Sequences of reward magnitude and runway performance

Three groups of rats underwent 24 days of training and 12 days of extinction (three trials per day) in a runway under conditions of increasing (I), decreasing (D), and random (R) sequences of reward magnitudes (0, 45, and 500 mg). The I Ss ran faster over the daily trials, the D Ss slowed down, and the R Ss ran at approximately equal speeds on each trial. The patterned running observed in training persisted in extinction, with the R Ss running fastest and the I Ss next. The results were discussed in terms of Capaldi’s sequential theory and Amsel’s frustration theory.     

The adjustment of goldfish to reduction in magnitude of reward in massed trials

For a group of goldfish trained in a runway under conditions of highly massed practice, reduction in magnitude of reward produced a gradual decline in performance to the level of a small-reward control group but no suggestion of negative successive contrast. These results are consistent with the suggestion that reward plays a somewhat different role in the learning of fish and rats. They also serve to extend the range of conditions under which the stimulus aftereffects of reward come to control the instrumental behavior of fish.     

Effects of reward amount and reward omission on short-term retention

A series of four experiments studied the retention of the response made on a just-preceding trial as a function of the presence, and amount, of food reward given on that trial. Rats were trained to alternate arm choices in a T-maze, and then were tested for alternation with 5- or 30-sec delays between runs. When the subjects had received prior experience with the reward amounts used in testing, larger rewards led to better retention than did small or no rewards. However, when reward omission first occurred during the test phase, it produced more alternation on the following trial than did reward presence. The results suggest that both reward amount and surprisingness determine short-term retention of responses paired with the rewards.     

The effects of differing type and magnitude of reward on the contrafreeloading phenomenon in rats

This investigation was made to determine the effects of the magnitude of reward on contrafreeloading, using food or water as reward. Two quantities were selected for each level of reward quality—a 20-mg-pellet food reward, a 45-mg-pellet food reward, a .01-cc water reward, and a .1-cc water reward. Seven days of training were followed by three test sessions. There was a significantly higher percent of contrafreeloding demonstrated with food as reward than with water and higher number of barpresses with small reward than with large. It was argued that a more appropriate measure should include reference to performance during training. In this approach, contrafreeloading with food and water were virtually the same.     

Effects of partial vs consistent reward in noncontingent pairings of stimuli with reward: A noncontingently produced positive contrast effect

Rats received pairings of two stimuli with reward noncontingently in the Skinner box. During noncontingent pairings, the bar was immobilized. For Group CC 100% of the presentations of both stimuli were rewarded (S₁ ±, S₂ ±), for Group PP 50% of the presentations of each stimulus were rewarded (S₁, ±, S₂±), and for Group PC one stimulus was followed by reward on 50% of its presentations, while the second stimulus was followed by reward on 100% of its presentations (S₁ ±, S₂ ±). A fourth group received the stimuli and reward nonpaired. In a subsequent rewarded test phase, the response facilitating effects of the stimuli were evaluated. In the test phase all groups that received reward paired with S₁, and S₂ performed better in the presence of S₁ and S₂ than the group for which the stimuli were not paired with reward. For groups that received the stimuli paired with reward, a difference due to schedule of reward occurred when schedule of reward was varied within Ss (Group PC), but not when varied between Ss (Group PP vs Group CC). The specific form of this finding was that Group PC’s performance in the presence of S₂ ± was more vigorous than its performance in the presence of S₁ ± and was more vigorous than the performance of Groups PP and CC to S₂. Group PC’s performance to S₁ ± did not differ from that of Groups PP and CC to S₁.     

Primary frustration differences following brief partial-reinforcement acquisition under varying magnitudes of reward

In Experiment I, rats which had received six partially reinforced runway acquisition trials, with a reward magnitude of 60 sec access to wet mash on rewarded trials, showed less persistent responding over highly massed extinction trials than subjects which had received the same acquisition schedule but reward magnitudes of either 1 or 10 45-mg pellets. In Experiment II, rats which had received six partially reinforced placements into one compartment of a two-compartment box, with 60 sec access to mash on rewarded placements, jumped a hurdle faster to escape nonreward than subjects which had received the same reward schedule but 10 45-mg pellets on rewarded trials. The data supported a primary frustration analysis for reward-magnitude manipulations within brief partial-reinforcement schedules.     

