Does Global Context Modulate Cerebral Asymmetries? A Review and New Evidence on Word Imageability Effects

In this article we examine whether the distribution of function across the right and left cerebral hemispheres for lexical processing is influenced by the global context within which words are presented. A review of previously published studies indicates that the ubiquitous right visual field (RVF)/left hemisphere advantage for word recognition may be reduced or eliminated for nouns, content words, or high image words, but only when such items are presented along with verbs, function words, or low image words. However, paradoxically, when the former items are presented in more homogeneous contexts, the RVF advantage is uniformly observed. We propose that the processing efficiency of a hemisphere for a given stimulus depends on that item's relation to the other stimuli provided, that is, the global context. This was examined in a visual half-field experiment that varied whether high and low image nouns were presented in homogeneous (blocked lists) or heterogeneous (mixed lists) contexts. An unvarying RVF advantage was observed for high image words in homogeneous contexts, but this advantage was eliminated when the same items were presented in heterogeneous contexts. We suggest that stimulus heterogeneity maximizes reliance on differing, but complementary, computational biases across hemispheres. Hence, the extent to which the left and right hemispheres are recruited for the recognition of individual word types can vary dynamically with variation in the stimulus environment.     

Influence of word class proportion on cerebral asymmetries for high- and low-imagery words

It has been claimed that the typical RVF/LH advantage for word recognition is reduced or eliminated for imageable, as compared to nonimageable, nouns. To determine whether such word-class effects vary depending on the stimulus list context in which the words are presented, we varied the proportion of high- and low-image words presented in a lateralized lexical decision task (0, 25, 50, 75, or 100% high image). Although the RVF/LH advantage for high-image words was unaltered by word-class proportion, a significant linear trend was obtained for the low-image words such that the RVF/LH advantage increased as the proportion of low-image words increased. We discuss the implications of these findings for models of how lexical processing is distributed across hemispheres.     

Hemispheric asymmetry in lexical decisions: the effects of grammatical class and imageability

It has been suggested that neural systems for lexical processing of nouns and verbs are anatomically distinct. The aim of the present study was to investigate if brain asymmetry for the processing of these two grammatical classes is also different. Neurologically intact adults performed a lateralized lexical decision task with grammatically unambiguous words of high, medium, and low degrees of imagery. For error scores a right visual field (RVF) advantage and an overall effect of imageability were obtained. For latency scores grammatical class and imageability modified visual field differences: in the noun class a RVF advantage was obtained only for low imagery nouns, while for the verbs the RVF advantage was present for both medium and low imagery verbs. These results suggest that the participation of right hemisphere neural systems in the processing of verbs is more limited than in the processing of nouns.     

Right hemisphere language processing: Lateral difference with imageable and nonimageable ambiguous words

Influence of imageability on hemispheric processing difference is studied in a lexical decision task with semantic priming. Homographs and ambiguous words were biased according to the prime toward their low or high imageable meanings and unilaterally presented in the visual field. A right visual field (RVF) superiority was observed; it was nonsignificant for the high imageable (HI) meaning but significant for the low imageable (LI) meaning of the ambiguous words. Thus the results seem to favor a bilateral hemispheric representation of HI words and a unilateral left representation of LI words. Theoretical implications of the results are discussed to the various models of ambiguous word access processing.     

Further evidence on the effect of word imageability in dyslexia

Subjects with acquired dyslexia sometimes find abstract words more difficult to read than concrete words. Three dyslexic patients were found to show performance corrrelating with the imageability of the material, but not with its concreteness. This could not be explained in terms of lexical complexity; indeed, derived nouns were easier to read than simple nouns. These effects were reliable across the three subjects. It was suggested that they were naming imaginal representations of the referents of imageable nouns.     

