German capitalization of nouns and the detection of letters in continuous text.

The missing-letter effect refers to the phenomenon that letters are more difficult to detect in common function words (such as the) than in content words. Assuming that the missing-letter effect is diagnostic of the extraction of text structure, we exploited a special feature of German--the convention to capitalize the initial letter of nouns. Given the great flexibility of word order in German, it was proposed that this convention might help readers specify the structure of the sentence. Therefore orthographic variations that violate the capitalization rules should disrupt structure extraction and should result in a reduced missing-letter effect. The results indicated that: 1) capitalization of function words eliminated the missing-letter effect, but not at the beginning of a sentence; 2) A missing-letter effect occurred when the capitalization of the first letter was correct, but was followed by typecase alternation, and also when the size of the initial letters was relatively large for function words, but relatively small for content words. The results were discussed with respect to the possible contributions of visual familiarity, structural role, and processing time to the missing-letter effect, taking into account that a capitalized initial letter conveys significant information about the word class for German readers. Thus, the present results indicate that readers take advantage not only of function words but of any other information (here the capitalization of nouns) that helps to extract the structure of a sentence.     

Age changes in the missing-letter effect revisited

When participants search for a target letter while reading, they make more omissions if the target letter is embedded in frequent function words than in less frequent content words. Reflecting developmental changes in component language and literacy skills, the size of this effect increases with age. With adults, the missing-letter effect is due to both word function and word frequency. With children, it is unclear whether the growing size of the missing-letter effect across development is due to a larger effect of word function, word frequency, or both because previous studies with children seeking to isolate the influence of word frequency and word function suffer from important methodological limitations. With these methodological limitations eliminated (Experiments 1 and 2), performance in a letter detection task was assessed for children in Grades 1, 2, 3, 4, and 7 as well as for undergraduate students. The results revealed that the influence of word function increases with age, whereas the effect of frequency is fairly stable across ages. Furthermore, normative predictability data collected in Experiment 3 revealed that third graders and undergraduate students were equally good at predicting function slots in a sentence.     

Eye movements as direct tests of the GO model for the missing-letter effect

When asked to detect target letters while reading a text, participants miss more letters in frequently occurring function words than in less frequent content words. To account for this pattern of results, known as the missing-letter effect, Greenberg, Healy, Koriat, and Kreiner proposed the guidance-organization (GO) model, which integrates the two leading models of the missing-letter effect while incorporating innovative assumptions based on the literature on eye movements during reading. The GO model was evaluated by monitoring the eye movements of participants while they searched for a target letter in a continuous text display. Results revealed the usual missing-letter effect, and many empirical benchmark effects in eye movement literature were observed. However, contrary to the predictions of the GO model, response latencies were longer for function words than for content words. Alternative models are discussed that can accommodate both error and response latency data for the missing-letter effect.     

Eye movements when reading: The importance of the word to the left of fixation

In reading, it is well established that word processing can begin in the parafovea while the eyes are fixating the previous word. However, much less is known about the processing of information to the left of fixation. In two experiments, this issue was explored by combining a gaze-contingent display procedure preventing parafoveal preview and a letter detection task. All words were displayed as a series of xs until the reader fixated them, thereby preventing forward parafoveal processing, yet enabling backward parafoveal or postview processing. Results from both experiments revealed that readers were able to detect a target letter embedded in a word that was skipped. In those cases, the letter could only have been identified in postview (to the left of fixation), and detection rate decreased as the distance between the target letter and the eyes' landing position increased. Most importantly, for those skipped words, the typical missing-letter effect was observed with more omissions for target letters embedded in function than in content words. This can be taken as evidence that readers can extract basic prelexical information, such as the presence of a letter, in the parafoveal area to the left of fixation. Implications of these results are discussed in relation to models of eye movement control in reading and also in relation to models of the missing-letter effect.     

The interaction of word frequency and word class: a test of the GO model's account of the missing-letter effect

When asked to detect target letters while reading a text, participants miss more letters in frequent function words than in less frequent content words. In this phenomenon, known as the missing-letter effect, two factors covary: word frequency and word class. According to the GO model, there should be an interaction between word class and word frequency with more omissions for function than for content words only among high-frequency words. This pattern would be due to the fact that function words could only assume a structure-supporting role if they are identified rapidly, which is only possible for high-frequency words. These predictions were tested by assessing omission rate for frequent and rare function and content words. Results lend support to the GO model with more omissions for frequent than for rare words, and more omissions for the function than for the content word among high-frequency words, but not among low-frequency words. These results were observed both in English (Experiment 1) and in French (Experiment 2).     

