Recovery of conditioned fear by a single postextinction shock: Effect of similarity of shock contexts and of time following extinction

Subjects in six experimental groups (n = 16 each) received one-trial passive avoidance (PA) training in which shock was delivered upon movement from a white wooden floor compartment to a black grid compartment. Then fear was extinguished (30 min) in the black compartment. After either 24 or 168 h, all the groups were treated in a room distinctively different from the training room. At each interval, one group received a shock in an apparatus similar to the conditioning box, another received a shock in a dissimilar apparatus, and another was placed in a neutral box. A PA test trial in the training apparatus indicated reinstatement of extinguished fear in all the groups given a postextinction shock except the 24-h dissimilar group. Control groups revealed that the extinction treatment was effective and that spontaneous recovery was not evident. The results were explained in terms of classical conditioning, stimulus generalization, and the broadening (flattening) of stimulus generalization gradients with time.     

Slow extinction of conditioned responding following exposure to two bouts of massed shock

Extinction of rats’ conditioned defensive freezing responses in a context associated with two bouts of massed shock (3 sec) separated by a long unreinforced interbout interval was slower than that in a context associated with distributed shock (60 sec). Resistance to extinction following two bouts of massed shock depended on the rats’ remaining undisturbed in the conditioning context during the long unreinforced interbout interval. Slow extinction of freezing was attributed to either the summation of temporal conditioning at the early and late session times or the formation of an association between the early and late bouts of shock. Importantly, the effects of the two bouts of massed shock could not be explained by what is known about the reinforcing effectiveness of massed shock.     

Reinstatement-induced recovery of a taste-LiCl association following extinction

Water-deprived rats were given a single exposure to saccharin and LiCl, either paired or unpaired. Half the subjects then received three saccharin-only exposures (extinction) in the training enclosure, followed by a single LiCl-only presentation (unconditioned stimulus reinstatement) 8 days after conditioning. The remaining subjects received six saccharin-only exposures, followed by LiCl reinstatement 13 days after conditioning. In both cases LiCl reinstatement occurred outside the training/test context. Appreciable recovery from extinction was observed after the partial loss of taste aversion obtained with three extinction sessions and the 8-day conditioning-reinstatement interval, but not after the asymptotic loss of taste aversion obtained with six extinction sessions and the 13-day conditioning-reinstatement interval. Conditioned taste aversions appear to be similar to more traditional associations with respect to both extinction and reinstatement-induced recovery from extinction. The results are discussed with reference to the event-memory, contextual-conditioning, and facilitated-retrieval hypotheses of postextinction reinstatement effects.     

The effects of electroconvulsive shock and sound-induced seizure on the retention of a passive avoidance response

SJL/J mice underwent one-trial passive avoidance training, followed immediately by either electroconvulsive shock (ES) or sound-induced seizure. Testing of the passive avoidance response occurred 72 h later. It was found that an ES-induced seizure, but not a sound-induced seizure, caused amnesia for the passive avoidance learning.     

Acquisition,extinction, and reacquisition of a conditional discrimination to avoid shock by goldfish

Goldfish, trained in the shuttlebox to avoid shock, were tested for the acquisition and extinction of a color-matching or a color-oddity conditional discrimination choice response, and then tested for reacquisition. Extinction affected the accuracy of the choice response but not the number of trials with response (response strength). Half of all groups were extinguished with changed signal colors, and half had the same signal colors experienced in acquisition. All groups had the same signal colors in reacquisition that they had experienced in acquisition. Changed-signal oddity groups decremented slightly faster than same-signal oddity groups, providing some support for a generalization decrement interpretation, but same- and changed-signal matching groups did not differ. All groups extinguished on the choice response by the end of extinction. All matching groups, and all oddity groups, regardless of their respective signal colors in extinction, reacquired at the same rate, and faster than in acquisition. These results imply conceptual generalization of extinction effects. Matching-trained groups were found to be slightly superior to oddity-trained groups in both acquisition and reacquisition. Comparisons of these results to positive reinforcement conditional discrimination extinction work, including some procedural suggestions, are made.     

