Effects of emotional arousal on multiple memory systems: evidence from declarative and procedural learning

Extensive evidence documents emotional modulation of hippocampus-dependent declarative memory in humans. However, little is known about the emotional modulation of striatum-dependent procedural memory. To address how emotional arousal influences declarative and procedural memory, the current study utilized (1) a picture recognition and (2) a weather prediction (WP) task (a probabilistic classification learning task), which have been shown to rely on hippocampal- and striatum-based memory systems, respectively. Observers viewed arousing or neutral pictures after (Experiment 1) or during (Experiment 2) WP training trials. A 1-wk delayed picture recognition memory test revealed enhanced declarative memory for arousing compared with neutral pictures. Arousal during encoding impaired initial WP acquisition but did not influence retention when tested after a 1-wk delay. Data from a subsequent 3-mo delayed test, however, suggested that arousal during acquisition may enhance remote WP retention. These results suggest a potential dissociation between how readily emotional arousal influences hippocampus-dependent and striatum-dependent memory systems in humans.     

Type of learning task impacts performance and strategy selection in decision making

In order to be adaptive, cognition requires knowledge about the statistical structure of the environment. We show that decision performance and the selection between cue-based and exemplar-based inference mechanisms can depend critically on how this knowledge is acquired. Two types of learning tasks are distinguished: learning by comparison, by which the decision maker learns which of two objects has a higher criterion value, and direct criterion learning, by which the decision maker learns an object's criterion value directly. In three experiments, participants were trained either with learning by comparison or with direct criterion learning and subsequently tested with paired-comparison, classification, and estimation tasks. Experiments 1 and 2 showed that although providing less information, learning by comparison led to better generalization (at test), both when generalizing to new objects and when the task format at test differed from the task format during training. Moreover, learning by comparison enabled participants to provide rather accurate continuous estimates. Computational modeling suggests that the advantage of learning by comparison is due to differences in strategy selection: whereas direct criterion learning fosters the reliance on exemplar processing, learning by comparison fosters cue-based mechanisms. The pattern in decision performance reversed when the task environment was changed from a linear (Experiments 1 and 2) to a nonlinear structure (Experiment 3), where direct criterion learning led to better decisions. Our results demonstrate the critical impact of learning conditions for the subsequent selection of decision strategies and highlight the key role of comparison processes in cognition.     

Effects of glucose on scopolamine-induced learning deficits in rats performing the Morris water maze task

In order to assess the effects of glucose on drug-induced spatial learning deficits, three experiments were conducted using the Morris water maze. Scopolamine and glucose were injected ip at various stages of training. Rats of Wistar strain served as subjects. In Experiment 1, scopolamine (0.4 mg/kg) and 10, 100, or 500 mg/kg of glucose were administered every day from the start of training, and the effect on acquisition was evaluated. In Experiment 2, scopolamine and 100 or 500 mg/kg of glucose were administered after 6 days of training, and the effect on performance was assessed. In Experiment 3, scopolamine and 500 mg/kg of glucose were injected after 2 days of training, and the effect on the following trial was tested. In all experiments, scopolamine impaired acquisition/performance of the task. Glucose at 500 mg/kg showed a significant enhancing effect on acquisition regardless of scopolamine injection only when injected daily from the start of training (Experiment 1). Glucose injected after the performance has reached asymptote (Experiment 2) did not affect performance, and glucose in the middle of training showed a slight but insignificant enhancing effect (Experiment 3). These results may suggest that the effect of glucose changes as a function of the degree of learning of the spatial learning task. The possibility of task specificity of the glucose effect was also discussed in relation to the cholinergic systems and local cerebral glucose utilization.     

