Is nevtral NEUTRAL? Visual similarity effects in the early phases of written-word recognition

For simplicity, contemporary models of written-word recognition and reading have unspecified feature/letter levels—they predict that the visually similar substituted-letter nonword PEQPLE is as effective at activating the word PEOPLE as the visually dissimilar substituted-letter nonword PEYPLE. Previous empirical evidence on the effects of visual similarly across letters during written-word recognition is scarce and nonconclusive. To examine whether visual similarity across letters plays a role early in word processing, we conducted two masked priming lexical decision experiments (stimulus-onset asynchrony = 50 ms). The substituted-letter primes were visually very similar to the target letters (u/v in Experiment 1 and i/j in Experiment 2; e.g., nevtral–NEUTRAL). For comparison purposes, we included an identity prime condition (neutral–NEUTRAL) and a dissimilar-letter prime condition (neztral-NEUTRAL). Results showed that the similar-letter prime condition produced faster word identification times than the dissimilar-letter prime condition. We discuss how models of written-word recognition should be amended to capture visual similarity effects across letters.     

Automatic letter priming in an alphabetic decision task

An alphabetic decision task was used to study effects of form priming on letter recognition at very short prime durations (20 to 80 msec). The task required subjects to decide whether a stimulus was a letter or a nonletter. Experiment 1 showed clear facilitatory effects of primes being either physically or nominally identical to the targets, with a stable advantage for the former. Experiment 2 demonstrated that uppercase letters are classified more rapidly as letters (vs. non-letters) when they are preceded by a briefly exposed, forward- and backward-masked, visually similar uppercase letter than when they are preceded by a visually dissimilar uppercase letter. Finally, Experiment 3 demonstrated that nominally identical and visually similar primes facilitate processing more than do nominally identical, visually dissimilar primes. The alphabetic decision task proved to produce sensitive and stable priming effects at the feature, letter, and response-choice level. The present results on letter-letter priming thus constitute a solid data base against which to evaluate other priming effects, such as word-letter priming. The results are discussed in light of current activation models of letter and word recognition and are compared with data simulated by the interactive activation model (McClelland & Rumelhart, 1981).     

Priming of abstract letter representations may be universal: The case of Arabic

Recent research on the Roman alphabet has demonstrated that the magnitudes of masked repetition priming are equivalent for letter pairs that have similar visual features across cases (e.g., c-C) and for letter pairs with dissimilar features (e.g., g-G). Here, we examined whether priming of abstract letter representations occurs in an orthographic system, Arabic, in which the letters show an intricate number of contextual forms. Arabic does not have a lowercase/uppercase distinction, but the letters exhibit different forms that depend on their position (initial, medial, final, or isolated) and their connectivity. Importantly, some letters look quite different across positions (e.g., (symbol in text) and (symbol in text), which correspond to the letter 'ayn), whereas others look very similar (e.g. (symbol in text), and (symbol in text), which correspond to the letter fā'). We employed a masked priming same-different task, in which native speakers of Arabic decided whether a target letter was the same as or different from a reference letter presented in a different position (middle vs. isolated). The results showed masked repetition priming effects of the same magnitude for letter pairs with similar and with dissimilar visual features across letter positions. These data support the view that priming of abstract letter representations is a universal phenomenon.     

A study of relative-position priming with superset primes

Four lexical decision experiments are reported that use the masked priming paradigm to study the role of letter position information in orthographic processing. In Experiments 1 and 2, superset primes, formed by repetition of 1 or 2 letters of the target (e.g., jusstice-JUSTICE) or by insertion of 1 or 2 unrelated letters (e.g., juastice-JUSTICE), generated significant priming compared with unrelated primes and did not differ significantly from an identity priming condition. In Experiment 3, identity primes generated significantly faster responses than subset primes formed by removal of 2 letters from the target (e.g., jutie-JUSTICE), and subset primes generated faster responses than substitution primes formed by substitution of 2 letters of the target with unrelated letters (e.g., jumlice-JUSTICE). In Experiment 4, insertion of 3 unrelated letters continued to generate facilitation relative to unrelated primes but significantly less so than the identity prime condition. The authors discuss the implications of these results for letter-position coding schemes.     

Is it a letter? Is it a number? Processing of numbers within SMS shortcuts

For efficiency reasons, words in electronic messages are sometimes formed by combining letters with numbers, as in gr8 for “great.” The aim of this study was to investigate whether a digit incorporated into a letter-digit shortcut would retain its numerosity. A priming paradigm was used with letter-digit shortcuts (e.g., gr8) and matched pseudoshortcuts (e.g., qr8) as primes. The primes were presented simultaneously with sets of dots (targets) for which even/odd decisions were required, or they appeared 250 msec before target onset. When pseudoshortcuts were presented, decision latencies were shorter when the target and the digit in the prime were matched in parity than when they were mismatched. This main effect of match was not significant for shortcuts. The results suggest that the number concepts of digits combined with letters become activated but are quickly suppressed or deactivated when the digit is part of an existing shortcut.     

