Object and action picture naming in English and Greek

When two orthographically similar words are displayed using rapid serial visual presentation (RSVP), the repeated letters in the second critical word (W2) are not detected, leading to a deficit in reporting this word known as repetition blindness (RB). In Turkish, letters containing diacritic markings (e.g., y, ö) are considered separate letters, yet are visually highly similar to their non-diacritic analogues (s,o). Two experiments used the phenomenon of RB to investigate whether diacritic letters are represented as more similar to their non-diacritic analogues than are two unrelated letters. In Experiment 1, substantially more RB was found for words differing in just a diacritic (i y im-isim) compared to orthographic neighbours (words differing in a visually non-similar letter, such as ilim-isim). In Experiment 2, the amount of RB for identical words (isim-isim) was comparable to words that differed by a single diacritic marking (i y im-isim). We conclude that diacritic letters are mentally represented as variants of their non-diacritic analogue. Letter / word recognition researchers may be interested in pursuing these findings using standard techniques such as backward masking and orthographic priming.     

A sublexical locus for repetition blindness: evidence from illusory words.

Six experiments used an illusory words paradigm to demonstrate that repetition blindness (RB) in orthographically similar words affects only the words' shared letters. Rapid serial visual presentation streams of words and word fragments allowed the unique letters of the 2nd critical word to combine with a subsequent fragment to create a word, as in rock shock ell. The illusory word shell was reported 2-3 times as frequently in RB conditions as in control conditions. Further experiments ruled out letter migration, contour summation, and differences in processing load as explanations for the results. These findings are inconsistent with current proposals that orthographic RB represents similarity inhibition or lexical competition or that it reflects problems with word-level token individuation.     

Are individual or consecutive letters the unit affected by repetition blindness?

When 2 similar words (e.g., react reach) are briefly sequentially displayed, the 2nd word may be omitted from the report, a phenomenon known as repetition blindness (RB). Previous researchers have suggested that consecutive letters are the unit affected by RB. Six experiments provided new data on orthographic RB. Two letters at the beginning or end of words resulted in RB, as did alternating interior letters (tactile earthly) and 3 letters with different relative positions (arid bird). However, no RB was found with a single final letter (show view). Observed RB may reflect pattern completion because RB for pairs like throat theory was reduced when the nonrepeated letters (eory) were consistent with only a single word. The experiments point to a model of orthographic RB in which both individual letters and letter sequences of length 2 or more play a role.     

Repetition blindness: levels of processing

Repetition blindness (RB) is the failure to detect or recall repetitions of words in rapid serial visual presentation. Experiment 1 showed that synonym pairs are not susceptible to RB. In Experiments 2 and 3, RB was still found when one occurrence of the word was part of a compound noun phrase. In Experiment 4, homonyms produced RB if they were spelled identically (even if pronounced differently) but not if spelled differently and pronounced the same. Similarly spelled but otherwise unrelated word pairs appeared to generate RB (Experiment 5), but Experiment 6 produced an alternative account. Experiments 7 and 8 demonstrated that repeated letters are susceptible to RB only when displayed individually, not as part of two otherwise different words. It is concluded that RB can occur at either an orthographic (possibly morphemic) level or a case-independent letter level, depending on which unit (words or single letters) is the focus of processing.     

Illusory words created by repetition blindness: a technique for probing sublexical representations

When two orthographically similar words are displayed using rapid serial visual presentation (RSVP), the repeated letters in the second critical word (W2) are not detected, leading to a deficit in reporting this word, a phenomenon known as repetition blindness (RB). The unrepeated letters in W2 do appear to be detected and available to feed activation to words compatible with them (Morris & Harris, 1999). When a fragment was strategically placed in the RSVP stream, as in GROW throw ank, observers reported seeing thank more often than in the control condition BEAT throw ank. Illusory words were facilitated by repetition blindness only when the recombining letters maintained their position in the words. Illusory word report was insensitive to the phonological similarity of the recombining letters; equal quantities of illusory words were created by sequences like china CHEAT THR (-->threat) and swung SWEAT THR (-->threat). In addition to being an interesting phenomenon in its own right, the illusory words paradigm may have considerable use as a tool for probing the perceptual units underlying visual word recognition.     

