Semantic transparency and masked morphological priming: the case of prefixed words

Tracking the consequences of morpho-orthographic decomposition using ERPs

We examined the effects of morpho-orthographic decomposition on complex word processing using a combination of masked priming and ERP recordings. The process of morpho-orthographic decomposition was primed by the prior presentation of complex non-words (formed by the combination a legal stem and legal affix, e.g. huntity, cornity, scanity) as prime stimuli. Targets were semantically transparent complex words (e.g., hunter), semantically opaque pseudocomplex words (e.g., corner), and simplex words (e.g., scandal) that contained the same stem as primes or a different stem (e.g., huntity-hunter vs. farmity-hunter). We found a large early (150-200 ms) priming effect for transparent complex words only, followed by widely distributed priming effects between 200 and 300 ms and more spatially focused N400 priming effects for all types of target. Furthermore, in the 150-200 ms time-window, the ERP waveforms generated by pseudocomplex words patterned with those of complex words, both of which generated less negative-going waveforms compared with simplex words. In the N400 time-window, on the other hand, complex words differed from both pseudocomplex and simplex words. The results provide further support for early morpho-orthographic segmentation processes that operate independently of semantic transparency, and suggest that the output of these processes only affects the subsequent processing of truly complex words.

Letter transpositions within morphemes and across morpheme boundaries

Recent evidence has revealed conflicting results regarding the influence of letter transpositions during the recognition of morphologically complex words. While some studies suggest that the disruption of the morpheme boundary through across-boundary transpositions (e.g., darnkess) leads to the absence of masked transposed-letter (TL) priming, other studies have found that TL priming occurs independently of whether or not letters have been transposed across the boundary. We conducted three experiments to test whether the difference between TL- within and TL-across priming is modulated by (a) the transposition of internal versus external letters of the stem (Experiment 1), (b) the overall proportion of affixed trials (Experiment 2), or (c) the relative frequency between prime and target (Experiment 3). The results revealed equal TL-within and TL-across boundary priming across all three experiments, which adds to previous findings suggesting that across-boundary transpositions do not interfere with the recognition of morphologically complex words.

Parallel Processing of Whole Words and Morphemes in Visual Word Recognition

Models of morphological processing make different predictions about whether morphologically complex written words are initially decomposed and recognized on the basis of their morphemic subunits or whether they can directly be accessed as whole words and at what point semantics begin to influence morphological processing. In this study, we used unprimed and masked primed lexical decision to compare truly suffixed ( darkest) and pseudosuffixed words ( glossary) with within-boundary ( d ra kest/g ol ssary) to across-boundary ( dar ek st/glos as ry) letter transpositions. Significant transposed-letter similarity effects were found independently of the morphological position of the letter transposition, demonstrating that, in English, morphologically complex whole-word representations can be directly accessed at initial word processing stages. In a third masked primed lexical decision experiment, the same materials were used in the context of stem target priming, and it was found that truly suffixed primes facilitate the recognition of their stem-target ( darkest–DARK) to the same extent as pseudosuffixed primes ( glossary–GLOSS), which is consistent with theories of early morpho-orthographic decomposition. Taken together, our findings provide evidence for both whole-word access and morphological decomposition at initial stages of visual word recognition and are discussed in the context of a hybrid account.

Morphological processing as we know it: an analytical review of morphological effects in visual word identification

The last 40 years have witnessed a growing interest in the mechanisms underlying the visual identification of complex words. A large amount of experimental data has been amassed, but although a growing number of studies are proposing explicit theoretical models for their data, no comprehensive theory has gained substantial agreement among scholars in the field. We believe that this is due, at least in part, to the presence of several controversial pieces of evidence in the literature and, consequently, to the lack of a well-defined set of experimental facts that any theory should be able to explain. With this review, we aim to delineate the state of the art in the research on the visual identification of complex words. By reviewing major empirical evidences in a number of different paradigms such as lexical decision, word naming, and masked and unmasked priming, we were able to identify a series of effects that we judge as reliable or that were consistently replicated in different experiments, along with some more controversial data, which we have tried to resolve and explain. We concentrated on behavioral and electrophysiological studies on inflected, derived, and compound words, so as to span over all types of complex words. The outcome of this work is an analytical summary of well-established facts on the most relevant morphological issues, such as regularity, morpheme position coding, family size, semantic transparency, morpheme frequency, suffix allomorphy, and productivity, morphological entropy, and morpho-orthographic parsing. In discussing this set of benchmark effects, we have drawn some methodological considerations on why contrasting evidence might have emerged, and have tried to delineate a target list for the construction of a new all-inclusive model of the visual identification of morphologically complex words.

Morphological processing during visual word recognition in developing readers: Evidence from masked priming

Masked priming studies with adult readers have provided evidence for a form-based morpho-orthographic segmentation mechanism that “blindly” decomposes any word with the appearance of morphological complexity. The present studies investigated whether evidence for structural morphological decomposition can be obtained with developing readers. We used a masked primed lexical decision design first adopted by Rastle, Davis, and New (2004), comparing truly suffixed ( golden–GOLD) and pseudosuffixed ( mother–MOTH) prime–target pairs with nonsuffixed controls ( spinach–SPIN). Experiment 1 tested adult readers, showing that priming from both pseudo- and truly suffixed primes could be obtained using our own set of high-frequency word materials. Experiment 2 assessed a group of Year 3 and Year 5 children, but priming only occurred when prime and target shared a true morphological relationship, and not when the relationship was pseudomorphological. This pattern of results indicates that morpho-orthographic decomposition mechanisms do not become automatized until a relatively late stage in reading development.

