Simulating single word processing in the classic aphasia syndromes based on the Wernicke-Lichtheim-Geschwind theory

The Wernicke-Lichtheim-Geschwind (WLG) theory of the neurobiological basis of language is of great historical importance, and it continues to exert a substantial influence on most contemporary theories of language in spite of its widely recognized limitations. Here, we suggest that neurobiologically grounded computational models based on the WLG theory can provide a deeper understanding of which of its features are plausible and where the theory fails. As a first step in this direction, we created a model of the interconnected left and right neocortical areas that are most relevant to the WLG theory, and used it to study visual-confrontation naming, auditory repetition, and auditory comprehension performance. No specific functionality is assigned a priori to model cortical regions, other than that implicitly present due to their locations in the cortical network and a higher learning rate in left hemisphere regions. Following learning, the model successfully simulates confrontation naming and word repetition, and acquires a unique internal representation in parietal regions for each named object. Simulated lesions to the language-dominant cortical regions produce patterns of single word processing impairment reminiscent of those postulated historically in the classic aphasia syndromes. These results indicate that WLG theory, instantiated as a simple interconnected network of model neocortical regions familiar to any neuropsychologist/neurologist, captures several fundamental "low-level" aspects of neurobiological word processing and their impairment in aphasia.     

Phonological recoding,rapid automatized naming,and orthographic knowledge

Phonological recoding, orthographic knowledge, and rapid automatized naming (RAN) are three major contributors to word identification. However, the interrelations between these components remain somewhat unclear. The current analyses focus on how phonological recoding and alphanumeric versus non-alphanumeric RAN contribute to different components of orthographic knowledge (word specific vs. general). Results indicate that alphanumeric and non-alphanumeric RAN contribute to orthographic knowledge components differently. Alphanumeric RAN relates more to word-specific orthographic knowledge, whereas non-alphanumeric RAN relates more to general orthographic knowledge. Furthermore, phonological recoding is more closely related to word-specific orthographic knowledge than to general orthographic knowledge.     

The specific-word frequency effect in speech production: Evidence from Spanish and French

The role of word frequency in lexical access during the production of homophones remains unresolved. In the current study, we address whether specific-word (the frequency of occurrence of the word “nun”) or homophone frequency (the summed frequency of words with the pronunciation /nΛn/) determines the production latencies of homophones. In Experiments 1a, 2a, and 3a, participants named pictures of high-frequency (e.g., “banco”–a bank: financial institution) and low-frequency (e.g., “banco”–park bench) Spanish (Experiments 1a and 2a) or French (Experiment 3a) homophones and control pictures of nonhomophone words matched in frequency with each of the two uses of the homophones. The naming latencies for low-frequency homophones were longer than those for high-frequency homophones. Furthermore, the naming latencies for homophones were indistinguishable from those for nonhomophone controls matched in specific-word frequency. In Experiments 1b, 2b, and 3b, the participants performed either object decision or picture–word matching tasks with the stimuli used in the corresponding Experiments 1a, 2a, and 3a. There were no reliable differences between high- and low-frequency homophones. The findings support the hypothesis that specific-word and not homophone frequency determines lexical access in speech production.     

The word class effect in the picture–word interference paradigm

The word class effect in the picture–word interference paradigm is a highly influential finding that has provided some of the most compelling support for word class constraints on lexical selection. However, methodological concerns called for a replication of the most convincing of those effects. Experiment 1 was a direct replication of Pechmann and Zerbst (2002 Pechmann, T. and Zerbst, D. 2002. The activation of word class information during speech production. Journal of Experimental Psychology: Learning, Memory, and Cognition, 28: 233–243. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Experiment 4). Participants named pictures of objects in the context of noun and adverb distractors. Naming took place in bare noun and sentence frame contexts. A word class effect emerged in both bare noun and sentence frame naming conditions, suggesting a semantic origin of the effect. In Experiment 2, participants named objects in the context of noun and verb distractors whose word class relationship to the target and imageability were orthogonally manipulated. As before, naming took place in bare noun and sentence frame naming contexts. In both naming contexts, distractor imageability but not word class affected picture naming latencies. These findings confirm the sensitivity of the picture–word interference paradigm to distractor imageability and suggest the paradigm is not sensitive to distractor word class. The results undermine the use of the word class effect in the picture–word interference paradigm as supportive of word class constraints during lexical selection.     

