Alleviating forgetting of active shock-avoidance by apparently unrelated food presentations

A series of four experiments investigated why forgetting of an active shock-avoidance response was reduced when an apparently unrelated appetitive experience occurred both prior to avoidance training and during the retention interval between training and testing. Experiments 1 and 2 demonstrated the reliability of the phenomenon and found that a sufficient condition for the effect was the presentation of food from a pellet dispenser (not an operant response per se). Experiment 3 demonstrated that the effect was not the result of enhanced activity. Experiment 4 showed that forgetting was still reduced when the appetitive experience occurred only prior to active avoidance or only during the retention interval. The results are discussed in regard to the reinstatement of the reinforcer representation.     

Combined effect of context change and retention interval on interference in causality judgments

Four experiments studied the effects of context change and retention interval on retroactive interference in human causal learning. Experiment 1 found evidence of retroactive interference. Experiment 2 found that either a 48-hr retention interval or a change in the context after the interference treatment decreased retroactive interference. An interaction between context change and retention interval effects was also found, eclipsing the context change effect after the 48-hr retention interval. Experiments 3 and 4 found additivity between context change and retention interval effects when participants were remained of the difference between physical contexts before the test, independently of whether the context change involved a return to the original acquisition context. These results add to the evidence suggesting that spontaneous forgetting is caused by a change in either the physical or the temporal contexts where information is acquired.     

The Influence of Retention Interval on the US Preexposure Effect: Changes in Contextual Blocking over Time

A number of studies manipulating the length of the interval between conditioning and testing indicate spontaneous recovery from overshadowing, suggesting that certain instances of overshadowing represent a deficit in memory retrieval rather than a failure of animals to form an association between the overshadowed stimulus and the US. The present series of experiments examined the influence of lengthening the retention interval on blocking, another stimulus selection phenomenon that is typically interpreted as an acquisition deficit. The results indicated that when subjects were tested shortly (3 days) after training conditioning to a taste blocked subsequent conditioning to an odor conditioned in compound with that taste (Experiment 1), whereas prior conditioning to an odor did not block subsequent conditioning to a taste conditioned in compound with that odor (Experiment 2). This pattern of results was essentially unchanged when testing occurred at a longer (21-day) retention interval. However, there was evidence of a US preexposure effect in Experiment 2 when subjects in the US ONLY control condition were tested at the 3-day retention interval, but not when testing occurred 21 days after conditioning. Experiments 3 and 4 examined whether this loss of the US preexposure effect over time might actually represent a change in the degree of contextual blocking as the retention interval is lengthened. Exposure to the conditioning context either during the interval between Phase 1 and Phase 2 of conditioning (Experiment 3) or prior to Phase 1 of conditioning (Experiment 4) alleviated this US preexposure effect suggesting that the loss of the US preexposure effect as the retention interval is lengthened observed in Experiment 2 is due to changes in the degree of blocking by contextual stimuli over time. The results are discussed in terms of differential susceptibility of forgetting of two functional roles played by a contextual stimuli in the current situation-context as a CS and context as a retrieval cue for other CS-US associations.     

Remembering the news: Modeling retention data from a study with 14,000 participants

A retention study is presented in which participants answered questions about news events, with a retention interval that varied within participants between 1 day and 2 years. The study involved more than 14,000 participants and around 500,000 data points. The data were analyzed separately for participants who answered questions in Dutch or in English, providing an opportunity for replication. We fitted models of varying complexity to the data in order to test several hypotheses concerning retention. Evidence for an asymptote in retention was found in only one data set, and participants with greater media exposure displayed a higher degree of learning but no difference in forgetting. Thus, forgetting was independent of initial learning. Older adults were found to have forgetting curves similar to those of younger adults.     

Ontogeny of early event memory: I. Forgetting and retrieval by 2- and 3-month-olds

In 2 experiments, 2-month-olds, trained in the mobile conjugate reinforcement paradigm for two daily sessions, showed retrieval deficits relative to 3-month-olds. In Experiment 1, tests of simple forgetting administered to 2-month-olds after retention intervals of 1, 3, 6, and 9 days (a period over which 3-month-olds remember the contingency) indicated that their forgetting was complete after delays greater than 1 day. In Experiment 2, reactivation treatments administered to 2- and 3-month-olds alleviated forgetting after a retention interval of 28, but not 35, days in the 3-month-old group only. Previously, alleviated forgetting by a reactivation treatment had been demonstrated in 2-month-olds after a delay of 18 days. In both of the present experiments, performance of the two age groups did not differ during the immediate retention test at the end of training. These results suggest that neither the age of the infant nor the age of the memory determines memory retrieval after long delays; instead, it appears to be determined by the length of time that a memory has been inaccessible (i.e., forgotten). We propose that factors which delay simple forgetting will correspondingly increase the length of the interval over which a retrieval cue can still be effective in a reactivation paradigm, irrespective of the age of the infant or the age of the memory.     

