Marlene Behrmann

Department of Psychology,
Center for the Neural Basis of Cognition, Carnegie Mellon University,
Pittsburgh, USA









Selected references - reading and the alexias  

Behrmann, M. & Plaut, D. C. (2013). Bilateral Hemispheric Processing of Words and Faces: Evidence from Word Impairments in Prosopagnosia and Face Impairments in Pure Alexia. Cerebral Cortex.
Notes: Considerable research has supported the view that faces and words are subserved by independent neural mechanisms located in the ventral visual cortex in opposite hemispheres. On this view, right hemisphere ventral lesions that impair face recognition (prosopagnosia) should leave word recognition unaffected, and left hemisphere ventral lesions that impair word recognition (pure alexia) should leave face recognition unaffected. The current study shows that neither of these predictions was upheld. A series of experiments characterizing speed and accuracy of word and face recognition were conducted in 7 patients (4 pure alexic, 3 prosopagnosic) and matched controls. Prosopagnosic patients revealed mild but reliable word recognition deficits, and pure alexic patients demonstrated mild but reliable face recognition deficits. The apparent comingling of face and word mechanisms is unexpected from a domain-specific perspective, but follows naturally as a consequence of an interactive, learning-based account in which neural processes for both faces and words are the result of an optimization procedure embodying specific computational principles and constraints
Department of Psychology, Center for the Neural Basis of Cognition, Carnegie Mellon University, Pittsburgh, PA 15213-3890, USA

Dundas, E. M., Plaut, D. C., & Behrmann, M. (2013). The joint development of hemispheric lateralization for words and faces. Journal of Experimental Psychology: General, 142, 348-358.
Notes: Consistent with long-standing findings from behavioral studies, neuroimaging investigations have identified a region of the inferior temporal cortex that, in adults, shows greater face selectivity in the right than left hemisphere and, conversely, a region that shows greater word selectivity in the left than right hemisphere. What has not been determined is how this pattern of mature hemispheric specialization emerges over the course of development. The present study examines the hemispheric superiority for faces and words in children, young adolescents and adults in a discrimination task in which stimuli are presented briefly in either hemifield. Whereas adults showed the expected left and right visual field superiority for face and word discrimination, respectively, the young adolescents demonstrated only the right-field superiority for words and no field superiority for faces. Although the children's overall accuracy was lower than that of the older groups, like the young adolescents, they exhibited a right visual field superiority for words but no field superiority for faces. Interestingly, the emergence of face lateralization was correlated with reading competence, measured on an independent standardized test, after regressing out age, quantitative reasoning scores, and face discrimination accuracy. Taken together, these findings suggest that the hemispheric organization of face and word recognition do not develop independently and that word lateralization, which emerges earlier, may drive later face lateralization. A theoretical account in which competition for visual representations unfolds over the course of development is proposed to account for the findings. (PsycINFO Database Record (c) 2013 APA, all rights reserved)
Department of Psychology, Carnegie Mellon University

Nestor, A., Behrmann, M., & Plaut, D. C. (2012). The Neural Basis of Visual Word Form Processing: A Multivariate Investigation. Cerebral Cortex.
Notes: Current research on the neurobiological bases of reading points to the privileged role of a ventral cortical network in visual word processing. However, the properties of this network and, in particular, its selectivity for orthographic stimuli such as words and pseudowords remain topics of significant debate. Here, we approached this issue from a novel perspective by applying pattern-based analyses to functional magnetic resonance imaging data. Specifically, we examined whether, where and how, orthographic stimuli elicit distinct patterns of activation in the human cortex. First, at the category level, multivariate mapping found extensive sensitivity throughout the ventral cortex for words relative to false-font strings. Secondly, at the identity level, the multi-voxel pattern classification provided direct evidence that different pseudowords are encoded by distinct neural patterns. Thirdly, a comparison of pseudoword and face identification revealed that both stimulus types exploit common neural resources within the ventral cortical network. These results provide novel evidence regarding the involvement of the left ventral cortex in orthographic stimulus processing and shed light on its selectivity and discriminability profile. In particular, our findings support the existence of sublexical orthographic representations within the left ventral cortex while arguing for the continuity of reading with other visual recognition skills
Center for the Neural Basis of Cognition, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA

