Exploring the forgetting mechanisms in working memory: Evidence from a reasoning span test

In working memory (WM) span tests participants have to maintain to-be-remembered information while processing other, potentially distracting, information. Previous studies have shown that WM span scores are greater when span lists start with a long processing task and end with a short processing task than when these processing tasks are presented in the reverse order (e.g., Towse, Hitch, & Hutton, 2000). In Experiment 1, we obtained a similar stimulus order effect in a reasoning span test, using reasoning sentences that were equated for length in terms of the number of constituent words, but which differed in processing complexity; span scores were greater when lists began with a complex sentence and ended with a simple sentence than when this stimulus order was reversed. In Experiment 2, the stimulus order effect was not found when processing duration was held constant while sentence complexity was varied using a computer-paced moving window presentation paradigm. These results suggest that duration-based constraints can affect degree of forgetting independently of the load generated during processing phases in WM span performance and therefore imply that time-related forgetting can occur in WM span tests, particularly when the difficulty of the processing component blocks active maintenance of to-be-remembered material.     

The Measurement of Verbal Working Memory Capacity and Its Relation to Reading Comprehension

Ninety-four subjects were tested on the Daneman and Carpenter (1980) reading span task, four versions of a related sentence span task in which reaction times and accuracy on sentence processing were measured along with sentence-final word recall, two number generation tasks designed to test working memory, digit span, and two shape-generation tasks designed to measure visual-spatial working memory. Forty-four subjects were retested on a subset of these measures at a 3-month interval. All subjects were tested on standard vocabulary and reading tests. Correlational analyses showed better internal consistency and test-retest reliability of the sentence span tasks than of the Daneman-Carpenter reading span task. Factor analysis showed no factor that could be related to a central verbal working memory; rotated factors suggested groupings of tests into factors that correspond to digitrelated tasks, spatial tasks, sentence processing in sentence span tasks, and recall in sentence span tasks. Correlational analyses and regression analyses showed that the sentence processing component of the sentence span tasks was the best predictor of performance on the reading test, with a small independent contribution of the recall component. The results suggest that sentence span tasks are unreliable unless measurements are made of both their sentence processing and recall components, and that the predictive value of these tasks for reading comprehension abilities lies in the overlap of operations rather than in limitations in verbal working memory that apply to both.     

The influence of story context on a working memory span task

The purpose of the present study was to examine factors that could influence whether recall performance in the reading span task (Daneman & Carpenter, 1980 ) would benefit from the contextual information from the sentences in the processing component of the task. More specifically, we investigated whether people would benefit from sentence sets that formed short stories or when the entire span task was one continuous story. Overall, there was a clear benefit for contextually related sentence sets (i.e., the story span tasks) compared to the traditional reading span task. However, the benefit was eliminated when the entire set formed one continuous story. These results support the recall reconstruction hypothesis for working memory (Towse, Cowan, Hitch, & Horton, 2008 ), which suggests that people may strategically use the content of the sentences from the processing component of the reading span task as memorial cues to reconstruct the target words of the storage component. However, this benefit is constrained to scenarios when the contextual cues are unique to a specific set.     

Role of Working Memory in Typically Developing Children’s Complex Sentence Comprehension

The influence of three mechanisms of working memory (phonological short-term memory (PSTM capacity), attentional resource control/allocation, and processing speed) on children's complex (and simple) sentence comprehension was investigated. Fifty two children (6-12 years) completed a nonword repetition task (indexing PSTM), concurrent verbal processing-storage task (indexing resource control/allocation), auditory-visual reaction time (RT) task (indexing processing speed), and a sentence comprehension task that included complex and simple sentences. Correlation and regression analyses were run to determine the association between the memory variables and sentence comprehension accuracy. Results revealed: (1) none of the memory variables correlated with simple sentence comprehension, (2) resource control/allocation and processing speed correlated significantly with complex sentence comprehension, even after covarying for age, and (3) attentional functioning and processing speed predicted complex sentence comprehension (after accounting for age). Results were interpreted to suggest that working memory is significantly involved in school age children's comprehension of familiar complex sentence structures.     

When motion improves working memory

ABSTRACT

In the present study, we used a complex span task to explore how memory traces resulting from Self-Performed Task (SPT) and Verbal Task (VT) are maintained in working memory. Participants memorised series of five sentences describing an action either through SPT or VT. Between pairs of sentences, participants performed a concurrent task that varied according to its nature and its cognitive load. The concurrent task was either a verbal task, a low cognitive load motor task or a high cognitive load motor task. A control condition served as a baseline. First, we observed that performance in SPT and VT did not decrease with verbal or motor suppression, but was lower with an increase of the cognitive load. This suggests that memory traces are maintained through attentional refreshing whatever the encoding (SPT or VT). Second, while the enactment effect was replicated in the control condition, it tended to vanish with a verbal concurrent task; moreover, it was reversed with motor concurrent tasks. Surprisingly, the latter effect resulted from an increase of VT memory performance when participants repeated the same gesture between sentences. Finally, our results provide additional evidence that the enactment effect does not rely on attention.     

