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.     

Can “words” be processed as integrated units?

Three experiments examined the information processing of letters embedded within one-syllable words and similar unpronounceable sequences. A speeded discrimination task was used to detect processing differences between words and nonwords in a situation where both the identity and position of critical display information was known to subjects before stimulus presentation. Results indicated that word pairs differing by two letters were more quickly discriminated than two words differing in a single letter, while nonword pairs differing in two letters were discriminated no faster than two nonwords differing in a single letter. A further comparison showed a performance advantage for words over nonwords in a condensation task that forced a scan of stimulus letters for correct responding. These results suggest that familiarity affects information processing at a perceptual level, and are incompatible with theories suggesting that familiarity effects are due to inferential factors following letter feature analysis.     

Lexical decisions in the right and left cerebral hemispheres

Subjects performed a lexical decision task in which letter-strings were presented unilaterally and tachistoscopically to the right and left visual fields. Four types of letter-strings were used: high frequency words, low frequency words, pronounceable nonwords, and unpronounceable nonwords. Measures of reaction time and error rate both showed a right visual field advantage for both classes of words and no difference between the hemispheres for either class of nonword. It was concluded that meaning is a more salient parameter of wordness than is pronounceability. Possible mechanisms for processing words presented to the left visual field were discussed.     

Modes of word recognition in the left and right cerebral hemispheres

Four experiments are reported examining the effects of word length on recognition performance in the left and right visual hemifields (LVF, RVF). In Experiments 1 and 2 length affected lexical decision latencies to words presented in the LVF but not to words presented in the RVF. This result was found for both concrete and abstract nouns. Changing from a normal horizontal format to the use of unconventionally "stepped" words, however, produced length effects for words in both visual hemifields (Experiment 3). The Length x VHF interaction was found once again in Experiment 4 where subjects classified words as either concrete or abstract. A model proposing two modes of visual processing of letter strings is presented to account for these findings. Mode A operates independent of string length and is seen only in left hemisphere analysis of familiar words. Mode B is length dependent: it is the only mode possessed by the right hemisphere but is displayed by the left hemisphere to nonwords and to words in abnormal formats.     

The role of assembled phonology in reading comprehension

The contribution of assembled phonology to phonological effects in reading comprehension was assessed. In Experiment 1, subjects judged the acceptability of sentences with regular, exception, and nonword homophone substitutions and orthographic controls. Significantly more errors occurred to sentences with regular-word homophones than to exception words, and error rates for nonword homophones were low and not significant. Experiment 2 showed that this was not due to differences in the sentence frames. In Experiment 3, the subjects judged as unacceptable those sentences containing an exception word that sounded correct when read according to spelling-to-sound rules. Significantly higher error rates occurred only for low-frequency exception words. Experiment 4 showed that task conditions affect semantic-categorization error rates for nonword homophones. These results indicate that both assembled and addressed phonology contribute to sentence and word comprehension, but the low error rate for nonwords suggests that an early lexical check may be applied.     

Further study of the electrophysiological correlates of lexical decision

Discriminations were required between words, pseudohomophones, and visually matched nonwords. Two tasks were employed, one which could be accomplished on the basis of a visual code (the REAL task, involving discrimination between words and both types of nonword) and another necessitating the use of a phonological code (the REAL/PSEUD task, words and pseudohomophones vs. nonwords). ERPs were recorded from three midline sites and from left and right inferior parietal sites. Two principal results were observed, (i) the peak latency of a late positive component, P637, covaried with RT, with variations in latency of around one half the corresponding RT variations, and (ii) the peak-to-peak amplitude of N100-P187 interacted with stimulus and task, such that it was larger for nonwords in the REAL task and words in the REAL/PSEUD task. No taskor stimulus-dependent asymmetries were observed in any ERP component. The P637 latency data support a model of RT variation based on the interaction of changes in parallel response preparation and stimulus evaluation processes. The observations with respect to N100-P187 suggest that ERPs are sensitive to factors related to the early processing of words and word-like visual material.     

Perception of visual letter strings in a case of left neglect: Manipulation of the word form

Patients with lesions in the right parietal lobe neglect the left side of nonwords much more than the left side of words. This has been interpreted in terms of a more automatic process in reading words. The case of a patient with left visual neglect after a vascular right parietooccipital lesion is presented. He showed the phenomenon of a word superiority effect over nonword in reading at the beginning in a clinical test with static cards; 6 months later, after some recovery, the same phenomenon could be demonstrated only with tachistoscopic presentation, and it occurred even inside the good right visual hemifield. The word form of visually presented stimuli was manipulated, showing that there was a striking effect particularly when spacing the letters of words in a task that requires naming the stimulus. The patient's performance is interpreted in terms of an attentional deficit occurring at an early level of spatial information processing.     