Efficiency of visual selection in duplex and conjunction conditions in partial report

Factors that determine the efficiency of visual selection were investigated in two precued partial-report experiments. There were four selection conditions: acolor condition (e.g., selecting purple letters among blue letters), aclass condition (e.g., selecting letters among digits), aduplex condition (e.g., selecting purple letters among blue digits; that is, the targets differed from the distractors both in color and in alphanumeric class), and aconjunction condition (e.g., selecting purple letters among blue letters and purple digits; that is, the targets differed from the distractors either in color or in alphanumeric class). The efficiency of visual selection was highest in the duplex condition and lowest in the conjunction condition. Thedifference in performance across the different selection conditions within subjects was accounted for by variation in the value of a single parameter of the fixed-capacity independent race model (FIRM) proposed by Shibuya and Bundesen (1988), which assumes independent parallel processing, limitations in both processing capacity and storage capacity, and time-invariant selectivity. By assuming that the factors that determine the efficiency of selection in the color and class conditions also underlie the efficiency of selection in the duplex and conjunction conditions, an extension of FIRM, FIRM⁺, accounted for therelationship with respect to efficiency of selection among the different conditions.     

On the time course of letter perception: A masked priming ERP investigation

In an experiment measuring event-related brain potentials (ERPs), single-letter targets were preceded by briefly presented masked letter primes. Name and case consistency were manipulated across primes and targets so that the prime was either the same letter as the target (or not), and was presented in the same case as the target (or not). Separate analyses were performed for letters whose upper- and lowercase forms had similar features (or not). The results revealed an effect of prime-target visual similarity between 120 and 180 msec, an effect of case-specific letter identity between 180 and 220 msec, and an effect of case-independent letter identity between 220 and 300 msec. We argue that these ERP results reflect processing in a hierarchical system for letter recognition that involves both case-specific and case-independent representations of alphabetic stimuli.     

Graded effects of number of inserted letters in superset priming

Three masked priming experiments investigated the effects of target word length and number of inserted letters on superset priming, where irrelevant letters are added to targets to form prime stimuli (e.g., tanble-table). Effects of one, two, three, and four-letter insertions were measured relative to an unrelated prime condition, the identity prime condition, and a condition where the order of letters of the superset primes was reversed. Superset primes facilitated performance compared with unrelated primes and reversed primes, and the overall pattern showed a small cost of letter insertion that was independent of target word length and that increased linearly as a function of the number of inserted letters. A meta-analysis incorporating data from the present study and two other studies investigating superset priming, showed an average estimated processing cost of 11 ms per letter insertion. Models of letter position coding are examined in the light of this result.     

Serial position effects in the identification of letters, digits, symbols, and shapes in peripheral vision

Three experiments measured serial position functions for character-in-string identification in peripheral vision. In Experiment 1, random strings of five letters (e.g., P F H T M) or five symbols (e.g., λ Б Þ Ψ ¥) were briefly presented to the left or to the right of fixation, and identification accuracy was measured at each position in the string using a post-cued two-alternative forced-choice task (e.g., was there a T or a B at the 4th position). In Experiment 2 the performance to letter stimuli was compared with familiar two-dimensional shapes (e.g., square, triangle, circle), and in Experiment 3 we compared digit strings (e.g., 6 3 7 9 2) with a set of keyboard symbols (e.g., % 4 @ < ?). Eye-movements were monitored to ensure central fixation. The results revealed a triple interaction between the nature of the stimulus (letters/digits vs. symbols/shapes), eccentricity, and visual field. In all experiments this interaction reflected a selective left visual field advantage for letter or digit stimuli compared with symbol or shape stimuli for targets presented at the greatest eccentricity. The results are in line with the predictions of the modified receptive field hypothesis proposed by Tydgat and Grainger (2009), and the predictions of the SERIOL2 model of letter string encoding.     

Letter-position coding in random consonant arrays

The processing of letter-position information in randomly arranged consonant strings was investigated using a masked prime variant of the alphabetic decision (letter/nonletter classification) task. In Experiment 1, primes were uppercase consonant trigrams (e.g., FMH) and targets were two uppercase Xs accompanied by the target letter or a nonletter (e.g., XMX, X%X). Response times were systematically faster when target letters were present in the prime string than when target letters were not present in the prime string. These constituent letter-priming effects were significantly stronger when the target letter appeared in the same position in the prime and target stimuli. This contrast between position-specific and position-independent priming was accentuated when subjects responded only when all the characters in the target string were letters (multiple alphabetic decision) in Experiments 2 and 3. In Experiment 4, when prime exposure duration was varied, it was found that position-specific priming develops earlier than position-independent priming. Finally, Experiment 5 ruled out a perceptual-matching interpretation of these results. An interpretation is offered in terms of position-specific and position-independent letter-detector units in an interactiveactivation framework.     