The impact of familiarization strategies on the missing-letter effect

When reading a text and searching for a target letter, readers make more omissions of the target letter if it is embedded in frequent function words than if it is in rare content words. While word frequency effects are consistently found, few studies have examined the impacts of passage familiarity on the missing-letter effect and studies that have present conflicting evidence. The present study examines the effects of passage familiarity, as well as the impacts of passage familiarization strategy promoting surface or deep encoding, on the missing-letter effect. Participants were familiarized with a passage by retyping a text, replacing all common nouns with synonyms, or generating a text on the same topic as that of the original text, and then completed a letter search task on the familiar passage as well as an unfamiliar passage. In Experiment 1, when both familiar and unfamiliar passages use the same words, results revealed fewer omissions for the retyping and synonyms conditions. However, in Experiment 2, when different words are used in both types of texts, no effect of familiarization strategy was observed. Furthermore, the missing-letter effect is maintained in all conditions, adding support to the robustness of the effect regardless of familiarity with the text.     

Contrasting effects of age of acquisition in lexical decision and letter detection

Two experiments studied attention in beginning and skilled readers of Dutch to letter information in function words and content words. Early and late acquired nouns and function words were presented to third-grade students and skilled adolescent readers. Target words were presented in short story contexts, as in the study of Greenberg, Koriat, and Vellutino (1998). Target nouns were matched on word frequency. Predictions of the structural account hypothesis of letter detection (Koriat, Greenberg, & Goldshmid, 1991) were confirmed. No age-of-acquisition effect was found. In contrast, a separately conducted lexical decision experiment using the same content word stimulus sets showed shorter decision latencies for early acquired words. The combined results suggest that during silent reading, when attention is focused on meaning, phonological processes may play a less prominent role than in lexical decision tasks that demand explicit control of phonological codes. The letter detection results confirmed predictions of the structural account hypothesis for both beginning and skilled readers. Taken together, these studies demonstrate that phonological processes in silent reading may play a less prominent role and that the structural account of letter processing is valid for languages other than Hebrew and English but probably is not the unique mechanism involved in letter detection.     

The effects of syntactic structure on letter detection in adjacent function words

In the present study, we examined letter detection in very frequent function-word sequences. It has been claimed that such sequences are processed in a unitized manner, thus preempting access to their constituent letters. In contrast, we showed that letter detection in the words for and the (1) was no more difficult when the words appeared in adjacent locations in a sentence (familiar) than when they appeared apart (less familiar sequence) and (2) was contingent upon the words' syntactic roles within the phrase. Thus, letter detection in for was easier when the sequence was separated by a clause boundary than when the words were part of the same clause. The advantage derived from clause separation was strongest when a comma divided clauses. These results challenge the unitization account of the "missing-letter" effect in common phrases and support a position where this phenomenon is seen to reflect the extraction of phrase structure during reading.     

The interaction of word frequency and word class: A test of the GO model's account of the missing-letter effect

When asked to detect target letters while reading a text, participants miss more letters in frequent function words than in less frequent content words. In this phenomenon, known as the missing-letter effect, two factors covary: word frequency and word class. According to the GO model, there should be an interaction between word class and word frequency with more omissions for function than for content words only among high-frequency words. This pattern would be due to the fact that function words could only assume a structure-supporting role if they are identified rapidly, which is only possible for high-frequency words. These predictions were tested by assessing omission rate for frequent and rare function and content words. Results lend support to the GO model with more omissions for frequent than for rare words, and more omissions for the function than for the content word among high-frequency words, but not among low-frequency words. These results were observed both in English (Experiment 1) and in French (Experiment 2).     

An analysis of the word-superiority effect

It is easier to decide which of two letters was presented tachistoscopically if the critical letter was in a word rather than in a scrambled word. We showed that this word-superiority effect holds just as strongly for pronounceable nonwords as for words, even when the critical letters are constant over all trials. This finding rules out word meaning and familiarity as variables accounting for the effect. In addition, it was found that the superiority of pronounceable stimuli holds for two-letter stimuli as well as four, and it is therefore concluded that the effect is not due to a memory limitation. An explanation of the effect in terms of the use of additional acoustic information is ruled out by showing that the effect was not diminished when the two possible words sounded exactly alike. An experiment using correctly and incorrectly spelled chemical formulas suggested that spelling regularities, regardless of pronounceability per se, account for the superiority effect. Finally, when decisions about two critical letters must be made on each trial, the correlation between being correct on one and on the other is higher for pronounceable stimuli under some conditions.     

