序列位置内隐学习产生机制的实验研究

内隐学习是当今认知和学习领域继内隐记忆之后又一重要的研究课题。该研究利用序列反应时研究程式,通过两个实验,对序列位置内隐学习产生的机制进行了探讨。结果表明：（１）在序列反应时任务程式中,随着反应一刺激间隔的延长,序列位置内隐学习的学习量逐渐减少;（２）异形同模式迁移组和异形异模式迁移组被试间内隐学习量无显著差异,被试未能内隐地习得抽象的序列模式。说明序列位置内隐学习产生的基础是水平联结,在该实验条件下没有发现垂直联结存在的证据。     

Operating characteristics of the implicit learning system supporting serial interception sequence learning

The memory system that supports implicit perceptual-motor sequence learning relies on brain regions that operate separately from the explicit, medial temporal lobe memory system. The implicit learning system therefore likely has distinct operating characteristics and information processing constraints. To attempt to identify the limits of the implicit sequence learning mechanism, participants performed the serial interception sequence learning (SISL) task with covertly embedded repeating sequences that were much longer than most previous studies: ranging from 30 to 60 (Experiment 1) and 60 to 90 (Experiment 2) items in length. Robust sequence-specific learning was observed for sequences up to 80 items in length, extending the known capacity of implicit sequence learning. In Experiment 3, 12-item repeating sequences were embedded among increasing amounts of irrelevant nonrepeating sequences (from 20 to 80% of training trials). Despite high levels of irrelevant trials, learning occurred across conditions. A comparison of learning rates across all three experiments found a surprising degree of constancy in the rate of learning regardless of sequence length or embedded noise. Sequence learning appears to be constant with the logarithm of the number of sequence repetitions practiced during training. The consistency in learning rate across experiments and conditions implies that the mechanisms supporting implicit sequence learning are not capacity-constrained by very long sequences nor adversely affected by high rates of irrelevant sequences during training.     

The neural correlates of implicit and explicit sequence learning: Interacting networks revealed by the process dissociation procedure

In two H2(15)O PET scan experiments, we investigated the cerebral correlates of explicit and implicit knowledge in a serial reaction time (SRT) task. To do so, we used a novel application of the Process Dissociation Procedure, a behavioral paradigm that makes it possible to separately assess conscious and unconscious contributions to performance during a subsequent sequence generation task. To manipulate the extent to which the repeating sequential pattern was learned explicitly, we varied the pace of the choice reaction time task-a variable that is known to have differential effects on the extent to which sensitivity to sequence structure involves implicit or explicit knowledge. Results showed that activity in the striatum subtends the implicit component of performance during recollection of a learned sequence, whereas the anterior cingulate/mesial prefrontal cortex (ACC/MPFC) supports the explicit component. Most importantly, we found that the ACC/MPFC exerts control on the activity of the striatum during retrieval of the sequence after explicit learning, whereas the activity of these regions is uncoupled when learning had been essentially implicit. These data suggest that implicit learning processes can be successfully controlled by conscious knowledge when learning is essentially explicit. They also supply further evidence for a partial dissociation between the neural substrates supporting conscious and nonconscious components of performance during recollection of a learned sequence.     

Position-item associations play a role in the acquisition of order knowledge in an implicit serial reaction time task

Knowledge of sequential regularities plays a key role in forms of explicit and implicit memory, such as working memory and motor skills. Despite important advances in the study of sequence knowledge in the past century, the theoretical development of implicit and explicit memory has occurred separately. Unlike the literature on implicit sequence learning, the explicit learning literature differentiates between 2 forms of representation of serial structure, chaining (C is the item following B in the sequence A-B-C-D) and ordinal position knowledge (C is the 3rd item). In 3 experiments, we demonstrate that these 2 forms of sequence knowledge can be acquired in implicit sequence learning. In Experiment 1, 2 trained sequences were recombined at transfer such that the strength of (a) associations between serial positions and sequence elements as well as (b) associations between successive sequence elements could be estimated. In Experiment 2, we compared sequence elements placed at the trained versus untrained serial position. Experiment 3 reduced cues that can be used to determine the start of a sequence within the stream of trials. Our results suggest that the discussion held in explicit memory research about different forms of representation of sequences knowledge also is relevant for implicit sequence learning.     

