On the flexibility of letter position coding during lexical processing: the case of Thai

In Indo-European languages, letter position coding is particularly noisy in middle positions (e.g., judge and jugde look very similar), but not in the initial letter position (e.g., judge vs. ujdge). Here we focus on a language (Thai) which, potentially, may be more flexible with respect to letter position coding than Indo-European languages: (i) Thai is an alphabetic language which is written without spaces between words (i.e., there is a degree of ambiguity in relation to which word a given letter belongs to) and (ii) some of the vowels are misaligned (e.g., [see text] ε:bn/ is pronounced as /bε:n/), whereas others are not (e.g., [see text]/a:p/ is pronounced as /a:p/). We conducted a masked priming lexical decision experiment with 3-4 letter Thai words (with vs. without an initial misaligned vowel) in which the prime was: (i) identical to the target, (ii) a nonword generated by transposing the two initial letters of the target, or (iii) a replacement-letter control nonword. Results showed a significant masked transposed-letter priming effect in the initial letter positions, which was similar in size for words with and without an initial misaligned vowel. These findings reflect that: (i) letter position coding in Thai is very flexible and (ii) the nature of the obtained priming effects is orthographic rather than phonological.     

Vowel processing during silent reading: evidence from eye movements

Two eye movement experiments examined whether skilled readers include vowels in the early phonological representations used in word recognition during silent reading. Target words were presented in sentences preceded by parafoveal previews in which the vowel phoneme was concordant or discordant with the vowel phoneme in the target word. In Experiment 1, the orthographic vowel differed from the target in both the concordant and discordant preview conditions. In Experiment 2, the vowel letters in the preview were identical to those in the target word. The phonological vowel was ambiguous, however, and the final consonants of the previews biased the vowel phoneme either toward or away from the target's vowel phoneme. In both experiments, shorter reading times were observed for targets preceded by concordant previews than by discordant previews. Implications for models of word recognition are discussed.     

Competition during the processing of quantifier scope ambiguities: evidence from eye movements during reading

We investigated the processing of sentences containing a quantifier scope ambiguity, such as Kelly showed a photo to each critic, which is ambiguous between the indefinite phrase (a photo) having one or many referents. Ambiguity resolution requires the computation of relative quantifier scope, with either a photo or each critic taking wide scope, thereby determining the number of referents. Using eye tracking, we established that multiple factors, including the grammatical function and surface linear order of quantified phrases, along with their lexical characteristics, interact during the processing of relative quantifier scope, with conflict between factors incurring a processing cost. We discuss the results in terms of theoretical accounts attributing sentence-processing difficulty to either reanalysis (e.g., Fodor, 1982) or competition between rival analyses (e.g., Kurtzman & MacDonald, 1993).     

Children's and adults' processing of anomaly and implausibility during reading: evidence from eye movements

The eye movements of 24 children and 24 adults were monitored to compare how they read sentences containing plausible, implausible, and anomalous thematic relations. In the implausible condition the incongruity occurred due to the incompatibility of two objects involved in the event denoted by the main verb. In the anomalous condition the direct object of the verb was not a possible verb argument. Adults exhibited immediate disruption with the anomalous sentences as compared to the implausible sentences as indexed by longer gaze durations on the target word. Children exhibited the same pattern of effects as adults as far as the anomalous sentences were concerned, but exhibited delayed effects of implausibility. These data indicate that while children and adults are alike in their basic thematic assignment processes during reading, children may be delayed in the efficiency with which they are able to integrate pragmatic and real-world knowledge into their discourse representation.     

The prosodic property of lexical stress affects eye movements during silent reading

The present study examined lexical stress in the context of silent reading by measuring eye movements. We asked whether lexical stress registers in the eye movement record and, if so, why. The study also tested the implicit prosody hypothesis, or the idea that readers construct a prosodic contour during silent reading. Participants read high and low frequency target words with one or two stressed syllables embedded in sentences. Lexical stress affected eye movements, such that words with two stressed syllables took longer to read and received more fixations than words with one stressed syllable. Findings offer empirical support for the implicit prosody hypothesis and suggest that stress assignment may be the completing phase of lexical access, at least in terms of eye movement control.     

The processing of metonymy: evidence from eye movements

The authors investigated the time course of the processing of metonymic expressions in comparison with literal ones in 2 eye-tracking experiments. Experiment 1 considered the processing of sentences containing place-for-institution metonymies such as the convent in That blasphemous woman had to answer to the convent; it was found that such expressions were of similar difficulty to sentences containing literal interpretations of the same expressions. In contrast, expressions without a relevant metonymic interpretation caused immediate difficulty. Experiment 2 found similar results for place-for-event metonymies such as A lot of Americans protested during Vietnam, except that the difficulty with expressions without a relevant metonymic interpretation was somewhat delayed. The authors argue that these findings are incompatible with models of figurative language processing in which either the literal sense is accessed first or the figurative sense is accessed first. Instead, they support an account in which both senses can be accessed immediately, perhaps through a single under-specified representation.     