整体语境和局部语境对代词理解的影响

通过眼动实验,考察了语篇理解中整体语境和局部语境对代词理解的影响。实验一是预备实验,发现名词与动词词组之间关系的典型性不同,整合的速度也不一样。实验二发现,代词的理解不是一次完成的,代词理解的初期受整体语境的语义偏向影响,而不受局部语境的影响。在第二阶段主要受到局部语境的影响。代词的理解过程比较符合Cook（2004）所提出的两阶段模型     

Personally familiar proper names are relatively successfully processed in the human right hemisphere; or, the missing link

Responding to our abstract in Brain and Language (Ohnesorge & Van Lancker, 1999), which proposed that famous proper nouns are successfully processed in both cerebral hemispheres, Schweinberger, Landgrebe, Mohr, and Kaufmann (2001) claimed that the "link" between personal names and the right hemisphere is "illusory." Ohnesorge and Van Lancker (2001) further described six experimental studies in which LVF/RH recognition of famous proper nouns was influenced by task conditions and stimulus familiarity. Here presenting two more experiments performed to explore the refutation presented by Schweinberger et al., this article confirms an ability of the right hemisphere to recognize famous proper nouns and explains why appropriate stimulus development and task conditions are essential in furthering our understanding of the role of the right hemisphere in processing personal relevance.     

Words, hemispheres, and dissociable subsystems: the effects of exposure duration, case alternation, priming, and continuity of form on word recognition in the left and right visual fields

Three experiments explore aspects of the dissociable neural subsystems theory of hemispheric specialisation proposed by Marsolek and colleagues, and in particular a study by [Deason, R. G., & Marsolek, C. J. (2005). A critical boundary to the left-hemisphere advantage in word processing. Brain and Language, 92, 251–261]. Experiment 1A showed that shorter exposure durations for lower-case words (13 ms) are associated with reduced right visual field (RVF) advantages compared with longer exposure durations (144 ms). Experiment 1B compared report accuracy for lower case and mixed case words at the same exposure duration (144 ms). The RVF advantage was reduced for mixed case words due to case alternation having more of an adverse effect in the RVF than in the LVF. Experiment 2 tested a different prediction of dissociable neural subsystems theory. Four-letter words were presented in mixed case in the LVF or RVF for 100 ms. They were preceded at the same location by a prime which could be in the same word in the same alternation pattern (e.g., FlAg–FlAg), the same word in the opposite alternation pattern (e.g., fLaG–FlAg), or an unrelated letter string in the same or opposite case alternation pattern (WoPk–FlAg or wOpK–FlAg). Relative to performance in the letter string prime conditions, which did not differ significantly between the two visual fields, there was more of an effect of word primes in the RVF than in the LVF. Importantly, the benefit of a word prime was the same whether the prime was in the same alternation pattern or was in the opposition alternation pattern. We argue that these results run contrary to the predictions of dissociable neural subsystems theory and are more compatible with theories which propose that a left hemisphere word recognition system is responsible for identifying written words, whether they are presented in the LVF or the RVF, and that letters are processed to an abstract graphemic level of representation before being identified by that system.     

How brand names are special: brands,words, and hemispheres

Previous research has consistently shown differences between the processing of proper names and of common nouns, leading to the belief that proper names possess a special neuropsychological status. We investigate the category of brand names and suggest that brand names also have a special neuropsychological status, but one which is different from proper names. The findings suggest that the hemispheric lexical status of the brand names is mixed--they behave like words in some respects and like nonwords in others. Our study used familiar upper case brand names, common nouns, and two different types of nonwords ("weird" and "normal") differing in length, as stimuli in a lateralized lexical decision task (LDT). Common nouns, brand names, weird nonwords, and normal nonwords were recognized in that decreasing order of speed and accuracy. A right visual field (RVF) advantage was found for all four lexical types. Interestingly, brand names, similar to nonwords, were found to be less lateralized than common nouns, consistent with theories of category-specific lexical processing. Further, brand names were the only type of lexical items to show a capitalization effect: brand names were recognized faster when they were presented in upper case than in lower case. In addition, while string length affected the recognition of common nouns only in the left visual field (LVF) and the recognition of nonwords only in the RVF, brand names behaved like common nouns in exhibiting length effects only in the LVF.     

