Phonological similarity in working memory

That phonologically similar words in a short-term memory test are more difficult to recall than phonologically dissimilar words is a well-known phenomenon. This effect is the phonological similarity decrement. In the present study, we examined whether this phonological similarity decrement is present when additional semantic information is available, as in a reading span test, as compared with a standard presentation, or in the context of an operation span test. The results revealed a phonological similarity facilitation. Phonologically similar words were remembered better than phonologically dissimilar words.     

Eye movements and the identification of spatially ambiguous words during Chinese sentence reading

Readers of Chinese must generally determine word units in the absence of visually distinct inter-word spaces. In the present study, we examined how a sequence of Chinese characters is parsed into words under these conditions. Eye movements were monitored while participants read sentences with a critical four-character (C1234) sequence. Three partially overlapping character groupings formed legal words in the ambiguous condition (C12, C23, and C34), two of which corresponded to context-consistent words (C12 and C34). Two nonoverlapping groupings corresponded to legal words in the control conditions (C12 and C34). In two experiments, readers spent more time viewing the critical character sequence and its two center characters (C23) in the ambiguous condition. These results argue against the strictly serial assignment of characters to words during the reading of Chinese text.     

Verbal working memory and sentence comprehension

This target article discusses the verbal working memory system used in sentence comprehension. We review the concept of working memory as a short-duration system in which small amounts of information are simultaneously stored and manipulated in the service of accomplishing a task. We summarize the argument that syntactic processing in sentence comprehension requires such a storage and computational system. We then ask whether the working memory system used in syntactic processing is the same as that used in verbally mediated tasks that involve conscious controlled processing. Evidence is brought to bear from various sources: the relationship between individual differences in working memory and individual differences in the efficiency of syntactic processing; the effect of concurrent verbal memory load on syntactic processing; and syntactic processing in patients with poor short-term memory, patients with poor working memory, and patients with aphasia. Experimental results from these normal subjects and patients with various brain lesions converge on the conclusion that there is a specialization in the verbal working memory system for assigning the syntactic structure of a sentence and using that structure in determining sentence meaning that is separate from the working memory system underlying the use of sentence meaning to accomplish other functions. We present a theory of the divisions of the verbal working memory system and suggestions regarding its neural basis.     

Phonological short-term memory contributions to sentence processing in young children

Two experiments investigated the contribution of phonological short-term memory to the processing of spoken sentences by 4- and 5-year-old children. In Experiment 1, sentences contained either short or longer words, and varied in syntactic structure. Overall, repetition but not comprehension of the sentences was significantly influenced by word length. In Experiment 2. children selected on the basis of their high phonological short-term memory ability were founded to be superior at repeating sentences to children of lower phonological short-term memory ability, although the two groups did not differ in their comprehension accuracy for the same sentences. In both experiments, comprehension and repetition performance were differently influenced by particular sentence structures. It is proposed that sentence repetition in children is constrained by phonological memory capacity, and is therefore directly influenced by memory-related factors that include the length and number of words in sentences, and individual differences in memory skills.     

Computational principles of working memory in sentence comprehension

Understanding a sentence requires a working memory of the partial products of comprehension, so that linguistic relations between temporally distal parts of the sentence can be rapidly computed. We describe an emerging theoretical framework for this working memory system that incorporates several independently motivated principles of memory: a sharply limited attentional focus, rapid retrieval of item (but not order) information subject to interference from similar items, and activation decay (forgetting over time). A computational model embodying these principles provides an explanation of the functional capacities and severe limitations of human processing, as well as accounts of reading times. The broad implication is that the detailed nature of cross-linguistic sentence processing emerges from the interaction of general principles of human memory with the specialized task of language comprehension.     

Contextual knowledge reduces demands on working memory during reading

An experiment is reported in which young, middle-aged, and older adults read and recalled ambiguous texts either with or without the topic title that supplied contextual knowledge. Within each of the age groups, the participants were divided into those with high or low working memory (WM) spans, with available WM capacity further manipulated by the presence or absence of an auditory target detection task concurrent with the reading task. Differences in reading efficiency (reading time per proposition recalled) between low WM span and high WM span groups were greater among readers who had access to contextual knowledge relative to those who did not, suggesting that contextual knowledge reduces demands on WM capacity. This position was further supported by the finding that increased age and attentional demands, two factors associated with reduced WM capacity, exaggerated the benefits of contextual knowledge on reading efficiency. The relative strengths of additional potential predictors of reading efficiency (e.g., interest, effort, and memory beliefs), along with knowledge, WM span, and age, are reported. Findings showed that contextual knowledge was the strongest predictor of reading efficiency even after controlling for the effects of all of the other predictors.     

Phonological and visual working memory in mental addition

The goal of the present research was to examine the role of working memory in mental arithmetic. Adults (n = 96) solved multidigit arithmetic problems (e.g., 52 + 3; 3 + 52) alone and in combination with either a phonological memory load (i.e., nonwords, such as gup) or a visual memory load (i.e., random pattern of asterisks). The participants solved problems presented in a vertical format significantly faster than problems presented in a horizontal format. They also solved double digit first problems (e.g., 52 + 3) more quickly than the reverse (e.g., 3 + 52), but only when the problems were presented horizontally. Performance was worse in the phonological load condition than in the visual load condition for the participants who solved problems presented horizontally, whereas performance was worse in the visual load condition than in the phonological load condition when problems were presented vertically. The present research provides evidence that both phonological and visual aspects of working memory are involved in mental arithmetic but that the role of each working memory component will depend on such factors as presentation format.     