Retention of a running response following appetitive acquisition,extinction, and discrimination

In Experiment 1, hungry rats received 30 rewarded runway trials and then either extinction trials followed by retention tests or just retention tests. Different groups were tested after retention intervals of 1 min, 1, 3, or 24 h, or 30 days. Retention of extinction training was a nonmonotonic, cubic function of time for the early portion of the response chain, with good retention at 1 min and 3 h and little retention at 1 h, 24 h, or 30 days. In the latter portions of the response chain, retention of extinction decreased monotonically with time. Retention following reward-only training varied little in time, though slight losses occurred after 30 days. Experiments 2–3 differed from Experiment 1 in imposing nonchoice discrimination training (reward vs. nonreward) instead of extinction following 30 rewarded trials. After different time intervals (.017, .75, 1.25, 3, and 24 h in Experiment 1; and .017, 1, and 3 h in Experiment 2), retention tests revealed poorest discrimination at intermediate intervals in the initial portion of the response chain, i.e., a Kamin effect appeared. The deficit seemed the result of a loss of response suppression to the cue that signaled nonreward. In latter segments of the response chain, a Kamin effect tended not to appear. Implications for a number of observations and theoretical views are noted.     

Effects of a backward conditioning procedure following acquisition on extinction of conditioned suppression

A one-trial-a-day procedure was used to investigate the effects of US-CS pairings on extinction of conditioned suppression of licking by rats. Following acquisition trials, response suppression was immediately eliminated when US preceded CS, but it reappeared during subsequent CS-alone presentations. Ss that received backward pairings reached a significant level of extinction one trial before Ss that received conventional extinction trials.     

An evaluation of Fresh Start as a catch-up intervention: a trial conducted by teachers

This paper describes a randomised controlled trial conducted with 10 secondary schools in England to evaluate the impact and feasibility of Fresh Start as an intervention to help new entrants with low prior literacy. Fresh Start is a synthetic phonics programme for small groups of pupils, here implemented three times per week over 22 weeks. The intervention was led by the schools themselves and assessed in cooperation with the independent evaluators. A group of 433 year 7 pupils (first year of secondary school) were identified by schools as having literacy attainment below “secure” KS2 level 4, and individually randomised to a treatment group or a waiting-list control. The pupils were assessed via GL’s New Group Reading Test. Missing data at pre- and post-test amounted to 3% of the total. The overall “effect” size in terms of gain scores from pre- to post-test was +0.24, and this was repeated in a sub-group analysis involving only FSM-eligible pupils. However, there was some imbalance between the two groups at the outset, and this must lead to a slight caution about the findings, and to some doubts about whether one or more schools unwittingly subverted the randomisation. Other than this, the aggregated trial shows that schools can conduct evaluations of their own interventions with firm guidance from experts, and under favourable conditions such as individual randomisation and lack of extended involvement by developers with a conflict of interests.     

An extinction cue reduces spontaneous recovery of a conditioned taste aversion

The effect of an auditory cue presented during extinction on spontaneous recovery of a conditioned taste aversion was investigated in three experiments. Experiment 1 demonstrated that the presence of the cue during extinction did not influence saccharin consumption during that phase, and that an aversion to saccharin in the absence of the cue was stronger at 18 days than at 1 day after extinction, representing spontaneous recovery rather than a renewal effect. Experiment 2 showed that a cue presented during extinction and testing reduced spontaneous recovery. Experiment 3 replicated that effect and showed that it depended on the cue’s correlation with extinction and not on an unconditioned effect; cues that had been presented during or prior to conditioning did not reduce spontaneous recovery when presented during testing. The cue’s potential to reduce spontaneous recovery through conditioned inhibition or configural cue learning is discussed, as is the possibility that the cue retrieves a saccharin extinction memory in a manner consistent with Bouton’s (1993) account of spontaneous recovery.     

Comparison of an SMS text messaging and phone reminder to improve attendance at a health promotion center： A randomized controlled trial

Objective To compare the efficacy of a short messaging service (SMS) text messaging and phone reminder to improve attendance rates at a health promotion center. Methods A total of 1 859 participants who had scheduled appointments in the health promotion center of our hospital from April 2007 to May 2007 were enrolled in the study and randomly assigned into 3 groups control (no reminder) group, SMS text messaging reminder group and telephone reminder group. Attendance rates and costs of interventions were collected. Results A total of 1848 participants were eligible for analysis. Attendance rates of control,SMS and telephone groups were 80.5%, 87.5% and 88.3%, respectively. The attendance rates were significantly higher in SMS and telephone groups than that in the control group, with odds ratio 1.698, 95% confidence interval 1.224 to 2.316, P=0.001 in the SMS group, and odds ratio 1.829, 95% confidence interval 1.333 to 2.509, P＜0.001 in the telephone group. However, there was no difference between the SMS group and the telephone group (P=0.670). The cost effectiveness analysis showed that the cost per attendance for the SMS group (0.31 Yuan) was significantly lower than that for the telephone group (0.48 Yuan). ConclusionSMS and telephone are effective reminders for improving attendance rate at a health promotion center. SMS reminder may be more cost-effective compared with the telephone reminder.     