Evidence for multiple routes in learning to read

We describe a multiple-route model of reading development in which coarse-grained orthographic processing plays a key role in optimizing access to semantics via whole-word orthographic representations. This forms part of the direct orthographic route that gradually replaces phonological recoding during the initial phases of reading acquisition. The model predicts distinct developmental trajectories for pseudo-homophone and transposed-letter effects - two benchmark phenomena associated with phonological recoding and coarse-grained orthographic processing, respectively. Pseudo-homophone effects should decrease over the first years of reading acquisition, whereas transposed-letter effects should initially increase. These predictions were tested in a lexical decision task with 334 children in grades 1-5, and 29 skilled adult readers. In line with the predictions, we found that the pseudo-homophone effect diminished as reading level increased, whereas the transposed-letter effect first increased and then diminished.

Early morphological decomposition during visual word recognition: evidence from masked transposed-letter priming

The present experiments were designed to explore the theory of early morpho-orthographic segmentation (Rastle, Davis, & New, Psychonomic Bulletin & Review 11,1090-1098, 2004), which postulates that written words with a true morphologically complex structure (cleaner) and those with a morphological pseudostructure (corner) are both decomposed into affix and stem morphemes. We used masked complex transposed-letter (TL) nonword primes in a lexical decision task. Experiment 1 replicated the well-known masked TL-priming effect using monomorphemic nonword primes (e.g., wran-WARN). Experiment 2 used the same nonword TL stems as in Experiment 1, but combined them with real suffixes (e.g., ish as in wranish-WARN). Priming was compared with that from nonsuffixed primes in which the real suffixes were replaced with nonmorphemic endings (e.g., el as in wranel-WARN). Significant priming was found in the suffixed but not in the nonsuffixed condition, suggesting that affix-stripping occurs at prelexical stages in visual word recognition and operates over early letter-position encoding mechanisms.

Sub- and supralexical information in early phases of lexical access

The present study investigated sub- and supralexical effects in morphological processing for inflected and pseudo complex words and pseudo words in lexical decision with masked and cross-modal priming. The results showed that the early stage of morphological processing is not only sensitive to whether the orthographic string can be segmented into an existing stem and affix, but also whether the full form is an existing word the meaning of which differs from the meaning of the segmented stem. It is thus likely that from early on morphological processing is probably not governed by morpho-orthographic processes alone, but is most likely sensitive to top-down information, perhaps originating from supralexical semantic connections between the words morphological family members. In addition, whereas semantic interpretability has a clear advantage later in processing, this stage seems to be sensitive to bottom-up form information as well. In a detailed theoretical discussion we show how these findings, along with earlier findings, are explained by a model that assumes that morphological information is represented at two interactive levels, corresponding to sublexical form (orthographic) and supralexical (semantic) information mediated by a lexical level. This allows supralexical (semantic) effects to feed top-down, predicting differences between regular inflected and pseudo complex words at the lexical level, affecting the early phases of processing for these words.

Effects of lexical status and morphological complexity in masked priming: An ERP study

Two masked priming experiments examined behavioural and event-related potential responses to simplex target words (e.g., flex) preceded by briefly presented, masked, derived word primes (flexible-flex), complex nonword primes formed by an illegal combination of the target word and a real suffix (flexify-flex), and simplex nonword primes formed by adding a nonsuffix word ending to the target (flexint-flex). Subjects performed a lexical decision task. Behavioural results showed that all prime types significantly facilitated target recognition. Priming effects were reflected in the electrophysiological data by reduced N250 and N400 amplitudes, and these priming effects were statistically equivalent for the three types of prime. The strong priming effects found with simplex primes in the present study, compared with prior research, are thought to be due to the combination of targets always being completely embedded in prime stimuli plus the reduced lexical inhibition that arises with nonword primes. In line with prior behavioural research, however, there was evidence for differential priming effects as a function of prime type in the N400 ERP component in Experiment 2, with greater priming effects for derived and pseudocomplex primes relative to simplex primes at lateral posterior electrode sites.

A dual-route approach to orthographic processing

In the present theoretical note we examine how different learning constraints, thought to be involved in optimizing the mapping of print to meaning during reading acquisition, might shape the nature of the orthographic code involved in skilled reading. On the one hand, optimization is hypothesized to involve selecting combinations of letters that are the most informative with respect to word identity (diagnosticity constraint), and on the other hand to involve the detection of letter combinations that correspond to pre-existing sublexical phonological and morphological representations (chunking constraint). These two constraints give rise to two different kinds of prelexical orthographic code, a coarse-grained and a fine-grained code, associated with the two routes of a dual-route architecture. Processing along the coarse-grained route optimizes fast access to semantics by using minimal subsets of letters that maximize information with respect to word identity, while coding for approximate within-word letter position independently of letter contiguity. Processing along the fined-grained route, on the other hand, is sensitive to the precise ordering of letters, as well as to position with respect to word beginnings and endings. This enables the chunking of frequently co-occurring contiguous letter combinations that form relevant units for morpho-orthographic processing (prefixes and suffixes) and for the sublexical translation of print to sound (multi-letter graphemes).

On the Interaction of Letter Transpositions and Morphemic Boundaries

Investigations of the impact of morphemic boundaries on transposed-letter priming effects have yielded conflicting results. Five masked priming lexical decision experiments were conducted to examine the interaction of letter transpositions and morphemic boundaries with English suffixed derivations. Experiments 1-3 found that responses to monomorphemic target words (e.g., SPEAK) were facilitated to the same extent by morphologically related primes containing letter transpositions that did (SPEAEKR) or did not (SPEKAER) cross a morphemic boundary. This pattern was also observed in Experiments 4 and 5, in which the targets (e.g. SPEAKER) were the base forms of the transposed-letter primes. Thus, in these experiments the influence of the morphological structure of a transposed-letter prime did not depend on whether the letter transposition crossed a morphological boundary.