Positive and negative successive contrast effects following multiple shifts in reward magnitude under high drive and immediate reinforcement

Multiple shifts in reward amount were given to rats in a straight runway. Both positive and negative contrast effects were observed. A positive contrast effect was observed, however, only if the shift from small to large reward occurred while the subject was evidencing a negative contrast effect. Implications for current conceptions of reinforcement contrast are discussed.     

Confusions between memories for performed and imagined actions: a developmental comparison

Children are often assumed to be more confused than adults are about the origin of self-generated memories (e.g., what they did or thought). The present experiments showed evidence in support of this assumption but only under some circumstances. In Experiment 1, 6- and 9-year-olds were as good as adults in distinguishing what they did from what they saw someone else do. However, children had particular trouble distinguishing what they did from what they imagined doing. Confusion between performed and imagined actions was evident across a range of actions. Clustering data also showed that information about origin is part of the memory for an event; all subjects recalled actions according to who performed what action (Experiment 1). Further, the presence of person categories as a basis for organization reduced clustering based on action class more for children than for adults (Experiment 1 vs. 2). Collectively, these findings indicate that children become sensitive to some distinctions in memories sooner than they do to others.     

Contextual influences on the interaction between conflicting memories in the rat

Contextual events redundant to the learning, in sequence, of passive and active avoidance were of one type for the former task and of another for the latter. During later testing, these contextual events were found to determine which of these acquired, conflicting dispositions would be manifested in behavior. Mutual interference in retention otherwise seen under similar circumstances seemed subordinate to the influence of the three types of contextual stimuli tested—drug (pentobarbital), compound (the experimental room in which conditioning took place), and a relatively unitary stimulus (a constantly sounding buzzer). The discussion considered the defining characteristics of a “contextual stimulus” and the mechanisms through which contextual events control the manifestation of learned behaviors and alleviation of interference in retention.     

Effects of sequences of sucrose reward magnitudes with short ITIs in rats

Two experiments assessed the role of aftereffect learning in rats rewarded with sucrose solutions. In Experiment 1, rats were trained in a single straight runway for two trials on each of 18 days, each trial terminating with either large (20% scurose) or small (3% sucrose) reward. The ITI was 3–5 min. The sequence of daily rewards for each of four groups was small-small (SS), small-large, (SL), large-small (LS), or large-large (LL). Response patterning and a simultaneous negative contrast effect were observed in LS and SL relative to the consistently rewarded controls. During 10 massed extinction trials, resistance to extinction was greatest for Group SL, followed in order by Groups SS, LL, and LS. Experiment 2 examined single alternation of large and small rewards administered for 10 trials on each of 31 days with an ITI of 60 sec. Reward for one group was 20% or 3% sucrose while another received 1 or 10 45-mg Noyes pellets. Appropriate patterning developed only in the food-pellet rewarded animals. The overall results suggest that sucrose rewards may produce high-amplitude and long-duration aftereffects which interfere with learning in designs employing several massed daily trials, but which may facilitate learning—relative to food-pellet rewards—with longer intertrial intervals and fewer daily trials.     

Effects of external reward on paired associate learning in a group setting

A study was conducted to determine the effects of external reward in the form of prizes on the performance of college students in a paired-associate learning task in which subjects were asked to recall a real word associated with a nonsense word. Two groups, one of whom was offered a prize, received the S-R pairs with no aid (no mediators); and two groups, one of whom was offered a prize, received the S-R pairs with a sentence-pictorial aid mediator. Results of two-way ANOVA supported the hypothesis that the No Prize/Aided and No Prize/NonAided groups would exhibit performance of higher quality than the groups offered prizes. The dependent measure was number of correct responses over six trials.     

Effects of signaled reward in instrumental conditioning: Enhanced learning on DRL and DRH schedules of reinforcement

The effects of signaled reward were examined using DRL and DRH schedules of reinforcement. In each case, one group of rats received a brief cue between the reinforced response and the reward, and a second group received brief cues at random times. With the DRL schedule (Experiment 1), signaled reward decreased response rate, increased response efficiency (number of responses per reinforcer), and increased resistence to satiation relative to the control group. With the DRH schedule (Experiment 2), signaled reward increased response rate, efficiency, and resistance to satiation. These results refute an overshadowing explanation of the effects of signaled reward and suggest that food-correlated cues enhance learning of the reinforcement contingencies.     

