Operant variability when reinforcement is delayed

Operant responses are often weakened when delays are imposed between the responses and reinforcers. We examined what happens when delayed reinforcers were contingent upon operant responsevariability. Three groups of rats were rewarded for varying their response sequences, with one group rewarded for high variability, another for middle, and the third for low levels. Consistent with many reports in the literature, responding slowed significantly in all groups as delays were lengthened. Consistent with other reports, large differences in variability were maintained across the three groups despite the delays. Reinforced variability appears to be relatively immune to disruption by such things as delays, response slowing, prefeeding, and noncontingent reinforcement. Furthermore, the small effects on variability depended on baseline levels: As delays lengthened, variability increased in the low group, was statistically unchanged in the middle group, and decreased in the high group, an interaction similar to that reported previously when reinforcement frequencies were lowered. Thus, variable operant responding is controlled by reinforcement contingencies, but sometimes differently than more commonly studied repetitive responding.     

On the determinants of induction in responding for sucrose when food pellet reinforcement is upcoming

Rats’ rates of leverpressing for low-concentration liquid-sucrose reinforcers in the first half of an experimental session increase when food pellet, rather than sucrose, reinforcers will be available in the second half. Experiment 1 determined that this induction effect was the outcome of food pellet reinforcement’s increasing response rates, not of continued sucrose reinforcement’s decreasing them. Experiments 2 and 3 showed that induction was primarily controlled by the conditions of reinforcement in the current session, not by those in the previous one. Experiment 4 showed little evidence that the induction was the outcome of Pavlovian processes. These results suggest that induction may occur because of processes operating at the level of the entire session. They also provide a link to a seemingly related area of study: contrast effects. Some of the results are consistent with what is known about contrast effects, but there are also several, yet unexplained differences.     

Preference reversal and delayed reinforcement

Pigeons chose, in a two-key discrete-trial procedure, between 2- and 4-sec access to grain, with the larger amount always presented 4 sec later than the smaller. As the delay between the choice and the availability of the smaller reinforcement was varied from .01 to 12 sec, all subjects reversed preference from the small-early to the large-late reinforcement. The values of delay at which preference reversed were approximately consistent with the matching law as adapted for delayed reinforcement.     

US 2012 Live: when the classroom becomes a newsroom

In November 2012, 300 students came together in the Media School at Bournemouth University in the UK to report the US Presidential Election. Over the course of 10 days, students published 176 articles on a rolling news website, garnering more than 20,000 hits. On election night itself, students produced 10 h of live coverage on both TV and radio, airing 30 pre-recorded video packages and 35 pre-recorded radio packages. This experiential project adopted a so-called ‘live case’ methodology that encapsulated a high degree of application and a certain level of structure, which allowed for the ‘variety and uncertainty’ or reality to intervene. It also empowered and enabled students to reflect on and evaluate their individual experiences in light of their own learning styles. This paper will discuss the challenges and successes experienced during this experiential project, and will provide a nine-step guide on how others could replicate a similar project.     

The effects of reinforcement and strategy training on impulsive responding.

Impulsive second-grade children received strategy training or strategy training combined with primary or secondary reinforcement. All training groups showed significantly longer response latencies and significantly fewer errors on the Matching Familiar Figures test immediately following training. The reinforcement groups had significantly longer latencies than the training-only group, and there was some indication that primary reinforcement was more effective than secondary reinforcement in producing response delay. The 3 training groups did not differ significantly on error scores.     

Conjunctive schedules of reinforcement IV: Effects on the pattern of responding of changes in requirement at reinforcement

The effects of different schedule requirements at reinforcement on patterns of responding by pigeons were assessed under conjunctive schedules with comparable response-number requirements, Under one conjunctive schedule (conjunctive fixed-interval fixed-ratio schedule), a response was reinforced after a 6-min interval had elapsedand a specific minimum number of responses had been emitted, Under a second conjunctive schedule, a response was reinforced after the 6-min fixed interval and upon completion of a tandem schedule requirement (conjunctive fixed-interval tandem schedule), This schedule retained the same required minimum number of responses as the first conjunctive schedule, but responses were never reinforced according to a fixed-ratio schedule; the tandem schedule was comprised of a fixed-ratio and a small (.1 to 10.0 sec) fixed-interval schedule, Under the conjunctive fixed-interval fixed-ratio schedule, responding was characterized by an initial pause, an abrupt transition to a high response rate, and a second transition to a lower rate that prevailed or slightly increased up to reinforcement, Under the conjunctive fixed-interval tandem schedule, pauses were extended, response rates were lower, and the initial high rate of responding was generally absent, The above effects depended upon the size of the fixed interval of the tandem schedule, The distinct pattern of responding generated by conjunctive fixed-interval fixed-ratio schedules depends upon occasional reinforcement of fixed-ratio responding and not merely on the addition of a minimum number of required responses.     