Time-dependent forgetting in visual short-term memory

ABSTRACT

Whether visual short-term memory can be lost over an unfilled delay, in line with time-dependent forgetting, is controversial and prior work has yielded mixed results. The present study explored time-dependent forgetting in visual short-term memory in relation to other factors. In three experiments, participants compared single target and probe objects over a 2 s or 10 s retention interval. The objects across trials were either similar or dissimilar (Experiment 1) and had to be remembered in the presence of an additional distractor (Experiment 2) or under conditions where the amount of time separating trials varied (Experiment 3). In all experiments, the retention interval manipulation made the biggest contribution to performance, with accuracy decreasing as the retention interval was lengthened from 2 s to 10 s. These results pose problems for interference and temporal distinctiveness models of memory but are compatible with temporal forgetting mechanisms such as decay.     

Long-term memory in pigeons: I. The role of discrimination problem difficulty assessed by reacquisition measures II. The role of stimulus modality assessed by generalization slope

Pigeons learned either an easy or a difficult line angle discrimination (Experiment 1) or wavelength discrimination (Experiment 2), and then they were given a reacquisition test of retention after delays of 1 min, 1 day, or 1 week. Both percentage of responses to the S+ in the initial 10-trial block and number of blocks to criterion showed a progressive memory loss which was greater for the difficult problem. These results extend recent findings by using a free operant rather than a discrete trial task and by varying problem difficulty by altering the dimensional separation between training stimuli. In Experiment 3, pigeons were given variable interval training with either a wavelength or a line angle stimulus, and then they were tested for generalization in extinction after delays of 1 min, 1 day, and 1 week. With both dimensions, the relative gradients became progressively flatter with increasing delay intervals. This replicates earlier findings and extends them to the line angle dimension. The evidence of substantial forgetting in the first 24 h in all three experiments suggests that operant free-response procedures are more sensitive to forgetting effects than are discrete trial tasks.     

Need probability affects retention: A direct demonstration

Recent memory theory has emphasized the concept ofneed probability—that is, the probability that a given piece of learned information will be tested at some point in the future. It has been proposed that, in real-world situations, need probability declines over time and that the memory-loss rate is calibrated to match the progressive reduction in need probability (J. R. Anderson & Schooler, 1991). The present experiments were designed to examine the influence of the slope of the need-probability curve on the slope of the retention curve. On each of several trials, subjects memorized a list of digits, then retained the digits in memory for 1, 2, 4, 8, or 16 sec. Some trials ended with a recall test; other trials ended with the message, “no test.” In Experiment 1, the likelihood of encountering a memory test (i.e., the need probability) was made to either increase or decrease as the retention interval increased; in Experiment 2, need probability either was flat (invariant across retention intervals) or decreased as the retention interval increased. The results indicated that the shape of the need-probability curve influenced the slope of the retention curve (Experiment 1) and that the effect became larger as the experimental session progressed (Experiment 2). The findings support the notion that memory adapts to need probabilities and that the rate of forgetting is influenced by the slope of the need-probability curve. In addition, all of the forgetting curves approximated a power function, suggesting that need probability influences the slope but not the form of forgetting.     

延时间隔和线索类型对遗忘学习判断的影响*

主要探讨不同延时间隔和线索类型对遗忘元认知判断的影响。采用传统的学习判断任务,让被试学习40对无意义配对词,并告知随后进行测试,当呈现第一个词时,被试能够回忆与之配对的后一个词。让被试预测当延迟不同时间（5分钟、1天和1周）进行测试时,他们能够记住（学习判断）或者遗忘（遗忘判断）后一词的可能性。最后,要求被试回忆所有词对。结果发现延时间隔对学习判断和遗忘判断有相似的影响;学习判断的等级和相对准确性均高于遗忘判断,说明人们对记住和遗忘的线索很敏感;相比于学习判断,人们监测自己遗忘能力的信心不足。研究结果表明人们能够利用延时间隔和线索类型来预测未来的测验成绩,对遗忘的监测能力低于对记住的监测。     