Odour and Proustian memory: reduction of context‐dependent forgetting and multiple forms of memory

In Experiment 1, the reintroduction of the same ambient odour (lemon or lavender) improved performance four weeks later in both free recall and recognition of a word list. This was a cross‐over design that allowed direct comparison between congruent and incongruent odour conditions. A further comparison with an additional group showed that memory was not improved by the presence of a different odour. Experiment 2 investigated the effect of two odour cues (lemon and lavender) in the same cross‐over design using three learning and memory tests: (1) free recall of a word list; (2) problem solving; and (3) spatial learning. While recall of the word list and spatial learning were best when the same odour was present at both learning and test, there was no such context‐dependent effect for the problem‐solving task. However, the presence of the lavender odour at test improved performance in the problem‐solving task, irrespective of the odour present at the first exposure. Thus although lavender had some effect on problem solving, we saw context‐dependent retrieval only in free recall and spatial learning. We discuss the implications of this dissociation. Copyright © 2001 John Wiley & Sons, Ltd.     

Automatic and intentional activation of task sets.

Four experiments examined automatic and intentional activation of task sets in a switching paradigm. Experiment 1 demonstrated incidental task sequence learning that was not accompanied by verbalizable task sequence knowledge. This learning did not affect task shift cost and may be attributed to automatic task-set activation. In Experiment 2, both shift cost and learning effect increased when the response-cue interval was short, indicating the influence of residual, persisting activation of the preceding task set. In Experiment 3, learning disappeared with a long cue-stimulus interval (CSI), which resulted in a strong preparation effect. This preparation, however, reduced reaction time level but was not specific to task shifts. Finally, Experiment 4 showed that a within-subject C     

Training on integrated versus separated Stroop tasks: The progression of interference and facilitation

Two experiments examined the course of interference and facilitation in the Stroop (1935) task during training. Two versions of the task were compared: integrated (e.g., the word RED in the color green) and separated (e.g., green asterisks above the word RED). Stimuli were congruent (RED in red), incongruent (GREEN in red), or neutral (XXX in red). Over 5-day (Experiment 1) and 10-day (Experiment 2) training sessions, facilitation due to congruence was small, stable, and equivalent in both task versions. In contrast, interference declined sharply on the integrated task over Days 1-3, then slowed to parallel the gradual decline on the separated task. Finally, training on the color naming task did not affect a word reading task administered after training. These findings imply that (a) Stroop interference initially reflects two problems—overcoming integration and managing two conflicting information sources; (b) with practice, the larger integration problem is solved relatively quickly, rendering the integrated and separated tasks quite comparable thereafter; and (c) facilitation and interference in the Stroop task may be independent. These results challenge extant theories of the Stroop effect, which do not predict such effects.     

Attentional mechanisms in learned predictiveness

Cues that reliably predict an outcome in an initial phase of training (Phase 1) are learned faster in a second phase of training (Phase 2) than cues that were unreliable in Phase 1. This result is observed despite objectively equal relationships between the cues and the outcomes in Phase 2, and consequently constitutes a nonnormative bias in learning. The present experiments sought to confirm that this learned predictiveness effect is the product of attentional processes (Experiment 1), and to test further whether these processes are under voluntary control or are automatic in nature (Experiment 2). In addition to the usual outcome prediction measure, eye-gaze behavior was also monitored. The results indicated an important role for top-down strategic attentional processes in the learned predictiveness task. In contrast, no evidence for an automatic attentional bias was found.     

The relationship between the structural mere exposure effect and the implicit learning process

Three experiments are reported that investigate the relationship between the structural mere exposure effect (SMEE) and implicit learning in an artificial grammar task. Subjects were presented with stimuli generated from a finite-state grammar and were asked to memorize them. In a subsequent test phase subjects were required first to rate how much they liked novel items, and second whether or not they thought items conformed to the rules of the grammar. A small but consistent effect of grammaticality was found on subjects' liking ratings (a "structural mere exposure effect") in all three experiments, but only when encoding and testing conditions were consistent. A change in the surface representation of stimuli between encoding and test (Experiment 1), memorizing fragments of items and being tested on whole items (Experiment 2), and a mismatch of processing operations between encoding and test (Experiment 3) all removed the SMEE. In contrast, the effect of grammaticality on rule judgements remained intact in the face of all three manipulations. It is suggested that rule judgements reflect attempts to explicitly recall information about training items, whereas the SMEE can be explained in terms of an attribution of processing fluency.     

