Mirror invariance dies hard during letter processing by dyslexic college students

Discrimination of reversible mirrored letters (e.g., d and b) poses a challenge when learning to read as it requires overcoming mirror invariance, an evolutionary-old perceptual tendency of processing mirror images as equivalent. The present study investigated when, in reading development, mirror-image discrimination becomes automatic during visual word recognition. The developmental trajectory of masked priming effects was investigated from 2nd to 6th grade and in adults, by manipulating letter type (nonreversible; reversible) and prime condition (control; identity; mirrored; rotated). Standardized identity priming increased along reading development. Beginning readers showed mirror invariance during reversible and nonreversible letter processing. A mirror cost (slower word recognition in mirrored-letter than identity prime condition) was found by 5th-grade but only for reversible letters. By 6th grade, orthographic processing was no longer captive of mirror invariance. A multiple linear regression showed that letter representations, but not phonological processes or age, were a reliable predictor of the rise of mirror-image discrimination in 2nd-4th-graders. The present results suggest a protracted development of automatic mirror-image discrimination during orthographic processing, contingent upon the quality of abstract letter representations. RESEARCH HIGHLIGHTS: We traced the developmental trajectory of mirrored-letter and rotated-letter priming effects (e.g., ibea and ipea as primes of IDEA) in visual word recognition. Beginning readers (2nd-4th-graders) showed mirror invariance and plane-rotation sensitivity in orthographic processing, thus still being susceptible to the perceptual biases in charge in object recognition. A mirror cost was found in 5th-graders but only for reversible letters; orthographic processing was no longer captive of mirror invariance by 6th-grade. The automation of mirror-image discrimination during orthographic processing depends on the quality of letter representations but not on phonological processes or age.

In skilled adult readers, transposed-letter effects (jugde-JUDGE) are greater for consonant than for vowel transpositions. These differences are often attributed to phonological rather than orthographic processing. To examine this issue, we employed a scenario in which phonological involvement varies as a function of reading experience: A masked priming lexical decision task with 50-ms primes in adult and developing readers. Indeed, masked phonological priming at this prime duration has been consistently reported in adults, but not in developing readers (Davis, Castles, & Iakovidis, 1998). Thus, if consonant/vowel asymmetries in letter position coding with adults are due to phonological influences, transposed-letter priming should occur for both consonant and vowel transpositions in developing readers. Results with adults (Experiment 1) replicated the usual consonant/vowel asymmetry in transposed-letter priming. In contrast, no signs of an asymmetry were found with developing readers (Experiments 2-3). However, Experiments 1-3 did not directly test the existence of phonological involvement. To study this question, Experiment 4 manipulated the phonological prime-target relationship in developing readers. As expected, we found no signs of masked phonological priming. Thus, the present data favour an interpretation of the consonant/vowel dissociation in letter position coding as due to phonological rather than orthographic processing.

Breaking the symmetry: Mirror discrimination for single letters but not for pictures in the Visual Word Form Area

Mirror invariance in the subsequent acquisition of a script with separate forms for reading and writing

The identification of visually presented words tolerates distortions in the input format, as Hannagan et al. Plos One, 7, e32121, (2012) demonstrated in a masked priming lexical decision task, showing sizable identity-priming effects with CAPTCHA-like primes. This tolerance to distortion has two potential explanations: bottom-up normalization in the encoding stage (Dehaene et al., Trends in Cognitive Sciences, 9, 335–341, 2005) or top-down lexical feedback (McClelland & Rumelhart, Psychological Review, 88, 375–407, 1981). To disentangle the predictions of these accounts, we conducted two masked identity-priming experiments with printed and CAPTCHA-like distorted primes on high- and low-frequency words. The rationale was that, in the distorted format, high-frequency words would benefit more from top-down feedback than low-frequency words. Results in the lexical decision experiment showed that, for high-frequency words, identity-priming effects were only slightly greater for printed than for CAPTCHA-like primes, whereas this difference was larger for low-frequency words. In contrast, when employing the same-different matching task, which does not require lexical access, the identity-priming effect was greater for printed primes and was unaffected by word frequency. Thus, during lexical access, top-down feedback may help normalize the visual input in the early stages of word recognition, challenging bottom-up models of visual word recognition.

