Visual complexity in letter-by-letter reading: "pure" alexia is not pure

Standard accounts of pure alexia have favoured the view that this acquired disorder of reading arises from damage to a left posterior occipital cortex mechanism dedicated to the processing of alphanumeric symbols. We challenge these accounts in two experiments and demonstrate that patients with this reading deficit are also impaired at object identification. In the first experiment, we show that a single subject, EL, who shows all the hallmark features of pure alexia, is impaired at picture identification across a large set of stimuli. As the visual complexity of pictures increases, so EL's reaction time to identify the stimuli increases disproportionately relative to the control subjects. In the second experiment, we confirm these findings with a larger group of five pure alexic patients using a selected subset of high- and low-visual complexity pictures. These findings suggest that the deficit giving rise to pure alexia is not restricted to orthographic symbols per se but, rather, is a consequence of damage to a more general-purpose visual processing mechanism.     

Preserved semantic priming effect in alexia

BH, a left-handed patient with alexia and nonfluent aphasia, was presented with a lexical-decision task in which words and pronounceable pseudowords were preceded by semantically related or unrelated picture primes (Experiment 1). In Experiment 2, BH was given an explicit reading task using the word lists from Experiment 1. Performance on Experiment 2 disclosed severe reading deficits in both oral reading and semantic matching of the words to pictures. However, in Experiment 1, BH demonstrated a significant semantic priming effect, responding more accurately and more quickly to words preceded by related primes than by unrelated primes. The present results suggest that even in a patient with severe alexia, implicit access to semantic information can be preserved in the absence of explicit identification. The possibility of categorical gradient in implicit activation (living vs. nonliving) in BH was also discussed, which, however, needs to be clarified in the further investigation.     

Reading speed and prose memory in older and younger adults.

A method is described for determining the minimum amount of time required to read a proposition in the context of a sentence. This threshold reading time was reliable, stable, and significantly longer for older adults than for younger adults. Prose memory was assessed for texts presented at varying speeds determined by the threshold reading time measure and by a whole-text reading time measure. Recall from these paced conditions was compared with recall from a self-paced condition. In general, age differences in recall tended to increase as the amount of time allowed for processing increased. The results of regression analyses suggest that although the basic speed of processing for a single sentence accounts for substantial variance in prose recall, processes that operate across sentence boundaries are also important and require further specification. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reading ability and semantic processing: Isolating speed of access.

Although much attention has focused on the efficiency of access to semantic information as a determinant of reading ability, previous research has confounded information access and decision processes. The authors used a matching task to study the time course of semantic access among college students. They studied the time course of processing by varying the stimulus onset between the two members of a stimulus pair. Semantic encoding functions obtained from this paradigm were used to isolate semantic access from the decision component of the matching task. Regression analyses indicated that the often-obtained correlation between speed of semantic processing and measures of reading ability is based on unique contributions from both semantic access and decision processes. The results undermine the hypothesis that the efficiency of access to semantic codes is a relatively age-variant contributor to individual differences in reading. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pure alexia: presentation of a case

INTRODUCTION AND CLINICAL CASE: A case of pure alexia, secondary to an occipital cerebral infarct, is presented, which initially appearing with bilateral amaurosis of two hours of duration, following by a significant difficulty to read, and according to patient, was a deficit to near vision and by criteria of ophthalmologists and optometrists was a presbyopia. Authors identified a lack of P-300 wave in study of endogenous component of events related potentials (ERP), to task of phonetic discrimination, and its normal registry to task of graphic discrimination. CONCLUSION: Therefore, we confirm the cliniconeurophysiologic diagnosis of a pure alexia without agraphia, by means of this non-invasive method studying cerebral cognitive process.     

Pure alexia and word-meaning deafness in a patient with multiple sclerosis

OBJECTIVE: To describe pure alexia and auditory comprehension problems in a young woman with multiple sclerosis (MS). PATIENT: A 33-year-old woman with MS who complained of difficulties in reading and comprehending spoken language was referred for a neuropsychological examination. Reading difficulties were confirmed and most of the reading errors were additions, omissions, and substitutions of single letters. While the patient reported that the letters seemed to disappear before her eyes, no general problems with visual attention, visual discrimination, or scanning were detected. No difficulties with spelling were reported. The auditory comprehension deficit is interpreted as a form of a semantic access disorder and is not due to generalized slowing in information processing or conceptual disintegration. CONCLUSIONS: Pure alexia is unusual in MS and to our knowledge only 1 other case has been reported (in Japanese). Memory impairments and slowed information processing are probably the most frequent cognitive sequelae of the disease and, consequently, the literature is biased toward the study of those cognitive domains. However, given the wide distribution of sclerotic plaques in MS, it could be argued that we should expect some variability of cognitive changes in MS. Striking deficits as seen in this patient should make us more sensitive to this possibility.     

Pure alexia without agraphia: a classical cortical syndrome revisited

A patient who developed pure alexia without agraphia following a stroke is described. An infarction of the left occipital pole was demonstrated by Magnetic Resonance Imaging (MRI). The literature on this rare syndrome is reviewed, and the localisation of damage in relation to the clinical findings discussed.     

