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.     

Neuropsychological evidence for case-specific reading: Multi-letter units in visual word recognition

We describe a patient (GK) who shows symptoms associated with Balint's syndrome and attentional dyslexia. GK was able to read words, but not nonwords. He also made many misidentification and mislocation errors when reporting letters in words, suggesting that his word-naming ability did not depend upon preserved position-coded, letter identification. We show that GK was able to read lower-case words better than upper-case words, but upper-case abbreviations better than lower-case abbreviations. Spacing the letters in abbreviations disrupted identification, as did mixing the case of letters within words. These data cannot be explained in terms of letter-based reading or preserved holistic word recognition. We propose that GK was sensitive to the visual familiarity of adjacent letter forms.     

Sequential letter and word recognition in deaf and hearing subjects

To examine the processing of sequentially presented letters of familiar and nonsense words, especially among Ss of vastly differing experience on sequential tasks, three groups of Ss were tested on letters of words spelled sequentially on an alphanumeric display and on letters of words fingerspelled. These were a deaf group (N=33) with little or no hearing and who varied in their fingerspelling ability; a staff group (N=12) who taught fingerspelling and were highly proficient; and a hearing group (N=19). Of principal interest was the finding that the hearing Ss did better on nonsense letter recognition, while the deaf group did better on word recognition. Word length was important except to the staff Ss on fingerspelled words, which also suggests that concentration on fingerspelling proficiency forces attention to the whole word and not its component letters. Hearing Ss, who are the group faced with an unfamiliar task, seemed to attend to each letter and hence had more difficulty with recognition of the longer unit.     

Perceptual salience of derivational suffixes in visual word recognition

This study analyzes the role of derivational suffixes in visual word recognition, tracking the eye movements of 31 participants in a sentence-reading task in Spanish. Perceptual salience of suffixes was operationalized as the proportion of letters represented by the suffixes with respect to the full words, that is, we relate the number of letters comprising the suffixes to the number of letters in the words in which they appear. The results reveal a significant role in first fixation duration of both word frequency – the more frequent the word, the shorter the fixations, and perceptual salience – the more salient the suffix, the longer the fixations. Moreover, in gaze duration, our results show a main effect of word length – the longer the word, the longer the fixations; word frequency; and significant interactions between word frequency and perceptual salience of suffixes on the one hand – the effect of word frequency is only significant when perceptual salience of suffixes is high, and between word frequency and word length on the other hand – the frequency effect decreases as word length increases. Overall results are interpreted in the light of the dual route models by which full-form and morphological processing interactively cooperate in visual word recognition.     

Letter visibility and word recognition: The optimal viewing position in printed words

It has repeatedly been shown that the time and accuracy of recognizing a word depend strongly on where in the word the eye is fixating. Word-recognition performance is maximal when the eye fixates a region near the word’s center, and decreases to both sides of this “optimal viewing position.” The reason for this phenomenon is assumed to be the strong drop-off of visual acuity: the visibility of letters decreases with increasing eccentricity from fixation location. Consequently, fewer letters can be identified when the beginning or ending of a word is fixated than when its center is fixated. The present study is a test of this visual acuity hypothesis. If the phenomenon is caused by letter visibility, then it should be sensitive to variations of visual conditions in which the letters are presented. By increasing the interletter distances of the word(e.g.,a_t_t_e_m_ p_ t), letter visibility was decreased. As expected from our hypothesis, the viewing-position effect became more exaggerated. An additional experiment showed that destroying word-shape information (e.g., aTtEmPt) decreased overall word-recognition performance but had no influence on the viewingposition effect. Varying the viewing position in words might thus be used as a paradigm, allowing one to separate out the contribution of letter information and supraletter information to word recognition.     

The effects of length and transposed‐letter similarity in lexical decision: Evidence with beginning,intermediate, and adult readers

Do length and transposed‐letter effects reflect developmental changes on reading acquisition in a transparent orthography? Can computational models of visual word recognition accommodate these changes? To answer these questions, we carried out a masked priming lexical decision experiment with Spanish beginning, intermediate, and adult readers (N=36, 44, and 39; average age: 7, 11, and 22 years, respectively). Target words were either short or long (6.5 vs. 8.5 letters), and transposed‐letter primes were formed by the transposition of two letters (e.g. aminal–ANIMAL) or by the substitution of two letters (orthographic control: arisal–ANIMAL). Children showed a robust length effect (i.e. long words were read slower than short words) that vanished in adults. In addition, both children and young adults showed a transposed‐letter priming effect relative to the control condition. A robust transposed‐letter priming effect was also observed in non‐word reading, which strongly suggests that this effect occurs at an early prelexical level. Taken together, the results reveal that children evolve from a letter‐by‐letter reading to a direct lexical access and that the lexical decision task successfully captures the changing strategies used by beginning, intermediate, and adult readers. We examine the implications of these findings for the recent models of visual word recognition.     