汉语双字多义词的识别优势效应

采用词汇判断法、命名法考察汉语双字多义词的识别优势效应。结果发现,在词汇判断任务中存在着多义词较单义词的识别优势,但这种识别优势只表现在低频词中。在命名任务中未发现多义词的识别优势。作者根据分布表征模型的观点对双字多义词的识别优势效应做出了可能的解释。     

Quantitative and Qualitative Hemispheric Asymmetry for Processing Japanese Kana

Native Japanese speakers identified three-letter kana stimuli presented to the left visual field and right hemisphere (LVF/RH), to the right visual field and left hemisphere (RVF/LH), or to both visual fields and hemispheres simultaneously (BILATERAL trials). There were fewer errors on RVF/LH and BILATERAL trials than on LVF/RH trials. Qualitative analysis of error patterns indicated that there were many fewer errors of first-letter identification than of last-letter identification, suggesting top-to-bottom scanning of the kana characters. In contrast to similar studies presenting nonword letter trigrams to native English speakers, qualitative error patterns were identical for the three visual field conditions. Taken together with the results of earlier studies, the results of the present experiment indicate that the ubiquitous RVF/LH advantage reflects a left-hemisphere superiority for phonetic processing that generalizes across specific languages. At the same time, qualitative aspects of hemispheric asymmetry differ from one language to the next and may depend on such things as the way in which individual characters map onto the pronunciation of words and nonwords.     

Different methods of lexical access for words presented in the left and right visual hemifields

Right-handed adults were asked to identify by name bilaterally presented words and pronounceable nonwords. For words in the normal horizontal format, word length (number of letters) affected left visual hemifield (LVF) but not right visual hemifield (RVF) performance in Experiments 1, 2, 3, 5, and 6. This finding was made for words of high and low frequency (Experiment 6) and imageability (Experiment 5). It also held across markedly different levels of overall performance (Experiments 1 and 2), and across different relative positionings of short and long words in the LVF and RVF (Experiment 3). Experiment 4 demonstrated that the variable affecting LVF performance is the number of letters in a word, not its phonological length. For pronounceable nonwords (Experiment 7) and words in unusual formats (Experiment 8), however, length affected both LVF and RVF performance. The characteristics identified for RVF performance in these experiments also hold for the normal reading system. In this (normal) system the absence of length effects for horizontally formatted words is generally taken to reflect the processes involved in lexical access. Length effects in the normal reading system are thought to arise when lexical access for unusually formatted words and for the pronunciation of nonwords requires the short-term storage of information at a graphemic level of analysis. The characteristics of LVF performance indicate that horizontally formatted words presented to the right cerebral hemisphere can only achieve lexical access by a method that requires the short-term storage of graphemic information. This qualitative difference in methods of lexical access applies regardless of whether the right hemisphere is seen as accessing words in the left hemisphere's lexicon or words in a lexicon of its own.     

Lexical decision and aphasia: Evidence for semantic processing

Wernicke's and Broca's-Conduction aphasics and a Global aphasic were presented with a lexical-decision task in which English words and pronounceable nonwords were preceded by semantically related, unrelated, or nonword primes. The patients were also given a simple semantic-judgment task using the word pairs from the lexical-decision task. Wernicke's aphasics performed similar to normals and Broca's-Conduction aphasics showing significantly shorter latencies in making real-word identifications when preceded by a semantically related word. In addition, both superordinate and coordinate associates showed semantic-priming effects. Performance on the semantic-judgment task showed significantly more impairment in the aphasic group than in the normal controls. These results suggest that aphasics with even severe language impairments retain stored semantic information that may be automatically activated, yet is inaccessible to conscious semantic decision during metalinguistic tasks.     

Being forward not backward: lexical limits to masked priming

This study investigated whether masked priming is mediated by existing memory representations by determining whether nonwords targets would show repetition priming. To avoid the potential confound that nonword repetition priming would be obscured by a familiarity response bias, the standard lexical decision and naming tasks were modified to make targets unfamiliar. Participants were required to read a target string from right to left (i.e., "ECAF" should be read as "FACE") and then make a response. To examine if priming was based on lexical representations, repetition primes consisted of words when read forwards or backwards (e.g., "face", "ecaf") and nonwords (e.g., "pame", "emap"). Forward and backward primes were used to test if task instruction affected prime encoding. The lexical decision and naming tasks showed the same pattern of results: priming only occurred for forward primes with word targets (e.g., "face-ECAF"). Additional experiments to test if response priming affected the LDT indicated that the lexical status of the prime per se did not affect target responses. These results showed that the encoding of masked primes was unaffected by the novel task instruction and support the view that masked priming is due to the automatic triggering of pre-established computational processes based on stored information.     