Evaluating a split processing model of visual word recognition: effects of orthographic neighborhood size

The split fovea theory proposes that visual word recognition of centrally presented words is mediated by the splitting of the foveal image, with letters to the left of fixation being projected to the right hemisphere (RH) and letters to the right of fixation being projected to the left hemisphere (LH). Two lexical decision experiments aimed to elucidate word recognition processes under the split fovea theory are described. The first experiment showed that when words were presented centrally, such that the initial letters were in the left visual field (LVF/RH), there were effects of orthographic neighborhood, i.e., there were faster responses to words with high rather than low orthographic neighborhoods for the initial letters ('lead neighbors'). This effect was limited to lead-neighbors but not end-neighbors (orthographic neighbors sharing the same final letters). When the same words were fully presented in the LVF/RH or right visual field (RVF/LH, Experiment 2), there was no effect of orthographic neighborhood size. We argue that the lack of an effect in Experiment 2 was due to exposure to all of the letters of the words, the words being matched for overall orthographic neighborhood count and the sub-parts no longer having a unique effect. We concluded that the orthographic activation found in Experiment 1 occurred because the initial letters of centrally presented words were projected to the RH. The results support the split fovea theory, where the RH has primacy in representing lead neighbors of a written word.     

Orthographic redundancy in letter recognition: Orthographic neighbourhood or orthographic context?

Abstract

In explaining the word-superiority effect (i.e. the better detection of a letter in a word than in a nonword), the Interactive Activation Model (IAM) of McClelland and Rumelhart (1981) and the Fuzzy Logical Model of Perception (FLMP) of Massaro (1979) emphasise the importance of orthographic redundancy (i.e. the regularities of letters within words) in different ways. In the IAM, orthographic redundancy is defined by the number of “friends”; that is, words sharing the same letters except one with the word containing the target letter. Such friends constitute the orthographic “neighbourhood”. FLMP stresses the orthographic “context”; that is, the similarity of the word with a representation in the lexicon. The orthographic neighbourhood and context are manipulated independently in Experiment 1, and the findings are better understood in terms of the orthographic neighbourhood. By increasing the number of friends in nonwords, better letter detection is also obtained in nonwords as compared with letter detection in random letter strings (Experiment 2). These findings, together with the position effects obtained, are more clearly in agreement with the IAM than with the FLMP.     

Relations between emotion, illusory word perception, and orthographic repetition blindness: Tests of binding theory

This study reports effects of meaning and emotion (taboo vs. neutral words) on an illusory word (IW) phenomenon linked to orthographic repetition blindness (RB). Participants immediately recalled rapid serial visual presentation (RSVP) lists consisting of two critical words (C1 and C2) containing shared letters, followed by a word fragment: for example, lake (C1) brake (C2) ush (fragment). For neutral critical words, participants often recalled C1, but not C2 or the fragment, reporting instead a nonoccurring or illusory word: here, brush (a blend of C2 and the fragment). Forward RB (defined as reduced report of orthographically similar C2s) was more common for neutral than for taboo C2s, and taboo IWs were reported significantly more often than were neutral IWs. Moreover, when both C2 and the potential IW were taboo, a new phenomenon emerged: Participants reliably reported both the IW and the intact C2. These and other results supported a binding theory of the IW phenomenon and orthographic RB.     

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.     

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.     

Orthographic similarity: The case of “reversed anagrams”

How orthographically similar are words such as paws and swap, flow and wolf, or live and evil? According to the letter position coding schemes used in models of visual word recognition, these reversed anagrams are considered to be less similar than words that share letters in the same absolute or relative positions (such as home and hose or plan and lane). Therefore, reversed anagrams should not produce the standard orthographic similarity effects found using substitution neighbors (e.g., home, hose). Simulations using the spatial coding model (Davis, Psychological Review 117, 713-758, 2010), for example, predict an inhibitory masked-priming effect for substitution neighbor word pairs but a null effect for reversed anagrams. Nevertheless, we obtained significant inhibitory priming using both stimulus types (Experiment 1). We also demonstrated that robust repetition blindness can be obtained for reversed anagrams (Experiment 2). Reversed anagrams therefore provide a new test for models of visual word recognition and orthographic similarity.     

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.     

Orthographic structure versus morphological structure: principles of lexical organization in a given language

Most models of visual word recognition in alphabetic orthographies assume that words are lexically organized according to orthographic similarity. Support for this is provided by form-priming experiments that demonstrate robust facilitation when primes and targets share similar sequences of letters. The authors examined form-orthographic priming effects in Hebrew, Arabic, and English. Hebrew and Arabic have an alphabetic writing system but a Semitic morphological structure. Hebrew morphemic units are composed of noncontiguous phonemic (and letter) sequences in a given word. Results demonstrate that form-priming effects in Hebrew or Arabic are unreliable, whereas morphological priming effects with minimal letter overlap are robust. Hebrew bilingual subjects, by contrast, showed robust form-priming effects with English material, suggesting that Semitic words are lexically organized by morphological rather than orthographic principles. The authors conclude that morphology can constrain lexical organization even in alphabetic orthographies and that visual processing of words is first determined by morphological characteristics.     