Letter visibility and word recognition: the optimal viewing position in printed words.

It has repeatedly been shown that the time and accuracy of recognizing a word depend strongly on where in the word the eye is fixating. Word-recognition performance is maximal when the eye fixates a region near the word's center, and decreases to both sides of this "optimal viewing position." The reason for this phenomenon is assumed to be the strong drop-off of visual acuity: the visibility of letters decreases with increasing eccentricity from fixation location. Consequently, fewer letters can be identified when the beginning or ending of a word is fixated than when its center is fixated. The present study is a test of this visual acuity hypothesis. If the phenomenon is caused by letter visibility, then it should be sensitive to variations of visual conditions in which the letters are presented. By increasing the interletter distances of the word (e.g., a_t_t_e_m_p_t), letter visibility was decreased. As expected from our hypothesis, the viewing-position effect became more exaggerated. An additional experiment showed that destroying word-shape information (e.g., aTtEmPt) decreased overall word-recognition performance but had no influence on the viewing-position effect. Varying the viewing position in words might thus be used as a paradigm, allowing one to separate out the contribution of letter information and supraletter information to word recognition.     

Eye movements when reading transposed text: the importance of word-beginning letters

Participants' eye movements were recorded as they read sentences with words containing transposed adjacent letters. Transpositions were either external (e.g., problme, rpoblem) or internal (e.g., porblem, probelm) and at either the beginning (e.g., rpoblem, porblem) or end (e.g., problme, probelm) of words. The results showed disruption for words with transposed letters compared to the normal baseline condition, and the greatest disruption was observed for word-initial transpositions. In Experiment 1, transpositions within low frequency words led to longer reading times than when letters were transposed within high frequency words. Experiment 2 demonstrated that the position of word-initial letters is most critical even when parafoveal preview of words to the right of fixation is unavailable. The findings have important implications for the roles of different letter positions in word recognition and the effects of parafoveal preview on word recognition processes.     

Letter visibility and the viewing position effect in visual word recognition

The ease with which printed words are recognized depends on the position at which the eyes initially fixate the word. In this study, we examined to what extent recognition performance for each fixation position depends on the average visibility of the word's constituent letters. Experiment 1 measured recognition performance to single letters embedded in strings of Xs (lengths of 5 and 7) for all combinations of letter position and initial fixation position in the string. In Experiment 2, recognition performance was measured for five-letter and seven-letter words as a function of initial fixation position in the word. Whereas average letter visibility showed a symmetric function in Experiment 1, the word recognition data of Experiment 2 showed the typical asymmetric curve. Combining the letter visibility data with measures of lexical constraint using absolute letter-in-string positions failed to capture the pattern in the word data. An alternative measure of constraint based on relative position coding of letters generated more accurate predictions.     

Reexamining the word length effect in visual word recognition: New evidence from the English Lexicon Project

In the present study, we reexamined the effect of word length (number of letters in a word) on lexical decision. Using the English Lexicon Project, which is based on a large data set of over 40,481 words (Balota et al., 2002), we performed simultaneous multiple regression analyses on a selection of 33,006 English words (ranging from 3 to 13 letters in length). Our analyses revealed an unexpected pattern of results taking the form of a U-shaped curve. The effect of number of letters was facilitatory for words of 3–5 letters, null for words of 5–8 letters, and inhibitory for words of 8–13 letters. We also showed that printed frequency, number of syllables, and number of orthographic neighbors all made independent contributions. The length effects were replicated in a new analysis of a subset of 3,833 monomorphemic nouns (ranging from 3 to 10 letters), and also in another analysis based on 12,987 bisyllabic items (ranging from 3 to 9 letters). These effects were independent of printed frequency, number of syllables, and number of orthographic neighbors. Furthermore, we also observed robust linear inhibitory effects of number of syllables. Implications for models of visual word recognition are discussed.     