Starrfelt, R. & Behrmann, M. (2011). Number reading in pure alexia-A review. Neuropsychologia, 49, 2283-2298.
Notes: It is commonly assumed that number reading can be intact in patients with pure alexia, and that this dissociation between letter/word recognition and number reading strongly constrains theories of visual word processing. A truly selective deficit in letter/word processing would strongly support the hypothesis that there is a specialized system or area dedicated to the processing of written words. To date, however, there has not been a systematic review of studies investigating number reading in pure alexia and so the status of this assumed dissociation is unclear. We review the literature on pure alexia from 1892 to 2010, and find no well-documented classical dissociation between intact number reading and impaired letter identification in a patient with pure alexia. A few studies report strong dissociations, with number reading less impaired than letter reading, but when we apply rigorous statistical criteria to evaluate these dissociations, the difference in performance across domains is not statistically significant. There is a trend in many cases of pure alexia, however, for number reading to be less affected than letter identification and word reading. We shed new light on this asymmetry by showing that, under conditions of brief exposure, normal participants are also better at identifying digits than letters. We suggest that the difference observed in some pure alexic patients may possibly reflect an amplification of this normal difference in the processing of letters and digits, and we relate this asymmetry to intrinsic differences between the two types of symbols
Center for Visual Cognition, Department of Psychology, Copenhagen University, O. Farimagsgade 2A, DK-1353 Copenhagen K, Denmark

Mycroft, R. H., Behrmann, M., & Kay, J. (2009). Visuoperceptual deficits in letter-by-letter reading? Neuropsychologia, 47, 1733-1744.
Notes: A longstanding and controversial issue concerns the underlying mechanisms that give rise to letter-by-letter (LBL) reading: while some researchers propose a prelexical, perceptual basis for the disorder, others postulate a postlexical, linguistic source for the problem. To examine the nature of the deficit underlying LBL reading, in three experiments, we compare the performance of seven LBL readers, matched control participants and one brain-damaged patient, OL, with no reading impairment. Experiment 1 revealed that the LBL patients were impaired, relative to the controls and to OL, on a same/different matching task using checkerboards of black and white squares. Given that the perceptual impairment extends beyond abnormalities with alphanumeric stimuli, the findings are suggestive of a more general visual processing deficit. This interpretation was confirmed in Experiments 2 (matching words and symbol strings) and 3 (visual search of letter and symbol targets), which compared the processing of linguistic and non-linguistic written stimuli, matched for visual complexity. In both experiments, the LBL patients displayed qualitatively similar effects of length and left-to-right sequential ordering on linguistic and non-linguistic stimuli. Moreover, there was a clear association between the perceptual impairments on these tasks and the slope of the reading latency function for the LBL patients. Taken together, these findings are consistent with a significant visuoperceptual impairment in LBL that adversely affects reading performance as well as performance on other non-reading tasks
South London and Maudsley NHS Trust, UK

Leff, A. P. & Behrmann, M. (2008). Treatment of reading impairment after stroke. Current Opinion in Neurology, 21, 644-648.
Notes: PURPOSE OF REVIEW: Reading impairments after left or right hemisphere stroke are common yet receive little attention from clinicians and therapists. In this review, we focus on the classification of acquired alexia and the current theory and practice underlying the rehabilitation of this diverse set of disorders. RECENT FINDINGS: The underlying behavioural impairments that dictate reading ability in the acquired alexias are becoming better understood; this, in turn, has led to targeted therapies being undertaken, mainly on a single subject basis. In hemianopic alexia, the most 'peripheral' of the acquired alexias, where text reading speed is determined largely by damage to the visual field, therapies have been directed at improving reading eye movements. In 'pure' alexia, techniques are usually aimed at improving whole-word recognition. In central alexic syndromes, where other language functions are also involved, the emphasis has been on strengthening connections between lexical and semantic representations, strengthening phonological representations, or both, and their association with lexical/semantic knowledge. SUMMARY: Despite targeted approaches to the rehabilitation of patients with alexia caused by stroke, there is still a preponderance of largely descriptive, single-case studies in the literature. In some syndromes, small trials have been attempted and the hope is that, in the future, more systematic investigations will be carried out so rehabilitation efforts can be built on a strong theoretical and empirical foundation. Well designed, single-case studies continue to play an important role in informing therapy, as these disorders are, by nature, heterogeneous
Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, UK.

