Assessing Sequential Knowledge through Performance Measures: The Influence of Short-term Sequential Effects

Studies on implicit sequence learning have employed the methodology oftask dissociations to show that tasks of conscious memory fail to reveal knowledge expressed in performance measures of learning. One critical requirement of this methodology is that the conscious memory tests tap the same type of information that is expressed in performance measures. When a deterministic sequence is being repeated during practice, identification of the exact type of sequential information that is learned can be achieved by a trial-by-trial comparison between the practised sequence and a control sequence. In Experiment 1 we examine whether short-term sequential effects are present in choice response time tasks and may therefore contaminate this trial-by-trial comparison. In Experiment 2 we control for these effects and demonstrate how specification of the exact sub-parts of the sequence that are learned is necessary before testing for task dissociations. Our findings indicate a dissociation between a response time task and a free generation task. This dissociation, however, is obtained for selected sub-parts of the sequence and may be caused by the insensitivity of the free-generation task to low confidence knowledge.     

Representation of memory for order of mental operations in cognitive tasks

Recent research shows that people learning a cognitive task acquire a memory for the order of operations applied, independent of the data to which those operations were applied. We designed two experiments to show how this sequence memory is represented. Experiment 1 compared predictions based on 3 possible sequence representation methods: composition, dyad transition, and associative chain. Latency and error results from a simple sequential task supported the associative chain representation. The associative links between operations presumably enhance performance by priming subsequent operations but do not operate in an all-or-none fashion. Experiment 2 explored whether transfer items that matched the first 2 rules and first 3 elements of a training item could bias participants toward executing a composed production learned during training. Latency and undetected error results were consistent with an associative chain representation but not with additional predictions made by the composition representation. These two experiments support the representation of operation sequences in memory as an associative chain.     

On the modularity of implicit sequence learning: independent acquisition of spatial, symbolic, and manual sequences

Learning sequential structures is of fundamental importance for a wide variety of human skills. While it has long been debated whether implicit sequence learning is perceptual or response-based, here we propose an alternative framework that cuts across this dichotomy and assumes that sequence learning rests on associative changes that can occur concurrently in distinct processing systems and support the parallel acquisition of multiple uncorrelated sequences. In three experiments we used a serial search task to test critical predictions of this framework. Experiments 1 and 2 showed that participants learnt uncorrelated sequences of auditory letters and manual responses, as well as sequences of visual letters, spatial locations, and manual responses simultaneously, as indicated by a reliable response time (RT) cost incurred by occasional deviants violating either of the sequences. This RT cost was reliable even when participants showing explicit knowledge were excluded. In Experiment 3 learning of spatial and nonspatial sequences was functionally dissociated: whereas a spatio-motor distractor task disrupted learning of location but not of letter sequences, a phonological distractor task had the reverse effect. The distractor tasks thus did not reduce unspecific attentional resources, but selectively disrupted the formation of sequential associations within spatial and nonspatial processing dimensions. These results support the view that implicit sequence learning rests on experience-dependent changes that can occur in parallel in multiple processing systems involved in spatial attention, object recognition, phonological processing, and manual response selection. The resulting dimension-specific sequence representations support independent predictions of what will appear next, where it will appear, and how one will have to respond to it.     

Congruency sequence effect without feature integration and contingency learning

The magnitude of congruency effects, such as the flanker-compatibility effects, has been found to vary as a function of the congruency of the previous trial. Some studies have suggested that this congruency sequence effect is attributable to stimulus and/or response priming, and/or contingency learning, whereas other studies have suggested that the control process triggered by conflict modulates the congruency effect. The present study examined whether sequential modulation can occur without stimulus and response repetitions and contingency learning. Participants were asked to perform two color flanker-compatibility tasks alternately in a trial-by-trial manner, with four fingers of one hand in Experiment 1 and with the index and middle fingers of two hands in Experiment 2, to avoid stimulus and response repetitions and contingency learning. A significant congruency sequence effect was obtained between the congruencies of the two tasks in Experiment 1 but not in Experiment 2. These results provide evidence for the idea that the sequential modulation is, at least in part, an outcome of the top-down control process triggered by conflict, which is specific to response mode.     