积极情绪反馈对注意捕获影响的实验研究

目的：研究采用“学习-测试”范式,通过3个实验探讨积极社会情绪反馈对注意捕获的影响。方法：实验1,在学习阶段做出反应后,分别给予积极情绪和中性情绪反馈,探讨积极情绪和中性情绪捕获注意的情况;实验2,学习阶段做出反应后,没有任何情绪反馈;实验3,改变学习阶段积极情绪和中性情绪反馈图片出现的频率,探讨图片出现频率对注意捕获的影响。结果：（1）与中性情绪相比,积极情绪捕获了较多注意（实验1）;（2）无情绪反馈时,经过多次练习的刺激作为干扰刺激也捕获到了注意（实验2）;（3）积极情绪影响刺激注意优先性的过程还受到积极情绪图片出现频率的影响（实验3）。结论：积极情绪捕获注意的机制中,也有自上而下目标驱动的机制在起作用;情绪图片出现的频率也会影响社社会情绪对注意的捕获。     

Losing control in front of a fearful face: The effect of emotional information on cognitive control

How is our cognitive control system modulated by emotional information, especially fearful stimuli? An intuitive hypothesis is that fearful stimuli would enhance cognitive control so that people could switch from the ongoing task to emergent events more quickly to secure themselves. To test this hypothesis, we investigated the influence of emotional information on the shift function of cognitive control by using the task-cueing procedure, in which face images were presented as cues. With the gender of faces indicating which task to do, we manipulated the emotional valence of faces (neutral vs. fearful), finding that the switch costs were larger in the trials containing fearful cues than in the trials containing neutral cues (Experiment 1). This effect was not caused by enlarging task-set interference (Experiment 2), nor by slowing down cue encoding (Experiment 3). Contrary to the intuitive hypothesis, our results suggested that the endogenous task-set reconfiguration process was impaired when fearful faces were presented. We speculated that the benefit of decreasing cognitive flexibility in face of fearful stimuli is to speed up response in a dangerous environment, and this accelerating response is achieved by suppressing the goal-directed system to permit the fast, automatic stimulus-driven system to govern behaviours.     

Losing control in front of a fearful face: the effect of emotional information on cognitive control

How is our cognitive control system modulated by emotional information, especially fearful stimuli? An intuitive hypothesis is that fearful stimuli would enhance cognitive control so that people could switch from the ongoing task to emergent events more quickly to secure themselves. To test this hypothesis, we investigated the influence of emotional information on the shift function of cognitive control by using the task-cueing procedure, in which face images were presented as cues. With the gender of faces indicating which task to do, we manipulated the emotional valence of faces (neutral vs. fearful), finding that the switch costs were larger in the trials containing fearful cues than in the trials containing neutral cues (Experiment 1). This effect was not caused by enlarging task-set interference (Experiment 2), nor by slowing down cue encoding (Experiment 3). Contrary to the intuitive hypothesis, our results suggested that the endogenous task-set reconfiguration process was impaired when fearful faces were presented. We speculated that the benefit of decreasing cognitive flexibility in face of fearful stimuli is to speed up response in a dangerous environment, and this accelerating response is achieved by suppressing the goal-directed system to permit the fast, automatic stimulus-driven system to govern behaviours.     

Place learning in virtual space III: Investigation of spatial navigation training procedures and their application to fMRI and clinical neuropsychology

This paper describes the utilization of a desktop virtual environment task, the Computer-Generated (C-G) Arena, in the study of human spatial navigation. First, four experiments examined the efficacy of various training procedures in the C-G Arena. In Experiment 1, participants efficiently located a hidden target after only observing the virtual environment from a fixed position (placement learning). In Experiment 2, participants efficiently located a hidden target after only observing an experimenter search the virtual environment (observational learning). In Experiment 3, participants failed to display alatent learning effect in the virtual environment. In Experiment 4, all training procedures effectively taught participants the layout of the virtual environment, but the observational learning procedure most effectivelytaught participants the location of a hidden target within the environment. Finally, two experiments demonstrated the application of C-G Arena procedures to neuroimaging (Experiment 5) and neuropsychological (Experiment 6) investigations of human spatial navigation.     