Implicit learning of what comes when and where within a sequence: The time-course of acquiring serial position-item and item-item associations to represent serial order

Much research has been conducted aimed at the representations and mechanisms that enable learning of sequential structures. A central debate concerns the question whether item-item associations (i.e., in the sequence A-B-C-D, B comes after A) or associations of item and serial list position (i.e., B is the second item in the list) are used to represent serial order. Previously, we showed that in a variant of the implicit serial reaction time task, the sequence representation contains associations between serial position and item information (Schuck, Gaschler, Keisler, & Frensch, 2011). Here, we applied models and research methods from working memory research to implicit serial learning to replicate and extend our findings. The experiment involved three sessions of sequence learning. Results support the view that participants acquire knowledge about order structure (item-item associations) and about ordinal structure (serial position-item associations). Analyses suggest that only the simultaneous use of the two types of knowledge acquisition can explain learning-related performance increases. Additionally, our results indicate that serial list position information plays a role very early in learning and that inter-item associations increasingly control behavior in later stages.     

Event Timing and age deficits in higher-order sequence learning

Recent studies have reported age deficits in learning sequences that contain subtle sequential regularities (e.g., Curran (1997) Psychological Research, 60(1-2), 24; D. V. Howard et al. (2004) Psychology and Aging, 19(1), 79; Howard, J. H. Jr, & Howard, D. V. (1997). Psychology and Aging, 12(4), 634). This finding is of potential theoretical interest, but the contribution of sequence event timing to this deficit has not been investigated. This study used an alternating serial reaction time task to examine implicit sequence learning in young adults when event timing mimicked that experienced by older adults in previous research. We varied the response-to-stimulus interval directly in Experiment 1 and indirectly by degrading the stimuli to influence response time in Experiment 2. Results indicate that these "aged" young adults learned the higher-order sequence structure implicitly, but they learned less than young controls and more than old adults on some measures of implicit learning in both experiments. In addition, these two different experimental manipulations produced distinct patterns of deficits despite having nearly identical effects on event sequence timing. These findings suggest that event timing alone cannot explain the age deficits observed in high-order implicit sequence learning.     

Serial reaction time performance following right parietal lobe damage

The serial reaction time task (SRT) is used to assess implicit sequence learning. Neuroimaging studies implicate parietal involvement; however, the necessity of this area is unclear. We tested six unilateral right parietal patients and compared their performance to matched controls. Both groups showed similar levels of learning and explicit awareness. Two patients with the largest lesions extending into either frontal or cerebellar regions showed no learning. These data suggest that implicit sequence learning can occur despite damage to the right parietal lobe.     

Implicit serial learning: Questions inspired by Hebb (1961)

Implicit serial learning occurs when indirect measures such as transfer reveal learning of a repeating sequence even when subjects are not informed ofthe repeating sequence, are not asked to learn it, and do not become of aware of it. This phenomenon is reminiscent of an experiment by Hebb(1961), who studied the repetition of sequences in a serial recall task. Two experiments investigated the relation between implicit serial learning and ideas about learning forwarded by Hebb and others who used his method. The experiments showed that implicit serial learning occurs even when the repeating sequence is intermixed with randomly generated sequences instead of being repeated continuously, that the organization of the sequence into regularly or irregularly grouped subsequences determines the extent of learning, and that the repetition effect observed does not depend on subjects' ability to recognize the repetition.     

Generalized lessons about sequence learning from the study of the serial reaction time task

Over the last 20 years researchers have used the serial reaction time (SRT) task to investigate the nature of spatial sequence learning. They have used the task to identify the locus of spatial sequence learning, identify situations that enhance and those that impair learning, and identify the important cognitive processes that facilitate this type of learning. Although controversies remain, the SRT task has been integral in enhancing our understanding of implicit sequence learning. It is important, however, to ask what, if anything, the discoveries made using the SRT task tell us about implicit learning more generally. This review analyzes the state of the current spatial SRT sequence learning literature highlighting the stimulus-response rule hypothesis of sequence learning which we believe provides a unifying account of discrepant SRT data. It also challenges researchers to use the vast body of knowledge acquired with the SRT task to understand other implicit learning literatures too often ignored in the context of this particular task. This broad perspective will make it possible to identify congruences among data acquired using various different tasks that will allow us to generalize about the nature of implicit learning.     