Generalized and specific expectancies: Sequential mediators of interpersonal behavior1

Two experiments confirmed sequential mediation of social interaction by investigating the effects of generalized expectancies on specific expectancies and the effects of specific expectancies on performance. Both experiments used a simulated tutoring task in which the subject took the role of tutor while a confederate took the role of student. In Experiment 1 subjects combined generalized expectancies about the effectiveness of certain tutoring responses with specific situational information to produce specific expectancies about the results of the tutoring responses under the experimental circumstances. Experiment 2 replicated this finding and showed that specific expectancies of the relative effectiveness of different responses influenced which response was performed more. Results were discussed in terms of cognitive motivation theory and social learning theory.     

Differential impact of relevant and irrelevant dimension primes on rule-based and information-integration category learning

Research has identified multiple category-learning systems with each being “tuned” for learning categories with different task demands and each governed by different neurobiological systems. Rule-based (RB) classification involves testing verbalizable rules for category membership while information-integration (II) classification requires the implicit learning of stimulus–response mappings. In the first study to directly test rule priming with RB and II category learning, we investigated the influence of the availability of information presented at the beginning of the task. Participants viewed lines that varied in length, orientation, and position on the screen, and were primed to focus on stimulus dimensions that were relevant or irrelevant to the correct classification rule. In Experiment 1, we used an RB category structure, and in Experiment 2, we used an II category structure. Accuracy and model-based analyses suggested that a focus on relevant dimensions improves RB task performance later in learning while a focus on an irrelevant dimension improves II task performance early in learning.     

Sequence learning by action,observation and action observation

The serial reaction time (SRT) task was used to compare learning of a complex sequence by action (participants responded to sequential stimuli), by observation (participants watched but did not respond to sequential stimuli), and by action‐observation (participants watched an expert model responding to sequential stimuli). Each of these groups was compared with an untrained control group. Experiment 1 indicated that both observation and action‐observation were sufficient to support learning of a 12‐item second‐order conditional (SOC) sequence. Experiment 2 confirmed these findings, and showed that, as indexed by reaction time (RT), the extent of learning by observation and by action‐observation was comparable to that of action‐based learning. Using a recognition test, Experiment 2 and 3 also provided evidence that, whereas learning by stimulus observation was explicit, learning by action‐observation was implicit. These findings are consistent with a connection between motor systems and implicit learning, but do not support the hypothesis that overt action is necessary for implicit learning.     

Context dependent learning in the serial RT task

This study investigated the development of contextual dependencies for sequential perceptual-motor learning on static features in the learning environment. In three experiments we assessed the effect of manipulating task irrelevant static context features in a serial reaction-time task. Experiment 1 demonstrated impaired performance after simultaneously changing display color, placeholder shape, and placeholder location. Experiment 2 showed that this effect was mainly caused by changing placeholder shape. Finally, Experiment 3 indicated that changing context affected both the application of sequence knowledge and the selection of individual responses. It is proposed either that incidental stimulus features are integrated with a global sequence representation, or that the changed context causes participants to strategically inhibit sequence skills.     

Comparisons of some learning models for response bias in signal detection

The effects of variations in signal probability and varying degrees of correct feedback on response bias were studied in a yes-no auditory signal detection task. The main finding was that the bias towards saying yes was an increasing function of the frequency of signal feedback events, but did not depend on the correctness of the feedback. Several learning models coupled with a simple psychophysical and decision model yielded predictions about overall biases and certain sequential statistics. Only one model, which can be decribed as an “informational” model, gave a good account of both observed overall biases and sequential statistics. This model assumes the observer’s response bias is strengthened for the feedback-reinforced response when the observer’s sensory information is ambiguous or is contradicted by the feedback information.     

The locus of self-inhibition in sequential retrieval

Self-inhibition refers to the suppression of a representational node following its use in a sequential task. Two general models of self-inhibition exist in the literature: one that models suppression following activation of a node (Houghton & Tipper, 1994), and one that models suppression following motor production of a node (MacKay, 1986). These two models make opposite predictions for units that are activated but not produced, with the post-activation model predicting interference and the post-production model predicting facilitation. These predictions were tested using operand--answer priming in two mental addition experiments. Addition problems with sums <10 were primed with addition problems that contained the correct sum as one of the operands (e.g., 5 + 8 preceding 3 + 2). Experiment 2 included an additional manipulation of prime-target discriminability to rule out episodic retrieval accounts of the interference effect. Both experiments indicated interference following operand-answer primes relative to control primes, consistent with the predictions of the post-activation model of self-inhibition.     