The word-superiority effect and phonological recoding

Previous work indicates that the locus of the word-superiority effect in letter detection is nonvisual and that letter names, but not letter shapes, are more accessible in words than in nonwords, that is, scrambled collections of letters (e.g., Krueger & Shapiro, 1979; Krueger & Stadtlander, 1991; Massaro, 1979). The nonvisual (verbal or lexical) coding may be phonological, or it may be more abstract. In the present study, a word advantage in the speed of letter detection was found even when the target letter was silent in the six-letter test word (e.g., s in island). Other test words varied in their frequency of occurrence in English and number of syllables (1, 2, or 3). The word advantage was larger for higher frequency words but was not affected by syllable length. The presence of unpronounceable nonwords and silent letters in the words discouraged reliance upon the phonological code but did not thereby eliminate the word advantage. Thus, the word-superiority effect with free viewing is not based entirely upon phonological recoding.     

Contrasting Effects of Letter-spacing in Alexia: Further Evidence that Different Strategies Generate Word Length Effects in Reading

The reading behaviour of two alexic patients (SA and WH) is reported. Both patients are severely impaired at reading single words, and both show abnormally strong effects of word length when reading. These two symptoms are characteristic of letter-by-letter reading. Experiment 1 examined the pattern of errors when the patients read large and small words. Further experiments examined the effects of inter-letter spacing on word naming (Experiments 2a and 2b) and the identification of letters in letter strings (Experiment 3). For both patients, letter identification was better for widely spaced letters in letter strings, and this effect was most pronounced for the central letters in the strings. This is consistent with abnormally strong flanker interference in letter identification. However, inter-letter spacing affected word reading behaviour in the two patients in different ways. SA's word reading improved with widely spaced letters; WH's word reading was disrupted. This suggests that these patients adopted different strategies when reading words. We conclude that several reading behaviours can elicit word length effects, and that these different behaviours can reflect strategic adaptation to a common functional deficit in patients. We discuss the implications both for understanding alexia and for models of normal word identification.     

The role of letter recognition in word recognition

In a paradigm that avoids methodological problems of earlier studies, evidence was gathered addressed to the question of whether we read letter by letter. If word recognition involves letter recognition, then the difficulty of recognizing a word should vary with the difficulty of recognizing its letters. This was tested by assessing letter difficulty in two letter discrimination tasks and in a letter naming task, and then comparing 15 adult subjects' visual recognition latency to 72 easy-letter words and to 72 difficult-letter words. Word frequency and word length were also manipulated. Results indicated no effect for letter difficulty, although recognition latency reliably decreased with word frequency and monotonically increased with word length (21 msec/letter), suggesting that we do not read letter by letter, but that whatever plays a role in word recognition is smaller than the word and correlated with word length in letters.     

Detecting phonemes and letters in text: Interactions between different types and levels of processes

In six experiments, subjects detected phonemes or letters in text presented auditorily or visually. Experiments 1 and 2 provided support for the hypothesis that a mismatch between the phoneme and letter representations of a target leads to detection errors. In addition, visual word unitization processes were implicated. Experiments 3 and 4 provided support for the hypothesis that the Gestalt goodness of pattern affected detection errors when subjects searched for letters. Experiments 5 and 6 demonstrated that the effects of unitization on the detection of letters in common words were decreased by altering the familiar configuration of the test words. The combined results of all six experiments lead to the conclusion that both visual and phonetic processes influence letter detection, that these processes communicate through a type of cross-checking, and that there are at least two levels of visual (and perhaps of phonetic) processing involved in the letter detection task.     

Multiletter Word Units in Visual Recognition: Direct Activation by Supraletter Visual Features

Multiletter priming effects have been interpreted as evidence for the representation of separable multiletter units in the visual word recognition system (Whiteley & Walker, 1994). The reported experiments examine whether the activation of such units is pre- or post-lexical. Experiments 2 and 3 employed priming in an alphabetic decision task in which subjects made a discrimination response to test stimuli which could be classed as either targets or foils. Targets were single letters, or consonant bigrams, present or absent in an immediately preceding word, or (Experiment 3 and 4) they were whole words semantically associated or not to a preceding word. Foils were single non-alphanumeric characters, a character plus a letter, or a word with one letter replaced by a character. Experiment 1 was a preliminary to determine the parameters of a sequential presentation manipulation. Experiment 2 compared conditions of simultaneous and sequential presentation where letters of prime words were presented together, or one at a time in rapid succession. With simultaneous presentation, responses to bigram targets were facilitated when these appeared in the prime word, while responses to individual constituent letters of those bigrams were not facilitated. Additionally, responses to primed bigram targets were faster than responses to primed single letter targets. The sequential presentation of prime words resulted in a qualitative change in the response pattern indicative of the disruption of multiletter unit activation. That change was replicated in Experiment 3 where semantic priming confirmed that the prime words were being processed to a level of meaning. The observations challenge a post-lexical account of the multiletter priming effects. Finally, Experiment 4 addressed the question of whether bigram priming reflects the intentional use of prime information to predict following targets. Strategic interpretations are undermined and it is argued that multiletter units are activated automatically as part of normal visual word recognition.     

