Nonword Letter Strings Research Articles

Privileged Functional Connectivity between the Visual Word Form Area and the Language System.

The visual word form area (VWFA) is a region in the left occipitotemporal sulcus of literate individuals that is purportedly specialized for visual word recognition. However, there is considerable controversy about its functional specificity and connectivity, with some arguing that it serves as a domain-general, rather than word-specific, visual processor. The VWFA is a critical region for testing hypotheses about the nature of cortical organization, because it is known to develop only through experience (i.e., reading acquisition), and widespread literacy is too recent to have influenced genetic determinants of brain organization. Using a combination of advanced fMRI analysis techniques, including individual functional localization, multivoxel pattern analysis, and high-resolution resting-state functional connectivity (RSFC) analyses, with data from 33 healthy adult human participants, we demonstrate that (1) the VWFA can discriminate words from nonword letter strings (pseudowords); (2) the VWFA has preferential RSFC with Wernicke's area and other core regions of the language system; and (3) the strength of the RSFC between the VWFA and Wernicke's area predicts performance on a semantic classification task with words but not other categories of visual stimuli. Our results are consistent with the hypothesis that the VWFA is specialized for lexical processing of real words because of its functional connectivity with Wernicke's area.SIGNIFICANCE STATEMENT The visual word form area (VWFA) is critical for determining the nature of category-related organization of the ventral visual system. However, its functional specificity and connectivity are fiercely debated. Recent work concluded that the VWFA is a domain-general, rather than word-specific, visual processor with no preferential functional connectivity with the language system. Using more advanced techniques, our results stand in stark contrast to these earlier findings. We demonstrate that the VWFA is highly specialized for lexical processing of real words, and that a fundamental factor driving this specialization is its preferential intrinsic functional connectivity with core regions of the language system. Our results support the hypothesis that intrinsic functional connectivity contributes to category-related specialization within the human ventral visual system.

Morphological processing during visual word recognition in Hebrew as a first and a second language

The present study examined whether sublexical morphological processing takes place during visual word-recognition in Hebrew, and whether morphological decomposition of written words depends on lexical activation of the complete word. Furthermore, it examined whether morphological processing is similar when reading Hebrew as a first language (L1) or as a second language (L2), and whether L1’s morphological background, Semitic or Indo-European, modulates morphological processing in L2 Hebrew (a Semitic language), among proficient readers. To reveal the sublexical processing of the Hebrew morphemes, the Root (R) and the Pattern (P), a lexical-decision task was conducted, in which all critical stimuli were non-word letter-strings manipulated to include or exclude real Hebrew morphemes. Different combinations of real (+) and pseudo (−) morphemes yielded four types of non-words (+R+P; +R−P; −R+P, −R−P). Three groups of proficient Hebrew readers were tested: L1 Hebrew, L1 English-L2 Hebrew, and L1 Arabic-L2 Hebrew. Results demonstrated significant differences in latency and accuracy of responses to the four morphological conditions, indicating that sublexical morphological processing occurs during visual word-recognition of morphologically structured letter-strings in Hebrew. Importantly, the activation of real Hebrew morphemes occurred in non-word stimuli, indicating that morphological processing in Hebrew is separable from lexical activation. Moreover, the same pattern of results was observed in all three L1 groups, indicating that proficient L2 readers exhibit morphological processing strategies that are tuned to the L2 morphology, regardless of their L1 background.

A comparison of brain activity evoked by single content and function words: An fMRI investigation of implicit word processing

Content and function words have different roles in language and differ greatly in their semantic content. Although previous research has suggested that these different roles may be mediated by different neural substrates, the neuroimaging literature on this topic is particularly scant. Moreover, fMRI studies that have investigated differences between content and function words have utilized tasks that focus the subjects' attention on the differences between these word types. It is possible, then, that task-related differences in attention, working memory, and decision-making contribute to the differential patterns of activation observed. Here, subjects were engaged in a continuous working memory cover task while single, task-irrelevant content and function words were infrequently and irregularly presented. Nonword letter strings were displayed in black font at a fast rate (2/s). Subjects were required to either remember or retrieve occasional nonwords that were presented in colored fonts. Incidental and irrelevant to the memory task, content and function words were interspersed among nonwords at intervals of 12 to 15 s. Both word types strongly activated temporal–parietal cortex, middle and anterior temporal cortex, inferior frontal gyrus, parahippocampal gyrus, and orbital frontal cortex. Activations were more extensive in the left hemisphere. Content words elicited greater activation than function words in middle and anterior temporal cortex, a sub-region of orbital frontal cortex, and the parahippocampal region. Words also evoked extensive deactivation, most notably in brain regions previously associated with working memory and attention.