Lexical inhibition and sublexical facilitation are surprisingly long lasting

When a listener hears a word (beef), current theories of spoken word recognition posit the activation of both lexical (beef) and sublexical (/b/, /i/, /f/) representations. No lexical representation can be settled on for an unfamiliar utterance (peef). The authors examined the perception of nonwords (peef) as a function of words or nonwords heard 10-20 min earlier. In lexical decision, nonword recognition responses were delayed if a similar word had been heard earlier. In contrast, nonword processing was facilitated by the earlier presentation of a similar nonword (baff-paff). This pattern was observed for both word-initial (beef-peef), and word-final (job-jop) deviation. With the word-in-noise task, real word primes (beef) increased real word intrusions for the target nonword (peef), but only consonant-vowel (CV) or vowel-consonant (VC) intrusions were increased with similar pseudoword primes (baff-paff). The results across tasks and experiments support both a lexical neighborhood view of activation and sublexical representations based on chunks larger than individual phonemes (CV or VC sequences).     

Detection of intraword and interword letter repetition: A test of the word unitization hypothesis

Do words, as familiar units or gestalts, tend to swallow up and conceal their letter components (Pillsbury, 1897)? Letters typically are detected faster and more accurately in words than in nonwords (i.e., scrambled collections of letters), and in more frequent words than in less frequent words. However, a word advantage at encoding, where the representation of the string is formed, might compensate for, and thus mask, a word disadvantage at decoding and comparison, where the component letters of the representation are accessed and compared with the target letter. To better reveal any such word disadvantage, a task was used in this study that increased the amount of letter processing. Subjects judged whether a letter was repeated within a six-letter word or a nonword (Experiment 1; intraword letter repetition) or was repeated between two adjacent unrelated six-letter words or nonwords (Experiment 2; interword letter repetition). Contrary to Pillsbury's word unitization hypothesis, both types of letter repetition (intraword and interword) were detected faster and just as accurately with words as with nonwords. In Experiment 2, however, interword letter repetition was detected less accurately on common words (but not on rare words or third-order pseudowords) than on the corresponding nonwords. Thus, although the familiar word does not deny access to its own component letters, it does make their comparison with letters from other words more difficult.     

When children write nonwords to dictation

Skill in written spelling of simple, monosyllabic nonwords was investigated in 9- to 11-year-old English children. Two aspects of their spellings were of interest: first, could they spell these nonwords so that they sounded correct (nonword spelling accuracy), and second, did their spellings show evidence of biasing from words heard earlier in the test sequence? Nonword spelling was poorer for children of this age than for tested adults. Nevertheless, significant biasing occurred in these children's spellings, though not to the same extent as in adults' nonword spellings, and significant correlations emerged between reading age, nonword spelling skill, susceptibility to biasing, and real word spelling skill. Children with a reading age greater than 11 years showed biasing from word spellings that was within range of that reported for adults, and, for these more skilled readers, word spelling accuracy correlated significantly with both susceptibility to biasing and with nonword spelling accuracy. These children were not as accurate as tested adults at spelling nonwords. Children with a reading age below 11 years were poorer at nonword spelling and showed no overall biasing, yet they also showed a significant correlation between word spelling skill and nonword biasing. Together with evidence from the same task from adults with specific spelling disorders, these results suggest that word knowledge had a direct (biasing) and an indirect (general word spelling knowledge) effect on the performance of the nonword spelling task. But although skill in word spelling may be a necessary prerequisite for nonword spelling, it need not always be sufficient.     