One of the key assumptions of the masked priming lexical decision task (LDT) is that primes are processed without requiring attentional resources. Here, we tested this assumption by presenting a dual-task manipulation to increase memory load and measure the change in masked identity priming on the targets in the LDT. If masked priming does not require attentional resources, increased memory load should have no influence on the magnitude of the observed identity priming effects. We conducted two LDT experiments, using a within-subjects design, to investigate the effect of memory load (via a concurrent matching task Experiment 1 and a concurrent search task in Experiment 2) on masked identity priming. Results showed that the magnitude of masked identity priming on word targets was remarkably similar under high and low memory load. Thus, these experiments provide empirical evidence for the automaticity assumption of masked identity priming in the LDT.

Mirror image discrimination with each eye in pigeons

Previous studies show that the primate and human visual system automatically generates a common and invariant representation from a visual object image and its mirror reflection. For humans, however, this mirror-image generalization seems to be partially suppressed through literacy acquisition, since literate adults have greater difficulty in recognizing mirror images of letters than those of other visual objects. At the neural level, such category-specific effect on mirror-image processing has been associated with the left occpitotemporal cortex (L-OTC), but it remains unclear whether the apparent “inhibition” on mirror letters is mediated by suppressing mirror-image representations covertly generated from normal letter stimuli. Using transcranial magnetic stimulation (TMS), we examined how transient disruption of the L-OTC affects mirror-image recognition during a same-different judgment task, while varying the semantic category (letters and non-letter objects), identity (same or different), and orientation (same or mirror-reversed) of the first and second stimuli. We found that magnetic stimulation of the L-OTC produced a significant delay in mirror-image recognition for letter-strings but not for other objects. By contrast, this category specific impact was not observed when TMS was applied to other control sites, including the right homologous area and vertex. These results thus demonstrate a causal link between the L-OTC and mirror-image discrimination in literate people. We further suggest that left-right sensitivity for letters is not achieved by a local inhibitory mechanism in the L-OTC but probably relies on the inter-regional coupling with other orientation-sensitive occipito-parietal regions.

Aims and objectives: Masked priming lexical decision research involving relatively high-proficient Japanese–English bilinguals suggests that past-tense and present-tense morphological connections (e.g., fell-FALL and looked-LOOK) are represented in their L2 (English) lexicons in a way that is similar to how they are represented in L1 (English) lexicons. The goal of the present research was to determine whether the same is true for low-proficient Japanese–English bilinguals. Methodology: Seventy-seven low-proficient Japanese–English bilinguals were tested in the masked priming lexical decision task. We manipulated the morphological or orthographic similarity between L2 English prime-target pairs. Data and analysis: We analyzed response latencies and error rates using (generalized) linear mixed-effects models. Findings: Although participants responded significantly faster to targets preceded by past-tense primes (e.g., fell-FALL and looked-LOOK) when compared to unrelated primes (e.g., slow-FALL and danger-LOOK), those priming effects were the same size as priming effects produced by orthographically similar primes (e.g., fill-FALL and lonely-LOOK), suggesting that the facilitation from past-tense primes is likely orthographic in nature. Nevertheless, the low-proficient bilinguals showed significant L2-L2 repetition priming (e.g., fall-FALL and look-LOOK), suggesting that, for those individuals, L2 (English) words are at least represented at the lexical level. Originality: The present study empirically confirmed a prediction, derived from a post hoc exploratory analysis in our previous research, that masked morphological priming effects are no larger than orthographic priming effects in low-proficient bilinguals. This indicates that a certain level of functional proficiency is required to observe morphological priming effects for Japanese–English bilinguals. Implications: Our results suggest that morphological connections in L2 are not yet established for low-proficient bilinguals, even when L2 words are lexically represented in their mental lexicon.