Accessing ambiguous words during sentence comprehension

In five experiments visual processing of sentences containing either a more frequent or a less frequent usage of an ambiguous word was examined. When prior or subsequent context was pragmatically related to the relevant sense of the ambiguous word, sentences intending the more frequent sense produced longer ambiguity detection times and shorter immediate comprehension times than sentences intending the less frequent sense. This relative frequency effect was not obtained in comprehension of corresponding unambiguous sentences containing relatively high or low frequency unambiguous synonyms of the senses. These results suggest that access of ambiguous word-senses tends to occur in order of relative frequency, and that multiple access of senses tends only to occur for low frequency usages. When the preceding verb imposed selection constraints on which sense could follow, the frequency effect did not occur consistently; and it was virtually eliminated when biasing context took the form of a previous sentence containing an unambiguous synonym of the relevant sense. Implications for models of access of unambiguous words in sentences, as well as for models of processing ambiguous sentences, are considered.     

The role of working memory in inferential sentence comprehension

Existing literature on inference making is large and varied. Trabasso and Magliano (Discourse Process 21(3):255–287, 1996) proposed the existence of three types of inferences: explicative, associative and predictive. In addition, the authors suggested that these inferences were related to working memory (WM). In the present experiment, we investigated whether WM capacity plays a role in our ability to answer comprehension sentences that require text information based on these types of inferences. Participants with high and low WM span read two narratives with four paragraphs each. After each paragraph was read, they were presented with four true/false comprehension sentences. One required verbatim information and the other three implied explicative, associative and predictive inferential information. Results demonstrated that only the explicative and predictive comprehension sentences required WM: participants with high verbal WM were more accurate in giving explanations and also faster at making predictions relative to participants with low verbal WM span; in contrast, no WM differences were found in the associative comprehension sentences. These results are interpreted in terms of the causal nature underlying these types of inferences.     

Phonological and working memory mechanisms involved in written spelling

Recent theories of spelling based on neuropsychological data and on computational modelling (Caramazza & Miceli, 1990; Caramazza, Miceli, Villa, & Romani, 1987; Glasspool & Houghton, 2005; Glasspool, Shallice, & Cipolotti, 2006; Miceli & Capasso, 2006; Rapp & Kong, 2002) assume that a working memory system is used to store identity and order of the graphemes, and propose that an impairment of this system, called Graphemic Buffer (GB), is marked by the presence of a number of typical effects. Recently, this disorder has been simulated by different versions of the Competitive Queuing model (Glasspool & Houghton, 2005; Glasspool et al., 2006). The effect of the disruption of this mechanism in written spelling was investigated by means of a dual task in the present study. Three-syllable and four-syllable words were presented to normal adults for aural presentation (Experiment 1) and spelling by copying (Experiment 2). In order to investigate the effects of dual tasks, and the possible involvement of phonological codes, three conditions were used: simple dictation, concurrent articulation, and foot tapping. The results showed strong effects of concurrent articulation, and were consistent with the hypothesis that this task disrupted the serial operations of readout and sequential planning of the GB. They were also consistent with the simulations of the Competitive Queuing model, suggesting possible loci of the effects.     

The effect of noun phrase type on working memory saturation during sentence comprehension

Double centre-embedded structures such as “the rat the cat the boy chased ate was brown” seem ungrammatical to many human subjects. Using an offline complexity judgement task, Gibson and Thomas (1999) demonstrated that people found such sentences no more difficult to understand when the second verb phrase (VP) was omitted, relative to a condition where all the required VPs were present. According to the Syntactic Prediction Locality Theory (SPLT; Gibson, 1998), this syntactic illusion is determined by the high working memory cost associated with the integration of the second VP. This cost could be reduced by replacing the third noun phrase (the boy) by a pronoun, making the reader more sensitive to the omission of the second VP. This hypothesis was tested in two experiments using French sentences. Both experiments confirmed the syntactic illusion when the second VP was not a pronoun. The second experiment measured the reading times of the VPs and showed that the pronoun induced a longer reading time of the final VP when the second VP was omitted. The overall results indicate a condition under which human subjects could process the most complex part of a sentence with more than one embedded relative clause. The overall results are consistent with most of the hypotheses derived from the SPLT although offline complexity judgements could not be the most sensitive measure to test some of these hypotheses.     

Phonological processing during silent reading in aphasic patients

In a task involving the detection of a predesignated letter during the silent reading of a series of passages, left-brain-damaged aphasic patients and right-brain-damaged patients showed patterns of performance consistent with those of normal individuals. Both of the brain-damaged groups were more likely to detect letters when they were pronounced in a typical way (e.g., g in "ago") than in an atypical way (e.g., g in "through"), suggesting the use of phonological recoding during silent reading. In addition, both of these groups were more likely to detect letters when they occurred in content than in function words, suggesting a differential processing of these word types. Possible differences in the strategies predominantly relied on for phonological recoding and for the differential processing of content and function words by different groups of patients are discussed.     

