Implicit versus explicit learning processes in a probabilistic, continuous fine-motor catching task

We compared the influences of explicit instruction and uninstructed implicit learning of correlations among visual events, in a fine-motor task. The task required visual tracking of a small "ball" of light and "catching" it by means of joystick manipulation. A general pattern of improvement with practice for instructed and "noninstructed" conditions was found. Additionally, both instructed and noninstructed conditions evidenced use of the predictive relationships among stimulus events. The improvement in overall performance caused by explicit verbal instructions was less than the improvement seen with the implicit learning condition. Further, instructed and noninstructed conditions showed different patterns of joystick activity. These findings suggest a qualitatively different approach to visual information processing and task performance for the instructional conditions     

When it does hurt to try: adult age differences in the effects of instructions on implicit pattern learning

Trying to learn sometimes impairs implicit learning of artificial grammars and of control systems. We asked whether such negative effects of trying also occur in implicit learning of subtle sequential regularities and whether such effects vary with adult age. Young (n=12, age=20–23) and older (n=24, age=60–80) adults completed an alternating serial response time task in which predictable pattern events alternated with random ones in a visual/spatial display. Half of the participants were informed about the pattern and were instructed to try to discover it (intentional instructions), and half were not (incidental instructions). Age-related deficits in implicit learning occurred for both conditions. In addition, for the older group, but not for the younger one, intentional instructions impaired implicit pattern learning. This negative effect of trying to learn demonstrates another similarity among implicit learning tasks, supporting the view that some common processes underlie different forms of implicit learning.     

Analysis of probabilistic classification learning in patients with Parkinson's disease before and after pallidotomy surgery

This study examined the characteristics of probabilistic classification learning, a form of implicit learning previously shown to be impaired in patients with basal ganglia dysfunction (e.g., Parkinson's disease). In this task, subjects learn to predict the weather using associations that are formed gradually across many trials, because of the probabilistic nature of the cue-outcome relationships. Patients with Parkinson's disease, both before and after pallidotomy, and age-matched control subjects, exhibited evidence of probabilistic classification learning across 100 training trials. However, pallidotomy appears to hinder the learning of associations most implicit in nature (i.e., weakly associated cues). Although subjects were most sensitive to single-cue associations when learning the task, there is evidence that cue combinations contribute significantly to probability learning. The utility of multiple dependent measures is discussed.     

Comparison of the distortion of probability information in decision under risk and an equivalent visual task

Decision makers typically overweight small probabilities and underweight large probabilities. However, there are recent reports that when probability is presented in the form of relative frequencies, this typical pattern reverses. We tested this hypothesis by comparing decision making in two tasks: In one task, probability was stated numerically, and in the other task, it was conveyed through a visual representation. In the visual task, participants chose whether a "stochastic bullet" should be fired at either a large target for a small reward or a small target for a large reward. Participants' knowledge of probability in the visual task was the result of extensive practice firing bullets at targets. In the classical numerical task, participants chose between pairs of lotteries with probabilities and rewards matched to the probabilities and rewards in the visual task. We found that participants' probability-weighting functions were significantly different in the two tasks, but the pattern for the visual task was the typical, not the reversed, pattern.     

反馈时间、反馈类型和掩蔽类型对概率类别学习的影响

通过操纵反馈时间(即时,延迟)、反馈类型(简单,丰富)和掩蔽类型(塔罗牌,空白矩形),考察概率类别学习的学习机制。结果发现:(1)被试的学习成绩在即时反馈条件下显著优于在延迟反馈条件下;(2)在即时反馈条件下,仅给予简单反馈,被试虽能出色地完成天气预报任务,但是不能正确地判断卡片预测晴天的概率,倾向内隐学习;(3)在其他条件下,被试能正确地判断卡片预测晴天的概率以及各卡片在天气预报任务中预测天气的重要程度,表明被试能外显地意识到这些线索的作用。综上,概率类别学习采用的是双系统学习机制,既依赖内隐学习,又依赖外显学习。     

What is the impact of the explicit knowledge of sequence regularities on both deterministic and probabilistic serial reaction time task performance?

The aim of this study was to explore the role of prior explicit sequence knowledge by comparing its influence on serial reaction time (SRT) performance with either a deterministic or a probabilistic sequence. The results confirm that, with a deterministic sequence, preliminary explicit learning improves SRT performance. On the other hand, with a probabilistic sequence, the results show no advantage for SRT performance in explicit-learning conditions. In addition, by using the process dissociation procedure (Jacoby, 1991), we show that performance on a subsequent generation task was more sustained by controlled processes for participants in the explicit-learning conditions than for those in the incidental condition. On the whole, these results, showing that the influence of explicit knowledge can be suppressed in certain specific conditions, are consistent with the intervention of both implicit and explicit mechanisms in SRT tasks, and the results also show that their relative influence can be modulated by the particular demands of the task.     