Imageability and word recognition in the left and right visual fields: a signal detection analysis

Identifying the information processing constraints that determine whether or not imagery moderates visual field asymmetries is essential for constructing a dynamic model of hemispheric interaction during language processing. In this investigation, we manipulated the global experimental context in which imageable and nonimageable words were presented by contrasting mixed and blocked word lists using a lateralized lexical decision task. Signal detection analyses were employed to assess whether global stimulus context and imageability differentially affect word discriminability (d prime) and response bias (log beta) across visual fields. Both discriminability and response bias varied with imageability and stimulus context, but to a comparable extent across visual fields. This suggests that both hemispheres are sensitive to the global context in which words are presented, and can adjust processing based not only on semantic characteristics of the words themselves, but also on the variability of items in the stimulus environment.     

Visual field differences in verbal tasks: Effects of task familiarity and sex of subject

Four experiments using normal subjects investigated differences in magnitude of the right visual field (RVF) superiority as a function of word material (frequency and concreteness/imageability status), nonword letter strings (some of which were homophonic with nonpresented real words), and type of task (overt naming or lexical decision with discriminatory manual responses) as well as sex of the subject and the subject's familiarity with the material. Both latency and error measures showed that RVF superiority was more consistent when overt naming was required and with male subjects. For female subjects engaged in lexical decisions, a left visual field (LVF) superiority was often apparent, especially in the first half of an experimental sequence; when actually naming the items aloud, they showed field asymmetries similar to males. Except from an analysis of errors, there was little evidence to support differential right hemisphere mediation of high frequency concrete/imageable materials. It is suggested that in females, right hemisphere space normally reserved for visuospatial processing may have been invaded by secondary speech mechanisms. These mechanisms appear to operate at an essentially lexical level and may act in a supportive or auxiliary capacity for difficult or unfamiliar material; they seem to be equally concerned with both phonological and graphological processing and may account for the well-known female superiority in verbal tasks and inferiority in visuospatial tasks. Other findings are discussed such as the degree of consistency of the field differences, both for the same subjects and for the same stimulus materials under different task requirements and experimental conditions.     

A case of literal alexia: evidence for a disconnection syndrome

We describe a patient with literal alexia, agraphia, and only minimal aphasia, resulting from a left occipito-parietal ischemic infarction. Neither impaired visual processing nor impaired oral output could explain the patient's letter reading deficit, since he retained the ability to match letters of mixed case, and remained able to spell aloud and to pronounce and comprehend orally spelled words. His residual word reading was characterized by better performance for nouns and highly imageable words than for functors , poorly imageable words, and nonwords. We propose that this patient's letter reading deficit was due to a partial disconnection of his visual from his linguistic systems, with residual word reading accomplished by a semantically mediated compensatory mechanism. We suggest, further, that the dissociations between word and letter reading observed in some alexic individuals may be attributed, in part, to a difference in the relative contributions of dorsal and ventral occipital structures to the reading process.     

Neurological origins of poor reading comprehension despite fast word decoding?

Barnes, Faulkner, and Dennis (2001) found that hydrocephalic children (mean age = 11.5 years) of average or above-average verbal intelligence exhibit poor reading comprehension despite their fast and accurate decoding skills on individual words. This finding attracts the attention of reading researchers because it appears to be against the following standard principle of reading comprehension failure (Gough & Hillinger, 1980), thereby provoking basic issues centering around it (e.g., Stanovich, 1991): Reading Comprehension = Word Decoding x Listening Comprehension. This formula indicates that when listening comprehension is kept well within the normal range, reading comprehension is highly correlated with word decoding (e.g., Perfetti, 1985). In contrast, with poor listening comprehension children would be poor readers however good they may be at reading words (e.g., Cain, Oakhill, & Bryant, 2000). Although Barnes et al. clearly demonstrated that children with hydrocephalus decoded individual words better than they comprehended text, it is not readily apparent whether their findings are inconsistent with the standard principle. The purpose of the present article is twofold. The first is to examine whether Barnes et al.'s findings constitute a counterexample of the above principle. (Note that Barnes et al. did not address this question.) The second and more important purpose is to discuss the possible origins of the decoding-better-than-sentence/text-comprehension pattern. We also present some pedagogical implications for poor readers such as hydrocephalic children.     