Background stimuli as a reminder after spontaneous forgetting: Role of duration of cuing and cuing-test interval

With a relatively complex maze, reliable forgetting is seen clearly when the training-to-test interval is 25 days. This forgetting is demonstrated by longer time to run the maze and by an increase in the number of errors and retracings from the last training trials to the first test trial. In this case, forgetting is a lapse, not a loss, since performance attains the last training trial level at a subsequent test. Furthermore, a reminder—a 90-sec exposure to background stimuli in the experimental room just prior to the test trial—that does not in itself contain sufficient information to facilitate performance in naive animals, significantly improves maze performance in rats that have “forgotten,” even on the first test trial. Two additional experiments were aimed at assessing the role of time and duration of pretest cuing. In the first experiment, the animals were presented the reminder (90 sec in duration) at different times before the test trial. The results show that this reminder significantly alleviates forgetting only when presented just prior to the test, and is less effective when given 1 or 24 h before the test. In the second experiment, contextual cues, which were presented just prior to testing in all experimental groups, varied in duration. The results showed that (1) animals given the reminder treatment for only 10 sec perform at the same level as controls; (2) cuing for 30 sec and especially for 90 sec alleviates forgetting; and (3) a longer exposure to background stimuli (300 sec) leads to intermediate levels of performance, probably due to a partial extinction of the cue value of these stimuli.     

Alcohol as a cue for extinction: State dependency produced by conditioned inhibition

A conditioned-emotional-response (CER) paradigm was used in two experiments to evaluate the effects of alcohol on extinction. In both experiments, rats received tone-shock pairings without alcohol and then received extinction trials either with or without alcohol (injections of saline, .75 or 1.5 g/kg ethanol). The high dose of alcohol suppressed baseline barpressing for food reward, but there was only weak evidence (Experiment 2) that it enhanced responding during the tone early in extinction. In both experiments, extinction of CER under the high alcohol dose was found to be state dependent, that is, post-extinction tests after saline injection showed a reinstatement of suppression to the tone. Experiment 2 indicated that this effect could be attributed to alcohol’s becoming a conditioned inhibitory stimulus as a result of its association with extinction. This supports the general suggestion that situational stimuli normally become inhibitory during the course of simple extinction and may have implications for the role that state-dependent learning plays in drug dependence.     

Savings in classical conditioning in the rabbit as a function of extended extinction

In the present experiments, savings phenomena following a limited amount of initial acquisition and extended extinction were examined. Experiments 1 and 2 compared rates of reacquisition following brief acquisition and various amounts of extinction in conditioning of the rabbit’s nictitating membrane and heart rate response, respectively. Experiment 3 compared rates of acquisition to a novel stimulus (e.g., light) following brief acquisition and various amounts of extinction to another stimulus (e.g., tone). In addition, in Experiment 3 recovery of responding to the extinguished stimulus during acquisition to the novel, cross-modal stimulus was examined. Experiments 1, 2, and 3 demonstrated that with a limited number of acquisition trials (1) there was a graded reduction in the rate of reacquisition as a function of the number of extinction trials in both conditioning preparations, (2) there was a graded reduction in the rate of cross-modal acquisition as a function of the number of extinction trials, but (3), in Experiment 3, recovery of responding to the extinguished stimulus during cross-modal training of the novel stimulus appeared uniformly robust even in the face of extended extinction.     

Resistance to extinction as a function of percentage of reward: A reinforcement-level interpretation

Three experiments investigated the effects of percentage of reinforcement on the resistance to extinction of an instrumental running response. In Experiment 1, with N-length held constant, 47% reinforcement during acquisition generated greater resistance to extinction (R_n) than did 77%. In Experiment 2, this result was replicated with both functional N-length and number of N-R transitions held constant. In Experiment 3, R_n was shown to be a function of both N-length and percentage of reinforcement. The results of all three experiments were discussed in terms of Capaldi’s reinforcement level theory and possible alternative explanations.     