Naming fluency in dyslexic and nondyslexic readers: Differential effects of visual crowding in foveal,parafoveal, and peripheral vision

Reading fluency is often indexed by performance on rapid automatized naming (RAN) tasks, which are known to reflect speed of access to lexical codes. We used eye tracking to investigate visual influences on naming fluency. Specifically, we examined how visual crowding affects fluency in a RAN-letters task on an item-by-item basis, by systematically manipulating the interletter spacing of items, such that upcoming letters in the array were viewed in the fovea, parafovea, or periphery relative to a given fixated letter. All lexical information was kept constant. Nondyslexic readers’ gaze durations were longer in foveal than in parafoveal and peripheral trials, indicating that visual crowding slows processing even for fluent readers. Dyslexics’ gaze durations were longer in foveal and parafoveal trials than in peripheral trials. Our results suggest that for dyslexic readers, influences of crowding on naming speed extend to a broader visual span (to parafoveal vision) than that for nondyslexic readers, but do not extend as far as peripheral vision. The findings extend previous research by elucidating the different visual spans within which crowding operates for dyslexic and nondyslexic readers in an online fluency task.     

Perceptual and categorical judgements of colour similarity

Consideration is given to the tasks that make judgements of colour similarity based on perceptual similarity rather than categorical similarity. Irrespective of whether colour categories are taken to be universal (Berlin & Kay, 1969) or language induced (Davidoff, Davies, & Roberson, 1999), it is widely assumed that colour boundaries, and hence categorical similarity, would be used when categorising colours. However, we argue that categorical similarity is more reliably used in implicit than in explicit categorisation. Thus, in Experiment 1, we found that category boundaries may be overridden in the explicit task of matching-to-sample: There was a similar strong tendency to ignore colour boundaries and to divide the range of coloured stimuli into two equal groups in both Westerners and in a remote population (Himba). In Experiment 2, we showed that a distinctive stimulus (focal colour) in the range affected the equal division in a matching-to-sample task. Experiment 3 tested the stability of a category boundary in an implicit task (visual search) that assessed categorical perception; only for this task was categorisation largely immune to range effects and largely based on categorical similarity. It is concluded that, even after colour categories are acquired, perceptual rather than categorical similarity is commonly used in judgements of colour similarity.     

Varieties of Anger: The Relation Between Emotion Terms and Components of Anger Expressions

Component theory (C. Smith & H. Scott, 1997) predicts that presence of component movements (action units) alters the decoded meaning of a basic emotional expression. We tested whether the meaning of the basic expression of anger varied when different components were present in the expression. Participants were asked to label variants of anger from Ekman and Friesen's Pictures of Facial Affect using 15 anger terms, and invariance of labeling was tested by manipulating the judgment task. Data were analyzed using consensus analysis, multidimensional scaling, and numerical scaling. Components did not result in consensus about fine distinctions in the meanings of the anger expressions. Varying the type of task strongly affected results. We believe this occurred because language elicits different categorization processes than evaluation of facial expressions nonverbally.     

Double dissociation between implicit and explicit affiliative motives: A closer look at socializing behavior in dyadic interactions

In the present research, we followed two objectives. First, we aimed to replicate the classic finding by McAdams, Jackson, and Kirshnit (1984) that strong implicit affiliative motives predict high levels of nonverbal socializing behavior (eye contact, laughing, smiling) in dyadic interactions with an unacquainted person. Second, we applied a dual-motives perspective and hypothesized a double dissociation between implicit and explicit motives. Whereas implicit motives were supposed to predict nonverbal socializing, the corresponding explicit motives were supposed to predict verbal socializing (i.e., self-disclosure). Using observational data from 123 university students in ostensibly casual conversations, the findings by McAdams et al. were replicated, and the double-dissociation hypothesis was confirmed. These results corroborate dual-motives theory in the domain of affiliative motivation.     

Words (but not tones) facilitate object categorization: evidence from 6- and 12-month-olds

Recent studies reveal that naming has powerful conceptual consequences within the first year of life. Naming distinct objects with the same word highlights commonalities among the objects and promotes object categorization. In the present experiment, we pursued the origin of this link by examining the influence of words and tones on object categorization in infants at 6 and 12 months. At both ages, infants hearing a novel word for a set of distinct objects successfully formed object categories; those hearing a sequence of tones for the same objects did not. These results support the view that infants are sensitive to powerful and increasingly nuanced links between linguistic and conceptual units very early in the process of lexical acquisition.     

The masked onset priming effect in picture naming

Reading aloud is faster when targets (e.g., PAIR) are preceded by visually masked primes sharing just the onset (e.g., pole) compared to all different primes (e.g., take). This effect is known as the masked onset priming effect (MOPE). One crucial feature of this effect is its presumed non-lexical basis. This aspect of the MOPE is tested in the current study. Dutch participants named pictures having bisyllabic names, which were preceded by visually masked primes. Picture naming was facilitated by first-segment but not last-segment primes, and by first-syllable as well as last-syllable primes. Whole-word primes with first or last segment overlap slowed down picture naming latencies significantly. The first-segment priming effect (i.e., MOPE) cannot be accounted for by non-lexical response competition since pictures cannot be named via the non-lexical route. Instead, the effects obtained in this study can be accommodated by a speech-planning account of the MOPE.