Within-session changes in responding during delayed matching-to-sample and discrimination procedures

Two experiments examined within-session changes in responding during discrimination procedures. In Experiment 1, rate of responding changed significantly within sessions during symbolic delayed matching-to-sample tasks when the delay between the stimulus and the choice period was short (1–5 sec), but not when it was long (8–12 sec). The percentage of responses that were correct did not change within sessions. In Experiment 2, response rates increased and then decreased within sessions during both S1 and S2 when successive discrimination procedures provided high, but not low, rates of reinforcement. Discrimination ratios sometimes increased within sessions. These results question two potential definitions of attention as explanations for within-session changes in response rates. They are more compatible with explanations based on concepts such as arousal, satiation, habituation, and interfering responses.     

Rate of reinforcement and session duration as determinants of within-session patterns of responding

Rats pressed levers for Noyes pellets or keys for sweetened condensed milk reinforcers delivered by multiple schedules. Session length and baseline rates of reinforcement were varied in two experiments. Rates of responding increased during the early part of the session and then decreased for both responses and reinforcers, as well as for all subjects and values of the independent variables. Changes in response rates across the session sometimes exceeded 500%. Respoiise rates peaked approximately 20 min after the beginning of the session, regardless of session duration, when subjects responded on a multiple variable interval 1-min variable interval 1-min schedule. The function was flatter for longer sessions than it was for shorter sessions. The function was flatter, more symmetrical, and peaked later for lower rates of reinforcement than for higher rates of reinforcement. The function appeared early in training, and further experience moved and reduced its peak. Variables related to reinforcement exerted more control over some aspects of this function than did variables related to responding. These within-session patterns of responding may have fundamental implications for experimental design and theorizing.     

Influence of schizotypy on responding and contingency awareness on free-operant schedules of reinforcement

Schedules of reinforcement typically produce reliable patterns of behaviour, and one factor that can cause deviations from these normally reliable patterns is schizotypy. Low scorers on the unusual experiences subscale of the Oxford-Liverpool Inventory of Feelings and Experiences performed as expected on a yoked random-ratio (RR), random-interval (RI) schedule of reinforcement, with significantly higher rates of responding on the RR schedule than in the RI schedule. However, high scorers in UE showed no such differences between response rates between the RR and RI schedules. In addition, contingency awareness scores were high, and did not differ in low UE scorers for both types of schedule, whilst awareness scores differed significantly between the schedules in high UE scorers, with more awareness of the RR schedule than the RI one. These results suggest that, as well as being unable to differentiate between the RR and RI schedules in terms of response rates, high UE scorers are also unable to verbally describe the RI schedule parameters.     

Habituation may contribute to within-session decreases in responding under high-rate schedules of reinforcement

Two experiments tested the hypothesis that habituation contributes to within-session decreases in responding. In Experiment 1, rats’ leverpressing was reinforced under a fixed ratio (FR) 4 schedule throughout the baseline sessions. During the dishabituation sessions, the first 21 min and the last 21 min were FR 4; dishabituating events occurred during the middle 3 min. The dishabituating events altered the manner of reinforcer delivery in four different ways. Response rates increased after all dishabituating events. In Experiment 2, rats responded on several FR and variable ratio (VR) schedules. The ratio requirement varied from 3 to 15. Within-session decreases in responding were steeper during FR schedules than during VR schedules. In addition, response rates were well described as linear functions of cumulative number of food pellets eaten within sessions. These results support the habituation hypothesis but do not rule out the possibility that other satiety variables might contribute simultaneously.     

Navigating privacy tensions when responding to online aggression at postsecondary institutions

Postsecondary institutions have a legal responsibility to ensure that students have access to a safe learning environment. While institutions adopt policies and hire administrators to protect students from harm, many are underprepared to support students when these harmful incidents happen online. This is of increased concern now that online aggression is pervasive across universities worldwide. While faculty, administrators and students agree that online aggression is a significant issue and that institutions ought to provide prevention and response services, there is concern that these efforts might violate privacy norms. We used the theory of privacy as contextual integrity (CI) to explore the tensions that postsecondary students and staff perceive regarding student privacy when responding to incidents of online aggression. To do so, we conducted focus groups with undergraduate students and student affairs administrators from a Historically Black College and University (HBCU) in the Mid-Atlantic USA. Our analysis surfaced three considerations that inform students' and staff's decision to report an incident of online aggression: their closeness to the person making the post, their perception of the online post content as a real threat and their knowledge of an authority figure who could help resolve the situation. We used CI theory to explain how these considerations can inform institutional policy, practice and future research.

Practitioner notes

What is already known about this topic

• Online aggression is a pervasive issue at postsecondary institutions worldwide that can contribute to psychological, academic and developmental issues.
• Postsecondary students and staff are unsure of how to respond to incidents of online aggression.
• There is a gap in policies and procedures for responding to online aggression at postsecondary institutions.

What this paper adds

• A novel use of Nissenbaum's (2010) theory of contextual integrity to understand students' and staff's perceptions of privacy.
• Students' and staff's decisions to intervene or report an online aggression incident are determined by their relationship to the perpetrator, the severity of the social media post and their knowledge of who to tell on campus.
• Students and staff are reluctant to inform the police out of fear of violence against the perpetrator.