Task-related functional connectivity of the caudate mediates the association between trait mindfulness and implicit learning in older adults

Accumulating evidence shows a positive relationship between mindfulness and explicit cognitive functioning, i.e., that which occurs with conscious intent and awareness. However, recent evidence suggests that there may be a negative relationship between mindfulness and implicit types of learning, or those that occur without conscious awareness or intent. Here we examined the neural mechanisms underlying the recently reported negative relationship between dispositional mindfulness and implicit probabilistic sequence learning in both younger and older adults. We tested the hypothesis that the relationship is mediated by communication, or functional connectivity, of brain regions once traditionally considered to be central to dissociable learning systems: the caudate, medial temporal lobe (MTL), and prefrontal cortex (PFC). We first replicated the negative relationship between mindfulness and implicit learning in a sample of healthy older adults (60–90 years old) who completed three event-related runs of an implicit sequence learning task. Then, using a seed-based connectivity approach, we identified task-related connectivity associated with individual differences in both learning and mindfulness. The main finding was that caudate-MTL connectivity (bilaterally) was positively correlated with learning and negatively correlated with mindfulness. Further, the strength of task-related connectivity between these regions mediated the negative relationship between mindfulness and learning. This pattern of results was limited to the older adults. Thus, at least in healthy older adults, the functional communication between two interactive learning-relevant systems can account for the relationship between mindfulness and implicit probabilistic sequence learning.     

What is learned from experience in a probabilistic environment?

Three experiments explored what is learned from experience in a probabilistic environment. The task was a simulated medical decision‐making task with each patient having one of two test results and one of two diseases. The test result was highly predictive of the disease for all participants. The base rate of the test result was varied between participants to produce different inverse conditional probabilities of the test result given the disease across conditions. Participants trained using feedback to predict a patient's disease from a test result showed the classic confusion of the inverse error, substituting the forward conditional probability for the inverse conditional probability when tested on it. Additional training on the base rate of the test result did little to improve performance. Training on the joint probabilities, however, produced good performance on either conditional probability. The pattern of results demonstrated that experience with the environment is not always sufficient for good performance. That natural sampling leads to good performance was not supported. Further, because participants not trained on joint probabilities did, however, know them but still committed the confusion of the inverse error, the hypothesis that having joint probabilities would facilitate performance was not supported. The pattern of results supported the conclusion that people learn all the necessary information from experience in a probabilistic environment, but depending upon what the experience was, it may interfere with their ability to recall to memory the appropriate sample set necessary for estimating or using the inverse conditional probability. Copyright © 2004 John Wiley & Sons, Ltd.     

Discovering syntactic deep structure via Bayesian statistics

In the Bayesian framework, a language learner should seek a grammar that explains observed data well and is also a priori probable. This paper proposes such a measure of prior probability. Indeed it develops a full statistical framework for lexicalized syntax. The learner's job is to discover the system of probabilistic transformations (often called lexical redundancy rules) that underlies the patterns of regular and irregular syntactic constructions listed in the lexicon. Specifically, the learner discovers what transformations apply in the language, how often they apply, and in what contexts. It considers simpler systems of transformations to be more probable a priori. Experiments show that the learned transformations are more effective than previous statistical models at predicting the probabilities of lexical entries, especially those for which the learner had no direct evidence.     

Implicit Memory in Korsakoff’s Syndrome: A Review of Procedural Learning and Priming Studies

Korsakoff's syndrome (KS) is characterized by dense anterograde amnesia resulting from damage to the diencephalon region, typically resulting from chronic alcohol abuse and thiamine deficiency. This review assesses the integrity of the implicit memory system in KS, focusing on studies of procedural learning and priming. KS patients are impaired on several measures of procedural memory, most likely due to impairment in cognitive functions associated with alcohol-related neural damage outside of the diencephalon. The pattern of performance on tasks of implicit priming suggests reliance on a residual, non-flexible memory operating more or less in an automatic fashion. Our review concludes that whether measures of implicit memory reveal intact or impaired performance in individuals with KS depends heavily on specific task parameters and demands, including timing between stimuli, the specific nature of the stimuli used in a task, and the integrity of supportive cognitive functions necessary for performance.     

