Past midnight: Semantic processing in an implicit learning task

Four experiments are reported which examine the nature of representations underlying an implicit learning task. When shown a series of clock faces, each bearing a time between 6 and 12 o'clock, subjects subsequently show a selection preference for novel clock faces between these times. Furthermore, they show no signs of being aware of the underlying rule governing this preference. This effect is also present when the representation of time of day is changed from analogue to digital between learning and test. In the final experiment subjects show no preference for seen over unseen clocks between these critical times. These data suggest that, for this particular task, implicit learning involves abstract representations.     

An abbreviated implicit spatial context learning task that yields greater learning

The spatial contextual cuing task (SCCT) (Chun & Jiang, 1998) is an implicit learning task that appears to depend on the medial temporal lobes. This unusual combination has been of interest in functional imaging studies and research with clinical populations, where testing time is at a premium. However, the original version of the SCCT is time-consuming. In this study, 29 young adults (age range, 18–22 years) completed the SCCT, in which participants respond to the orientation of a target in arrays containing 11 distractors. Either 12 (original version) or 6 (abbreviated version) arrays repeated across the experiment, with the remaining novel arrays being generated randomly. Results revealed that the magnitude of learning (faster responses to repeated versus novel arrays) was larger when there were fewer repeated arrays, with no explicit awareness in most participants. Thus, the abbreviated version remained implicit, with the additional benefit of increasing the magnitude of learning.     

Episodic knowledge and implicit learning

Despite nearly 20 years of controversy, researchers are still divided over the contributions of abstract and episodic knowledge to performance on implicit learning tasks, and whether these types of knowledge exert their effects unintentionally or unconsciously. The present paper reviews the evidence taken to support the episodic account of implicit learning. Although substantial evidence suggests that episodic knowledge influences performance on implicit learning tasks, at present there are no techniques for testing whether these influences occur outside of awareness. It is argued that future research should investigate whether the retrieval of episodic knowledge in implicit learning tasks is insensitive to intentional control, rather than focus on the issue of awareness. Preliminary evidence suggesting that episodic knowledge can exert a nonintentional influence on task performance is reviewed, followed by a discussion of the status of consciousness as an explanatory construct in psychology.     

Nonintentional task set activation: Evidence from implicit task sequence learning

Studies have shown that task sets could be configured endogenously (i.e., on the basis of memory) according to an explicit sequence or exogenously according to a task cue. In two experiments, we examined whether an implicitly learned sequence could facilitate task set configuration without participants’ intention. These experiments led to opposite conclusions regarding this question, but their methodology made it impossible to distinguish between the interpretations. We altered the task-switching paradigm by embedding a hidden task sequence, while randomizing all other aspects, including perceptual (i.e., task cues) and motor elements. We found that a sequence of tasks, proper, was learned implicitly and that the memory of that sequence endogenously facilitated task decision processes without the participants’ explicit knowledge.     

Making children gesture brings out implicit knowledge and leads to learning

Speakers routinely gesture with their hands when they talk, and those gestures often convey information not found anywhere in their speech. This information is typically not consciously accessible, yet it provides an early sign that the speaker is ready to learn a particular task (S. Goldin-Meadow, 2003). In this sense, the unwitting gestures that speakers produce reveal their implicit knowledge. But what if a learner was forced to gesture? Would those elicited gestures also reveal implicit knowledge and, in so doing, enhance learning? To address these questions, the authors told children to gesture while explaining their solutions to novel math problems and examined the effect of this manipulation on the expression of implicit knowledge in gesture and on learning. The authors found that, when told to gesture, children who were unable to solve the math problems often added new and correct problem-solving strategies, expressed only in gesture, to their repertoires. The authors also found that when these children were given instruction on the math problems later, they were more likely to succeed on the problems than children told not to gesture. Telling children to gesture thus encourages them to convey previously unexpressed, implicit ideas, which, in turn, makes them receptive to instruction that leads to learning.     