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.     

Some linguistic determinants of Swedish word recognition

Native Swedish words and words of foreign origin were studied in a word fill-in task (Experiment 1), in a task in which words were explicitly classified as being native or loan words (Experiment 2), and in a lexical decision task in which a small onset asynchrony was introduced in displaying a word's letter pattern (Experiment 3). The findings obtained show that, both in simple printed word recognition and when asked to make explicit judgments about origin, readers are sensitive to phonological features of words not marked in Swedish orthography. It was further found that previewing a substring of word-initial letters which determines a word's root morpheme will prime recognition, whereas previewing a randomly selected pattern of letters inhibits recognition.     

The effects of interletter spacing in visual-word recognition

Despite the importance of determining the effects of interletter spacing on visual-word recognition, this issue has often been neglected in the literature. The goal of the present study is to shed some light on this topic. The rationale is that a thin increase in interletter spacing, as in c a s i n o, may reduce lateral interference among internal letters without destroying a word's integrity and/or allow a more precise encoding of a word's letter positions. Here we examined whether identification times for word stimuli in a lexical decision task were faster when the target word had a slightly wider than default interletter spacing value relative to the default settings (e.g., c a s i n o vs. casino). In Experiment 1, we examined whether interletter spacing interacted with word-frequency, whereas in Experiment 2, we examined whether interletter spacing interacted with word length. Results showed that responses to words using a thin increase in interletter spacing were faster than the responses to words using the default settings—regardless of word-frequency and word length. Thus, interletter spacing plays an important role at modulating the identification of visually presented words.     

Neighborhood frequency effects and letter visibility in visual word recognition.

Two experiments are described that measured lexical decision latencies and errors to five-letter French words with a single higher frequency orthographic neighbor and control words with no higher frequency neighbors. The higher frequency neighbor differed from the stimulus word by either the second letter (e.g., ASTRE-AUTRE) or the fourth letter (CHOPE-CHOSE). Neighborhood frequency effects were found to interact with this factor, and significant interference was observed only to CHOPE-type words. The effects of neighborhood frequency were also found to interact with the position of initial fixation in the stimulus word (either the second letter or the fourth letter). Interference was greatly reduced when the initial fixation was on the critical disambiguating letter (i.e., the letter P in CHOPE). Moreover, word recognition was improved when subjects initially fixated the second letter relative to when they initially fixated the fourth letter of a five-letter word, but this second-letter advantage practically disappeared when the stimulus differed from a more frequent word by its fourth letter. The results are interpreted in terms of the interaction between visual and lexical factors in visual work recognition.     

Effects of increased letter spacing on word identification and eye guidance during reading

The effect of increasing the space between the letters in words on eye movements during reading was investigated under various word-spacing conditions. Participants read sentences that included a high- or low-frequency target word, letters were displayed normally or with an additional space between adjacent letters, and one, two, or three spaces were present between each word. The spacing manipulations were found to modulate the effect of word frequency on the number and duration of fixations on target words, indicating, more specifically, that letter spacing affected actual word identification under various word-spacing conditions. In addition, whereas initial fixations landed at the preferred viewing position (i.e., to the left of a word’s center) for sentences presented normally, landing positions were nearer the beginnings of words when letter spacing was increased, and even nearer the beginnings of words when word boundary information was lacking. Findings are discussed in terms of the influence of textual spacing on eye movement control.     

Lexical processes and eye movements in neglect dyslexia

Neglect dyslexia is a disturbance in the allocation of spatial attention over a letter string following unilateral brain damage. Patients with this condition may fail to read letters on the contralesional side of an orthographic string. In some of these cases, reading is better with words than with non-words. This word superiority effect has received a variety of explanations that differ, among other things, with regard to the spatial distribution of attention across the letter string during reading. The primary goal of the present study was to explore the interaction between attention and lexical processes by recording eye movements in a patient (F.C.) with severe left neglect dyslexia who was required to read isolated word and non-word stimuli of various length. F.C.'s ocular exploration of orthographic stimuli was highly sensitive to the lexical status of the letter string. We found that: (1) the location to which F.C. directed his initial saccade (obtained approximately 230 ms post-stimulus onset) differed between word and non-word stimuli; (2) the patient spent a greater amount of time fixating the contralesional side of word than non-word strings. Moreover, we also found that F.C. failed to identify the left letters of a string despite having fixated them, thus showing a clear dissociation between eye movement responses and conscious access to orthographic stimuli. Our data suggest the existence of multiple interactions between lexical, attentional and eye movement systems that occur from very initial stages of visual word recognition.     

