上下文熟悉效应对元记忆监测和记忆的影响

在认知任务中,伴随编码和检索的外围信息被称为上下文,其本身并不是编码或检索的目标。如果学习时的上下文在其后进行提取时重复出现,不管是否对应之前的学习项目,都会增加个体再认正确的概率。这种由于上下文增强项目熟悉感而促进记忆效果的现象就称为上下文熟悉效应。本研究通过两个实验探究上下文熟悉效应对元记忆监测及记忆的影响机制。其中,元记忆监测是以学习判断和信心判断为指标。记忆成绩则是以再认正确率为指标。研究结果显示:第一,上下文熟悉效应影响元记忆监测:学习判断等级上,恢复条件显著高于新条件,且不受任务难度影响; 信心判断等级上,简单任务时恢复条件与新条件无显著差异,困难任务时恢复条件显著高于新条件。第二,上下文熟悉效应影响记忆成绩:再认成绩上,简单任务时新条件显著高于恢复条件; 困难任务时恢复条件显著高于新条件。研究得出结论:上下文熟悉效应对元记忆监测和记忆都有显著影响,任务难度起调节作用。     

Gender differences in memory for objects and their locations: a study on automatic versus controlled encoding and retrieval contexts

Object-location memory is the only spatial task where female subjects have been shown to outperform males. This result is not consistent across all studies, and may be due to the combination of the multi-component structure of object location memory with the conditions under which different studies were done. Possible gender differences in object location memory and its component object identity memory were assessed in the present study. In order to disentangle these two components, an object location memory task (in which objects had to be relocated in daily environments), and a separate object identity recognition task were carried out. This study also focused on the conditions under which object locations were encoded and retrieved. Only half of the participants were aware of the fact that object locations had to be retrieved later on. Moreover, by applying the 'process dissociation procedure' to the object location memory assessments and the 'remember-know' paradigm to the object identity measure, the amount of explicit (conscious) and implicit (unconscious) retrieval was estimated for each component. In general, females performed better than males on the object location memory task. However, when controlled for object identity memory, females no longer outperformed males, whereas they did not obtain a higher general object identity memory score, nor did they have more explicit or implicit recollection of the object identities. These complicated effects might stem from a difference between males and females, in the way locations or associations between objects and locations are retrieved. In general, participants had more explicit (conscious) recollection than implicit (unconscious) recollection. No effect of encoding context was found, nor any interaction effect of gender, encoding and retrieval context.     

Immediate recall influences the effects of pre-encoding stress on emotional episodic long-term memory consolidation in healthy young men

The stress-associated activation of the hypothalamus-pituitary-adrenal axis influences memory. Several studies have supported the notion that post-learning stress enhances memory consolidation, while pre-retrieval stress impairs retrieval. Findings regarding the effects of pre-encoding stress, in contrast, have been rather inconsistent. In the current two studies, the impact of an immediate retrieval task on these effects was explored. In the first study, 24 healthy young male participants were exposed to a psychosocial laboratory stressor (Trier Social Stress Test) or a control condition before viewing positive, negative, and neutral photographs, which were accompanied by a brief narrative. Immediate as well as delayed (24?h later) free recall was assessed. Stress was expected to enhance emotional long-term memory without affecting immediate recall performance. Stress caused a significant increase in salivary cortisol concentrations but had no significant effects on immediate or delayed retrieval performance, even though a trend toward poorer memory of the stress group was apparent. Based on these findings, the second experiment tested the hypothesis that the beneficial effects of stress on emotional long-term memory performance might be abolished by an immediate recall test. In the second study (n?=?32), the same design was used, except for the omission of the immediate retrieval test. This time stressed participants recalled significantly more negative photographs compared to the control group. The present study indicates that an immediate retrieval attempt of material studied after stress exposure can prevent or even reverse the beneficial effects of pre-encoding stress on emotional long-term memory consolidation.     