Short Article: Tracking the Transition from Sublexical to Lexical Processing: On the Creation of Orthographic and Phonological Lexical Representations

Participants read aloud nonword letter strings, one at a time, which varied in the number of letters. The standard result is observed in two experiments; the time to begin reading aloud increases as letter length increases. This result is standardly understood as reflecting the operation of a serial, left-to-right translation of graphemes into phonemes. The novel result is that the effect of letter length is statistically eliminated by a small number of repetitions. This elimination suggests that these nonwords are no longer always being read aloud via a serial left-to-right sublexical process. Instead, the data are taken as evidence that new orthographic and phonological lexical entries have been created for these nonwords and are now read at least sometimes by recourse to the lexical route. Experiment 2 replicates the interaction between nonword letter length and repetition observed in Experiment 1 and also demonstrates that this interaction is not seen when participants merely classify the string as appearing in upper or lower case. Implications for existing dual-route models of reading aloud and Share's self-teaching hypothesis are discussed.

Visual Binding of English and Chinese Word Parts is Limited to Low Temporal Frequencies

Some perceptual mechanisms manifest high temporal precision, allowing reports of visual information even when that information is restricted to windows smaller than 50 ms. Other visual judgments are limited to much coarser time scales. What about visual information extracted at late processing stages, for which we nonetheless have perceptual expertise, such as words? Here, the temporal limits on binding together visual word parts were investigated. In one trial, either the word 'ball' was alternated with 'deck', or 'dell' was alternated with 'back', with all stimuli presented at fixation. These stimuli restrict the time scale of the rod identities because the two sets of alternating words form the same image at high alternation frequencies. Observers made a forced choice between the two alternatives. Resulting 75% thresholds are restricted to 5 Hz or less for words and nonword letter strings. A similar result was obtained in an analogous experiment with Chinese participants viewing alternating Chinese characters. These results support the theory that explicit perceptual access to visual information extracted at late stages is limited to coarse time scales.

Behavioral and Brain Wave Evidence for Automatic Processing of Orthographically Regular Letter Strings

Evidence for the automatic processing of nonword letter strings was sought in subjects who performed two different perceptual tasks. Twelve subjects detected valid words. Twelve other subjects detected Gestalt patterns that contained no letters. The targets and two types of nonword letter strings were interspersed in a stream of nonletter images. Behavioral data showed significant effects of orthographic regularity of letter strings in the group that detected words, but not in the group that detected Gestalt patterns. Brain-wave responses showed the effect of orthographic regularity in both groups. The responses were significantly larger for regular than for irregular strings. This showed that brain waves can be used to study the operation of reading processes in subjects who are performing a task that does not require reading ability.

Semantic priming impairment in HIV

HIV+ subjects have shown impairment on tests of executive function including automatic attention and verbal tasks. Impairment of semantic priming in HIV patients would suggest a disruption of automatic semantic activation. We examined semantic priming in HIV+ individuals and HIV- control participants with no history of substance abuse, neurologic or psychiatric disorder unrelated to HIV. HIV+ participants were divided into cognitively normal and cognitively impaired subgroups on the basis of a neuropsychological battery of 15 tests. Participants were presented with English words and nonword letter strings and indicated if the stimulus was a word or nonword. The nonwords were orthographically and phonologically correct and were created by rearranging the letter sequence of words ("ulpit"). All words had an obvious antonym ("deep"); two-thirds were presented as sequential antonym pairs ("enter"-"exit"). There were no group differences in speed of response to nonwords, indicating no generalized reaction time deficit. While control and cognitively normal HIV+ participants showed an effect of priming on reaction time to correctly detected words, cognitively impaired HIV+ participants did not. The lack of semantic priming demonstrated by cognitively impaired HIV+ participants suggests that they have lessened activation of automatic semantic networks.

Phonology can help or hurt the perception of print.

Phonological manipulations affect performance in a letter search task that requires only a shallow level of processing. In Experiment 1, phonology reduced accuracy in the letter search task when a pseudohomophone (GAIM) contained a target letter ("i") that was missing in the spelling of its (nonpresented) sound-alike base word (GAME). In Experiment 2, phonology increased accuracy in the letter search task when the target letter was present in both the spelling of the pseudohomophone and the spelling of its sound-alike base word ("m" in GAIM and GAME). In Experiment 3, we showed that the phonology-hurts effect of Experiment 1 is not peculiar to nonword letter strings but generalizes to familiar words. In Experiment 4, we obtained a phonology-hurts effect on correct response times when stimuli were visible until participants responded (stimuli were not masked).