Working memory, attention control, and the N-back task: a question of construct validity

The N-back task requires participants to decide whether each stimulus in a sequence matches the one that appeared n items ago. Although N-back has become a standard "executive" working memory (WM) measure in cognitive neuroscience, it has been subjected to few behavioral tests of construct validity. A combined experimental- correlational study tested the attention-control demands of verbal 2- and 3-back tasks by presenting n = 1 "lure" foils. Lures elicited more false alarms than control foils in both 2- and 3-back tasks, and lures caused more misses to targets that immediately followed them compared with control targets, but only in 3-back tasks. N-back thus challenges control over familiarity-based responding. Participants also completed a verbal WM span task (operation span task) and a marker test of general fluid intelligence (Gf; Ravens Advanced Progressive Matrices Test; J. C. Raven, J. E. Raven, & J. H. Court, 1998). N-back and WM span correlated weakly, suggesting they do not reflect primarily a single construct; moreover, both accounted for independent variance in Gf. N-back has face validity as a WM task, but it does not demonstrate convergent validity with at least 1 established WM measure.     

Effects of age, speed of processing, and working memory on comprehension of sentences with relative clauses

Two hundred participants, 50 in each of four age ranges (19-29, 30-49, 50-69, 70-90) were tested for working memory, speed of processing, and the processing of sentences with relative clauses. In Experiment 1, participants read four sentence types (cleft subject, cleft object, subject-subject, subject-object) in a word-by-word, non-cumulative, self-paced reading task and made speeded plausibility judgments about them. In Experiment 2, participants read two types of sentences, one of which contained a doubly center embedded relative clause. Older participants' comprehension was less accurate and there was age-related slowing of online processing times in all but the simplest sentences, which increased in syntactically complex sentences in Experiment 1. This pattern suggests an age-related decrease in the efficiency of parsing and interpretation. Slower speed of processing and lower working memory were associated with longer online processing times only in Experiment 2, suggesting that task-related operations are related to general speed of processing and working memory. Lower working memory was not associated with longer reading times in more complex sentences, consistent with the view that general working memory is not critically involved in online syntactic processing. Longer online processing at the most demanding point in the most demanding sentence was associated with better comprehension, indicating that it reflects effective processing under some certain circumstances. However, the poorer comprehension performance of older individuals indicates that their slower online processing reflects inefficient processing even at these points.     

工作记忆、语境限制强度和句子长度对二语词汇学习的影响

本研究选取初二、高二、大三三个年龄段的被试,考察在句子阅读过程中,工作记忆容量、语境限制强度和句子长度对第二语言词汇学习的影响。研究结果发现,在句子阅读条件下,工作记忆容量是影响第二语言词汇学习的重要因素,高工作记忆容量促进了第二语言词汇的学习;在中等和长句子的条件下,语境的限制性越强,词汇学习的成绩越好;相比初二年龄组被试,高二和大三年龄组被试,在低语境限制性的情况下,阅读的句子越长,第二语言词汇学习效果越差。研究结果说明,个体工作记忆的容量,以及阅读材料等变量,都是影响自然阅读条件下二语词汇学习的重要因素。     

Processing and storage in working memory span

Two experiments are reported that address theoretical assumptions as to the nature of working memory involved in working memory span tasks (Daneman & Carpenter, 1980). Experiment 1 used a version of the sentence span task, and Experiment 2 combined arithmetic verification with recall of presented words. In each experiment, working memory processing span was assessed independently of temporary storage span prior to their combination. Combined task performance under high demand for each component resulted in substantial residual performance for both task elements, particularly in Experiment 2. The results do not challenge the utility of the sentence span task as a measure of on-line cognition, but they raise concerns as to how resource might be allocated to processing and storage elements of the task within a single flexible resource pool, or between different resources of a multiple component working memory system. Although both models lack predictive power regarding resource allocation in these tasks, the multiple resource model appears to offer the better account.     

Stimulus similarity decrements in children's working memory span

Two experiments investigated the impact of the relationship between processing and storage stimuli on the working memory span task performance of children aged 7 and 9 years of age. In Experiment 1, two types of span task were administered (sentence span and operation span), and participants were required to recall either the products of the processing task (sentence-final word, arithmetic total) or a word or digit unrelated to the processing task. Experiment 2 contrasted sentence span and operation span combined with storage of either words or digits, in tasks in which the item to be remembered was not a direct product of the processing task in either condition. In both experiments, memory span was significantly greater when the items to be recalled belonged to a different stimulus category from the material that was processed, so that in sentence span tasks, number recall was superior to word recall, and in operation span tasks, word recall was superior to number recall. Explanations of these findings in terms of similarity-based interference and response competition in working memory are discussed.     