Cavity sintering in pure nickel

Experimental measurements of the kinetics of cavity elimination by annealing are reported for pure nickel. A sample of nickel was crept to implant creep cavities in the grain boundaries. The cavity radius distribution in the sample was obtained after measuring approximately 3000 cavity diameters over an area of 4.7 × 10⁻⁵m². The sample was then vacuum annealed for 7 days at 800°C to cause the cavities to shrink, and the radii distribution of the remaining cavities was determined. From the cavity radii distributions, converted from area to volume, it was possible to determine the rate of cavity shrinkage as a function of the cavity radius. It is shown that the rate of cavity shrinkage is driven by the surface free energy, possibly affected by the internal gas pressure, and controlled by grain boundary self diffusion.     

Abnormal grain growth in pure materials

Thompson et al. [Acta metall.35, 887 (1987)] have proved that if a large grain of size R_A is introduced in a matrix which has Hillert's [Acta metall.13, 227 (1965)] quasi-stationary grain size distribution this large grain will decrease its size relative to the critical radius of the distribution, R_Cr, so that d(R_A/R_Cr)/dt < 0. In the present work the effect of having a matrix distribution different from Hillert's is examined. It is shown that in such case the behaviour of an abnormally large grain is more complex and either d(R_A/R_Cr)/dt < 0 or d(R_A/R_Cr)/dt > 0 are initially possible. The present analysis is applied to lognormal distributions with different values of side deviation.     

Reading in two alphabets

Many speakers of Serbo-Croatian read the language in two phonemically precise and partially overlapping alphabets. Twenty years of experiments directed toward this ability have led to deeper understandings of the role of speech-related processes in reading and the contrasts and similarities among the world's alphabetic writing systems.     

Clinical-radiologic correlations in pure sensory stroke

Clinical-radiologic correlations in 27 patients with pure sensory strokes (PSS) were retrospectively studied. Dysesthesias from pontine lesions were more severe than those from thalamic lesions. Pontine PSS but not thalamic PSS selectively affected vibration and position sense, leaving pinprick and temperature perceptions intact. Thalamic lesions but not pontine tended to spare the trunk.     

Sources of Individual Differences in Reading Comprehension and Reading Fluency.

This study examined the common and distinct contributions of context-free and context reading skill to reading comprehension and the contributions of context-free reading skill and reading comprehension to context fluency. The 113 4th-grade participants were measured in reading comprehension, read aloud a folktale, and read aloud the folktale's words in a random list. Fluency was scaled as speed (words read correctly in 1 min) and time (seconds per correct word). Relative to list fluency, context fluency was a stronger predictor of comprehension. List fluency and comprehension each uniquely predicted context fluency, but their relative contributions depended on how fluency was scaled (time or speed). Results support the conclusion that word level processes contribute relatively more to fluency at lower levels while comprehension contributes relatively more at higher levels. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial interactions in perceived speed

Previous research has shown that the perception of motion within a local region is influenced by other motions within neighboring areas (eg induced motion). Here, a study is reported of the perceived speed of dots moving within a circular target region, which was surrounded by other motions within a larger surrounding area. The perceived speed of the central dots was found to be fastest when the surround was stationary; it became slower as the speed of motion in the surround was increased. This decrease in the perceived target speed with increases in surround velocity occurred regardless of whether the direction in which the surround moved was the same as or opposite to the motion of the target region. This result cannot be explained by using simple models of perceived speed that depend only upon such factors as the magnitude of relative motion between center and surround. The spatial area over which these motion interactions occur was also investigated.     

高速钢轧辊在棒材生产线上的应用

介绍了高速钢轧辊的特性以及优点,并通过对西林钢铁集团轧钢总厂三轧作业区全连续棒材生产线在高速钢轧辊使用过程中,使用条件、事故处理以及使用效果等方面的总结,介绍高速钢轧辊的应用前景与效益。     

Processing speed, naming speed, and reading.

With increasing age, children name familiar objects more rapidly, and these naming times are related to reading ability. The aim of this research was to determine if age-related change in naming time reflects (1) automatic access of familiar names due to greater familiarity with the named objects or (2) global change in speed of processing. To distinguish these explanations, 144 8- to 13-yr-olds were administered measures of global processing time, naming time, and reading ability. Results of path analyses and structural-equation modeling were consistent with the second explanation. That is, naming time was predicted by measures of processing speed but not by age. In addition, naming time was linked to reading recognition, which was linked to reading comprehension. Age was also linked to reading recognition, indicating that other age-related variables need to be incorporated into the causal model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Saccadic Inhibition in Reading.

In 5 experiments, participants read text that was briefly replaced by a transient image for 33 ms at random intervals. A decrease in saccadic frequency, referred to as saccadic inhibition, occurred as early as 60-70 ms following the onset of abrupt changes in visual input. It was demonstrated that the saccadic inhibition was influenced by the saliency of the visual event (Experiment 3) and was not produced in response to abrupt but irrelevant auditory stimuli (Experiment 1). Display changes restricted to an area either inside or outside the perceptual span required for normal reading produced strong saccadic inhibition (Experiment 2). Finally, Experiments 4 and 5 demonstrated higher level cognitive or attentional modulation of the saccadic inhibition effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)