The word superiority effect: Dependence on short-term memory factors

Two experiments were conducted to test whether the word superiority effect, that letters in words are perceived more accurately than letters in nonwords, could be attributed to short-term memory (STM) factors. One hypothesis attributed the word superiority effect to superior maintenance of words in STM. Another hypothesis was that letters in STM have considerable positional uncertainty which is overcome by the orthographic characteristics of the words. Both experiments utilized a simultaneous same-different task, where subjects compared two four-letter strings, one on top of the other, which were presented tachistoscopically. In Experiment I, the two presented strings were either both words or both nonwords and a word superiority effect was obtained. This result was interpreted as disconfirming the STM maintenance hypothesis. In Experiment II, letters were removed from one of the two letter strings, making the serial position of the comparison unambiguous. The word superiority effect disappeared. This result was interpreted as supporting the positional uncertainty hypothesis.     

Letters and words in word identification

Studies by Barron and Henderson (1977) and Johnson (1975) provide evidence that whole words may be the unit of identification in word perception, rather than single letters. Johnson found that words were matched faster than a letter to the first letter in a word. Barron and Henderson found faster matching times for words than for legal non-word items in a letter-matching task. These findings support the interpretation that words are identified before individual letters. If so, a word-frequency effect should be expected. Experiments 1 and 2 tested for word vs. first-letter-in-word differences, as well as for a word-frequency effect in simultaneous and delayed visual matching tasks. In the simultaneous task, first letters in words were matched faster than words. In the delayed task, there was no difference between matching words or matching the first letters in words. With both tasks there was a word-frequency effect for word matches but not for first-letter-in-word matches. In Experiment 3, first-letter matching time was unrelated to word frequency or lexical status, although it did vary with orthographic legality. These results, on the whole, are consistent with a race model in which identifications take place simultaneously at word, letter-cluster, and letter levels, rather than a sequential model in which the whole word is identified before the component letters.     

Feature frequency effects in recognition memory

Rare words are usually better recognized than common words, a finding in recognition memory known as the word-frequency effect. Some theories predict the word-frequency effect because they assume that rare words consist of more distinctive features than do common words (e.g., Shiffrin & Steyvers's, 1997, REM theory). In this study, recognition memory was tested for words that vary in the commonness of their orthographic features, and we found that recognition was best for words made up of primarily rare letters. In addition, a mirror effect was observed: Words with rare letters had a higher hit rate and a lower false-alarm rate than did words with common letters. We also found that normative word frequency affects recognition independently of letter frequency. Therefore, the distinctiveness of a word's orthographic features is one, but not the only, factor necessary to explain the word-frequency effect.     

Part-whole relationships in the processing of small visual patterns

Subjects seem to react to a word faster than they react to a letter within a word. One interpretation is that words are processed holistically; another is that all visual stimuli are processed in terms of components, but that more stimulus information is available for use when the targets are words than when they are letters within words. The results of three experiments indicate that the word or pattern-level advantage occurs even when the stimulus information in the two situations is equated, but if the perceptual arrays cannot be unitized (e.g., consonant sequences), a pattern-level advantage does not occur. In addition, the experiments provide substantial evidence to indicate that if letter arrays cannot be unitized, then they are processed on a componentby-component basis, rather than holistically. Finally, the appropriate definition ofholistic processing is considered.     

What do letter migration errors reveal about letter position coding in visual word recognition?

Dividing attention across multiple words occasionally results in misidentifications whereby letters apparently migrate between words. Previous studies have found that letter migrations preserve within-word letter position, which has been interpreted as support for position-specific letter coding. To investigate this issue, the authors used word pairs like STEP and SOAP, in which a letter in 1 word could migrate to an adjacent letter in another word to form an illusory word (STOP). Three experiments show that both same-position and adjacent-position letter migrations can occur, as well as migrations that cross 2 letter positions. These results argue against position-specific letter coding schemes used in many computational models of reading, and they provide support for coding schemes based on relative rather than absolute letter position.