Dual-task interference in perceptual category learning

The effect of a working-memory-demanding dual task on perceptual category learning was investigated. In Experiment 1, participants learned unidimensional rule-based or information integration category structures. In Experiment 2, participants learned a conjunctive rule-based category structure. In Experiment 1, unidimensional rule-based category learning was disrupted more by the dual working memory task than was information integration category learning. In addition, rule-based category learning differed qualitatively from information integration category learning in yielding a bimodal, rather than a normal, distribution of scores. Experiment 2 showed that rule-based learning can be disrupted by a dual working memory task even when both dimensions are relevant for optimal categorization. The results support the notion of at least two systems of category learning a hypothesis-testing system that seeks verbalizable rules and relies on working memory and selective attention, and an implicit system that is procedural-learning based and is essentially automatic.     

Remembered duration: working memory and the reproduction of intervals

On the basis of attention allocation models of time estimation, the role of working memory in prospective duration reproduction is explored. In four experiments, adult participants performed a counting task (duration, 400 sec) that allowed coordinative and sequential demands on working memory to be varied. After completing the counting task, the participants reproduced the time that they had worked on this task It emerged that (1) increased coordinative demands on working memory (but not increased sequential demands) reduced the accuracy of prospective duration reproduction (Experiments 1 and 2), (2) presenting context information during the reproduction phase enhanced the accuracy of the reproduced duration (Experiment 3), and (3) individual differences in coordinative working memory capacity affected duration reproduction in the same direction as the experimental manipulation of coordinative task demands (Experiment 4). The results suggest that attention allocation models of time estimation may benefit from taking a more differentiated view of the types of attentional demands that affect temporal cognition.     

Practice effects on two memory retrievals from a single cue

The effects of practice on 2 retrievals from a single cue were investigated. In Experiment 1, participants were given extended single-task practice and were then tested on a dual memory retrieval task. Perfomance was consistent with a sequential retrieval model proposed by T. C. Rickard and H. Pashler (2003). In Experiment 2, participants practiced both single- and dual-retrieval tasks extensively. Initially, data from all participants indicated sequential retrieval. However, participants who grouped the 2 response outputs were eventually able to perform the dual task with a latency that approached the prediction of a parallel race model. Models that assume a transition from sequential to parallel retrieval with practice, along with other models that assume an immutable retrieval bottleneck at all practice levels, are considered.     

The processing of task-irrelevant emotion and colour in the Approach-Avoidance Task

When processing information about human faces, we have to integrate different sources of information like skin colour and emotional expression. In 3 experiments, we investigated how these features are processed in a top-down manner when task instructions determine the relevance of features, and in a bottom-up manner when the stimulus features themselves determine process priority. In Experiment 1, participants learned to respond with approach-avoidance movements to faces that presented both emotion and colour features (e.g. happy faces printed in greyscale). For each participant, only one of these two features was task-relevant while the other one could be ignored. In contrast to our predictions, we found better learning of task-irrelevant colour when emotion was task-relevant than vice versa. Experiment 2 showed that the learning of task-irrelevant emotional information was improved in general when participants’ awareness was increased by adding NoGo-trials. Experiment 3 replicated these results for faces and emotional words. We conclude that during the processing of faces, both bottom-up and top-down processes are involved, such that task instructions and feature characteristics play a role. Ecologically significant features like emotions are not necessarily processed with high priority. The findings are discussed in the light of theories of attention and cognitive biases.     