Activation of phonological codes during reading: evidence from errors detection and eye movements

This experiment explored the role of phonology in the activation of word meanings when homophonic and nonhomophonic errors were embedded in meaningful texts. The resulting data supported the position that phonological codes are activated very early in eye fixation and are compatible with the verification model of Van Orden (1987).     

On the role of set when reading aloud: A dissociation between prelexical and lexical processing

Two experiments investigated the role that mental set plays in reading aloud using the task choice procedure developed by Besner and Care [Besner, D., & Care, S. (2003). A paradigm for exploring what the mind does while deciding what it should do. Canadian Journal of Experimental Psychology, 57, 311–320]. Subjects were presented with a word, and asked to either read it aloud or decide whether it appeared in upper/lower case. Task information, in the form of a brief auditory cue, appeared 750 ms before the word, or at the same time as the word. Experiment 1 yielded evidence consistent with the claim that at least some pre-lexical processing can be carried out in parallel with decoding the task cue (the 0 SOA condition yielded a smaller contrast effect than the long SOA condition). Experiment 2 provided evidence that such processing is restricted to pre-lexical levels (the word frequency effect was equivalent at the 0 SOA and the long SOA). These data suggest that a task set is a necessary preliminary to lexical processing when reading aloud.     

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.     

Contrasting five different theories of letter position coding: evidence from orthographic similarity effects

Five theories of how letter position is coded are contrasted: position-specific slot-coding, Wickelcoding, open-bigram coding (discrete and continuous), and spatial coding. These theories make different predictions regarding the relative similarity of three different types of pairs of letter strings: substitution neighbors, neighbors-once-removed, and double-substitution neighbors. In Experiment 1, we used an illusory word paradigm and found that neighbor-once-removed similarity contexts resulted in fewer illusory word reports than substitution neighbors but more illusory words than double-substitution neighbors. In Experiments 2 and 3, we used a masked form priming technique with a lexical-decision task. The pattern of facilitation was as predicted by spatial coding but was incompatible with slot-coding, Wickelcoding, and both versions of open-bigram coding. These results provide further support for the SOLAR (self-organizing lexical aquisition and recognition) model of visual word identification.     

Focus identification during sentence comprehension: evidence from eye movements

Three eye movement experiments investigated focus identification during sentence comprehension. Participants read dative or double-object sentences (i.e., either the direct or indirect object occurred first), and a replacive continuation supplied a contrast that was congruous with either the direct or the indirect object. Experiments 1 and 2 manipulated focus by locating only adjacent to either the direct or indirect object of dative (Experiment 1) or double-object (Experiment 2) sentences. Reading-time effects indicated that the surface position of the focus particle influenced processing. In addition, Experiment 1 reading times were longer when the replacive was incongruous with the constituent that only adjoined, and particle position modulated a similar effect in Experiment 2. Experiment 3 showed that this effect was absent when only was omitted. We conclude that the surface position of a focus particle modulates focus identification during on-line sentence comprehension.     

Inferences about predictable events: eye movements during reading

 Eye fixations were recorded to assess whether, how, and when readers draw inferences about predictable events. Predicting context sentences, or non-predicting control sentences, were presented, followed by continuation sentences in which a target word referred to a predictable event (inferential word) or an unlikely event (non-predictable word). There were no effects on initial target word processing measures, such as launch and landing sites, fixation probability, first-fixation duration, or first-pass reading time. However, relative to the control condition, the predicting context (1) speeded up reanalysis of the inferential word, as revealed by a reduction in second-pass reading time and regressions, and (2) interfered with processing of the non-predictable word, as shown by an increase in regressions. These results indicate that predictive inferences are active at late text integration processes, rather than at early lexical-access processes. The pattern of findings suggests that these inferences involve initial activation of rather general concepts following the inducing context, and that they are completed or refined with delay, after the inferential target word is read. Received: 4 January 2000 / Accepted: 23 October 2000     

Eye movements reveal the on-line computation of lexical probabilities during reading

Skilled readers are able to derive meaning from a stream of visual input with remarkable efficiency. In this article, we present the first evidence that statistical information latent in the linguistic environment can contribute to an account of reading behavior. In two eye-tracking studies, we demonstrate that the transitional probabilities between words have a measurable influence on fixation durations, and using a simple Bayesian statistical model, we show that lexical probabilities derived by combining transitional probability with the prior probability of a word's occurrence provide the most parsimonious account of the eye movement data. We suggest that the brain is able to draw upon statistical information in order to rapidly estimate the lexical probabilities of upcoming words: a computationally inexpensive mechanism that may underlie proficient reading.     

