Second-order schedules of token reinforcement with pigeons: effects of fixed- and variable-ratio exchange schedules

Pigeons' key pecks produced food under second-order schedules of token reinforcement, with light-emitting diodes serving as token reinforcers. In Experiment 1, tokens were earned according to a fixed-ratio 50 schedule and were exchanged for food according to either fixed-ratio or variable-ratio exchange schedules, with schedule type varied across conditions. In Experiment 2, schedule type was varied within sessions using a multiple schedule. In one component, tokens were earned according to a fixed-ratio 50 schedule and exchanged according to a variable-ratio schedule. In the other component, tokens were earned according to a variable-ratio 50 schedule and exchanged according to a fixed-ratio schedule. In both experiments, the number of responses per exchange was varied parametrically across conditions, ranging from 50 to 400 responses. Response rates decreased systematically with increases in the fixed-ratio exchange schedules, but were much less affected by changes in the variable-ratio exchange schedules. Response rates were consistently higher under variable-ratio exchange schedules than tinder comparable fixed-ratio exchange schedules, especially at higher exchange ratios. These response-rate differences were due both to greater pre-ratio pausing and to lower local rates tinder the fixed-ratio exchange schedules. Local response rates increased with proximity to food under the higher fixed-ratio exchange schedules, indicative of discriminative control by the tokens.     

Behavioral and pharmacological variables affecting risky choice in rats.

The effects of manipulations of response requirement, intertrial interval (ITI), and psychoactive drugs (ethanol, phencyclidine, and d-amphetamine) on lever choice under concurrent fixed-ratio schedules were investigated in rats. Responding on the "certain' lever produced three 45-mg pellets, whereas responding on the "risky" lever produced either 15 pellets (p = .33) or no pellets (p .67). Rats earned all food during the session, which ended after 12 forced trials and 93 choice trials or 90 min, whichever occurred first. When the response requirement was increased from 1 to 16 and the ITI was 20 s, percentage of risky choice was inversely related to fixed-ratio value. When only a single response was required but the ITI was manipulated between 20 and 120 s (with maximum session duration held constant), percentage of risky choice was directly related to length of the ITI. The effects of the drugs were investigated first at an ITI of 20 s, when risky choice was low for most rats, and then at an ITI of 80 s, when risky choice was higher for most rats. Ethanol usually decreased risky choice. Phencyclidine did not usually affect risky choice when the ITI was 20 s but decreased it in half the rats when the ITI was 80 s. For d-amphetamine, the effects appeared to he related to baseline probability of risky choice; that is, low probabilities were increased and high probabilities were decreased. Although increase in risky choice as a function of the ITI is at variance with previous ITI data, it is consistent with foraging data showing that risk aversion decreases as food availability decreases. The pharmacological manipulations showed that drug effects on risky choice may be influenced by the baseline probability of risky choice, just as drug effects can be a function of baseline response rate.     

THE EFFECTS OF FIXED-TIME REINFORCEMENT SCHEDULES ON FUNCTIONAL RESPONSE CLASSES: A TRANSLATIONAL STUDY

Research on functional response classes has applied significance because less severe forms of problem behavior have been found to co‐occur with more severe forms. In addition, the most severe forms of problem behavior are sometimes targeted for intervention without monitoring other less severe forms. In such cases, it is unknown whether and how untreated forms of problem behavior covary with the targeted behaviors. The present study employed a translational procedure (with button presses as the target behavior) to investigate response covariation under noncontingent reinforcement with typically developing preschoolers. The results indicated that noncontingent reinforcement was generally effective in decreasing all response class members when only one member was targeted.     

Development of key-pecking, pause, and ambulation during extended exposure to a fixed-interval schedule of reinforcement

Six pigeons key-pecked under a fixed-interval (FI) 3-min schedule of food presentation. Each pigeon was studied for 200 daily sessions with 15 intervals per session (3,000 total food presentations). Analyses included the examination of latency to first peck (pause), mean rate of key pecking, and ambulation. Characterizations of stable performance were assessed across measures of behavior and evaluated using commonly employed stability criteria. Stability of response rate and pause was identified better by assessments that evaluated variability and trend, rather than just variability. Between-subject differences in rate of acquisition and terminal values of steady-state performance of pause were observed, and stable pause durations took longer to develop than did stable key-pecking rates. Relative variability in response rate and pause duration decreased as the means increased. A temporally organized pattern of key-pecking (the so-called FI scallop) developed within 50 sessions of exposure to the schedule. Overall ambulation decreased during the early sessions of exposure and further analyses showed greater rates of ambulation during the pause than after it for 4 of the 6 pigeons. Performance under the FI 3-min schedule developed relatively slowly, and key-pecking, pause, and ambulation developed at different rates.     