Letter position information and printed word perception: the relative-position priming constraint

Six experiments apply the masked priming paradigm to investigate how letter position information is computed during printed word perception. Primes formed by a subset of the target's letters facilitated target recognition as long as the relative position of letters was respected across prime and target (e.g., "arict" vs. "acirt" as primes for the target "apricot"). Priming effects were not influenced by whether or not absolute, length-dependent position was respected (e.g., "a-ric-t" vs. "arict"/"ar-i-ct"). Position of overlap of relative-position primes (e.g., apric-apricot; ricot-apricot; arict-apricot) was found to have little influence on the size of priming effects, particularly in conditions (i.e., 33 ms prime durations) where there was no evidence for phonological priming. The results constrain possible schemes for letter position coding.     

Visual similarity effects in immediate verbal serial recall

The role of visual working memory in temporary serial retention of verbal information was examined in four experiments on immediate serial recall of words that varied in visual similarity and letters that varied in the visual consistency between upper and lower case. Experiments 1 and 2 involved words that were either visually similar (e.g. fly, cry, dry; hew, new, few ) or were visually distinct (e.g. guy, sigh, lie; who, blue, ewe ). Experiments 3 and 4 involved serial recall of both letter and case from sequences of letters chosen such that the upper- and lower-case versions were visually similar, for example Kk, Cc, Zz, Ww , or were visually dissimilar, for example Dd, Hh, Rr, Qq . Hence in the latter set, case informationwas encoded interms of both the shape and the size of the letters. With both words and letters, the visually similar items resulted in poorer recall both with and without concurrent articulatory suppression. This visual similarity effect was robust and was replicated across the four experiments. The effect was not restricted to any particular serial position and was particularly salient in the recall of letter case. These data suggest the presence of a visual code for retention of visually presented verbal sequences in addition to a phonological code, and they are consistent with the use of a visual temporary memory, or visual "cache", in verbal serial recall tasks.     

Dissociated backward priming effects in lexical decision and pronunciation tasks

Backward priming was examined at 150- and 500-msec prime-target stimulus onset asynchronies (SOAs) using visually presented primes and targets in lexical decision and pronunciation tasks. Two kinds of backward relations were used: compound items for which targets and primes formed a word in the backward direction (e.g., prime: HOP; target: bell), and noncompound items for which targets and primes did not form a word but were associatively related in the backward but not the forward direction (e.g., prime: BABY; target: stork). Results showed that backward priming effects were equivalent for compounds and noncompounds. However, for lexical decisions, backward priming occurred at both SOAs, whereas for pronunciation, it occurred only at the 150-msec SOA. We discuss how this SOA-dissociated backward priming effect in lexical decision and pronunciation tasks poses a serious challenge for all theories of semantic priming.     

Task- and location-switching effects on visual attention

In two experiments, we examined the effects of task and location switching on the accuracy of reporting target characters in an attentional blink (AB) paradigm. Single-character streams were presented at a rate of 100 msec per character in Experiment 1, and successive pairs of characters on either side of fixation were presented in Experiment 2. On each trial, two targets appeared that were either white letters or black digits embedded in a stream of black letter distractors, and they were separated by between zero and five items in the stream (lags 1-6). Experiment 1 showed that report of the first target was least accurate if it immediately preceded the second target and if the two targets were either both letters or both digits (task repetition cost). Report of the second target was least accurate if one or two distractors intervened between the two targets (the U-shaped AB lag effect) and if one target was a letter and the other a digit (task switch cost). Experiment 2 added location uncertainty as a factor and showed similar effects as Experiment 1, with one exception. Lag 1 sparing (the preserved accuracy in reporting the second of two targets if the second immediately follows the first) was completely eliminated when the task required attention switching across locations. Two-way additive effects were found between task switching and location switching in the AB paradigm. These results suggests separate loci for their attentional effects. It is likely that the AB deficit is due mainly to central memory limitations, whereas location-switching costs occur at early visual levels. Task-switching costs occur at an intermediate visual level, since the present task switch involved encoding differences without changes in stimulus-response mapping rules (i.e., the task was character identification for both letters and digits).     

Masked priming is abstract in the left and right visual fields

Two experiments assessed masked priming for words presented to the left and right visual fields in a lexical decision task. In both Experiments, the same magnitude and pattern of priming was obtained for visually similar (kiss-KISS) and dissimilar (read-READ) prime–target pairs. These findings provide no support for the hypothesis that word identification is mediated by separate and lateralized abstract and specific visual form systems. Strikingly, equivalent priming was observed when primes and targets were presented to the same or opposite visual fields, suggesting that priming occurs after visual information from the two hemispheres is integrated.     