Phonological codes are assembled before word fixation: evidence from boundary paradigm in sentence reading

This experiment employed the boundary paradigm during sentence reading to explore the nature of early phonological coding in reading. Fixation durations were shorter when the parafoveal preview was the correct word than when it was a spelling control pseudoword. In contrast, there was no significant difference between correct word and pseudohomophone previews. These results suggest that the phonological codes are assembled before word fixation and are used for lexical access. Moreover, there was evidence that orthographic codes influence the activation of word meaning. We found that fixation durations were shorter for orthographically similar parafoveal previews, and this orthographic priming effect is limited to pseudohomophones. Thus, it seems that both the orthographic and the phonological similarities of the parafoveal preview to the target play a part in the facilitative effects of the preview.     

Past experience influences object representation in working memory

The nature of object representation in working memory is vital to establishing the capacity of working memory, which in turn shapes the limits of visual cognition and awareness. Although current theories discuss whether representations in working memory are feature-based or object-based, no theory has considered the role of past experience. However, work with humans and non-human primates suggests that once participants learn which features are important for category membership, these diagnostic features become more salient than non-diagnostic features in long-term memory and object recognition. Critically, the brain areas involved in this diagnosticity effect are also recruited during working memory tasks. We report two experiments testing whether a diagnosticity effect exists in working memory; and whether it is present when visual information is encoded into working memory, or if it is the result of maintenance within working memory. Results showed a diagnosticity effect which was present at encoding. Maintenance did not influence the nature of object representation in working memory. These findings show that the meaning we glean from our past experience has a profound influence on the nature of object representation in working memory.     

Effects of working memory and reading acceleration training on improving working memory abilities and reading skills among third graders

Working memory (WM) plays a crucial role in supporting learning, including reading. This study investigated the influence of reading acceleration and WM training programs on improving reading skills and WM abilities. Ninety-seven children in third grade were divided into three study groups and one control group. The three study groups each received a different combination of two training programs: only reading acceleration, WM followed by reading acceleration, and reading acceleration followed by WM. All training programs significantly improved reading skills and WM abilities. Compared with the control group, the group trained with only the reading acceleration program improved word accuracy, whereas the groups trained with a combination of reading and WM programs improved word and pseudo-word fluency. The reading-acceleration-alone group and the WM-program-followed-by-reading-acceleration group improved phonological complex memory. We conclude that a training program that combines a long reading acceleration program and a short WM program is the most effective for improving the abilities most related to scholastic achievement.     

Inhibitory control during sentence reading in dyslexic children.

The present study focused on the nature of the reading disability of children with the guessing subtype of dyslexia (who read fast and inaccurately). The objective was to separate the excitatory account of their reading disturbance (i.e., in guessers the words' resting levels of activation are oversensitive to semantic context) from the inhibitory account (i.e., guessers tend to react prematurely to (false) candidate words that are activated in the lexicon). To disentangle the above accounts, guessers and normal readers were presented with a sentential priming task (SPT). In the SPT, subjects had to determine whether the final word of a sentence was semantically congruent or incongruent with the sentence, but had to inhibit their 'congruent' or 'incongruent' response in case of an occasionally presented pseudoword. To evoke guessing, each pseudoword closely resembled either a valid congruent or incongruent word. Guessing referred to prematurely accepting a pseudoword as a word that either appropriately or inappropriately completed the sentence. The extent to which subjects guessed at word meaning was evidenced by the false recognition rates (FRR) of the misspelled terminal words. Analyses on the FRRs of the pseudowords showed that guessers had significantly more difficulty in suppressing the 'go tendency' triggered by the pseudowords. It was concluded that the impulsive reading style of guessers should be ascribed to a less efficient suppression mechanism rather than to excessive reliance on contextual information. Specifically, the data were explained by assuming that the availability of the pseudoword's candidate meaning activated the hand to respond with, and that guessers found difficulty in suspending this response until they analyzed all letters in the stimulus and they could be sure of its spelling.     

Parafoveal preview during reading: effects of sentence position

Two experiments examined parafoveal preview for words located in the middle of sentences and at sentence boundaries. Parafoveal processing was shown to occur for words at sentence-initial, mid-sentence, and sentence-final positions. Both Experiments 1 and 2 showed reduced effects of preview on regressions out for sentence-initial words. In addition, Experiment 2 showed reduced preview effects on first-pass reading times for sentence-initial words. These effects of sentence position on preview could result from either reduced parafoveal processing for sentence-initial words or other processes specific to word reading at sentence boundaries. In addition to the effects of preview, the experiments also demonstrate variability in the effects of sentence wrap-up on different reading measures, indicating that the presence and time course of wrap-up effects may be modulated by text-specific factors. We also report simulations of Experiment 2 using version 10 of E-Z Reader (Reichle, Warren, & McConnell, 2009), designed to explore the possible mechanisms underlying parafoveal preview at sentence boundaries.