Tests enhance retention and transfer of spatial learning

Many studies have reported that tests are beneficial for learning (e.g., Roediger & Karpicke, 2006a). However, the majority of studies on the testing effect have been limited to a combination of relatively simple verbal tasks and final tests that assessed memory for the same material that had originally been tested. The present study explored whether testing is beneficial for complex spatial memory and whether these benefits hold for both retention and transfer. After encoding a three-dimensional layout of objects presented in a virtual environment, participants completed a judgment-of-relative-direction (JRD) task in which they imagined standing at one object, facing a second object, and pointed to a third object from the imagined perspective. Some participants completed this task by relying on memory for the previously encoded layout (i.e., the test conditions), whereas for others the location of the third object was identified ahead of time, so that retrieval was not required (i.e., the study condition). On a final test assessing their JRD performance, the participants who learned through test outperformed those who learned through study. This was true even when corrective feedback was not provided on the initial JRD task and when the final test assessed memory from vantage points that had never been practiced during the initial JRD.     

Context reinstatement and memory for intrinsic versus extrinsic context: The role of item generation at encoding or retrieval

According to many theoretical accounts, reinstating study context at the time of test creates optimal circumstances for item retrieval. The role of context reinstatement was tested in reference to context memory in several experiments. On the encoding phase, participants were presented with words printed in two different font colors (intrinsic context) or two different sides of the computer screen (extrinsic context). At test, the context was reinstated or changed and participants were asked to recognize words and recollect their study context. Moreover, a read‐generate manipulation was introduced at encoding and retrieval, which was intended to influence the relative salience of item and context information. The results showed that context reinstatement had no effect on memory for extrinsic context but affected memory for intrinsic context when the item was generated at encoding and read at test. These results supported the hypothesis that context information is reconstructed at retrieval only when context was poorly encoded at study.     

Brief,pre-retrieval stress differentially influences long-term memory depending on sex and corticosteroid response

Previous work has indicated that stress generally impairs memory retrieval. However, little research has addressed discrepancies that exist in this line of work and the factors that could explain why stress can exert differential effects on retrieval processes. Therefore, we examined the influence of brief, pre-retrieval stress that was administered immediately before testing on long-term memory in males and females. Participants learned a list of 42 words varying in emotional valence and arousal. Following the learning phase, participants were given an immediate free recall test. Twenty-four hours later, participants submerged their non-dominant hand in a bath of ice cold (Stress) or warm (No Stress) water for 3 min. Immediately following this manipulation, participants’ memory for the word list was assessed via free recall and recognition tests. We observed no group differences on short-term memory. However, male participants who showed a robust cortisol response to the stress exhibited enhanced long-term recognition memory, while male participants who demonstrated a blunted cortisol response to the stress exhibited impaired long-term recall and recognition memory. These findings suggest that the effects of brief, pre-retrieval stress on long-term memory are sex-specific and mediated by corticosteroid mechanisms.     

Odour‐based context reinstatement effects with indirect measures of memory: The curious case of rosemary

Previous studies examining environmental context‐dependent memory (ECDM) effects using indirect measures of memory have produced inconsistent findings. We report three experiments that examined ECDM in an indirect memory paradigm (word‐fragment completion) using ambient odours as environmental contexts. Expt 1 manipulated the odour present at learning and testing (rosemary or lemon) to produce reinstated‐context or switched‐context conditions. Reinstating rosemary led to a striking ECDM effect, indicating that indirect memory testing can be sensitive to ECDM manipulations. Odour ratings also indicated that rosemary induced a more unpleasant mood in participants than lemon. Expt 2 assessed the influence on indirect retrieval of odour‐based mood induction as well as odour distinctiveness, and indicated that rosemary's capacity to promote ECDM effects appears to arise from an additive combination of its unpleasantness‐inducing properties and its distinctiveness. Expt 3 partially supported these proposals. Overall, our findings indicate that some odours are capable of producing ECDM effects using indirect testing procedures. Moreover, it appears that it is the inherent proprieties of odours on dimensions such as unpleasantness and distinctiveness that mediate the emergence of ECDM effects, thereby explaining the particular potency of rosemary's mnemonic influence when it is reinstated.     