Ego-threat interpretive bias in test anxiety: On-line inferences

Abstract

The hypothesis that test anxiety is associated with an on-line bias towards threatening interpretations of ambiguous information was explored by means of a lexical decision task. Ambiguous sentences (concerned with ego-threat, physical-threat, or non-threat events) were presented to high- and low- test-anxiety subjects. Sentences were followed by a disambiguating word or a very wordlike corresponding nonword, which either confirmed or disconfirmed the threat implied by the sentence. A control condition involved the presentation of words and nonwords alone, without being primed by the sentences. Results indicated that there were no differences in lexical decision times as a function of test anxiety when words and nonwords were presented alone. In contrast, when they were primed, high-anxiety subjects took longer to respond correctly to the ego-threat confirming nonword, and to the ego-threat disconfirming word, compared with low-anxiety subjects; likewise, high-anxiety subjects responded faster to the ego-threat confirming word than to the ego-threat disconfirming word, compared with low-anxiety subjects. These results suggest that test anxious individuals are likely to draw inferences with an ego-threat meaning, but not with a physical-threat meaning, when reading ambiguous sentences.     

The interfering effect of word perception on letter identification

Subjects identified a single lowercase letter in a visual display by pressing one of two buttons. Two letters were assigned to each response. Groups received one of three context conditions: word, nonword, or single-letter displays. In words and nonwords, the flanking letters adjacent to the target varied as to whether they were response compatible or incompatible with the target. Single letters produced faster response latencies than either multi-letter condition, and words yielded slower latencies than did nonwords. Items Containing an incompatible-response flanking letter produced longer latencies than items containing a compatible flanking letter. Subgroups of subjects with different characteristic processing patterns were identified with a separate test. These subgroups were differentially affected by the context conditions in the letter-identification task. A greater subgroup difference was found in nonwords than in words.     

A dissociative word-frequency X levels-of-processing interaction in episodic recognition and lexical decision tasks

The effects of levels-of-processing and word frequency were directly compared in three different memory tests. In the episodic recognition test, the subjects decided whether or not a word or a pronounceable nonword had been previously studied. In the two lexical decision tests with either pronounceable or unpronounceable nonwords as distractors, the subjects decided whether a test item was a word or a nonword. There were four main results: (1) in all three tests, reaction times (RTs) in response to studied words were faster if they had received semantic rather than rhyme processing during study; (2) in the episodic recognition test, RTs were faster for low- than for high-frequency words; in both lexical decision tests, RTs were faster for high- than for low-frequency words, though less so when the nonword distractors were unpronounceable; (3) prior study facilitated lexical decisions more in response to low- than to high-frequency words, thereby attenuating the word-frequency effect, but more so when the nonword distractors were pronounceable; (4) in the lexical decision test with pronounceable nonword distractors, relative to prior rhyme processing, prior semantic processing facilitated performance more for high- than for low-frequency words, whereas the opposite was the case in the episodic recognition test. Discussion focused on the relationship of these results to current views of the mechanisms by which (1) word frequency and depth of processing affect performance in implicit and explicit memory tests, and (2) repetition priming attenuates word-frequency effects for lexical decisions.     

Event-related potentials in phonological matching tasks

Two experiments investigated Event-Related Potentials (ERPs) in matching tasks. In Experiment 1 subjects judged, in separate conditions, whether two words rhymed or were written in the same case. The CNV developing between the two words was larger in the latter task compared to the former at the right temporal site. In the rhyme judgment task, an increased late negativity differentiated the ERPs to nonrhyming words from those that rhymed with the previously presented word. This difference was maximal at the midline and over the right hemisphere. Experiment 2 further investigated ERPs in the rhyme judgment task, increasing memory demands with an extended interstimulus interval (ISI) and varying the number of items subjects had to hold in memory during this period (one vs. three). Irrespective of memory load, CNVs during the ISI were more negative from the left hemisphere, and the ERPs to the rhyming and nonrhyming words showed the same differences as in Experiment 1. The CNV asymmetries are interpreted as being associated with the engagement of lateralized short-term memory processes. The rhyme/nonrhyme differences are possibly related to the “N400” component elicited by semantically incongruous words. Possible reasons for their scalp distribution are discussed.     

Modulation of brain activity during phonological familiarization

We measured brain activity in 12 adults for the repetition of auditorily presented words and nonwords, before and after repeated exposure to their phonological form. The nonword phoneme combinations were either of high (HF) or low (LF) phonotactic frequency. After familiarization, we observed, for both word and nonword conditions, decreased activation in the left posterior superior temporal gyrus, in the bilateral temporal pole and middle temporal gyri. At the same time, interaction analysis showed that the magnitude of decrease of activity in bilateral posterior temporal lobe was significantly smaller for LF nonwords, relative to words and HF nonwords. Decrease of activity in this area also correlated with the size of behavioral familiarization effects for LF nonwords. The results show that the posterior superior temporal gyrus plays a fundamental role during phonological learning. Its relationship to sublexical and lexical phonological processing as well as to phonological short-term memory is discussed.