manner in which we do so may have a dramatic impact on the target behavior. To obtain the results we want, it is helpful to understand what happens when we use partial reinforcement , or the reinforcement of the desired behavior on some occasions, but not others.
Concerns about the effects of piecework on worker well-being contributed to the Fair Labor Standards Act of 1938, which included a provision for a minimum hourly wage.
Psychologists have identified many ways to apply partial reinforcement, but we will concentrate on two variations: ratio schedules and interval schedules. In a ratio schedule of partial reinforcement, reinforcement depends on the number of times a behavior occurs. In an interval schedule of partial reinforcement, reinforcement depends on the passage of a certain amount of time. Either type of schedule, ratio or interval, can be fixed or variable. In fixed schedules, the requirements for reinforcement never vary. In variable schedules, the requirements for reinforcement are allowed to fluctuate from trial to trial, averaging a certain amount over the course of a learning session.
Fixed Ratio Schedules
A fixed ratio (FR) schedule requires that a behavior occur a set number of times for each reinforcer. Continuous reinforcement, discussed earlier, is equivalent to a FR of 1. If we now raise our requirement to two behaviors per reinforcer, we have a FR schedule of 2, and so on. Using the Skinner box, we can investigate the influence of FR schedules on the rate at which a rat will press a bar for food. To do so, we track cumulative responses as a function of time. FR schedules produce a characteristic pattern of responding. In general, responses are fairly steady, with a significant pause following each reward. As the amount of work for each reward is increased, responding becomes slower (see Figure 8.9).
Schedules of Reinforcement.
The schedule used to deliver reinforcement has a big impact on the resulting behavior. In general, the variable schedules produce higher rates of responding than do their fixed counterparts. The fixed interval schedule produces a characteristic pattern of low rates of responding at the beginning of the interval and accelerated responding as the end of the interval approaches.
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