EFFECTS OF A SIGNALED DELAY TO REINFORCEMENT IN THE PREVIOUS AND UPCOMING RATIOS ON BETWEEN-RATIO PAUSING IN FIXED-RATIO SCHEDULES

Domestic hens responded under multiple fixed‐ratio fixed‐ratio schedules with equal fixed ratios. One component provided immediate reinforcement and the other provided reinforcement after a delay, signaled by the offset of the key light. The components were presented quasirandomly so that all four possible transitions occurred in each session. The delay was varied over 0, 4, 8, 16, and 32 s with fixed‐ratio 5 schedules, and over 0, 8 and 32 s with fixed‐ratio 1, 15 and 40 schedules. Main effects of fixed‐ratio value and delay duration were detected on between‐ratio pauses. Pauses were longer when the multiple‐schedule stimulus correlated with a delayed‐reinforcer component was presented, with the longest pauses occurring at the transition from a component with an immediate reinforcer to one with a delayed reinforcer. Pause durations were shortest during immediate components. Overall, both the presence or absence of a delay in the upcoming component, and the presence or absence of a delay in the preceding component affected pause length, but the upcoming delay had the larger effect. Thus changes in delay had similar effects to past reports of the effects of changes in response force, response requirement, and reinforcer magnitude in multiple fixed‐ratio fixed‐ratio schedules.     

Some determinants of remote behavioral history effects in humans

Undergraduates were exposed to a series of reinforcement schedules: first, to a fixed-ratio (FR) schedule in the presence of one stimulus and to a differential-reinforcement-of-low-rate (DRL) schedule in the presence of another (multiple FR DRL training), then to a fixed-interval (FI) schedule in the presence of a third stimulus (FI baseline), next to the FI schedule under the stimuli previously correlated with the FR and DRL schedules (multiple FI FI testing), and, finally, to a single session of the multiple FR DRL schedule again (multiple FR DRL testing). Response rates during the multiple FI FI schedule were higher under the former FR stimulus than under the former DRL stimulus. This effect of remote histories was prolonged when either the number of FI-baseline sessions was small or zero, or the time interval between the multiple FR DRL training and the multiple FI FI testing was short. Response rates under these two stimuli converged with continued exposure to the multiple FI FI schedule in most cases, but quickly differentiated when the schedule returned to the multiple FR DRL.     

Failing safely: Increasing theology and religious studies students’ resilience and academic confidence via risk‐taking in formative assessment

Students increasingly appear anxious, risk‐averse, and worried about getting things “wrong.” They may appear to lack intellectual curiosity, and be unwilling to engage in independent study. This essay explores how teaching and assessment in theology and religious studies might help students learn to take intellectual risks, and increase their resilience. One approach is to encourage students to experiment and “fail safely,” to increase their confidence that they understand what is expected of them, and to help them begin to understand learning as more broadly formational, not always directed toward a grade. I suggest three strategies: more formative assessment; a stronger narrative about the purpose of formative assessment; and an appeal to values, virtue, and the cultivation of character. Via these approaches, students might be encouraged to understand assessment in less utilitarian terms and increase their resilience for a world characterized by volatility, uncertainty, complexity, and ambiguity, prepared both critically and dispositionally to thrive and contribute positively to society.     

Understanding the prevalence and correlates of implicit theories of weight in the United States: Insights from a nationally representative sample

Objectives: The primary aim of this research is to understand how mindsets about weight controllability in the United States relate to population health. We examined the distribution of people’s implicit theories of weight, from an incremental (controllable) to an entity (not controllable) mindset, in a nationally representative sample, as well as their relation to: sociodemographic factors, beliefs about behaviour and genetics as causes of obesity and engagement in weight management-relevant behaviours.

Methods: We report data from the National Cancer Institute’s Health Information National Trends Survey 4.

Results: A majority of respondents endorsed an incremental mindset of body weight, but endorsement of this mindset was stronger among younger, white respondents, and those with a higher income and more educational attainment. A stronger incremental mindset was related to stronger behaviour and weaker genetic causal beliefs about obesity, as well as a tendency to report increased engagement in weight management-relevant behaviours.

Conclusions: Our research provides evidence that although incremental mindsets are more common overall and associated with engagement in health behaviours that can contribute to or detract from population health, incremental mindsets are less common among individuals from more marginalised groups.     

从归因疗法到内隐理念：德韦克的心理学理论体系及影响

为更好地理解美国当代著名心理学家卡罗尔·德韦克(Carol S. Dweck)的心理学理论体系,对其学术成果进行了系统的整理与分析,发现可按时间维度将其理论划分为四个相继形成的主题：(1)习得性无助和归因的关系主题;(2)成就目标理论主题;(3)内隐智力理念主题;(4)内隐理念主题。这些主题促进了归因、智力、动机、人格等心理学理论的发展,已经被广泛地应用于健康、教育、人际关系及管理等实践领域,对学界与社会产生了深刻的影响。