Transposed-letter effects in reading: Evidence from eye movements and parafoveal preview.

Three eye movement experiments were conducted to examine the role of letter identity and letter position during reading. Before fixating on a target word within each sentence, readers were provided with a parafoveal preview that differed in the amount of useful letter identity and letter position information it provided. In Experiments 1 and 2, previews fell into 1 of 5 conditions: (a) identical to the target word, (b) a transposition of 2 internal letters, (c) a substitution of 2 internal letters, (d) a transposition of the 2 final letters, or (e) a substitution of the 2 final letters. In Experiment 3, the authors used a further set of conditions to explore the importance of external letter positions. The findings extend previous work and demonstrate that transposed-letter effects exist in silent reading. These experiments also indicate that letter identity information can be extracted from the parafovea outside of absolute letter position from the first 5 letters of the word to the right of fixation. Finally, the results support the notion that exterior letters play important roles in visual word recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do readers obtain preview benefit from word n + 2? A test of serial attention shift versus distributed lexical processing models of eye movement control in reading.

Two experiments tested predictions derived from serial lexical processing and parallel distributed models of eye movement control in reading. The boundary paradigm (K. Rayner, 1975) was used, and the boundary location was set either at the end of word n - 1 (the word just to the left of the target word) or at the end of word n - 2. Serial lexical processing models predict that there should be preview benefit only when the boundary is set at word n - 1 (when the target word will be the next word fixated) and no preview benefit when the boundary is set at word n - 2. Parallel lexical models, on the other hand, predict that there should be some preview benefit in both situations. Consistent with the predictions of the serial lexical processing models, there was no preview benefit for a target word when the boundary was set at the end of word n - 2. Furthermore, there was no evidence of parafoveal-on-foveal effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preview benefit during eye fixations in reading for older and younger readers.

Older and younger readers read sentences as their eye movements were recorded, and the boundary paradigm (Rayner, 1975) was used to present either a valid or an invalid parafoveal preview of a target word. During the saccade to the target word, the preview word changed to the target word. For early measures of processing time (first fixation duration and single fixation duration), the standard preview benefit effect (shorter fixation times on the target word with a valid preview than an invalid preview) was obtained for both older and younger readers. However, for gaze duration and go-past time, the preview benefit was somewhat attenuated in the older readers in comparison to the younger readers, suggesting that on some fixations older readers obtain less preview benefit from the word to the right of fixation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Smooth-pursuit eye movement dysfunction and liability for schizophrenia: Implications for genetic modeling.

41 nonpsychiatric Ss, 38 probands with schizophrenia, and 99 of their relatives were studied. Oculomotor functioning was bimodally distributed for probands and relatives. Oculomotor dysfunction was not present in all families with a schizophrenic proband. In those families in which it was present, there were significant phenotypic correlations between oculomotor functioning and schizophrenia-related characteristics. The patterns of familial resemblance in the families in whom oculomotor dysfunction was present were consistent with nonadditive genetic variance contributing both to oculomotor dysfunction and to the relationship between oculomotor dysfunction and clinical symptoms. These results suggest that schizophrenia may be etiologically heterogeneous and that oculomotor dysfunction may help to identify nonadditive genetic variance for this disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of foveal processing difficulty on the perceptual span in reading: Implications for attention and eye movement control.

Two experiments were conducted to examine the effects of foveal processing difficulty on the perceptual span in reading. Subjects read sentences while their eye movements were recorded. By changing the text contingent on the reader's current point of fixation, foveal processing difficulty and the availability of parafoveal word information were independently manipulated. In Experiment 1, foveal processing difficulty was manipulated by lexical frequency, and in Experiment 2 foveal difficulty was manipulated by syntactic complexity. In both experiments, less parafoveal information was acquired when processing in the fovea was difficult. We conclude that the perceptual span is variable and attentionally constrained. We also discuss the implications of the results for current models of the relation between covert visual–spatial attention and eye movement control in reading. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of working memory capacity in retrieval.

The verbal fluency task that requires generation of category exemplars and appears to be an example of what M. Moscovitch (1995) calls a strategic test of memory retrieval. Four experiments explored the role of individual differences in working memory (WM) capacity on verbal fluency under various secondary load conditions. High WM participants consistently recalled more exemplars. However, load conditions caused a decline in recall only for high WM participants. Low WM participants showed no effect of secondary workload on exemplar generation. WM group differences and load effects were observed even in the 1st min of retrieval, which suggests that differences were not due to differences in knowledge. A model of retrieval is supported that relies on cue-based-automatic activation, monitoring of output for errors, controlled suppression of previously recalled items, and controlled strategic search. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Depression in multiple sclerosis: Relationship to working memory capacity.

Recent research has shown that depression in multiple sclerosis (MS) is associated with deficits on cognitively demanding tasks. One explanation for this relationship is that depressed NIS patients may have reduced working memory capacity. The present study was designed to test this hypothesis. Depressed NIS patients were compared with nondepressed MS patients and nondepressed healthy controls on a task of working memory capacity (reading span) and a short-term memory task not taxing working memory capacity (word span). In support of the capacity-reduction model, compared with the nondepressed groups, depressed MS patients performed significantly worse on reading span but not on word span. Additionally, reading span was significantly correlated with capacity-demanding tasks shown to be impaired in depressed NIS patients in previous reports. Results suggest that depressed MS patients are characterized by limited working memory capacity and that the central executive component of the working memory system may be most affected. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Manipulation of working memory information is impaired in Parkinson's disease and related to working memory capacity.