McKeeff, T. J. & Behrmann, M. (2004). Pure alexia and covert reading: Evidence from Stroop tasks. Cognitive Neuropsychology, 21, 443-458.
Notes: T.J. McKeeff, Department of Psychology, Princeton University, Princeton, NJ 08544
Patients with pure alexia (also referred to as letter-by-letter readers) show a marked word-length effect when naming visually presented words, evidenced by a monotonic increase in response time (or decrease in accuracy) as a function of the number of letters in the string. Interestingly, despite the difficulty in overtly reporting the identity of some words, many patients exhibit fast and above-chance access to lexical and/or semantic information for the same words. To explore the extent of this covert reading, we examined the degree of interference afforded by the inconsistent (word identity and colour label do not match) versus neutral condition in a Stroop task in a pure alexic patient, EL. EL shows evidence of covert reading on a semantic categorisation task and a lexical decision task. She also demonstrates covert reading by exhibiting Stroop interference of the same magnitude as a matched control subject, when naming the colour of the ink in which a word is printed. When the word shares some but not all letters with the colour name (BLOW instead of BLUE), neither subject shows interference. In contrast with the control subject, EL does not show Stroop interference when various orthographic changes (degraded visual input, cursive font) or phonological or semantic changes are made to the word. These findings indicate that although some implicit processing of words may be possible, this processing is rather rudimentary. Not surprising, this implicit activation may be insufficient to support overt word identification. We explain these findings in the context of a single, integrated account of pure alexia.

Behrmann, M., Shomstein, S. S., Black, S. E., & Barton, J. J. (2001). The eye movements of pure alexic patients during reading and nonreading tasks. Neuropsychologia, 39, 983-1002.
Notes: Department of Psychology, Carnegie Mellon University, Pittsburgh, PA 15213-3890, USA.
We compared the eye-movements of two patients who read letter-by-letter (LBL) following a left occipital lobe lesion with those of normal control subjects and of hemianopic patients in two tasks: a nonreading visual search task and a text reading task. Whereas the LBL readers exhibited similar eye-movement patterns to those of the other two groups on the nonreading task, their eye movements differed significantly during reading, as reflected in the disproportionate increase in the number and duration of fixations per word and in the regressive saccades per word. Importantly, relative to the two control groups, letter-by-letter readers also made more fixations per word as word length increased, especially as word frequency and word imageability decreased. Two critical results emerged from these experiments: First, the alteration in the oculomotor behavior of the LBL readers during reading is similar to that seen in normal readers under difficult reading conditions, as well as in beginning readers and in those with developmental dyslexia, and appears to reflect difficulties in processing the visual stimulus. Second, the interaction of length with frequency and with imageability in determining the eye movement pattern is consistent with an interactive activation model of normal word recognition in which weakened activation of orthographic input can nevertheless engage high-level lexical factors

Montant, M. & Behrmann, M. (2001). Phonological activation in pure alexia. Cognitive Neuropsychology, 18, 697-727.
Notes: Pure alexia is a reading impairment in which patients appear to read letter-by-letter. This disorder is typically accounted for in terms of a peripheral deficit that occurs early on in the reading system, prior to the activation of orthographic word representations. The peripheral interpretation of pure alexia has recently been challenged by the phonological deficit hypothesis, which claims that a postlexical disconnection between orthographic and phonological information contributes to or is responsible for the disorder. Because this hypothesis was mainly supported by data from a single patient (IH), who also has surface dyslexia, the present study re-examined this hypothesis with another pure alexic patient (EL). In contrast to patient IH, EL did not show any evidence of a phonological deficit. Her pattern of performance in naming was not qualitatively different from that of normal readers; she appeared to be reading via a mode of processing resulting in strong serial and lexical effects, a pattern often observed in normal individuals reading unfamiliar stimuli. The present results do not obviously support the phonological hypothesis and are more consistent with peripheral interpretations of pure alexia. The peripheral and the phonological accounts of pure alexia are discussed in light of two current models of visual word recognition

Montant, M. & Behrmann, M. (2000). Pure alexia. Neurocase, 6, 265-294.

Behrmann, M., Nelson, J., & Sekuler, E. B. (1998). Visual complexity in letter-by-letter reading: "pure" alexia is not pure. Neuropsychologia, 36, 1115-1132.
Notes: Department of Psychology, Carnegie Mellon University, Pittsburgh, PA 15213-3890, USA. ; ABSTRACT: Standard accounts of pure alexia have favoured the view that this acquired disorder of reading arises from damage to a left posterior occipital cortex mechanism dedicated to the processing of alphanumeric symbols. We challenge these accounts in two experiments and demonstrate that patients with this reading deficit are also impaired at object identification. In the first experiment, we show that a single subject, EL, who shows all the hallmark features of pure alexia, is impaired at picture identification across a large set of stimuli. As the visual complexity of pictures increases, so EL's reaction time to identify the stimuli increases disproportionately relative to the control subjects. In the second experiment, we confirm these findings with a larger group of five pure alexic patients using a selected subset of high- and low-visual complexity pictures. These findings suggest that the deficit giving rise to pure alexia is not restricted to orthographic symbols per se but, rather, is a consequence of damage to a more general-purpose visual processing mechanism 199904