Development of the letter identity span in reading: evidence from the eye movement moving window paradigm

By means of the moving window paradigm, we examined how many letters can be identified during a single eye fixation and whether this letter identity span changes as a function of reading skill. The results revealed that 8-year-old Finnish readers identify approximately 5 characters, 10-year-old readers identify approximately 7 characters, and 12-year-old and adult readers identify approximately 9 characters to the right of fixation. Comparison with earlier studies revealed that the letter identity span is smaller than the span for identifying letter features and that it is as wide in Finnish as in English. Furthermore, the letter identity span of faster readers of each age group was larger than that of slower readers, indicating that slower readers, unlike faster readers, allocate most of their processing resources to foveally fixated words. Finally, slower second graders were largely not disrupted by smaller windows, suggesting that their word decoding skill is not yet fully automatized.     

Aging and the use of interword spaces during reading: Evidence from eye movements

In an eye movement experiment, we assessed the performance of young (18–30 years) and older (65 + years) adult readers when sentences contained conventional interword spaces, when interword spaces were removed, or when interword spaces were replaced by nonlinguistic symbols. The replacement symbol was either a closed square (■) that provided a salient (low-spatial-frequency) cue to word boundaries, or an open square (□) that provided a less salient cue and included features (vertical and horizontal lines) similar to those found in letters. Removing or replacing interword spaces slowed reading times and impaired normal eye movement behavior for both age groups. However, this disruption was greater for the older readers, particularly when the replacement symbol did not provide a salient cue as to word boundaries. Specific influences of this manipulation on word identification during reading were assessed by examining eye movements for a high- or low-frequency target word in each sentence. Standard word frequency effects were obtained for both age groups when text was spaced normally, and although the word frequency effect was larger when spaces were removed or filled, the increases were similar across age groups. Therefore, whereas older adults’ normal eye movements were substantially disrupted when text lacked conventional interword spaces, the process of lexical access associated with the word frequency effect was no more difficult for older than for young adults. The indication, therefore, is that although older adults struggle from the loss of conventional cues to word boundaries, this is not due to additional difficulties in word recognition.     

Distinct processing for pictures of animals and objects: evidence from eye movements

Many studies have suggested that emotional stimuli orient and engage attention. There is also evidence that animate stimuli, such as those from humans and animals, cause attentional bias. However, categorical and emotional factors are usually mixed, and it is unclear to what extent human context influences attentional allocation. To address this issue, we tracked participants' eye movements while they viewed pictures with animals and inanimate images (i.e., category) as focal objects. These pictures had either negative or neutral emotional valence, and either human body parts or nonhuman parts were near the focal objects (i.e., context). The picture's valence, arousal, position, size, and most of the low-level visual features were matched across categories. The results showed that nonhuman animals were more likely to be attended to and to be attended to for longer times than inanimate objects. The same pattern held for the human contexts (vs. nonhuman contexts). The effects of emotional valence, category, and context interacted. Specifically, in images with a negative valence, focal animals and objects with human context had comparable numbers of gaze fixations and gaze duration. These results highlighted the attentional bias to animate parts of a picture and clarified that the effects of category, valence, and picture context interacted to influence attentional allocation.     

The role of phonology in the activation of word meanings during reading: evidence from proofreading and eye movements.

Six experiments explored the role of phonology in the activation of word meanings when words were embedded in meaningful texts. Specifically, the studies examined whether participants detected the substitution of a homophone mate for a contextually appropriate homophone. The frequency of the incorrect homophone, the frequency of the correct homophone, and the predictability of the correct homophone were manipulated. Also, the impact of reading skill was examined. When correct homophones were not predictable and participants had a range of reading abilities, the evidence indicated that phonology plays a role in activating the meanings of low-frequency words only. When the performance of good and poor readers was examined separately, the evidence indicated that good readers primarily activate the meanings of words using the direct route, whereas poor readers primarily activate the meanings of words using the phonological route.     

Immediate disambiguation of lexically ambiguous words during reading: Evidence from eye movements

Sentences containing lexically ambiguous words were read as readers' eye movements were monitored. On half of the trials, the dominant meaning of the ambiguous word was instantiated, while in the other half, the subordinate meaning was instantiated. Furthermore, on half of the trials, an adjective or modifier immediately preceded the target noun (kitchen table, statistical table), which was consistent with either the dominant or subordinate meaning. The results of the experiment demonstrate that readers are able to immediately utilize the modifier to select the appropriate meaning of the ambiguous word.     

Working memory and inferences: evidence from eye fixations during reading

Eye fixations during reading were monitored to examine the relationship between individual differences in working memory capacity-as assessed by the reading span task-and inferences about predictable events. Context sentences predicting likely events, or non-predicting control sentences, were presented. They were followed by continuation sentences in which a target word represented an event to be inferred (inferential word) or an unlikely event (non-predictable word). A main effect of reading span showed that high working memory capacity was related to shorter gaze durations across sentence regions. More specific findings involved an interaction between context, target, and reading span on late processing measures and regions. Thus, for high- but not for low-span readers, the predicting condition, relative to the control condition, facilitated reanalysis of the continuation sentence that represented the inference concept. This effect was revealed by a reduction in regression-path reading time in the last region of the sentence, involving less time reading that region and fewer regressions from it. These results indicate that working memory facilitates elaborative inferences during reading, but that this occurs at late text-integration processes, rather than at early lexical-access processes.