Stress modulates the use of spatial versus stimulus-response learning strategies in humans

Animal studies provided evidence that stress modulates multiple memory systems, favoring caudate nucleus-based "habit" memory over hippocampus-based "cognitive" memory. However, effects of stress on learning strategy and memory consolidation were not differentiated. We specifically address the effects of psychosocial stress on the applied learning strategy in humans. We designed a spatial learning task that allowed differentiating spatial from stimulus-response learning strategies during acquisition. In 13 subsequent trials, participants (88 male and female students) had to locate a "win" card out of four placed at a fixed location in a 3D model of a room. Relocating one cue in the last trial allowed inferring the applied learning strategy. Half of them participated first in the "Trier Social Stress Test." Salivary cortisol and heart rate measurements were taken. Stressed participants used a stimulus-response strategy significantly more often than controls. Subsequent verbal report revealed that spatial learners had a more complete awareness of response options than stimulus-response learners. Importantly, learning performance was not affected by stress. Taken together, stress prior to learning facilitated simple stimulus-response learning strategies in humans-at the expense of a more cognitive learning strategy. Depending on the context, we consider this as an adaptive response.     

Study-time effect on free recall within and out of context

Three experiments examined whether or not the study-time effect, which was observed when recall took place in the original environmental context, was eliminated or markedly diminished when recall took place in a different environmental context. A total of 456 undergraduates studied a list of words for either a short or long study time before receiving an oral free recall test under conditions where the original environmental context was or was not reinstated. Environmental context was manipulated by the combination of physical features of the room, subsidiary task, and experimenter. Inter-item association was minimised in Experiment 1, and free recall performance was measured independently of inter-item association in Experiments 2 and 3. The results were: (1) a greater study-time effect was found when the original context was reinstated than when it was not reinstated, and (2) the study-time effect disappeared when neither contextual nor inter-item associative cues were available. The results suggest that environmental context is involved in the production of the study-time effect.     

Does scene context always facilitate retrieval of visual object representations?

An object-to-scene binding hypothesis maintains that visual object representations are stored as part of a larger scene representation or scene context, and that scene context facilitates retrieval of object representations (see, e.g., Hollingworth, Journal of Experimental Psychology: Learning, Memory and Cognition, 32, 58-69, 2006). Support for this hypothesis comes from data using an intentional memory task. In the present study, we examined whether scene context always facilitates retrieval of visual object representations. In two experiments, we investigated whether the scene context facilitates retrieval of object representations, using a new paradigm in which a memory task is appended to a repeated-flicker change detection task. Results indicated that in normal scene viewing, in which many simultaneous objects appear, scene context facilitation of the retrieval of object representations-henceforth termed object-to-scene binding-occurred only when the observer was required to retain much information for a task (i.e., an intentional memory task).     

Study-time effect on free recall within and out of context

Three experiments examined whether or not the study-time effect, which was observed when recall took place in the original environmental context, was eliminated or markedly diminished when recall took place in a different environmental context. A total of 456 undergraduates studied a list of words for either a short or long study time before receiving an oral free recall test under conditions where the original environmental context was or was not reinstated. Environmental context was manipulated by the combination of physical features of the room, subsidiary task, and experimenter. Inter-item association was minimised in Experiment 1, and free recall performance was measured independently of inter-item association in Experiments 2 and 3. The results were: (1) a greater study-time effect was found when the original context was reinstated than when it was not reinstated, and (2) the study-time effect disappeared when neither contextual nor inter-item associative cues were available. The results suggest that environmental context is involved in the production of the study-time effect.     