Implications for practice and/or policy

• Raise awareness about responding to online aggression incidents.
• Implement online bystander intervention training programs to increase awareness and self-efficacy to intervene in unclear situations.
• Develop clear policies regarding online aggression, as well as a trustworthy procedure for how to respond.

     

Partial reinforcement delayed extinction effect after regularly alternating reward training

When extinction is delayed very long, the superior resistance to extinction of the random schedule group relative to the alternating schedule group disappears (partial reinforcement delayed extinction effect, PRDE). Two experiments assessed the effects of reinforcement/nonreinforcement on Trial 1 on the PRDE. Following extended partial reinforcement acquisition training in a runway, rats received extinction training after a short (1-day) or long (23-day) retention interval. The schedules used in Experiment 1 were: a single-alternation (SA) schedule beginning each day with a rewarded (r) trial, for Group r-SA; an SA schedule beginning with a nonrewarded (n) trial, for Group n-SA; and a random (Rd) schedule, for Group Rd. The schedules and group names used in Experiment 2 were r-SA, Rd, and r-Rd. The results were that (1) rats given r-SA schedules yielded considerable resistance under delayed extinction, (2) those given Rd and r-Rd schedules showed a decline in resistance to extinction over a long retention interval, (3) those given the n-SA schedule showed relatively low resistance at both retention intervals, although retention deficit was not greater than in the case of the Rd schedule, and thus, (4) the PRDE was found in both experiments, although only weakly in Experiment 1. The results indicated that a regularly alternating reward pattern was a more important determinant than was type of reward on Trial 1 for the PRDE. The PRDE due to differential retention deficits among schedules is discussed on the basis of dual-process associative sequential mechanisms and cognitive rule-encoding mechanisms.     

Sum of responding as a function of sum of reinforcement on two-key concurrent schedules

Four pigeons pecked for food reinforcers delivered by several two-key concurrent schedules. The sum of the rates of reinforcement provided by the component schedules varied from 25 to 300 reinforcers/h. The ratio of the rates of reinforcement remained constant at 1:4. The sum of the rates of responding generated by the component schedules increased with increases in the sum of the rates of reinforcement which the components provided. The increase in response rate was predicted by equations proposed by Catania (1963) and by Herrnstein (1970). But the data conformed more closely to Herrnstein’s equation.     

The generality of within-session patterns of responding: Rate of reinforcement and session length

Rats and pigeons responded for food delivered according to multiple schedules. The session length varied from 10 to 120 min, and the programmed rate of reinforcement varied from 15 to 240 reinforcers per hour. Response rates usually changed systematically within experimental sessions. For both rats and pigeons, responding reached a peak after an approximately constant amount of time since the beginning of the session, regardless of session length. When rats, but not pigeons, served as subjects, the peak rates of responding occurred later in the session and the within-session changes were smaller for lower than for higher rates of reinforcement. The similarities between the results for rats and for pigeons when session length varied suggest that at least one of the factors that produces the within-session changes in responding is shared by the present species, responses, and reinforcers. The differences in results when rate of reinforcement varied are more difficult to interpret.     

Double standards: when an undergraduate dissertation becomes the object of two different assessment approaches

Within a transnational educational programme, students residing in the Czech Republic obtain baccalaureate degrees from an accredited American college. The college has a distinctive approach towards learning, co‐creation of knowledge and the use of mentors. Part of the degree assessment is an undergraduate dissertation, which serves as a capstone experience. The Czech partner instituted a policy whereby students could obtain a second local degree by, among other things, using the same dissertation. This study examines the situation confronting mentors from the American college. It considers assessment as an integral component of a constellation of educational assumptions and pedagogic values: a paradigm. It analyses the competing/conflicting, paradigms involved and discusses ways in which educational practice was reconsidered and changed to allow a single work product to be authentically and meaningfully assessed under both approaches.     

Extinction responding following partial reinforcement: The effects of number of rewarded trials and magnitude of reward

Rats were trained on a daily partial reward schedule of small magnitude of reward (S), nonreward (N), and large magnitude of reward (L), which began with SN or SSNN for all animals. The remainder of the daily schedule was defined by the factorial combination of the number of rewards (1 vs. 3) and the magnitude of reward (S vs. L). Following 18 days of such training, 20 trials of extinction were administered. It was found that increasing the number of rewarded trials in a partial reinforcement schedule decreased resistance to extinction. Furthermore, increased number of large-magnitude rewards reduced resistance to extinction to a greater extent than increased number of small-magnitude rewards.     

双筋矩形截面梁受压钢筋不屈服时的截面设计探讨与教学

双筋矩形截面梁正截面受弯承载力计算是混凝土结构课程的重要教学内容。当学生进行双筋矩形截面梁正截面受弯承载力计算时,受压钢筋达不到屈服强度是设计中会遇到的情况。如何在此情况下进行结构设计,是学生学习这部分内容的一个难题。本文通过算例分析,将受压钢筋达不到屈服强度时如何进行截面计算的两种方法进行对比,给出了各个方法的控制条件,在此基础上,对如何进行这部分教学内容进行探讨,旨在提高教学质量并锻炼学生思考、解决工程问题的能力。