Geometric and semantic similarity in visual masking

Semantic and geometric or physical similarity were manipulated separately in a backward-masking situation. When the target was a word to be read aloud, formal similarity between the letters of target and mask facilitated target recognition, as did associative similarity. Masking a target word by its own anagram also facilitated whole word report. In contrast, formal similarity was inhibitory rather than facilitatory of report when the target was spelled letter-by-letter, rather than read whole. This was true even for the same target words whose whole report was facilitated by formal similarity. A model to account for this reversal in the broader context of the neural substrate of reading is advanced. It is proposed that letter and word processing are fundamentally different in that letters are recognized by hierarchical feature analysis while words are stored and recognized wholistically by diffuse and redundant networks. Implications of the results for the study of reading are discussed.     

On letter frequency effects

In four experiments we examined whether the frequency of occurrence of letters affects performance in the alphabetic decision task (speeded letter vs. pseudo-letter classification). Experiments 1A and 1B tested isolated letters and pseudo-letters presented at fixation, and Experiments 2A and 2B tested the same stimuli inserted at the 1st, 3rd, or 5th position in a string of Xs. Significant negative correlations between letter frequency and response times to letter targets were found in all experiments. The correlations were found to be stronger for token frequency counts compared with both type frequency and frequency rank, stronger for frequency counts based on a book corpus compared with film subtitles, and stronger for measures counting occurrences as the first letter of words compared with inner letters and final letters. Correlations for letters presented in strings of Xs were found to depend on letter case and position-in-string. The results are in favor of models of word recognition that implement case-specific and position-specific letter representations.     

Letter position dyslexia in Arabic: from form to position

This study reports the reading of 11 Arabic-speaking individuals with letter position dyslexia (LPD), and the effect of letter form on their reading errors. LPD is a peripheral dyslexia caused by a selective deficit to letter position encoding in the orthographic-visual analyzer, which results in migration of letters within words, primarily of middle letters. The Arabic orthography is especially interesting for the study of LPD because Arabic letters have different forms in different positions in the word. As a result, some letter position errors require letter form change. We compared the rate of letter migrations that change letter form with migrations that do not change letter form in 10 Arabic-speaking individuals with developmental LPD, and one bilingual Arabic and Hebrew-speaking individual with acquired LPD. The results indicated that the participants made 40% letter position errors in migratable words when the resulting word included the letters in the same form, whereas migrations that changed letter form almost never occurred. The error rate of the Arabic-Hebrew bilingual reader was smaller in Arabic than in Hebrew. However, when only words in which migrations do not change letter form were counted, the rate was similar in Arabic and Hebrew. Hence, whereas orthographies with multiple letter forms for each letter might seem more difficult in some respects, these orthographies are in fact easier to read in some forms of dyslexia. Thus, the diagnosis of LPD in Arabic should consider the effect of letter forms on migration errors, and use only migratable words that do not require letter-form change. The theoretical implications for the reading model are that letter form (of the position-dependent type found in Arabic) is part of the information encoded in the abstract letter identity, and thus affects further word recognition processes, and that there might be a pre-lexical graphemic buffer in which the checking of orthographic well-formedness takes place.     

Perceptual grouping in visual word recognition

Four experiments are presented in which printed texts are read for their meaning. Some of the texts were mutilated by altering the size of selected letters. In Experiments 1, 2, and 3, the number of words mutilated per passage and the number of letters changed per word were both manipulated. In all three experiments, reading was slowed as a function of the number of words changed per passage, while the number of letters changed per word had a much smaller effect. The interaction between the number of words and number of letters changed was not significant in any of the experiments. It is difficult to explain these results merely in terms of changes in the discriminability of letters. In Experiment 2 all uppercase text was used, which argues against an explanation in terms of supraletter features such as word envelope. We propose an explanation in terms of visual attention and the perceptual grouping required prior to feature recognition. The last experiment supports this explanation through the counterintuitive finding that adding letters of intermediate size can improve legibility by allowing grouping processes to associate large and small letters as belonging to the same word object.