Task integration as a factor in secondary-task effects on sequence learning

In several studies it has been found that implicit sequence learning is impaired by the concurrent performance of a secondary task. In most studies the task was to count high-pitched tones when high-pitched and low-pitched tones were presented in a random sequence. In this paper the hypothesis is examined that dual-task interference in the particular combination of tasks results from task integration, in particular from the learning of an integrated visual-auditory sequence in which every second (auditory) element is random. Instead of the tone-counting task a similar go/no-go task was used in which foot responses to high-pitched tones were performed. In Exp. 1 the sequence of tones was random in one condition, but in two other conditions repeated tone sequences of 5 and 6 elements were combined with visual sequences of 6 elements. Under dual-task test conditions, implicit learning of the visual as well as the auditory sequences was better with the auditory sequence of 6 elements than of 5 elements, while under single-task test conditions the nature of the tone sequence had no effect. In Exp. 2 the superior implicit learning with the 6-element sequence was replicated with different test procedures in which either the visual or auditory sequence was changed to random or in which the two sequences remained intact but were shifted by one element relative to each other. Randomization of the visual or auditory sequences not only impaired visual or auditory RT, respectively, but also impaired RT to stimuli in the other modality, and this cross-modal effect was almost as strong as the intra-modal effect of randomization. Finally, in Exp. 3 it was shown that integrated visual-auditory sequences are learned only when responses to both of them are required, but not when the tones can be neglected. These results are consistent with a conception of implicit learning as (at least partly) a basic and nonselective type of learning of all potentially behaviorally relevant relations between stimuli in the environment and one's own actions.     

高低情感开放性者概率内隐序列学习进程差异

大五人格情感开放性子量表(openness/feeling)能否预测内隐序列学习的问题存在争议。本研究采用概率性内隐序列学习范式, 比较高低情感开放性者在各反应刺激间隔(response stimulus interval, 即RSI)的差异。发现：(1) RSI = 0 ms和250 ms, 高分组在转移组块后习得高概率序列, RSI = 500 ms及以上在其之前习得; 所有RSI点低分组都在其之前习得。每个RSI点只有高分组习得低概率序列。证明随RSI增加两者内隐进程有本质差异, openness/feeling子量表可预测内隐序列学习个体差异。(2)低概率序列可作为测量概率性内隐序列学习及个体差异的新指标, 经典转移组块、再认、生成任务的测量效果却十分有限。     

Bodily self and schizophrenia: The loss of implicit self-body knowledge

Schizophrenia spectrum has been associated with a disruption of the basic sense of self, which pertains, among others, the representation of one's own body. We investigated the impact of either implicit or explicit access to the representation of one's own body-effectors on bodily self-awareness, in first-episode schizophrenia (FES) patients and healthy controls (HCs). We contrasted their performance in an implicit self-recognition task (visual matching) and in an explicit self/other discrimination task. Both tasks employed participant's own and others' body-effectors. Concerning the implicit task, HCs were more accurate with their own than with others' body-effectors, whereas patients did not show such self-advantage. Regarding the explicit task, both groups did not exhibit a self-advantage, and patients showed a higher percentage of self-misattribution errors. Neither self/other nor implicit/explicit effects were found in both groups when processing inanimate-objects. We propose that FES patients suffer of a disturbed implicit sense of bodily self.     

Attentional load and implicit sequence learning

A widely employed conceptualization of implicit learning hypothesizes that it makes minimal demands on attentional resources. This conjecture was investigated by comparing learning under single-task and dual-task conditions in the sequential reaction time (SRT) task. Participants learned probabilistic sequences, with dual-task participants additionally having to perform a counting task using stimuli that were targets in the SRT display. Both groups were then tested for sequence knowledge under single-task (Experiments 1 and 2) or dual-task (Experiment 3) conditions. Participants also completed a free generation task (Experiments 2 and 3) under inclusion or exclusion conditions to determine if sequence knowledge was conscious or unconscious in terms of its access to intentional control. The experiments revealed that the secondary task impaired sequence learning and that sequence knowledge was consciously accessible. These findings disconfirm both the notion that implicit learning is able to proceed normally under conditions of divided attention, and that the acquired knowledge is inaccessible to consciousness. A unitary framework for conceptualizing implicit and explicit learning is proposed.     

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.     

Memory in pediatric patients undergoing conscious sedation for aversive medical procedures.

This study investigated preserved memory in 26 pediatric cancer patients (65% boys, 77% Caucasian, mean age = 12.5 years) undergoing midazolam-induced conscious sedation during painful medical procedures to treat hematological or oncological diseases. The sedative midazolam had a significant anterograde amnesic effect on participants' performance on a visual recognition (explicit) memory task but not on a visual perceptual facilitation (implicit) memory task. That implicit memory scores were relatively unaffected while explicit memory scores deteriorated significantly indicates that leaning occurred while participants were sedated, even when participants did not recollect the learning event. These findings, which replicate those of M. R. Polster, R. A. McCarthy, G. O'Sullivan, P. A. Gray, and G. R. Park (1993) in a study of adults, have implications for the development and treatment of conditioned anxiety reactions associated with aversive medical procedures.     