Recently, Nespor et al (2003) have argued that consonants play a more important role at the lexical level than vowels. This proposal has received direct support from studies showing that 16/20/30-month-old infants are better at processing specific consonantal than vocalic information while learning new words (Nazzi, 2005; Nazzi & New, 2007). This proposal is also supported, although indirectly, by studies on adults. Adults have been found to rely more on consonants than on vowels when asked to transform a nonword into a real word (Cutler et al., 2000). Moreover, adults presented with a continuous stream of syllables are able to segment it into "lexical units" by relying on consonantal but not vocalic information (Bonatti et al., 2005). In our study, we directly investigate this issue using a visual masked priming lexical decision task (an oral version being currently implemented). The test items are bisyllabic (CVCV or VCVC) and trisyllabic (CVCVCV or VCVCVC) words, which are presented following four different primes: identity (e.g., joli-joli), unrelated (vabu-joli), same consonants (jalu-joli) and same vowels (vobi-joli). Priming was found for the identity and same consonants conditions, not for the same vowels condition, supporting the privileged role of consonants at the lexical level.

Where is mirror invariance? Masked priming effects by mirrored and rotated transformations of reversible and nonreversible letters

The role of the written script in shaping mirror-image discrimination: Evidence from illiterate, Tamil literate, and Tamil-Latin-alphabet bi-literate adults

The role of letter features on the consonant-bias effect: Evidence from masked priming

This study presents a conceptual replication of Jacob et al.’s (2018) comparison of L2 early-stage processing of derived vs. inflected words. Previous studies on this issue focused predominantly on L2 learners from morphologically complex, alphabetic L1s, and generally showed L2 decompositional processing of derived but not inflected words. This replication study examined whether the previous claim for a qualitative difference in L2 early-stage processing of derived and inflected words could generalize to L2 English learners from a morphologically isolating, logographic L1, i.e., Chinese learners of L2 English. Results from a masked priming lexical decision task showed qualitatively the same magnitude of priming in the derivational, inflectional, and form control conditions for Chinese learners of English, suggesting reliance on surface form information in the early-stage processing of both derived and inflected words. Results of the current study add to the literature on L2 early-stage processing of derived vs. inflected words.

ABSTRACTObjective: Previous literature in the monolingual domain has showed that letter position is not encoded in an absolute-position manner. However, with the exception of the unpublished work by Font [(2001). Rôle de la langue dansl’accès au lexique chez les bilingues: Influence de la proximité orthographique et sémantique interlangue surla reconnaissance visuelle de mots (Unpublished Doctoral thesis). Université Paul Valery, Montpellier)], there is no study investigating this issue with bilinguals. According to Font, the recognition of cognate words is affected by the position of the deviant letter. This calls the validity of the input-coding scheme of the most relevant computational model of bilingual word recognition (The Bilingual Interactive Activation Plus Model [BIA+; Dijkstra, T., & vanHeuven, W. J. (2002). The architecture of the bilingual word recognition system: From identification to decision. Bilingualism: Language and Cognition, 5, 175–197. doi:10.1017/S1366728902003012; Dijkstra, T., Miwa, K., Brummelhuis, B., Sappelli, M., & Baayen, H. (2010). How cross-language similarity and task demands affect cognate recognition. Journal of Memory and Language, 62, 284–301. doi:10.1016/j.jml.2009.12.003]) into question, since it holds that letter positions are perfectly encoded. The aim of the present research was to further examine the way letter position is encoded during non-native reading by manipulating the deviant-letter position of European Portuguese (EP)-English (EN) cognate words.Method: To that purpose 288 stimuli (144 Portuguese-English translation words [72 cognates and 72 noncognates] and 144 pseudowords) were selected. Cognates were assigned to two experimental conditions according to deviant-letter position: 1) at end of the word (matriz-MATRIX); and 2) at the beginning of the word (coala-KOALA). A third condition varying both at the beginning and at the end (e.g., escala-SCALE) was also included as a control to test how the degree of cross-language overlap modulates the results. Twenty-eight proficient Portuguese-English bilinguals were asked to perform a masked priming lexical decision task in English.Results: The results revealed faster responses for cognates with greater degree of cross-language overlap (Conditions 1 and 2). More important, priming effects were not modulated by deviant-letter position, i.e., the size of priming was similar across condition 1 and 2.Conclusion: Although a priori, no amendments seems to be needed in the “front-end” of the coding scheme of the BIA+ model when cognate words are considered, future studies should be developed in order to explore if these results are restricted to outer deviant-letters.