Timing matters: Temporal dynamics of stress effects on memory retrieval

Stress may impair memory retrieval. This retrieval impairment has been attributed to the action of the stress hormone cortisol, which is released with a delay of several minutes after a stressful encounter. Hence, most studies tested memory retrieval 20–30 min after stress, when the stress-induced cortisol increase peaks. In the present experiment, we investigated whether retrieval impairments can also be found at later intervals after stress. To this end, participants learned a list of words on day 1. Twenty-four hours later, they were first exposed to a stressor or a nonstressful control manipulation and completed a recognition test for the words either immediately thereafter, 25 min later, or 90 min later. Our findings showed that stress did not impair memory retrieval when memory was tested immediately after the stressor, before cortisol levels were elevated. However, retrieval performance was impaired 25 min after stress, when cortisol levels peaked, as well as 90 min after the stressor, when cortisol levels had already returned to baseline. The retrieval impairment 90 min after stress appeared to be even stronger than the one after 25 min. These findings suggest that the detrimental effects of stress on retrieval performance may last longer than is usually assumed.     

Auditory feedback and memory for music performance: Sound evidence for an encoding effect

Research on the effects of context and task on learning and memory has included approaches that emphasize processes during learning (e.g., Craik & Tulving, 1975) and approaches that emphasize a match of conditions during learning with conditions during a later test of memory (e.g., Morris, Bransford, & Franks, 1977; Proteau, 1992; Tulving & Thomson, 1973). We investigated the effects of auditory context on learning and retrieval in three experiments on memorized music performance (a form of serial recall). Auditory feedback (presence or absence) was manipulated while pianists learned musical pieces from notation and when they later played the pieces from memory. Auditory feedback during learning significantly improved later recall. However, auditory feedback at test did not significantly affect recall, nor was there an interaction between conditions at learning and test. Auditory feedback in music performance appears to be a contextual factor that affects learning but is relatively independent of retrieval conditions.     

Influences of environmental context on the recency effect in free recall

A total of 208 undergraduate participants incidentally encoded a list of seven pairs of familiar words in two experiments. A 30-sec calculation task was imposed before and after each pair was encoded. Participants received a free recall test 24 h (Experiment 1) or 10 min (Experiment 2) after the encoding session, under conditions in which the original environmental context was reinstated or not. The environmental context was manipulated in terms of the combination of the physical features of the room, the subsidiary task conducted, the experimenter (Experiment 1), or background music (Experiment 2). A recency effect appeared when the original environmental context was reinstated in both experiments, even though the IPI/RI ratio was too small to produce recency effects according to the ratio rule. The results imply that the environmental context should be taken into account for the recency effect.     

The effects of cortisol increase on long-term memory retrieval during and after acute psychosocial stress

In this study the effects of stress-induced cortisol increases on long-term memory retrieval during and after acute psychosocial stress were examined. Seventy male students were exposed to either a psychosocial stress task or to a non-stressful control task. During and after this task, retrieval was tested for idiosyncratic emotionally negative and neutral word pair associations that were learned 1 day or 5 weeks earlier. Within the stress condition, retrieval of negative words, 5 weeks after learning, was impaired both during and after the stress task compared to the control group. Further, during the stress task, when sympathetic activity was enhanced, impaired retrieval of both neutral and emotional words was significantly related to enhanced cortisol response. In contrast, after the stress task, when cortisol levels were still increased but sympathetic activity was low again, no association was found between cortisol increase and retrieval of either neutral or emotional material. These results are in line with the previous animal research showing that when arousal is high, cortisol increase can impair memory retrieval.     

Timing is essential for rapid effects of corticosterone on synaptic potentiation in the mouse hippocampus

Stress facilitates memory formation, but only when the stressor is closely linked to the learning context. These effects are, at least in part, mediated by corticosteroid hormones. Here we demonstrate that corticosterone rapidly facilitates synaptic potentiation in the mouse hippocampal CA1 area when high levels of the hormone and high-frequency stimulation coincide in time, but not when corticosterone is given either before or after repetitive stimulation. This effect could not be blocked by antagonists of the mineralocorticoid receptor and glucocorticoid receptor (spironolactone and RU 38486, respectively). These data provide a biological substrate for the important behavioral observation that stress and corticosteroid hormones can facilitate learning and memory processes.     