Differential constraints on the working memory and reading abilities of individuals with learning difficulties and typically developing children

This study examined the factors that constrain the working memory span performance and reading ability of individuals with generalized learning difficulties. In the study, 50 individuals with learning difficulties (LD) and 50 typically developing children (TD) matched for reading age completed two working memory span tasks. Participants also completed independent measures of the processing and storage operations involved in each working memory span task and Raven's Coloured Progressive Matrices. The results showed that despite an equivalent level of working memory span, the relative importance of the constraints on working memory differed between the groups. In addition, working memory span was not closely related to word recognition or sentence comprehension performance in the LD group. These results suggest that the working memory span performance of LD and TD individuals may reflect different working memory limitations and that individuals with generalized learning difficulties may approach cognitive tasks in a qualitatively different way from that of typically developing individuals.     

Attention switching and working memory spans

Barrouillet and Camos () concluded from their developmental study on working memory that when performing complex span tasks, individuals maintain memory items by switching rapidly their attention from processing to storage while performing the concurrent task. Thus, a processing component that would require a continuous attentional focusing should have a highly detrimental effect on span. The present study verifies two predictions issuing from this hypothesis by comparing the classical self‐paced reading and operation span tasks with new computer‐paced tasks in adults. First, any increase in the pace at which the processing component of a working memory span task has to be performed impedes switching and then leads to lower spans. Second, when presented at a fast pace, even simple activities such as reading letters or adding and subtracting 1 to small numbers have an effect on spans as detrimental as complex activities like reading and understanding sentences or solving complex equations.     

Executive control is shared between sentence processing and digit maintenance: Evidence from a strictly timed dual-task paradigm

We investigated whether the comprehension of syntactically difficult sentences taxes the executive control component of working memory more than the comprehension of their easier counterparts. To that end, we tested the effect of sharing executive control between sentence comprehension and the maintenance of a digit load in two dual-task experiments with strictly controlled timing (Barrouillet, Bernardin, & Camos, 2004). Recall was worse after participants had processed one (Experiment 2) or two (Experiment 1) difficult sentences than after they had processed one or two easy sentences, respectively. This finding suggests that sentence processing and the maintenance of a digit load share executive control. Processing syntactically difficult sentences seems to occupy executive control for a longer time than processing their easy counterparts, thereby blocking refreshments of the memory traces of the digits so that these traces decay more and recall is worse. There was no effect of the size of the digit load on sentence-processing performance (Experiment 2), suggesting that sentence processing completely occupied executive control until processing was complete.     

工作记忆广度：资源限制、记忆消退还是转换机制？

为了检验工作记忆广度有限性的3种假说,即资源限制假说、记忆消退假说和转换机制假说,实验要求被试首先完成一项转换效率任务,然后完成工作记忆广度任务。结果发现,加工负荷对工作记忆广度具有重要影响,保持时间不影响工作记忆广度,转换效率与工作记忆广度也没有显著相关。实验结果支持工作记忆广度受认知资源限制的观点     

Children's working-memory processes: a response-timing analysis

Recall response durations were used to clarify processing in working-memory tasks. Experiment 1 examined children's performance in reading span, a task in which sentences were processed and the final word of each sentence was retained for subsequent recall. Experiment 2 examined the development of listening-, counting-, and digit-span task performance. Responses were much longer in the reading-and listening-span tasks than in the other span tasks, suggesting that participants in sentence-based span tasks take time to retrieve the semantic or linguistic structure as cues to recall of the sentence-final words. Response durations in working-memory tasks helped to predict academic skill and achievement, largely separate from the contributions of the memory spans themselves. Response durations thus are important in the interpretation of span task performance.     

Discrimination of differences in digitally manipulated phoneme length during speech

The present study investigated differences in the thresholds of phoneme duration in word and sentence contexts by participants' sex. In the word condition, 27 participants listened to two pairs of words in a dual pair discrimination task. One pair contained the same durations of /s/, and the other pair contained different durations of /s/. Participants were to select the pair which contained different durations of /s/ in the words. In the sentence condition, the other set of 27 participants listened to two pairs of sentences and selected the pair containing different durations of /s/ in the sentences. Throughout these tasks, the participants' just-noticeable-difference and trials-to-completion were analyzed. The results showed that the participants demonstrated better performance in detecting just-noticeable-difference in the sentence condition than in the word condition. In addition, a sex difference was found in just-noticeable-difference in both conditions with better performance in men than women. No significant differences in trials-to-completion were found in either condition.     