Sequence learning and selection difficulty

The authors studied the role of attention as a selection mechanism in implicit learning by examining the effect on primary sequence learning of performing a demanding target-selection task. Participants were trained on probabilistic sequences in a novel version of the serial reaction time (SRT) task, with dual- and triple-stimulus participants having to ignore irrelevant items in the SRT display. Despite large performance decrements under dual- and triple-stimulus configurations, testing under single-stimulus conditions revealed no impairment to sequence learning. These findings suggest that implicit sequence learning is resistant to disruption of the selection process. Results are discussed in terms of a componential model of attention and in relation to the implicit-explicit distinction.     

Explicit Awareness does not Modulate Retrograde Interference Effects in Sequence Learning

Motor sequences are learned explicitly or implicitly based on conscious awareness of the sequence. Interference happens when two sequences are learned successively. Here, we aimed to determine whether implicit and explicit sequence learning are affected differently by retrograde interference. Young healthy volunteers participated in either a control or interference group and either an explicit or implicit learning condition. We used a modified serial reaction time task to induce sequence learning and control awareness. Results showed that the overall amount of sequence learning was greater in the explicit condition compared to implicit. However, sequence learning was equally susceptible to retrograde interference under either condition. We conclude that although susceptible to interference, explicit awareness improves overall sequence learning compared to implicit conditions.     

An egocentric frame of reference in implicit motor sequence learning

We investigated which frame of reference is evoked during implicit motor sequence learning. Participants completed a typical serial reaction time task. In the first experiment, we isolated egocentric and allocentric frames of reference and found that learning was solely in an egocentric reference frame. In a second experiment, we isolated hand-centered space from other egocentric frames of reference. We found that for a one-handed sequencing task, the sequence was coded in an egocentric reference frame but not a hand-centered reference frame. Our results are restricted to implicit learning of novel sequences in the early stages of learning. These findings are consistent with claims that the neural mechanisms involved in motor skill learning operate in egocentric coordinates.     

序列统计结构对内隐序列学习发展的影响

采用序列学习研究范式,考察小三到大三学生内隐序列学习的发展规律及制约因素。结果表明:(1)各年龄组被试均能在序列学习中获得序列规则;(2)不同年龄组被试序列反应时存在显著差异,说明内隐序列学习从小三到大三之间一直存在发展变化;(3)被试在高统计结构下的反应时要低于低统计结构下的,且这种差异不存在发展变化,说明高统计结构下的内隐学习成绩要好于低统计结构下的;(4)外显被试的量随年龄增长而增加,说明对序列学习的有意识加工能力随年龄增长而提高。     

Visual artificial grammar learning by rhesus macaques (<Emphasis Type="Italic">Macaca mulatta</Emphasis>): exploring the role of grammar complexity and sequence length

Humans and nonhuman primates can learn about the organization of stimuli in the environment using implicit sequential pattern learning capabilities. However, most previous artificial grammar learning studies with nonhuman primates have involved relatively simple grammars and short input sequences. The goal in the current experiments was to assess the learning capabilities of monkeys on an artificial grammar-learning task that was more complex than most others previously used with nonhumans. Three experiments were conducted using a joystick-based, symmetrical-response serial reaction time task in which two monkeys were exposed to grammar-generated sequences at sequence lengths of four in Experiment 1, six in Experiment 2, and eight in Experiment 3. Over time, the monkeys came to respond faster to the sequences generated from the artificial grammar compared to random versions. In a subsequent generalization phase, subjects generalized their knowledge to novel sequences, responding significantly faster to novel instances of sequences produced using the familiar grammar compared to those constructed using an unfamiliar grammar. These results reveal that rhesus monkeys can learn and generalize the statistical structure inherent in an artificial grammar that is as complex as some used with humans, for sequences up to eight items long. These findings are discussed in relation to whether or not rhesus macaques and other primate species possess implicit sequence learning abilities that are similar to those that humans draw upon to learn natural language grammar.     