Degree of learning,interpolated tests,and rate of forgetting

The purpose of the two experiments reported here was to observe the effects of degree of learning, interpolated tests, and retention interval, primarily on the rate of forgetting of a list of words, and secondarily on hypermnesia for those words. In the first experiment, all the subjects had one study trial on a list of 20 common words, followed by two tests of recall. Half of the subjects had further study and test trials until they had learned the words to a criterion of three correct consecutive recalls. Two days later, half of the subjects under each learning condition returned for four retention tests, and 16 days later, all the subjects returned for four tests. Experiment 2 was similar, except that all the subjects had at least three study trials followed by four recall tests on Day 1, intermediate tests were given 2 or 7 days later, and they all had final tests 14 days later. The results showed that rate of forgetting was attenuated by an additional intermediate set of tests but not by criterion learning. Hypermnesia was generally found over the tests that were given after a retention interval of 2 or more days. The best predictor of the amount of hypermnesia over a set of tests was the difference between overall cumulative recall and net recall on the first test of the set.     

Differential effectiveness of various prior-cuing treatments in the reactivation and maintenance of memory

In 3 experiments, changes were examined in the characteristics of newly acquired and reinstated memories over time in preweanling rats. Experiment 1 indicated that forgetting after conditioning was monotonic, with the upper limit of retention at approximately 120 min posttraining. In Experiment 2, Ss were exposed to various elements of the training episode before testing, after either a 3- or a 24-hr retention interval. The results indicated that the prior-cuing treatments were differentially effective and that the effectiveness of a reactivation treatment may change as a function of the retention interval. Experiment 3 indicated that Ss expressed a conditioned aversion at much longer intervals following reactivation treatments than after initial conditioning. Furthermore the susceptibility of the reinstated memory to forgetting was dependent on the prior-cuing treatment used. The results suggest a change in the memorial representation of the conditioning episode over time.     

Very rapid forgetting: Reply to Muter

We reply to the commentary in which Muter (1995) disputes the findings and arguments of Cunningham, Healy, Till, Fendrich, and Dimitry (1993) concerning the rate of forgetting from primary memory. Although Muter (1980) had reported very rapid forgetting when secondary memory processes were minimized, Cunningham et al. found that the rate of forgetting from primary memory was no more rapid when secondary memory processes were minimal than it was when secondary memory processes were substantial. We locate the discrepancy between the two studies specifically at recall performance on the 0-sec retention interval, and we argue that the very rapid forgetting found by Muter (1980) can be attributed in large part to the fact that although subjects in his experiments did not expect to recall the letters after a filled retention interval, at the time of encoding and after an unfilled delay they did have a high overall expectancy to recall the letters.     

Divided attention facilitates intentional forgetting: evidence from item-method directed forgetting

This study examined the effects of post-cue interval and cognitive load on item-method directed forgetting. The results of Experiment 1 (free recall test) and Experiment 2 (cued recall test) showed that forget item retention increased as the post-cue interval increased. Moreover, increasing the cognitive load of participants by asking them to perform a secondary counting task did not impair, but rather facilitated, the intentional forgetting of the studied item under long post-cue interval conditions. These results and analyses of recall gains from the additional use of the independent cue suggest that the improved recall of forget items caused by an increase in the post-cue interval came from an automatic process, and that after receiving the forget cue, participants did not engage a suppression operation that was resource-demanded. The current findings suggest that forgetting is more effective when participants perform a secondary task after receiving the forget cue.     

Is there really very rapid forgetting from primary memory? The role of expectancy and item importance in short-term recall

In two experiments, subjects recalled one of two letter segments following a digit-filled retention interval. In Experiment 1, recall expectancy was manipulated by using precues that correctly informed or misinformed subjects concerning which letter segment wou;d be tested for recall. In Experiment 2, item importance was varied by precuing one segment as important but requiring that the uncued segment be recalled first. Recall performance was very low under conditions of low expectancy and low segment importance, but the slopes of the retention-functions did not demonstrate more rapid forgetting than under standard -conditions. The previous observations of very rapid forgetting from primary memory may be a function of an elevated initial recall level in the earlier studies. Our retention functions were compared with predictions of the Estes perturbation model. The findings suggested that when secondary memory processes were reduced, forgetting order information from primary memory occurred at the same rate as that estimated on the basis of previous studies using the standard distractor task.     

Acquisition and retention of a letter-detection skill

In two experiments, we examined the acquisition and retention of a letter-detection skill with a consistent-mapping procedure. In Experiment 1, subjects were trained from 0 to 4 sessions at detecting the letter H in displays containing random letters, and retesting occurred after a 1-month delay. Performance improved and in some cases became more automatic, and the performance level was maintained over the retention interval. When tested with a prose passage, the high error rate on the word THE was eliminated after training and after the retention interval, regardless of the amount of training. In Experiment 2, two subjects were given 12 sessions of training followed by a retention test 6 months later. For 1 subject there was also a retention test 15 months after acquisition. Performance improved dramatically with training, and substantial but not complete automaticity was achieved. Performance on the retention tests was close to the final acquisition level. The surprising lack of forgetting in this study was contrasted with the substantial forgetting typically found in studies of verbal learning.     