ADHD children outperform normal children in an artificial grammar implicit learning task: ERP and RT evidence

This study focuses on Implicit learning (IL) in children. One of the main debates in this field concerns the occurrence of IL indicators in experimental settings and its manifestation in different populations. In this research, we are looking for evidence of the occurrence of IL in normal children and in children with Attention Deficit Hyperactive Disorder (ADHD), based on the relationship between accuracy, reaction time and event-related potentials (ERPs). Our results show differences between the analyzed groups with respect to markers for electrophysiological activity and reaction time, but not for accuracy. In consequence, we suggest that research in IL should explore different indicators and their relationship with the cognitive processing levels involved. In addition, IL might involve different forms of information processing in normal children and children with ADHD. We discuss the possible impact of these findings for future research.     

The combination of explicit and implicit learning processes in task control

Summary Two experiments look at the combination of explicit and implicit learning processes on a single task. Subjects are required to control the rate of sugar output in a small sugar production factory while maintaining cordial relations with the union. Experiment 1 investigates whether subjects can learn to control this task, which relies on their knowing about both salient and nonsalient relationships. It looks at how performance on the task relates to explicit verbalisable knowledge (as assessed by written questionnaire). Experiment 2 considers alternative ways of tapping the more implicit aspects of subjects' knowledge.     

Comparison of implicit and explicit learning processes in a probabilistic task

This experiment compared the performance with explicit (rule-application and rule-discovery) and implicit (nonrule-instructed) learning approaches on the performance of a probabilistic video game task requiring fine motor control. 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 occurred for all conditions. All conditions showed use of predictive relations among stimulus events. However, task performance of the rule-application and rule-discovery conditions were inferior to the nonrule-instructed implicit condition, particularly during the early phases of rule acquisition and application. This pattern strongly suggests substantial performance costs associated with attempting to discover or apply probabilistic rules. Decrements are likely due to increased cognitive demands associated with attempting to remember and strategically apply provided probability rules or attempting to discover and apply potentially important and useful probability information from a complex visual display.     

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.     

Evaluating the relationship between explicit and implicit knowledge in a sequential reaction time task

Can knowledge underlying a simple perceptual-motor skill be unconscious? Three experiments (a) trained participants on a 4-choice reaction time (RT) task in which the stimulus on each trial was determined by a repeating 12-element sequence and (b) studied the extent to which participants' knowledge of this sequence was implicit, that is, unavailable for conscious access. Participants proved via an indirect test to have acquired knowledge of the sequence, because their RTs increased when the sequence was changed. To evaluate whether this knowledge was consciously accessible, participants were asked to perform an "objective" free-generation or recognition test of sequence knowledge. Results show that sequence knowledge is fully accessible on these objective tests. Moreover, it is demonstrated in this procedure that old-new recognition cannot be explained by unconscious attribution of perceptual-motor fluency. The question is raised whether distinct implicit (procedural) and explicit (declarative) forms of knowledge are acquired when participants learn a perceptual-motor skill.     

Adding the goal to learn strengthens learning in an unintentional learning task

Previous research has demonstrated that contingency learning can take place in the absence of the intention to learn. For instance, in the color-word contingency learning task, each distracting word is presented most often in a given target color (e.g., "month" in red and "plate" in green), and less often in the other colors. Participants respond more quickly and accurately when the word is presented in the expected rather than an unexpected color, even though there is no reason why they would have the intention to learn the contingencies between the words and the colors. It remains to be determined, however, whether learning in such situations would benefit or suffer from adding the goal to learn contingencies. In the reported experiment, half of the participants were informed that each word was presented most often in a certain color, and they were instructed to try to learn these contingencies. The other half of the participants were not informed that contingencies would be present. The participants given the learning goal produced a larger response time contingency effect than did the control participants. In contrast to some results from other learning paradigms, these results suggest that intentional learning adds to, rather than interferes with, unintentional learning, and we propose an explanation for some of the conflicting results.     