Behrmann, M., Plaut, D. C., & Nelson, J. (1998). A literature review and new data supporting an interactive account of letter-by-letter reading. Cognitive Neuropsychology, 15, 7-51.
Notes: We present a theoretical account of letter-by-letter (LBL) reading that reconciles discrepant findings associated with this form of acquired dyslexia. We claim that LBL reading is caused by a deficit that affects the normal activation of the orthographic representation of the stimulus. In spite of this lower-level deficit, the degraded orthographic information may be processed further, and lexical, semantic, and higher-order orthographic information may still influence the reading patterns of these patients. In support of our position, we present a review of 57 published cases of LBL reading is presented in which we demonstrate that a peripheral deficit was evident in almost all of the patients and that, simultaneously, strong effects of lexical/semantic variables were observed on reading performance. We then go on to report findings from an empirical analysis of seven LBL readers in whom we document the joint effects of lexical variables (word frequency and imageability) and word length on naming latency. We argue that the reading performance of these patients reflects the residual functioning of the same interactive system that supported normal reading premorbidly.

Watt, S., Jokel, R., & Behrmann, M. (1997). Surface dyslexia in nonfluent progressive aphasia. Brain and Language, 56, 211-233.
Notes: Rotman Research Institute, Baycrest Centre for Geriatric Care, Toronto, Canada. This article presents the case of a 59-year-old male, JH, with a 6-year history of primary progressive aphasia (PPA), a disorder characterized by isolated language deterioration with relative preservation of other cognitive abilities. JH also shows typical features of surface dyslexia, a reading disorder exemplified by the selective preservation of phonological reading. One recent theory is that surface dyslexia in individuals with PPA results from a loss of semantic knowledge. In this paper we consider an additional possibility and present data supporting the notion that surface dyslexia may also arise from the malfunction in the links between semantic representations and phonology. JH has remarkably preserved lexical semantic knowledge when assessed on tasks that do not require verbal output. Further, item-by-item comparisons of his oral reading and comprehension ability show no significant correspondence between his reading and semantic knowledge. These findings lead us to conclude that, in JH's case, the surface dyslexia is attributable not to a semantic deficit per se but rather to the inability to access phonological information from semantics. JH's language profile is considered in relation to potential sources of surface dyslexia and other cases of progressive aphasia 9706

Behrmann, M. & McLeod, J. (1995). Rehabilitation for pure alexia: Efficacy of therapy and implications for models of normal word recognition. Neuropsychological Rehabilitation, 5, 149-180.

Behrmann, M. & Shallice, T. (1995). Pure alexia: A nonspatial visual disorder affecting letter activation. Cognitive Neuropsychology, 12, 409-454.
Notes: Several different interpretations have been offered to explain the mechanism giving rise to the linear relationship between word length and reading time shown by patients with pure alexia or letter-by-letter reading. One interpretation attributes this word length effect to a spatial impairment in which there is a left- right gradient of processing efficiency. This fundamental resource limitation requires that the patient focus on each letter in turn to increase its signal-to-noise ratio and discriminability, especially for letters towards the end of the string. An alternative view attributes the word length effect to a letter activation deficit that disrupts the rapid and efficient processing of single letters. In this paper, we examine these two hypotheses in relation to DS, a letter-by-letter reader. DS is able to distribute her attention to multiple locations in parallel and her performance is unaffected by the absolute or relative spatial location of the letters in a string. She is, however, impaired at reporting the identity of a letter independent of its spatial location and requires an abnormally long time to process each letter. Furthermore, investigations of DS's reading, using Howard's (1991) analyses of reaction time distributions, suggest that she processes each letter in a sequentially order. Based on the results of these studies, we propose that prototypic pure alexia is a nonspatial visual disorder that affects the activation of individual letters

Behrmann, M. (1994). Neglect dyslexia: Attention and word recognition. In M.J.Farah & G. Ratcliff (Eds.), The neuropsychology of high-level vision. Collected tutorial essays (pp. 173-214). Hillsdale,NJ: Erlbaum.