Moving beyond Coltheart’s <Emphasis Type="Italic">N</Emphasis>: A new measure of orthographic similarity

Visual word recognition studies commonly measure the orthographic similarity of words using Coltheart’s orthographic neighborhood size metric (ON). Although ON reliably predicts behavioral variability in many lexical tasks, its utility is inherently limited by its relatively restrictive definition. In the present article, we introduce a new measure of orthographic similarity generated using a standard computer science metric of string similarity (Levenshtein distance). Unlike ON, the new measure—named orthographic Levenshtein distance 20 (OLD20)—incorporates comparisons between all pairs of words in the lexicon, including words of different lengths. We demonstrate that OLD20 provides significant advantages over ON in predicting both lexical decision and pronunciation performance in three large data sets. Moreover, OLD20 interacts more strongly with word frequency and shows stronger effects of neighborhood frequency than does ON. The discussion section focuses on the implications of these results for models of visual word recognition.     

Visual and phonological codes in repetition blindness.

Repetition blindness (RB) is the inability to detect or recall a repeated word in rapid serial visual presentation. The role of visual versus phonological (name) similarity in RB was examined. RB was found for single letters, whether printed in the same or different cases, and for single digits, whether represented verbally (nine), as arabic numerals (9), or in a mixture of the 2 formats. Hence, visual similarity is not necessary to produce RB. RB was obtained between homophonic pairs (won/one), showing that phonological similarity is sufficient to produce RB, although visual identity also contributes to RB. It is proposed that RB results when the codes used for initial registration of the targets in short-term memory are similar. This initial code may be predominantly visual or predominantly phonological.     

Identity and similarity in repetition blindness: no cross-over interaction

The difficulty in reporting both occurrences of a repeated item is a phenomenon referred to as repetition blindness (RB). RB has been proposed to result from temporal limitations in creating separate episodic tokens for a twice-activated type. Recently, Chialant and Caramazza (Cognition 63 (1997) 79-119) disputed the conventional view that RB for non-identical words (orthographic RB, as in lice and lick) results from the same mechanism as identity RB, and proposed that orthographic RB arises from competition for lexical selection. Supporting evidence was that identical and merely similar words showed different amounts of RB as a function of stimulus onset asynchrony (lag). Four experiments failed to replicate Chialant and Caramazza's finding that identity RB decreases, but orthographic RB increases, as a function of lag. Instead, RB for all stimuli, including homonym pairs, declined monotonically with lag. These results are consistent with a common mechanism underlying RB for identical and orthographically similar words and with prior research suggesting that RB in similar words occurs at a sublexical level.     

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.     

The role of thought suppression in building mental blocks

This research examined the role of thought suppression in the formation of mental blocks. In Experiment 1, participants were asked to generate a series of creative associates for two target words after initially suppressing a word that was semantically related to one of the two target words. Participants produced fewer responses, and experienced a greater sensation of being mentally blocked, when attempting to produce associates for the target word that was semantically related to the suppressed word. In Experiment 2, participants either thought about or suppressed a series of words prior to completing a word fragment completion task. Each word either corresponded exactly to one of the word fragment solutions (target primes) or resembled one of the solutions but was slightly different in its orthographic properties (negative primes). Participants performed most poorly on the items for which they had initially suppressed negative primes.     

Do transposed-letter effects occur across lexeme boundaries?

A masked priming lexical decision experiment was conducted to examine whether or not assignment of letter position in a word can be influenced by lexeme boundaries. The experiment was run in Basque, which is a strongly agglutinating language with a high proportion of inflected and compound words. Nonword primes were created by transposing two nonadjacent letters that crossed or did not cross morphological boundaries. Specifically, we compared morphologically complex prime-target pairs (e.g.,arbigide-ARGIBIDE) with orthographic controls (e.g.,arkipide-ARGIBIDE; note that ARGIBIDE is a compound of ARGI + BIDE) and noncompound pairs (e.g.,ortakila-ORKATILA) with orthographic controls (e.g.,orbahila-ORKATILA). Results showed that transposed-letter effects were virtually the same for compound and noncompound words, both when the orthographic control condition was used as a baseline and when the identity condition was used as a baseline. Thus, transposed-letter similarity effects seem to be orthographic in nature. We examine the implications of these results for the models of visual word recognition.     

Transposed-letter and laterality effects in lexical decision

Two divided visual field lexical decision experiments were conducted to examine the role of the cerebral hemispheres in transposed-letter similarity effects. In Experiment 1, we created two types of nonwords: nonadjacent transposed-letter nonwords (TRADEGIA; the base word was TRAGEDIA, the Spanish for TRAGEDY) and two-letter different nonwords (orthographic controls: TRATEPIA). In Experiment 2, the controls were one-letter different nonwords (TRAGEPIA) instead of two-letter different nonwords (TRATEPIA). The effect of transposed-letter similarity was substantially greater in the right visual field (left hemisphere) than in the left visual field. Furthermore, nonwords created by transposing two letters were more competitive than the nonwords created by substituting one or two letters of a target word. We examine the implications of these findings for the models of visual word recognition.