Paired associate learning in reading-disabled children: evidence for a rule-learning deficiency

Two experiments examined whether normal and disabled readers differed in the utilization of rules in a paired associate learning task. Experiment 1 required children to learn symbol-word associates. Children were assigned to one of three conditions: nonrule, consistent rule, or inconsistent rule. When present, the rule was based on semantic opposites. Subjects benefited from having the rule, but disabled readers showed less improvement across four test blocks than both chronological age (CA) controls and reading age (RA) controls, particularly in the inconsistent condition. Experiment 2 required subjects to learn symbol-symbol associations in one of three conditions: nonrule, consistent rule, or inconsistent rule. When present, the rule specified the locations of a subsidiary figure in each symbol according to the pattern top-right, bottom-left. Disabled and normal readers did not differ in the nonrule condition where reliance on visual memory would be an effective strategy. Normal readers were superior to disabled readers in both rule conditions. In addition, disabled readers in the inconsistent rule condition were less able than normal readers to apply the rule in a generalization task where memory demands were reduced. Results supported the hypothesis that disabled readers have greater difficulty than normal readers inducing and/or using rules, particularly when they are inconsistent. It is suggested that difficulties in acquiring or using complex and inconsistent rules may be one important source of problems learning spelling-sound correspondence rules, which in English are complex and inconsistent.     

Secondary-task effects on classification learning

Probabilistic classification learning can be supported by implicit knowledge of cue-response associations. We investigated whether forming these associations depends on attention by assessing the effect of performing a secondary task on learning in the probabilistic classification task (PCT). Experiment I showed that concurrent task performance significantly interfered with performance of the PCT. Experiment 2 showed that this interference did not prevent learning from occurring. On the other hand, the secondary task did disrupt acquisition of explicit knowledge about cue-outcome associations. These results show that concurrent task performance can have different effects on implicit and explicit knowledge acquired within the same task and also underscore the importance of considering effects on learning and performance separately.     

Intact implicit learning in autism spectrum conditions

Individuals with autism spectrum condition (ASC) have diagnostic impairments in skills that are associated with an implicit acquisition; however, it is not clear whether ASC individuals show specific implicit learning deficits. We compared ASC and typically developing (TD) individuals matched for IQ on five learning tasks: four implicit learning tasks—contextual cueing, serial reaction time, artificial grammar learning, and probabilistic classification learning tasks—that used procedures expressly designed to minimize the use of explicit strategies, and one comparison explicit learning task, paired associates learning. We found implicit learning to be intact in ASC. Beyond no evidence of differences, there was evidence of statistical equivalence between the groups on all the implicit learning tasks. This was not a consequence of compensation by explicit learning ability or IQ. Furthermore, there was no evidence to relate implicit learning to ASC symptomatology. We conclude that implicit mechanisms are preserved in ASC and propose that it is disruption by other atypical processes that impact negatively on the development of skills associated with an implicit acquisition.     

Unique behavioral strategies in visuomotor learning: Hope for the non-learner

The existence of individual differences in motor learning capability is well known but the behaviors or strategies that contribute to this variability have been vastly understudied. What performance characteristics distinguish an expert level performer from individuals who experience little to no success, those labeled non-learners? We designed a rule-based visuomotor task which requires identification (discovery) and then exploitation of specific explicit and implicit task components that requires a specific movement pattern, the task rule, for goal achievement. When participants first attempt the task, they are informed about the goal, but are naïve to the task rule. Therefore, the purpose of this experiment is to determine how acquisition of both implicit and explicit task components, the inherent elements of the task rule, reveals differing strategies associated with performance and task success. We test the hypothesis that an examination of performance will reveal sub-groups with varying levels of success. Further, for each subgroup, we expect to find a unique relationship between visual Time-in-Target feedback (a measure of success) and subsequent updating of each task component. Out of 32 non-disabled adults, we identified three distinct sub-groups: (Low Performer/Non-Learner (LP, N = 9), Moderate Performer (MP, N = 12) and High Performer (HP, N = 11)). A quantitative analysis of behavioral patterns reveals three findings: First, the LP sub-group demonstrated significantly lower task success which was associated with difficulty identifying the explicit component of the task. Second, the HP sub-group acquired the two task components in parallel over practice. Third, when both explicit and implicit component performance is plotted across sub-groups, a task component continuum emerges that seamlessly progresses from low to moderate to high performer groups. An exploratory analysis reveals that self-reported level of prior lifetime accumulation of video game and physical activity experience is a significant predictor of individual task performance (R² = 0.50). In summary, what appears to be a key distinction between varying levels of human rule-based motor learning is the process by which feedback is used to update performance of inherent elements of the task rule. Evidence of a performance continuum and limited prior experience suggests that Low Performer/Non-Learners are generally inexperienced with these kinds of tasks, although the role of genetics and other innate learning capabilities in visuomotor learning is still largely unknown. These findings provoke new research directions toward probing the differential performance strategies associated with expertise and the development of interventions aimed to convert non-learners into learners.