An implicit enumeration method for an exact test of weighted kappa

The kappa coefficient is one of the most widely used measures for evaluating the agreement between two raters asked to assign N objects to one of K nominal categories. Weighted versions of kappa enable partial credit to be awarded for near agreement, most notably in the case of ordinal categories. An exact significance test for weighted kappa can be conducted by enumerating all rater agreement tables with the same fixed marginal frequencies as the observed table, and accumulating the probabilities for all tables that produce a weighted kappa index that is greater than or equal to the observed measure. Unfortunately, complete enumeration of all tables is computationally unwieldy for modest values of N and K. We present an implicit enumeration algorithm for conducting an exact test of weighted kappa, which can be applied to tables of non‐trivial size. The algorithm is particularly efficient for ‘good’ to ‘excellent’ values of weighted kappa that typically have very small p‐values. Therefore, our method is beneficial for situations where resampling tests are of limited value because the number of trials needed to estimate the p‐value tends to be large.     

The Fisher-Pitman permutation test: an attractive alternative to the F test

The Fisher-Pitman permutation test is shown to possess significant advantages over conventional alternatives when analyzing differences among independent samples with unequal variances.     

Effects of aging on implicit sequence learning: Accounting for sequence structure and explicit knowledge

The present research was intended to examine the sequence learning ability of elderly people — with a focus on comparing sequences with different structural characteristics and on properly assessing explicit knowledge. Experiment 1 showed that learning-related improvements in serial reaction time task performance were greater for young than elderly subjects, and elderly subjects were especially poor at learning a sequence with complex structural characteristics. Measures of recognition memory showed that neither young nor elderly subjects showed above-chance explicit knowledge of the sequences. Experiment 2 was designed to test the validity and sensitivity of the explicit recognition measures by comparing young subjects in groups given all random trials, given sequence trials with implicit instructions, or given sequence trials with explicit instructions. Experiment 2 confirmed the sensitivity of the recognition measures to explicit knowledge, so it is concluded that group effects in Exp. 1 reflect age-related differences in implicit learning.     

Self-generated cognitive fluency as an alternative route to preference formation

People tend to prefer fluently processed over harder to process information. In this study we examine two issues concerning fluency and preference. First, previous research has pre-selected fluent and non-fluent materials. We did not take this approach yet show that the fluency of individuals’ idiosyncratic on-line interactions with a given stimulus can influence preference formation. Second, while processing fluency influences preference, the opposite also may be true: preferred stimuli could be processed more fluently than non-preferred. Participants performed a visual search task either before or after indicating their preferred images from an array of either paintings by Kandinsky or decorated coffee mugs. Preferred stimuli were associated with fluent processing, reflected in facilitated search times. Critically, this was only the case for participants who gave their preferences after completing the visual search task, not for those stating preferences prior to the visual search task. Our results suggest that the spontaneous and idiosyncratic experience of processing fluency plays a role in forming preference judgments and conversely that our first impressions of preference do not drive response fluency.     

Mindfulness reduces habitual responding based on implicit knowledge: Evidence from artificial grammar learning

Participants were unknowingly exposed to complex regularities in a working memory task. The existence of implicit knowledge was subsequently inferred from a preference for stimuli with similar grammatical regularities. Several affective traits have been shown to influence AGL performance positively, many of which are related to a tendency for automatic responding. We therefore tested whether the mindfulness trait predicted a reduction of grammatically congruent preferences, and used emotional primes to explore the influence of affect. Mindfulness was shown to correlate negatively with grammatically congruent responses. Negative primes were shown to result in faster and more negative evaluations. We conclude that grammatically congruent preference ratings rely on habitual responses, and that our findings provide empirical evidence for the non-reactive disposition of the mindfulness trait.     

Semantic processing in an incidental learning task

Recent research on implicit learning has suggested that perceptual learning could account for the observed dissociation between task performance and associated verbal knowledge. We report three experiments that investigate whether performance in an incidental learning task is based on knowledge held primarily at a perceptual or a semantic level. The results indicate that, under the task conditions described, processing of the semantic content of the stimuli is an automatic process. The implications of this result for implicit learning are discussed.