Effects of acute stress and GluN2B-containing NMDA receptor antagonism on object and object–place recognition memory

The mechanisms underlying the complex effects of acute stress on memory are incompletely understood. Previous work suggests that the activation of N-methyl-d-aspartate (NMDA) receptors specifically containing GluN2B subunits may underlie the disruptions in spatial memory retrieval caused by acute stress (Wong et al., 2007 PNAS 104:11471). The present experiments were designed to assess whether a similar mechanism is involved in recognition memory. Recognition memory retrieval was assessed in Sprague–Dawley rats using an object recognition test and an object–place recognition test, both of which rely on patterns of spontaneous exploration. Exposure to acute stress for 30 min immediately before the test phase of either test disrupted memory retrieval. Administration of the GluN2B-selective antagonist Ro25-6981 (6 mg/kg; i.p.) enhanced memory in the object recognition test regardless of whether animals were exposed to acute stress. In the object–place test, Ro25-6981 had no effect on memory retrieval in the absence of stress but promoted memory following acute stress. These data highlight the specific contributions made by GluN2B-containing NMDA receptors to recognition memory for different types of stimuli.     

任务类型对面孔联合效应和特征效应的调节

采用特征-联合范式的研究发现, 面孔再认阶段可记录到明显的联合效应和特征效应; 然而, 与再认同属情景记忆的另一任务(来源提取)条件的相应效应尚未报道, 背景信息一致性对联合面孔和特征面孔提取的调节作用以及面孔不同特征对特征效应的影响也未考察。为澄清上述问题, 本文采用特征-联合范式, 并以位置为背景展开研究。实验含一个学习任务和两个测验任务(再认和来源提取)。结果显示, 再认和来源提取阶段均记录到显著的联合效应和特征效应, 且两类效应均在来源提取阶段更强; 任务类型与位置背景一致性交互影响提取绩效; 面孔外部特征和内部特征对特征效应的影响相似。表明联合效应和特征效应具有显著的任务类型敏感性, 这些效应是联合面孔和特征面孔的熟悉性较强且对源面孔的回忆加工相对较弱的结果, 且这两类面孔的提取为背景一致性所调节; 任务类型对两类效应的调节与双重加工理论模型相吻合。     

Walking through doorways causes forgetting: Further explorations

Previous research using virtual environments has revealed a location-updating effect in which there is a decline in memory when people move from one location to another. Here we assess whether this effect reflects the influence of the experienced context, in terms of the degree of immersion of a person in an environment, as suggested by some work in spatial cognition, or by a shift in context. In Experiment 1, the degree of immersion was reduced by using smaller displays. In comparison, in Experiment 2 an actual, rather than a virtual, environment was used, to maximize immersion. Location-updating effects were observed under both of these conditions. In Experiment 3, the original encoding context was reinstated by having a person return to the original room in which objects were first encoded. However, inconsistent with an encoding specificity account, memory did not improve by reinstating this context. Finally, we did a further analysis of the results of this and previous experiments to assess the differential influence of foregrounding and retrieval interference. Overall, these data are interpreted in terms of the event horizon model of event cognition and memory.     

Walking through doorways causes forgetting: Further explorations

Previous research using virtual environments has revealed a location-updating effect in which there is a decline in memory when people move from one location to another. Here we assess whether this effect reflects the influence of the experienced context, in terms of the degree of immersion of a person in an environment, as suggested by some work in spatial cognition, or by a shift in context. In Experiment 1, the degree of immersion was reduced by using smaller displays. In comparison, in Experiment 2 an actual, rather than a virtual, environment was used, to maximize immersion. Location-updating effects were observed under both of these conditions. In Experiment 3, the original encoding context was reinstated by having a person return to the original room in which objects were first encoded. However, inconsistent with an encoding specificity account, memory did not improve by reinstating this context. Finally, we did a further analysis of the results of this and previous experiments to assess the differential influence of foregrounding and retrieval interference. Overall, these data are interpreted in terms of the event horizon model of event cognition and memory.