It has been suggested that in patients with Parkinson's disease (PD), difficulties in the manipulation of information, which result in problems in executive tasks, are related to a reduction of working memory capacity (J. D. E. Gabrieli, J. Singh, G. T. Stebbins, & C. G. Goetz, 1996). The present study selectively varied the manipulation demand irrespective of the maintenance requirement. In a group of 14 PD patients, performance declined overproportionally with the increasing task demand and was significantly correlated with a measure of working memory capacity. These results suggest that the complexity of working memory processing may decisively contribute to the exhaustion of resources in PD patients. Increasing complexity may either affect their manipulation ability directly or impede the management of inhibitory control requirements inherent to the task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Generality and modifiability of working memory among skilled and less skilled readers.

Investigated whether individual differences in working memory are related to a general system and whether the predictability of working memory to academic achievement is enhanced under dynamic testing conditions. Exp 1 correlated 11 working memory tasks with short-term memory and achievement measures. Convergent and discriminant validity for the working memory measures was established. Although a confirmatory factor analysis supported the notion that the working memory tasks reflect 2 operations, these operations produced similar correlational patterns to achievement. Exp 2 supported a 2-factor model under dynamic testing procedures, and those procedures contribute significant variance to reading performance. Overall, the results suggest that (1) working memory operates as a general system independent of reading skill and (2) dynamic testing procedures enhance the prediction of reading performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A capacity theory of comprehension: Individual differences in working memory.

A theory of the way working memory capacity constrains comprehension proposes that both processing and storage are mediated by activation and that the total amount of activation available in working memory varies among individuals. Individual differences in working memory capacity for language can account for qualitative and quantitative differences among college-age adults in several aspects of language comprehension. One aspect is syntactic modularity: The larger capacity of some individuals permits interaction among syntactic and pragmatic information, so that their syntactic processes are not informationally encapsulated. Another aspect is syntactic ambiguity: The larger capacity of some individuals permits them to maintain multiple interpretations. The theory is instantiated as a production system model in which the amount of activation available to the model affects how it adapts to the transient computational and storage demands that occur in comprehension. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The interactive effects of listwide control, item-based control, and working memory capacity on Stroop performance.

Hypothesized top-down and bottom-up mechanisms of control within conflict-rich environments were examined by presenting participants with a Stroop task in which specific words were usually presented in either congruent or incongruent colors. Incongruent colors were either frequently (high contingency) or infrequently (low contingency) paired with the word. These items were embedded within lists consisting of either 100% congruent or 100% incongruent filler items to create mostly congruent or mostly incongruent lists. Results indicated a significant item-specific congruency effect, which was largest for high contingency responses and within mostly congruent lists. In addition, a significant listwide congruency effect was obtained, and this interacted with working memory capacity (WMC). There were larger listwide congruency effects for low WMC individuals. Finally, the pattern of Stroop interference across lists for low WMC individuals was dependent upon the congruency of the preceding trial. These results support multiple forms of cognitive control, as well as contingency learning, as mechanisms underlying proportion congruence effects in Stroop and other conflict tasks. These findings are interpreted within Braver, Gray, and Burgess's (2007) dual mechanisms of control theory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Implicit learning in problem solving: The role of working memory capacity.

Participants solving the Balls and Boxes puzzle for the first time were slowed in proportion to the level of working memory (WM) reduction resulting from a concurrent secondary task. On a second and still challenging solution of the same puzzle, performance was greatly improved, and the same WM load did not impair problem-solving efficiency. Thus, the effect of WM capacity reduction was selective for the first solution of the puzzle, indicating that learning to solve the puzzle, a vital part of the first solution, is slowed by the secondary WM-loading task. Retrospective verbal reports, tests of specific puzzle knowledge, and a recognition test of potential strategies all indicated that participants were unaware of their knowledge of the puzzle, suggesting that it had been learned implicitly. Concurrent protocols collected from participants supported this conclusion and further suggested that participants were not aware of learning to solve the puzzle as this learning occurred. These results provide evidence that implicit learning depends on WM capacity and that implicit memory can play an important role in problem solving. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The capacity of visual working memory for features and conjunctions

Short-term memory storage can be divided into separate subsystems for verbal information and visual information, and recent studies have begun to delineate the neural substrates of these working-memory systems. Although the verbal storage system has been well characterized, the storage capacity of visual working memory has not yet been established for simple, suprathreshold features or for conjunctions of features. Here we demonstrate that it is possible to retain information about only four colours or orientations in visual working memory at one time. However, it is also possible to retain both the colour and the orientation of four objects, indicating that visual working memory stores integrated objects rather than individual features. Indeed, objects defined by a conjunction of four features can be retained in working memory just as well as single-feature objects, allowing sixteen individual features to be retained when distributed across four objects. Thus, the capacity of visual working memory must be understood in terms of integrated objects rather than individual features, which places significant constraints on cognitive and neurobiological models of the temporary storage of visual information.     