Forgetting in spatial memories acquired in a virtual environment

This study examined forgetting in spatial memories acquired in a virtual environment. In the two experiments, participants learned the locations of eight objects. In Experiment 1, the objects were presented as photographs in either a laboratory or in an equivalent virtual environment. Irrespective of learning condition, accuracy of recall of the locations was found to deteriorate after a retention interval of approximately 1 week. In Experiment 2, following virtual learning, three groups of participants performed a series of non‐spatial tasks of low, intermediate or high difficulty. The tasks were presented in a retention interval of 2 hours. A comparison of recall accuracy before and after presentation of the interference tasks indicated that that the groups were not differentially affected by the difficulty of the retroactive interference tasks. However, the groups differed in their subjective assessment of the mental workload involved in the tasks. The results are discussed with reference to a prominent theory of forgetting. Copyright © 2007 John Wiley & Sons, Ltd.     

The effects of interference and retention delay on temporal generalization performance

This study investigated the effect of forgetting of the standard duration on temporal discrimination in a generalization task. In two experiments, participants were given a temporal generalization task with or without a retention delay between the learning of the standard duration and the testing of the comparison durations. During this delay, they either performed or did not perform an interference task. Results failed to reveal any effect of 15-min and 24-h retention delays on time judgments (Experiment 1). However, when an interference task was performed during the 15-min delay (Experiment 2), there was a subjective shortening effect, indicating that the standard duration was judged shorter with than without an interference task. These findings suggest that when an interference task occurs immediately after initial temporal encoding, it affects the process of consolidation in reference memory.     

Time and order effects on causal learning

Five experiments were conducted to explore trial order and retention interval effects upon causal predictive judgments. Experiment 1 found that participants show a strong effect of trial order when a stimulus was sequentially paired with two different outcomes compared to a condition where both outcomes were presented intermixed. Experiment 2 found that a 48-h retention interval eliminates the trial order effect, so that participants gave a global judgment about the relationship between the stimulus and the two outcomes equivalent to the one given by participants that received the two phases intermixed. This result was replicated in Experiment 3 in a situation in which the probability of the outcome in the presence of the cue was changed from .5 for both outcomes (Experiments 1, 2, 4, and 5) to .75 and .25 for outcomes 1 and 2, respectively. Experiment 4 found that retention intervals ranging from 45 min to 48 h eliminated the trial order effect similarly. Experiment 5 found that a 10-min retention interval replicated the effect of time upon sequential training found in precedent experiments, regardless of whether participants remained within the laboratory during the retention interval or spent it outside. The combined results of this experimental series suggest that retention intervals reduce retroactive interference in causal learning by allowing participants to use all the information presented across phases, rather than differentially increasing or decreasing retrieval of information about each of them.     

Retrieval-induced forgetting and mental imagery

In the present article, we present four experiments in which we examined whether mental imagery can initiate retrieval-induced forgetting. Participants were presented with word pairs (Experiments 1, 2, and 3) or narratives (Experiment 4) and then engaged in selective mental imagery about half of the details from half of the categories. The results indicated that mental imagery can produce the same pattern of impairment as retrieval practice (Experiment 1) and postevent questioning (Experiment 4). Additionally, mental imagery-invoked, retrievalinduced forgetting was found for category cued recall (Experiments 1, 3, and 4) and cued recall (Experiment 2); it was found to dissipate across a 24-h delay, but only when there was no pre-delay test (Experiment 3). Such retrieval-induced forgetting was also found for imagining from the first-person and third-person perspectives (Experiment 4). From these findings, we suggest that the underlying retrieval processes behind mental imagery can initiate retrieval-induced forgetting. The findings are discussed in terms of inhibitory processes.     

负性情绪材料的定向遗忘及心理机制

采用项目法定向遗忘的研究范式,在两个实验中分别采用文字和图片材料考察了情绪性记忆定向遗忘的效果及其心理机制。实验中采用了中性和负性两种实验材料,设置了两种记忆指令出现时间（2秒后提示和5秒后提示）,相对于中性材料,被试更不容易忘记负性材料。记忆指令出现的时间只影响图片材料的定向遗忘。研究表明负性情绪会干扰定向遗忘,选择性编码理论可以解释情绪性文字材料的定向遗忘,而抑制理论更能解释情绪性图片材料的定向遗忘效应。