Masked repetition and phonological priming in picture naming

We report a series of picture naming experiments in which target pictures were primed by briefly presented masked words. Experiment 1 demonstrates that the prior presentation of the same word prime (e.g.,rose-rose) facilitates picture naming independently of the target’s name frequency. In Experiment 2, primes that were homophones of picture targets (e.g.,rows-rose) also produced facilitatory effects compared with unrelated controls, but priming was significantly larger for targets with low-frequency names relative to targets with high-frequency names. In Experiment 3, primes that were higher frequency homophones of picture targets produced facilitatory effects compared with identical primes. These results are discussed in relation to different accounts of the effects of masked priming in current models of picture naming.     

Transposed-Letter Priming Across Inflectional Morpheme Boundaries

This study reports findings from two experiments testing whether a transposed-letter (TL) priming effect can be obtained when the transposition occurs across morphological boundaries. Previous studies have primarily tested derivationally complex words or compound words, but have not examined a more rule-based and productive morphological structure, i.e., inflectionally complex words, using masked priming. Experiment 1 tested TL priming with nonword primes and inflected targets (FOCUSING). Nonword primes were formed by transposing letters either within the root morpheme (fcousing) or across two morphemes (focuisng). Experiment 2 used the same nonword primes, but had the root words as targets (FOCUS). Both experiments showed similar TL priming effects for within-morpheme and across-boundary positions, indicating that morphological decomposition takes place only after letter positions in a word have been assigned. This finding provides additional evidence to previous research testing derived and compound words showing TL priming regardless of the position of transposition.     

Associative and phonological priming effects after letter search on the prime

Responses to target words typically are faster and more accurate after associatively related primes (e.g., "orange-juice") than after unrelated primes (e.g., "glue-juice"). This priming effect has been used as an index of semantic activation, and its elimination often is cited as evidence against semantic access. When participants are asked to perform a letter search on the prime, associative priming typically is eliminated, but repetition and morphological priming remain. It is possible that priming survives letter search when it arises from activity in codes that are represented before semantics. This experiment examined associative and phonological priming to determine whether priming from phonologically related rhymes would remain after letter search (e.g., "moose-juice"; rhyming items were orthographically dissimilar). When participants read the primes, equivalent associative and phonological priming effects were obtained; both effects were eliminated after letter search. The impact of letter search on semantic and phonological access and implications for the structural arrangement of lexical and semantic memory are discussed.     

Temporal limits of selection and memory encoding: A comparison of whole versus partial report in rapid serial visual presentation

People often fail to recall the second of two visual targets presented within 500 ms in rapid serial visual presentation (RSVP). This effect is called the attentional blink. One explanation of the attentional blink is that processes involved in encoding the first target into memory are slow and capacity limited. Here, however, we show that the attentional blink should be ascribed to attentional selection, not consolidation of the first target. Rapid sequences of six letters were presented, and observers had to report either all the letters (whole-report condition) or a subset of the letters (partial-report condition). Selection in partial report was based on color (e.g., report the two red letters) or identity (i.e., report all letters from a particular letter onward). In both cases, recall of letters presented shortly after the first selected letter was impaired, whereas recall of the corresponding letters was relatively accurate with whole report.     

Semantic similarity influences early morphological priming in Serbian: A challenge to form-then-meaning accounts of word recognition

Semantically similar (e.g., coolant-COOL) primes have produced greater facilitation than have form-similar but semantically dissimilar (e.g., rampant-RAMP) primes when English words have appeared in the forward-masked primed lexical decision task (Feldman, O'Connor, & Moscoso del Prado Martín, Psychonomic Bulletin & Review 16: 684-691, 2009). These results challenge claims that form-based, semantically blind activation underlies early morphological facilitation. Some have argued that the English materials in previous studies were not ideally constructed, insofar as the types of spelling changes to affixed stems differed in the semantically similar and dissimilar pairs. The present study exploited Serbian's bialphabetism, rich morphology, and homographic (form-identical) stems to replicate early effects of semantic similarity. Furthermore, it incorporated within-target manipulations of prime type and of alphabet, such that the alphabets of the prime-target pairs matched in Experiment 1a and alternated in Experiment 1b. Importantly, no letter or phoneme changes occurred between the stems of the primes and targets. These results revealed significant effects of semantic similarity that are comparable with and without alphabet alternation. The semantic effects in Serbian replicated almost exactly those in English (Feldman et al., Psychonomic Bulletin & Review 16: 684-691, 2009), which suggests that even early in the course of processing, morphemes are units of meaning as well as of form. The results failed to support models of lexical processing that postulate sequential access, first to the morphological form, and then to the semantic aspects of words.