Letter encoding in visual word identification: More evidence for a word-integration explanation for parafoveal preview effects in reading.

A letter string presented briefly in the parafovea facilitates naming a foveally presented word provided that the two stimuli are orthographically similar. The facilitation is asymmetrical in that to obtain it, both letter strings must have the first letters in common. One possible explanation, a letter-integration hypothesis, proposes that readers only identify the letters at the beginning of the parafoveal stimulus, an action that facilitates processing the target. Another explanation, a word-integration hypothesis, postulates that all the letters of the parafoveal stimulus are identified and that the asymmetry occurs because the first letters of the parafoveal stimulus are weighted more heavily than the later ones. The two accounts differ in the way the position of the first letter is determined. To distinguish the views, English and Hebrew stimuli were presented to 7 bilingual readers. 12 normal students participated as controls. Readers could not anticipate the position of the first letters; hence, if the letter-integration explanation is correct, the asymmetry in the priming should be attenuated. Consistent with the word-integration explanation, however, priming occurred when the target shared the beginning letters with the prime in both languages. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Speech recognition and working memory capacity in young-elderly listeners: Effects of hearing sensitivity.

Young normal-hearing listeners and young-elderly listeners between 55 and 65 years of age, ranging from near-normal hearing to moderate hearing loss, were compared using different speech recognition tasks (consonant recognition in quiet and in noise, and time-compressed sentences) and working memory tasks (serial word recall and digit ordering). The results showed that the group of young-elderly listeners performed worse on both the speech recognition and working memory tasks than the young listeners. However, when pure-tone audiometric thresholds were used as a covariate variable, the significant differences between groups disappeared. These results support the hypothesis that sensory decline in young-elderly listeners seems to be an important factor in explaining the decrease in speech processing and working memory capacity observed at these ages. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Irrelevant tones produce an irrelevant speech effect: Implications for phonological coding in working memory.

Addresses the possibility that tones disrupt serial recall of visually presented material in the same way as speech. A stream of changing tones is as disruptive of visual serial recall as 4 syllables (Exps 1 and 2). Similar effects were also shown with a repeated syllable that changed only in pitch (Exp 3). Just as for speech, the effect of tones is not at encoding but during storage of the serial lists (Exp 4 and 5). The results suggest that speech and tones are equipotent in their capacity to disrupt short-term memory. A "blackboard" model of working memory to account for the effects is outlined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simple and complex word spans as measures of working memory capacity.

Five experiments investigated the effects of word length in simple word span tasks and complex operation and reading span tasks and the relationship between these tasks and reading comprehension. The 1st 2 experiments showed word length effects using both simple and complex memory span tasks and that both simple and complex span tasks correlated with reading comprehension. In the 3rd experiment, articulatory suppression did not eliminate word length effects. The final experiments showed that articulatory suppression eliminated the effect of word length when words were sampled with replacement from small fixed pools but not when sampled without replacement from a large pool. The word pool effects were not a result of concreteness of the words. It is concluded that the reading span does not measure a working memory specific to reading. Further, in immediate memory experiments, repeating words from trial to trial may lead to a more limited coding than is used with nonrepeated words. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Intact attentional control of working memory encoding in schizophrenia.

This study reports evidence that individuals with schizophrenia (SC) demonstrate intact attentional selection for visual working memory (WM) storage. A group of 62 participants with SC and 55 control participants without SC were studied in a series of 5 experiments that examined the ability to use top-down and bottom-up cues to guide WM encoding, as well as the ability to spontaneously select a subset of representations for storage. Participants with SC exhibited a consistent and robust ability to use selective attention in the control of WM in all 5 experiments, demonstrating a remarkable island of preserved functioning given the broad spectrum of impairments of attention and WM that have been widely reported in those with SC. These findings indicate that attention is not globally impaired in SC and make it possible to delineate more precisely the nature of the specific impairment of attention in this disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eye movement guidance in reading: The role of parafoveal letter and space information.

The relation between parafoveal letter and space information in eye movement guidance during reading was investigated in 2 experiments. Contingent upon the reader's fixation, the type of parafoveal information available to the right of fixation was varied by (a) space information only, (b) space information with letter information added at some delay, or (c) letter and space information simultaneously. In addition, the onset of the relevant parafoveal information was delayed between 0 and 250 ms into the fixation. The time course of processing the 2 types of information (letters or spaces) differed, as did the nature of their impact on the eye movement record. Although both letter and space information influenced saccade length and initial landing positions within words, only letter information had an effect on fixation duration. In addition, fixation duration was affected only by information entering within the first 50 ms of the fixation, whereas saccade length was affected by information arriving at any time during the fixation. The results are consistent with a model of eye movement control (A. W. Inhoff and K. Raner [see PA, Vol 75:6513] and A. Pollatsek et al [see PA, Vol 74:27114]) in which 2 independent processes are operating in tandem to determine when and where to move the eyes during reading. (PsycINFO Database Record (c) 2010 APA, all rights reserved)