Phonology can help or hurt the perception of print.

Phonological manipulations affect performance in a letter search task that requires only a shallow level of processing. In Experiment 1, phonology reduced accuracy in the letter search task when a pseudohomophone (GAIM) contained a target letter ("i") that was missing in the spelling of its (nonpresented) sound-alike base word (GAME). In Experiment 2, phonology increased accuracy in the letter search task when the target letter was present in both the spelling of the pseudohomophone and the spelling of its sound-alike base word ("m" in GAIM and GAME). In Experiment 3, we showed that the phonology-hurts effect of Experiment 1 is not peculiar to nonword letter strings but generalizes to familiar words. In Experiment 4, we obtained a phonology-hurts effect on correct response times when stimuli were visible until participants responded (stimuli were not masked).

Text-contingent color aftereffects: a reexamination.

Five experiments reexamined color aftereffects contingent on the semantic properties of text (Allan, Siegel, Collins, & MacQueen, 1989). The influence of different assessment techniques and the effect of eye movements and overlapping contour information on the induction of color aftereffects by word and nonword letter strings were determined. Experiment 1 showed that no aftereffect was found when a traditional method of assessing color aftereffects was used. Experiments 2 and 4 demonstrated color aftereffects for both words and nonwords, but only when subjects fixated the same locus during induction and testing and only when assessed with the technique described by Allan et al. (1989). If, however, eye movements were made during induction, no color aftereffect was obtained (Experiment 3). Induction to nontext patterns with properties similar to those of text but with fewer overlapping contours resulted in a strong color aftereffect (Experiment 5). These results suggest that the color aftereffect contingent on text is very weak and is not dependent on semantic factors, but that it is a product of induction to local color and orientation information.

A “popout” effect with words and nonwords

Previous research (Flowers & Lohr, 1985) has not found evidence for the “popout” phenomenon (e.g., Treisman, 1988) with word and nonword letter strings. Flowers and Lohr utilized a visual search task that employed a circular arrangement of stimuli. This format does not optimize spatial contiguity, which has been shown to facilitate stimulus detection in certain contexts (Bryant & Soraci, 1992; Soraci, Carlin, Deckner, & Baumeister, 1990). The present study examined popout with words and nonwords in a same-different task, using a visual array format in which interstimulus contiguity increased with changes in set size. With these arrays, no popout effect was evidenced under conditions of high featural overlap between targets and distractors. However, under conditions of low featural overlap, a popout effect for both words and nonwords was found.

Color aftereffect contingent on text.

During adaptation, two different letter strings (each five or six letters) were presented to subjects alternately, one in green and the other in magenta. The extent to which these letter strings subsequently elicited a color aftereffect was assessed. In different experiments, the chromatic letter strings consisted of words and nonwords. The results indicated that letter strings that form English words can contingently elicit a color aftereffect. This was the case even when the words were anagrams. There was no evidence that nonword letter strings could contingently elicit such an aftereffect, even when the nonwords conformed to English orthography. The results are relevant to understanding other contingent color aftereffects (McCollough effects), illusory color noted by computer operators who work at monochrome (green or amber) displays, and the processing of text.

Recognition of visual letter strings following injury to the posterior visual spatial attention system

Abstract Unilateral posterior lesions often produce a deficit in visual spatial attention. One result of this deficit is a loss of information from a word contralateral to the lesion when presented simultaneously with an ipsilateral word (interword extinction). However, when a single word presented at fixation covers the same visual angle there is frequently no extinction (Sieroff & Michel, 1987). Why are centred words not extinguished? Our studies attempt to discover the reason by comparing centred word and nonword letter strings. Nonwords do show extinction. Words are processed more accurately and show little evidence of extinction. Compound words appear to act like normal words, but segmenting letters into separate strings increases extinction. These results suggest that spatial attention is unnecessary for access to the lexical network that produces a visual word form.

Cueing spatial attention during processing of words and letter strings in normals

Abstract Work with patients has shown that lesions of the right posterior cortex produce a deficit that affects ability to report letters on the left side of a foveal nonsense string but has little effect on foveal words. We have proposed that this is the result of a deficit in visual spatial attention. The current studies use cues on the left and right of foveally centred letter strings to bias visual spatial attention in normals. The studies show that the cues serve to bias report to the cued side very strongly for nonword letter strings and are less effective the more wordlike the string becomes. These results show that covert attention controls access of letters to consciousness in those cases where spatial attention is used to organise input.