内隐序列学习不受注意负荷的影响:来自眼动的证据

利用眼动记录方法,采用内隐序列学习的观察范式,通过操纵注意负荷高和低,考察内隐序列学习是否需要注意参与。结果发现:(1)在高、低注意负荷条件下都出现了内隐序列学习效应;(2)高注意负荷条件下眼跳反应时长于低注意负荷条件下的;(3)高、低注意负荷序列内隐序列学习量差异不显著,表明内隐序列学习不受注意负荷影响。     

The study of sequence learning in individuals with schizophrenia: A critical review of the literature

The serial reaction time task (SRTT) has been used extensively to study implicit sequence learning. A number of studies have used the SRTT to examine sequence learning in schizophrenia patients. Despite these studies, it remains unclear whether sequence learning is impaired in patients, whether antipsychotic medications affect sequence learning, and what types of sequential information patients might have difficulty learning. Methodological limitations have made it difficult to obtain good answers to these questions. Methodological innovations from the general SRTT literature that have not yet been adopted in the schizophrenia literature could provide better answers.     

Auditory sequence learning: differential sensitivity to task relevant and task irrelevant sequences

Using a serial reaction time task, this study examines whether learning of auditory sequences is possible without a corresponding motor response, i.e., by listening alone. The dual sequence paradigm used by Mayr (in Journal of the Experimental Psychology: Learning memory and cognition 22:350–354, 1996, Experiment 1) was adapted to the auditory domain. Four different actors spoke the same four colour words. These were presented such that speaker identity followed one sequence, and the word spoken followed a different sequence. Subjects were asked to respond (with a key press) to one of these dimensions (identity or word), and ignore the other. Results showed learning for either type of stimulus, but only when it was responded to. No learning of either type of auditory sequence by listening alone was found. The results add evidence to visual implicit learning studies that have failed to find learning of event sequences when spatial or response selection was not an important factor in processing. The findings are discussed in the context of implicit learning as a general and fundamental cognitive process.     

Implicit visual learning and the expression of learning

Although the existence of implicit motor learning is now widely accepted, the findings concerning perceptual implicit learning are ambiguous. Some researchers have observed perceptual learning whereas other authors have not. The review of the literature provides different reasons to explain this ambiguous picture, such as differences in the underlying learning processes, selective attention, or differences in the difficulty to express this knowledge. In three experiments, we investigated implicit visual learning within the original serial reaction time task. We used different response devices (keyboard vs. mouse) in order to manipulate selective attention towards response dimensions. Results showed that visual and motor sequence learning differed in terms of RT-benefits, but not in terms of the amount of knowledge assessed after training. Furthermore, visual sequence learning was modulated by selective attention. However, the findings of all three experiments suggest that selective attention did not alter implicit but rather explicit learning processes.     

Attention modulates the learning of multiple contingencies

We employed a novel version of the serial reaction time task to test the idea that human implicit learning allows the simultaneous learning of multiple independent contingencies and that this learning may proceed in the absence of attention. Using probabilistic sequences, we showed that both a primary sequence (the focus of the experimental task) and a statistically independent secondary sequence could be learned across 4,800 target localization trials, provided the perceptual load of the primary task was low. However, learning of the secondary sequence was abolished under conditions of high perceptual load. These findings suggest that there are attentional limitations on the learning of multiple contingencies.     

Implicit probabilistic sequence learning is independent of explicit awareness

Studies into interactions between explicit and implicit motor sequence learning have yielded mixed results. Some of these discrepancies have been attributed to difficulties in isolating implicit learning. In the present study, the effect of explicit knowledge on implicit learning was investigated using a modified version of the Alternating Serial Response Time (ASRT) task, a probabilistic sequence learning paradigm that yields continuous and relatively pure measures of implicit learning. Results revealed that implicit learning occurred to the same extent, whether or not subjects had explicit knowledge. Some evidence, however, indicated that explicit knowledge could interfere with the expression of implicit learning early in training. In addition, there were dissociations between learning measures, in that reaction time and accuracy were differentially affected by explicit knowledge. These findings indicate that implicit sequence learning occurs independently of explicit knowledge, and help to explain previous discrepant findings.