Effects of varied and partial reward on discrete-trial patterning of rats

Rats were trained in the discrete-trial operant apparatus with single alternation of large reward and small reward or large reward and nonreward. followed by either transfer or extinction. The results showed that both groups acquired appropriate response patterning, that patterning is conditioned, and that the stimuli which control patterning are derived from reward conditions on immediately preceding trials. A modification of the sequential hypothesis of instrumental learning was proposed to account for the results.     

听力理解中的歧义辨识

歧义是语言本身及语言交际中普遍存在的现象。歧义所表现出的不确定性,常常成为干涉外语学习者听力理解的羁绊。了解歧义的特征和一般规律,学会辩识歧义的基本方法,有助于学习者听力理解中的语义推断。     

Transfer between nonreward and delay of reward following minimal acquisition training

Four groups of rats were given six acquisition trials under continuous reward, continuous delay of reward, partial reward, or partial delay of reward, following which all Ss received continuous delay. It was found that the partial reward and the partial delay of reward groups were significantly more persistent during the shift phase than the continuous reward group. No differences were found over trials between either the two partial groups or between each one and the continuous delay group.     

“古史辨”在学术与思潮间的两难之境

以顾颉刚为首的"古史辨"派对现代史学的建立曾经起到举足轻重的作用.本文通过对古史辨派学术理念与学术范围的清理,分析古史辨派在学术与思潮两个方面表现出来的品质以及它们相互之间的关系.     

Effects of Three Variables on the Performance of Middle- and Lower-Class Children in Discriminating Similar Letters in Words

Abstract

Ninety 4-year-olds were given a matching-to-standard pretest to determine the degree to which they confused similar letters. All Ss except the control group were trained on matching trigrams in sessions that varied in three ways: (1) the letter distinguishing the two choices differed by one or many features; (2) the standard was present or absent when S tried to match it; and (3) the S did or did not have the overlay procedure, the opportunity to place his choice over the standard. The initial test was readministered to all Ss. The overlay procedure significantly improved posttest scores. Components of the error totals were differentially influenced by the variables. No overall differences in the effect of the variables were found by social class.     

Instrumental escape learning in the rat at 24-hour intertriai interval: Effects of magnitude and schedule of reinforcement

Three experiments investigated the effects of magnitude and schedule of reinforcement and level of training in instrumental escape learning at a 24-h intertriai interval. In Experiment I, two magnitudes of reinforcement were factorially combined with two schedules of reinforcement (CRF and PRF). Under PRF, large reward produced greater resistance to extinction than did small reward, while the reverse was true under CRF. In Experiment II, two levels of acquisition training were factorially combined with three schedules of reinforcement (CRF, single-alternation, and nonalternated PRF). Patterned running was observed late in acquisition in the single-alternation extended-training condition. Resistance to extinction was greater for the nonalternated PRF condition than for the single-alternation condition following extended acquisition, and the reverse was true following limited acquisition. Experiment III confirmed the extinction findings of Experiment II. The results of all three experiments supported an analysis of escape learning at spaced trials in terms of Capaldi’s (1967) sequential theory.     

E-learning commodity or community: Disciplinary differences between online courses

Differences in curriculum and teaching styles across disciplines in higher education courses are also evident in online courses. This study used two widely available sources of data, CMS tool usage logs and course evaluations, to analyze differences between online courses in disciplinary quadrants (hard-pure, hard-applied, soft-pure, soft-applied) at a large metropolitan university, over five years (2002 and 2007). For 2007, results revealed significant differences in tool usage between disciplines, particularly for assessment tools. Hard-pure courses used Tests and Pool tools more often than did soft-pure courses. The Document tool was used most extensively in applied courses. Data from course evaluations, for spring 2007 online courses, suggested that applied disciplines had a shorter learner–instructor transactional distance than did pure disciplines. Results suggest that over five years, e-learning in pure disciplines has become more commoditized, while e-learning in applied disciplines has become more diversified and more oriented to community practice.