Retrieving texts from an external store: the effects of an explanatory context and of semantic fit between text and address

Summary External-information storage may reduce the load on human memory. But if information is preserved in an external store the task of retrieving information from that store puts new demands on memory. This creates a trade-off between internal and external storage. One of the prerequisites for external retrieval is learning an address. In this study, the trade-off between internal and external retrieval is exemplified by contrasting the memorization of written texts with the memorization of addresses under which these texts are stored in a computer file. In Experiment 1 Ss were tested for the retention of addresses. In Experiment 2 they were tested for the retention of texts, but had the choice between memorizing the texts and memorizing an address under which the texts were available. Independent variables were the availability of an explanatory context, and the semantic fit between address and text. An explanatory context improved address learning in Experiment 1 and unaided recall in Experiment 2. It did not influence the utilization of addresses as tested in Experiment 2. The semantic fit between address and text had a considerable impact on both the learning and the utilization of addresses. Whereas some subjects were assigned standard addresses, others generated their own addresses. Self-generated addresses had effects similar to standard addresses selected for high semantic fit. It is suggested that learning an external address involves an internal representation of the material stored under that address.     

Peak Shift on an Artificial Dimension

Blough (1975) proposed an elemental model of generalization and discrimination phenomena in which stimuli from physical dimensions, such as wavelength, are conceptualized as overlapping sets of elements. In order to test predictions generated by this model, we constructed an artificial 'dimension' of stimuli as a series of overlapping sets of arbitrary 'icons' (small, unrelated shapes). In Experiment 1, we trained pigeons to discriminate two neighbouring stimuli from this artificial dimension and then assessed their responses to other stimuli from the dimension. The results of these tests typified those obtained with stimuli from genuine physical dimensions-that is, we obtained positive and negative peak shifts. In Experiment 2, human subjects were given a similar discrimination task and produced an analogous set of results to those of the pigeons. These results support Blough's elemental theory and are not readily accommodated by Pearce's (1987) configural theory. In Experiment 3, both humans and pigeons were trained and tested with stimuli from a real physical dimension (luminance). The pigeons' results were again consistent with Blough's analysis, but those of the humans suggested the use of more sophisticated strategies that are unavailable to pigeons and that lie outside the scope of elemental models of discrimination learning.     

Generalizing attentional control across dimensions and tasks: Evidence from transfer of proportion-congruent effects

Three experiments investigated transfer of list-wide proportion congruent (LWPC) effects from a set of congruent and incongruent items with different frequency (inducer task) to a set of congruent and incongruent items with equal frequency (diagnostic task). Experiments 1 and 2 mixed items from horizontal and vertical Simon tasks. Tasks always involved different stimuli that varied on the same dimension (colour) in Experiment 1 and on different dimensions (colour, shape) in Experiment 2. Experiment 3 mixed trials from a manual Simon task with trials from a vocal Stroop task, with colour being the relevant stimulus in both tasks. There were two major results. First, we observed transfer of LWPC effects in Experiments 1 and 3, when tasks shared the relevant dimension, but not in Experiment 2. Second, sequential modulations of congruency effects transferred in Experiment 1 only. Hence, the different transfer patterns suggest that LWPC effects and sequential modulations arise from different mechanisms. Moreover, the observation of transfer supports an account of LWPC effects in terms of list-wide cognitive control, while being at odds with accounts in terms of stimulus–response (contingency) learning and item-specific control.     

编码时间对序列视觉信息整合的影响

本研究采用空白单元格定位任务,探讨序列刺激整合的时间特性。实验1重复前人的实验,验证了时间间隔对整合绩效的影响;实验2系统操纵了对先前刺激的编码时间与时间间隔,结果发现,编码时间越长,记忆的效果越好,虽然会妨碍对随后刺激的知觉,但整合绩效越高;而随着时间间隔的延长,延长编码时间带来的优势逐渐减弱。结论提示,人们能够整合视觉短时记忆和视知觉的信息,而且这种整合的时间特性不同于知觉整合。     

Exploring the relationship between new word learning and short-term memory for serial order recall,item recall,and item recognition

We reexplored the relationship between new word learning and verbal short-term memory (STM) capacities, by distinguishing STM for serial order information, item recall, and item recognition. STM capacities for order information were estimated via a serial order reconstruction task. A rhyme probe recognition task assessed STM for item recognition. Item recall capacities were derived from the proportion of item errors in an immediate serial recall task. In Experiment 1, strong correlations were observed between item recall and item recognition, but not between the item STM tasks and the serial order task, supporting recent theoretical positions that consider that STM for item and serial order rely on distinct capacities. Experiment 2 showed that only the serial order reconstruction task predicted independent variance in a paired associate word–nonword learning task. Our results suggest that STM capacities for serial order play a specific and causal role in learning new phonological information.