Hemispheric specialization for syntactic form

Pure nouns, verb-derived nouns, category-ambiguous words, and adjectives, all ending in -er, and matched for low and moderate-high frequency, were presented in each visual field to 24 normal, right-handed females. The four word classes were recognized at the same rate in the LVF, and at a significantly higher rate in the RVF. Contrary to earlier reports, there were no differences among pure nouns, verb-derived nouns, and category-ambiguous words, and effects appeared to be independent of word frequency. Neither hemisphere was demonstrated to give preferential access to the syntactic forms tested.     

“Does degree of asymmetry relate to performance?” A critical review

In a recent paper, Chiarello, Welcome, Halderman, and Leonard (2009) reported positive correlations between word-related visual field asymmetries and reading performance. They argued that strong word processing lateralization represents a more optimal brain organization for reading acquisition. Their empirical results contrasted sharply with those of another such large-scale study, by Boles, Barth, and Merrill (2008). We reported negative correlations between asymmetry and performance when both were measured using the same visual lexical tasks. Most recently, within-task negative correlations were also reported by Hirnstein, Leask, Rose, and Hausmann (2010). Here two major differences between studies are explored. Task purity refers to the influence of the same mental processes on both the asymmetry and performance measures, and is arguably maximal in studies measuring both within the same task. The other difference concerns the measurement of asymmetry. Linear corrections for ceiling and floor effects were used by Chiarello et al. and Hirnstein et al., while we used a more appropriate nonlinear one. Their results are difficult to interpret for those reasons. The operation of a third variable to which both asymmetry and performance are positively correlated could also be a factor in the Chiarello et al. findings. The Boles et al. findings reflect a negative correlation between an asymmetric visual lexical process and performance measured within the same task.     

Congruity effects in the survival processing paradigm

Five experiments were conducted to investigate a proposal by Butler, Kang, and Roediger (2009) that congruity (or fit) between target items and processing tasks might contribute, at least partly, to the mnemonic advantages typically produced by survival processing. In their research, no significant survival advantages were found when words were preselected to be highly congruent or incongruent with a survival and control (robbery) scenario. Experiments 1a and 1b of the present report show that survival advantages, in fact, generalize across a wide set of selected target words; each participant received a unique set of words, sampled without replacement from a large pool, yet significant survival advantages remained. In Experiment 2, we found a significant survival advantage using words that had been preselected by Butler et al. to be highly unrelated (or irrelevant) to both the survival and control scenarios. Experiment 3 showed a significant survival advantage using word sets that had been preselected to be highly congruent with both scenarios. Finally, Experiment 4 mixed congruent and incongruent words in the same list, more closely replicating the design used by Butler et al., and a highly reliable main effect of survival processing was still obtained (although the survival advantage for the congruent words did not reach conventional levels of statistical significance). Our results suggest that the null effects of survival processing obtained by Butler et al. may not generalize beyond their particular experimental design.     

Phonological typicality influences sentence processing in predictive contexts: reply to Staub, Grant, Clifton, and Rayner (2009)

In 2 separate self-paced reading experiments, Farmer, Christiansen, and Monaghan (2006) found that the degree to which a word's phonology is typical of other words in its lexical category influences online processing of nouns and verbs in predictive contexts. Staub, Grant, Clifton, and Rayner (2009) failed to find an effect of phonological typicality when they combined stimuli from the separate experiments into a single experiment. We replicated Staub et al.'s experiment and found that the combination of stimulus sets affects the predictiveness of the syntactic context; this reduces the phonological typicality effect as the experiment proceeds, although the phonological typicality effect was still evident early in the experiment. Although an ambiguous context may diminish sensitivity to the probabilistic relationship between the sound of a word and its lexical category, phonological typicality does influence online sentence processing during normal reading when the syntactic context is predictive of the lexical category of upcoming words.     