“热”执行对注意缺陷多动障碍和阅读障碍儿童言语工作记忆的影响

ADHD儿童在与背外侧前额叶(DLPFC)相关的"冷"执行功能上的缺陷已大量证实,但在与眼眶和中前额叶皮层(OMPFC)相关的"热"执行功能上,ADHD儿童是否存在缺陷则未可知。与儿童赌博任务实验范式(该任务中"热"启动对"冷"执行起到抑制作用)不同,本研究考察趣味言语N-back任务是否对ADHD和阅读障碍儿童的成绩有促进作用。枯燥N-back任务考察的是言语工作记忆的纯认知特征,而趣味任务则卷入了"热"执行对"冷"执行的影响。结果表明,在枯燥任务上,ADHD和阅读障碍儿童的成绩均明显低于正常儿童,二者之间差异不显著,在趣味任务成绩上,ADHD儿童与正常儿童的成绩没有显著差异,而阅读障碍儿童成绩落后于正常控制组和ADHD组,在成绩变化的趋势上,ADHD儿童在趣味任务上成绩明显提高,而阅读障碍儿童则无明显改善。结果说明ADHD和阅读障碍儿童的言语工作记忆均存在明显的缺陷,但是机制不同,"热"执行对提高ADHD的言语工作记忆有明显的促进作用,ADHD的"冷"执行缺陷能够通过"热"执行的调节得到改善。     

简单算术对汉语特定句型的结构启动

结构启动是指个体在产生或理解一个结构时,倾向于重复使用或仿照刚刚加工过的结构。与句法启动不同的是,结构启动除了以句子,也可以以其它抽象结构作为启动项。Scheepers et al. (2011) 首次以具有结构偏向性的抽象算式作为启动项,证实了高附着和低附着的简单算式对英语母语者产出高附着和低附着关系从句具有结构启动效应。在此基础上,本研究引用数学算式作为启动项,以汉语特定句型结构NP1+有+NP2+恨+(AP)为切入点,分别选取汉语成人和儿童受试,检验简单算式对汉语母语者产出或理解特定句型的结构启动效应。本研究发现：1）算式结构对汉语特定句型的产出具有结构启动效应。2）算式结构对汉语歧义句的解读具有结构启动效应。3）儿童和成人在产出和理解的启动实验中具有不同结构启动效应,且儿童的结构启动效应比成人的结构启动效应更强。4）算式结构和语言句式在认知上具有共享的结构表征。     

The reliability and stability of verbal working memory measures

The psychometric properties of several commonly used verbal working memory measures were assessed. One hundred thirty-nine individuals in five age groups (18–30, 50–59, 60–69, 70–79, and 80+ years) were tested twice (Time I and Time II) on seven working memory span measures (alphabet span, backward digit span, missing digit span, subtract 2 span, running item span, and sentence span for syntactically simple and complex sentences), with an interval of approximately 6 weeks between testing. There were significant effects of age on all but two of the tasks. All the measures had adequate internal consistency. Correlations between performances at Time I and Time II were significant for all the tasks, other than the missing digit span task. The magnitude of the correlations was similar across the age groups and ranged from .52 to .81. Classification of subjects into discrete memory span groups on the basis of a single measure was highly inconsistent across testing sessions and tasks. Classification into upper and lower quartiles was more stable than using a cutoff score for group membership or than classification into high-, medium-, and low-span groups. Correlational analyses showed that there was a moderate relationship between performances on many of the span tasks. Confirmatory factor analysis suggested that six of the seven tasks reflected a common factor. Both test—retest reliability and stability of classification improved when a composite measure reflecting performance on several tasks was used.     

Phonological similarity effects in simple and complex span tasks

Three experiments were conducted to examine the effect of phonological similarity in simple and complex memory span tasks. In Experiment 1, participants performed either a simple or a complex span task, and the memoranda within lists were either phonologically similar or distinct. Phonologically similar lists consisted of words that rhymed.The simple span task was word span. There were two complex span tasks; one was the original reading span task, and the other was a variant of reading span in which all the sentences within a list were contextually related. The classic phonological similarity decrement was observed in word span. In contrast, phonological similarity facilitation was observed in both versions of reading span. This facilitation effect was further investigated in Experiment 2 using two new versions of reading span. In Experiment 2, the sentences in reading span were either short or long, and the memoranda were presented separately from, and were unrelated to, the sentences. Again, words within phonologically similar lists rhymed, and again, facilitation was observed. In Experiment 3, phonological similarity was operationalized in terms of feature overlap, rather than rhyme. The classic phonological similarity decrement was still observed in word span, but facilitation was not observed in complex span. The results suggest that phonological similarity, when operationalized using words that rhyme, serves as a list retrieval cue and that complex span tasks are more dependent on cue-driven memory retrieval mechanisms than are simple span tasks.