Access to spoken language and the acquisition of orthographic structure: evidence from deaf readers.

Sensitivity to two types of orthographic structure was investigated: linguistically based orthographic regularity and summed single letter positional frequency. Deaf college students were found to make use of positional frequency information no less than hearing college students; however, the extent to which they made use of orthographic regularities in word recognition was related to their speech production skills. In one task, subjects were presented nonword letter strings for short durations, each followed by a masking stimulus and a target letter. They were asked to indicate whether or not the target had been present in the letter string. It was found that the accuracy of deaf subjects with good speech, like that of hearing subjects, was considerably greater for orthographically regular than irregular strings. In contrast, the accuracy of deaf subjects with poor speech was much less related to orthographic regularity. In a second task, in which subjects made judgements about how word-like various letter strings appeared, the judgements of the hearing subjects were more influenced by regularity than those of deaf subjects with poor speech. These results are discussed in terms of how expertise in speech relates to appreciation of orthographic regularity.

Semantic Priming of Nonwords in Lexical Decision

This research investigated semantic priming of nonwords in a timed lexicaldecision task. The nonword letter strings were anagrams of, and orthographically and phonetically similar to, words that were either related or unrelated to previously presented prime words. To compare the nature of priming effects in lexical and nonword decisions, two different stimulus onset asynchronies (SOAs) were used, a short one (250 ms), intended to produce automatic activation of concepts related to the primes, and a long one (1500 ms), intended to produce attentional activation. Priming effects were greater for words at the short SOA than at the long one. Nonwords showed the reverse pattern, with greater priming effects at the long SOA than at the short one.

Reading without phonology?

Responses to items such as brane are slower and/or more error prone than responses to items such as slint in lexical decision (is this string spelt like a real word?). The received view is that this “pseudohomophone” effect is attributable to phonological receding. Taft (1982) has challenged this view, offering instead a grapheme-grapheme account which assumes that graphemes that map onto a common phoneme develop the ability to activate each other without reference to phonological mediation. Taft's grapheme-grapheme account is tested in two experiments. Experiment 1 shows that the presentation of a pseudohomophone facilitates the response to a subsequently presented word (e.g., groce–gross). Experiment 2 shows that nonword letter strings that are translatable into words by the application of putative grapheme-grapheme rules (e.g., gloce–gloss) produce no facilitation. These results are consistent with the notion of a phonological influence but inconsistent with the grapheme–grapheme account. Loci for this pseudohomophone priming effect are discussed.

Word repetition, lexical access, and the process of searching words and sentences

Subjects were asked to search a list of words for nonword letter strings. Such exposure to these words was sufficient to (a) speed subsequent search of a new list containing these words whether this search was for nonwords or required deeper semantic evaluation, and (b) reduce errors in interpretive search of prose passages. One account of these results is that exposure to written words facilitates subsequent lexical access and that lexical access operates similarly in a variety of uses of written material. The results of our three experiments extend, with word lists and both scrambled and coherent text, the finding of D. L. Scarborough, C. Cortese, and H. S. Scarborough (Journal of Experimental Psychology: Human Perception and Performance, 1977 , 3, 1–17) that exposure to single words facilitates lexical judgments of single words. Our results together with those of Scarborough et al. suggest that recency of exposure may contribute to word “frequency” effects in reading and in learning from written material.

Automatic Processing as a Function of Age and Reading Ability

GUTTENTAG, ROBERT E., and HAITH, MARSHALL M. Automatic Processing as a Function of Age and Reading Ability. CmLD DEVELOPMENT, 1978, 49, 707-716. Early and late first-grade children, third-grade poor and good readers, and adults named pictures under several interference conditions: with embedded intracategory or extracategory words, pronounceable or nonpronounceable letter strings, and visual noise. Interference attributable to word category was found for all groups except the early first grade. Interference from letters was found for all groups except a subgroup of 5 early first-grade children who also made errors on a picture-word matching task. Only adults and third-grade good readers were reliably affected by whether the nonword letter strings were pronounceable. It was concluded that even children who are poor readers and normal children with only 9 months of formal reading instruction extract meaning from familiar printed words automatically. The results are also discussed in terms of the relation between controlled and automatic processing of letters and words and the role of automatic decoding in the reading comprehension deficit of poor readers.

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.