词汇具体性对情绪名词效价加工影响的ERP研究

具体性和抽象性是词汇同一特性的两极, 是直接影响词汇加工过程的重要因素。本研究采用快速序列视觉呈现范式, 结合脑电技术探讨在有限注意资源内, 词汇具体性对情绪名词加工过程的影响。结果发现：名词加工早期和晚期阶段的ERP成分受到情绪效价的调节, 情绪词比中性词诱发了更大的N170和LPC波幅; 名词加工早期和晚期阶段的ERP成分也受到词汇具体性的调节, 具体词比抽象词诱发了更大的N170和LPC波幅; 词汇具体性影响情绪名词加工的晚期阶段, LPC波幅能够分辨出不同情绪效价的抽象词, 对于具体词仅能区分出情绪与非情绪, 这说明抽象词可能比具体词负载了更多的情绪信息, 反映出对情绪信息的精细加工过程。     

Sex differences in processing aggression words using the Emotional Stroop task

There is a robust relationship between the salience of stimulus materials presented in the Emotional Stroop task and inhibition of response in clinical populations. Researchers have now found information‐processing biases in both forensic and non‐forensic samples presented with threatening or aggressive stimuli [Cohen et'al., 1998; Eckhardt and Cohen, 1997; Smith and Waterman, 2003; Van Honk et'al., 2001]. We sought to explore sex differences in processing words relating to acts of direct and indirect aggression using a group of undergraduates (50 males and 50 females). Participants also completed self‐report questionnaires (AQ and EXPAGG) to allow some consideration of the relationship between objective and subjective measures. We predicted that males would demonstrate delayed responses when presented with words relating to acts of direct aggression. We also predicted that high levels of physical aggression would be the best predictor of bias for direct aggression words, high levels of verbal aggression would be the best predictor of bias for indirect aggression words, physical aggression would predict bias in males, and verbal aggression would predict bias in females. Males demonstrated a perceptual bias for words relating to acts of direct aggression, taking significantly longer to correctly colour name direct aggression words. Females were slower to correctly colour name indirect aggression words, but not significantly so. Verbal aggression, as expected, predicted bias performance for indirect aggression words but anger rather than physical aggression was the best predictor of bias for direct aggression words. Gender was a predictor for bias with both sets of words. Contrary to our predictions, it was observed that a high level of physical aggression was the best predictor of bias in both males and females. These data provide further evidence to confirm the saliency of aggression words to aggressive individuals in non‐forensic populations. Aggress. Behav. 00:00–00, 2005. © 2005 Wiley‐Liss, Inc.     

Lack of habituation to shocking words: The attentional bias to their spatial origin is context free

Following a suggestion made by Aquino and Arnell (2007), we assumed that the processing of emotional words is influenced by their context of presentation. Supporting this idea, previous studies using the emotional Stroop task in its visual or auditory variant revealed different results depending on the mixed versus blocked presentation of the stimuli (Bertels, Kolinsky, Pietrons, & Morais, 2011; Richards, French, Johnson, Naparstek, & Williams, 1992). In the present study, we investigated the impact of these presentation designs on the occurrence of spatial attentional biases in a modified version of the beep-probe task (Bertels, Kolinsky, & Morais, 2010). Attentional vigilance to taboo words as well as non-spatial slowing effects of these words were observed whatever the mixed or blocked design, whereas attentional vigilance to positive words was only observed in the mixed design. Together with the results from our previous study (Bertels et al., 2010), the present data support the reliability of the effects of shocking stimuli, while vigilance to positive words would only be observed in a threatening context.