Learned predictiveness training modulates biases towards using boundary or landmark cues during navigation

A number of navigational theories state that learning about landmark information should not interfere with learning about shape information provided by the boundary walls of an environment. A common test of such theories has been to assess whether landmark information will overshadow, or restrict, learning about shape information. Whilst a number of studies have shown that landmarks are not able to overshadow learning about shape information, some have shown that landmarks can, in fact, overshadow learning about shape information. Given the continued importance of theories that grant the shape information that is provided by the boundary of an environment a special status during learning, the experiments presented here were designed to assess whether the relative salience of shape and landmark information could account for the discrepant results of overshadowing studies. In Experiment 1, participants were first trained that either the landmarks within an arena (landmark-relevant), or the shape information provided by the boundary walls of an arena (shape-relevant), were relevant to finding a hidden goal. In a subsequent stage, when novel landmark and shape information were made relevant to finding the hidden goal, landmarks dominated behaviour for those given landmark-relevant training, whereas shape information dominated behaviour for those given shape-relevant training. Experiment 2, which was conducted without prior relevance training, revealed that the landmark cues, unconditionally, dominated behaviour in our task. The results of the present experiments, and the conflicting results from previous overshadowing experiments, are explained in terms of associative models that incorporate an attention variant.     

Predicting and manipulating the incidence of inattentional blindness

Inattentional blindness (IB) occurs when an observer, who is engaged in a resource-consuming task, fails to notice an unexpected although salient stimulus appearing in their visual field. The incidence of IB is affected by changes in stimulus-driven properties, but little research has examined individual differences in IB propensity. We examine working memory capacity (WMC), processing styles (flicker task), inhibition (Stroop task), and training in predicting IB. WMC is associated with IB (Experiments 1 and 2) but neither processing style (Experiment 1) nor inhibition (Experiment 2) was associated. In Experiment 2, prior training on a task reduced the incidence of IB compared to no prior training, and this effect was significantly larger when trained on the same tracking task as that used in the IB task rather than a different task. We conclude that IB is related to WMC and that training can influence the incidence of IB.     

Post-encoding emotional arousal enhances consolidation of item memory,but not reality-monitoring source memory

The current study examined whether the effect of post-encoding emotional arousal on item memory extends to reality-monitoring source memory and, if so, whether the effect depends on emotionality of learning stimuli and testing format. In Experiment 1, participants encoded neutral words and imagined or viewed their corresponding object pictures. Then they watched a neutral, positive, or negative video. The 24-hour delayed test showed that emotional arousal had little effect on both item memory and reality-monitoring source memory. Experiment 2 was similar except that participants encoded neutral, positive, and negative words and imagined or viewed their corresponding object pictures. The results showed that positive and negative emotional arousal induced after encoding enhanced consolidation of item memory, but not reality-monitoring source memory, regardless of emotionality of learning stimuli. Experiment 3, identical to Experiment 2 except that participants were tested only on source memory for all the encoded items, still showed that post-encoding emotional arousal had little effect on consolidation of reality-monitoring source memory. Taken together, regardless of emotionality of learning stimuli and regardless of testing format of source memory (conjunction test vs. independent test), the facilitatory effect of post-encoding emotional arousal on item memory does not generalize to reality-monitoring source memory.     

Latent spatial learning in an environment with a distinctive shape

Four experiments were conducted with rats in order to determine whether being placed on a platform in one corner of a rectangular swimming pool results in latent spatial learning. Rats in Experiments 1-3 received four trials a day of being placed on the platform. During a subsequent test trial, in which they were released into the pool without the platform, the rats exhibited a preference for swimming in the correct corners of the pool (those with the same geometric properties as the corner containing the platform during training), than the two remaining, incorrect corners. This effect was seen when the interval between the final placement trial and the test trial was as much as 24 hr (Experiment 2) and after varying numbers of sessions of placement training (Experiment 3). Experiment 4 revealed that when the test took place in a kite-shaped arena, after placement training in a rectangle, a stronger preference was shown for the corner that was geometrically equivalent to the correct rather than the incorrect corners in the rectangle. The placement treatment is said to result in latent spatial learning based on the development of S-S associations.     