Reversal from blocking in humans as a result of posttraining extinction of the blocking stimulus

In a blocking procedure, conditioned stimulus (CS) A is paired with the unconditioned stimulus (US) in Phase 1, and a compound of CSs A and X is then paired with the US in Phase 2. The usual result of such a treatment is that X elicits less conditioned responding than if the A-US pairings of Phase 1 had not occurred. Obtaining blocking with human participants has proven difficult, especially if a behavioral task is used or if the control group experiences reinforcement of a CS different from the blocking CS in Phase 1. In the present series, in which human participants and a behavioral measure of learning were used, we provide evidence of blocking, using the above described control condition. Most important, we demonstrate that extinction of the blocking CS (A) following blocking treatment reverses the blocking deficit (i.e., increases responding to X). These results are at odds with traditional associative theories of learning, but they support current associative theories that predict that posttraining manipulations of the competing stimulus can result in a reversal of stimulus competition phenomena.     

Comparison of retention and extinction of a visual discrimination as an index of forgetting in mice

The retention and extinction of a visual discrimination was examined in BALB/c mice. The mice were trained to perform a go/no-go discrimination task in parallel runways. Initial training resulted in an intermediate level of performance. Testing consisted of an additional session using either retention (Experiment 1) or extinction (Experiment 2) at one of five time intervals between 1 and 30 days. It was found in Experiment 1 that forgetting progressively increased over intervals of between 14 and 30 days. In Experiment 2, extinction testing induced more impairment of performance, so that forgetting occurred earlier relative to retention testing in Experiment 1. However, in both experiments, the measure of performance by a discrimination ratio revealed the same amount of forgetting when the training-test interval was 30 days. These results define the forgetting curve for such a discrimination by mice. They are discussed in terms of possible factors involved in forgetting.     

Effects of proximal unconditioned stimulus preexposure on ingestional aversions learned as a result of taste presentation following drug treatment

Taste aversions were conditioned by exposing subjects to a 1.0% saccharin solution 30 min after an injection of lithium chloride. The aversion learning was disrupted if subjects had also received an additional lithium injection some time earlier (Experiments 1–3). This interference effect of US preexposure was a decreasing function of the preexposure interval, beyond the optimal interval (105 min) for observing the phenomenon (Experiment 1), and was directly related to the dose of the preexposure injection (Experiment 2). No interference with conditioning occurred at short (e.g., 30-min) preexposure intervals (Experiment 1), probably because under these circumstances the preexposure injection itself conditioned a strong aversion (Experiment 4). At moderate (105-min) but not at short (30-min) preexposure intervals, the interference with aversions learned as a result of taste exposure following drug injection was comparable to the interference with learning in a more conventional forward conditioning procedure (Experiments 3 and 4). These findings are similar to previously documented effects of proximal CS- and US-preexposure and are consistent with recent stimulus rehearsal and opponent-process theories.     

Reductions in resistance to extinction and spontaneous recovery as a function of changes in transportational and contextual stimuli

Thirty rats received 10 sessions of baseline training in which leverpressing was reinforced according to a variable-interval (VI) 60-sec schedule. Twenty-four of the subjects were then assigned to one of four groups that received five sessions of extinction, with groups being differentiated in a 2 by 2 factorial design on the basis of: (1) changes in stimuli accompanying transportation of subjects from home cages to the laboratory and placement in the apparatus, and/or (2) changes in contextual stimuli within the apparatus. During the sixth session of extinction, the transportational and contextual stimuli previously associated with baseline training were reinstated. The remaining six rats experienced changes in both transportational and contextual stimuli but were maintained on the VI 60-sec schedule of reinforcement. Changes in either transportational or contextual stimuli reduced resistance to extinction and spontaneous recovery, and substantial increments in responding occurred upon reinstatement of the transportational and contextual stimuli associated with baseline training. Evidence for summation of the two sources of stimulus change was obtained. Changes in transportational and contextual stimuli produced only a brief disruption in responding when reinforcement of leverpressing was continued.     

课程热的反思

从存在的事实来看，一股“课程热”正在中华大地掀起。课程热的兴起是时代的呼唤，历史的必然。新一轮基础教育课程改革为课程热提供了社会生存空间，中国教学论的衰落使得课程热成为可能，国外课程的兴盛则使课程热成为必然，课程本身的多义化则给课程热提供了学术空间，课程热的兴起是符合我国教育现实的，但也应该看到，课程热也会导致一系列不良后果。“大课程论”背景下的教学(论)生存空间太小，在热了课程的同时，不应冷了教学。     

Persistence early and late in extinction as a function of number of continuous reinforcements preceding partial reinforcement training

In two experiments rats were given straight-alley training in the following sequence: continuous reward (CR), partial reward (PR), extinction (EXT). Independent groups differed only in the amount of CR training. In both experiments,. early-EXT performance was directly related to amount of CR training and late-EXT performance was inversely related to amount of CR training. These data were related to a possible specific s_F intensity hypothesis, an extension of frustration theory.