学习材料的背景颜色对认知负荷及学习的影响

本研究采用2×2的多因素混合实验设计,探讨了物理学习环境之一的学习材料背景颜色对认知负荷及学习的影响。结果发现：（1）背景颜色在对认知负荷的影响上与任务类型产生交互作用,在解决创造性问题时,暖色调（如红色）背景下的认知负荷显著高于冷色调（如蓝色）。（2）从学习成绩上看,暖色调（如红色）更有利于记忆测试问题的解决,冷色调（如蓝色）更有利于创造性问题的解决。（3）认知负荷与任务绩效呈一定程度相关。     

Preexposure effects in the spatial domain: Dissociation between latent inhibition and perceptual learning

In 4 experiments, rats were given intermixed or blocked preexposure to an array of landmarks that subsequently defined the location of a hidden goal in a Morris pool task. Previous research has shown that intermixed preexposure to pairs of adjacent landmarks retards learning whereas preexposure to individual landmarks facilitates subsequent learning (J. Prados, V. D. Chamizo, & N. J. Mackintosh, 1999). Accordingly, in Experiment 1, intermixed and blocked preexposure to pairs of adjacent landmarks was found to retard learning. In Experiment 2, however, a scheduling effect was found: Rats given intermixed preexposure to the individual landmarks learned faster than rats given blocked or no preexposure. Experiment 3 showed that intermixed (but not blocked) preexposure to pairs of landmarks resulted in a facilitatory effect when preexposure and test were carried out in different contexts. Experiment 4 replicated within a single experiment the main results observed in Experiments 1 and 3. This pattern of results suggests that intermixed preexposure engages learning processes other than latent inhibition that facilitate subsequent learning of the navigation task.     

Associative and Normative Accounts of Negative Transfer

Subjects were given a prediction task in which they had to learn that one cue, P (positive), was followed by the outcome, and a compound of P and another cue, N (negative), was not followed by the outcome. Next, N was tested in compound with a transfer cue, T, which had signalled the outcome but had never been compounded with N. Experiment 1 confirmed an important assumption of the Rescorla-Wagner model (Wagner & Rescorla, 1972) that negation of T should depend on the specific P cue compound with N being positively contingent. Experiments 2 and 3 confirmed the model's prediction that no decrement in negative transfer should be observed following postlearning devaluation of P. Unfortunately, the model did not anticipate that a large proportion of devaluation trials relative to learning trials would attenuate negative transfer (Experiment 4), nor did it predict that negative transfer would occur when P was neutral during the learning stage and was only later made positive (Experiment 3). The results can be accommodated by the Rescorla-Wagner model if one assumes that absent cues have their associative strengths altered.     

Improving conditional discrimination learning and memory in five-year-old children: Differential outcomes effect using different types of reinforcement

Previous studies have demonstrated that discriminative learning is facilitated when a particular outcome is associated with each relation to be learned. When this training procedure is applied (the differential outcomes procedure; DOP), learning is faster and better than when the typical common outcomes procedure or nondifferential outcomes (NDO) is used. Our primary purpose in the two experiments reported here was to assess the potential advantage of DOP in 5-year-old children using three different strategies of reinforcement in which (a) children received a reinforcer following a correct choice (“ + ”), (b) children lost a reinforcer following an incorrect choice (“ ? ”), or (c) children received a reinforcer following a correct choice and lost one following an incorrect choice (“ + / ? ”). In Experiment 1, we evaluated the effects of the presence of DOP and different types of reinforcement on learning and memory of a symbolic delayed matching-to-sample task using secondary and primary reinforcers. Experiment 2 was similar to the previous one except that only primary reinforcers were used. The results from these experiments indicated that, in general, children learned the task faster and showed higher performance and persistence of learning whenever differential outcomes were arranged independent of whether it was differential gain, loss, or combinations. A novel finding was that they performed the task better when they lost a reinforcer following an incorrect choice (type of training “ ? ”) in both experiments. A further novel finding was that the advantage of the DOP over the nondifferential outcomes training increased in a retention test.