Black, S. E. & Behrmann, M. (1994). Localization in alexia. In A.Kertesz (Ed.), Localization and neuroimaging in neuropsychology (1 ed., pp. 331-376). San Diego: Academic Press.
Notes: (The authors combine a review of the classical lesion evidence, the anatomy of the visual system, and the rapidly growing literature on various models of reading with the results of recent 15O PET imaging studies and the information processing approach in cognitive psychology. Included are their own studies of neglect dyslexia)

Klein, D., Behrmann, M., & Doctor, E. (1994). The evolution of deep dyslexia: Evidence for the spontaneous recovery of the semantic reading route. Cognitive Neuropsychology, 11, 579-611.
Notes: Most theoretical accounts of deep dyslexia postulate at least two independent deficits which give rise to the observed pattern of reading impairment. One deficit is an inability to derive phonology from ortography sublexically and the second is an impairment in semantically mediated reading. These deficits generate a host of symptoms including an impairment in reading nonwords, a part-of-speech and imageability effect in word reading, and, importantly, the occurrence of semantic paraphasias. It is possible, then, that during recovery of deep dyslexia, either one or both of these underlying deficits resolve. We describe a case, RL, with deep dyslexia who showed significant change in his reading performance in the absence of any therapeutic intervention. At 18 months post-onset, unlike at 6 months post-onset, RL no longer produced any purely semantic errors nor did he show effects of imageability or part-of-speech on his oral reading. Despite this change, RL's ability to read nonwords did not improve significantly over this time period. These findings suggest that selective and spontaneous recovery of the semantic reading route can occur independent of significant change in the sublexical reading route

Behrmann, M. & Bub, D. (1992). Surface dyslexia and dysgraphia: Dual routes, single lexicon. Cognitive Neuropsychology, 9, 209-251.
Notes: The dual route interpretation of surface dyslexia as a deficit in word-specific activation has been challenged recently by computational models that incorporate a unitary print-to-sound mechanism. The most current of these makes no allowance for word-specific nodes, but obtains the pronounciation of regular and exception words by weighted connections between graphemic and phonemic units. Damaging the model in a variety of ways produces a pattern that appears consistent with the performance of many surface dyslexic patients. Exception words are mispronounced more often than regular words, though accuracy deteriorates on both categories. In addition, frequency has no clear-cut effect on the probability of reading an exception word correctly. We describe the existence of a variant of the syndrome that is not fully captured by the above simulations. MP, a surface dyslexic, demonstrates a dissociation between lexical and nonlexical pronounciation of written words. We also show that performance on irregular words varies as a function of their frequency. We provide evidence that the locus of the subject's deficit arises at the level of the representations in a single orthographic lexicon that subserves both reading and writing

Behrmann, M., Moscovitch, M., & Mozer, M. (1991). Directing attention to words and nonwords in normal subjects and in a computational model: Implications for neglect dyslexia. Cognitive Neuropsychology, 8, 213-248.
Notes: In a previous paper we suggested that patients with neglect dyslexia process information appearing on the unattended side. This information, if encoded sufficiently, may be used to trigger top-down knowledge, leading to the interaction of spatial attention and lexicality. The current studies examine this question in normal people. Subjects' attention was biased to the end of a letter string by a cue (underline bar), and lexical decisions were made to the underlined section of the letter string (for example, east and garm). These studies showed that reaction times were slower when distracting information appeared on the left than when no distractors were present (for example, arm). Furthermore, when the distractors played a lexical role and formed a word with the underlined string (for example farm), lexical decisions were even slower. These results showed that distractors are processed at least to the level of lexical access and influence reading performance of the attended underlined string. We have also considered these findings in the light of an existing connectionist network of spatial attention and word recognition and have accounted for the data in a series of simulations. The convergence of findings from the neuropsychological, cognitive, and computational work supports the interaction between attention and higher-order lexical knowledge.

Behrmann, M., Moscovitch, M., Black, S. E., & Mozer, M. (1990). Perceptual and conceptual mechanisms in neglect dyslexia. Two contrasting case studies. Brain, 113, 1163-1183.
Notes: The contribution of peripheral, data-driven effects is contrasted with conceptual, 'top-down' effects to the reading performance of 2 subjects with neglect dyslexia following a single right hemisphere lesion. Several tasks were administered, manipulating the physical, lexical or morphemic properties of the stimuli in an attempt to establish whether the attentional deficit disrupts reading at an early or late stage of processing. Both subjects were impaired at detecting elementary stimulus features on the left side of the display but were even more impaired at identifying conjoined features. One subject's performance was influenced by structural manipulations which altered the low-level representation of the stimulus. The other was less affected by structural changes of the stimuli but was influenced by the lexical and morphemic status of the words. This apparent double dissociation is interpreted as arising from a graded attentional deficit at a single locus, early in the reading process where low-level information is detected. When the deficit is not severe sufficient information may be picked up and may interact with higher order lexical knowledge to offset partially the peripheral malfunction. For a severe attentional deficit, top-down knowledge is not engaged as insufficient information is processed on the left-hand side. This hybrid view of attention provides insight into the mechanisms underlying neglect dyslexia and bears on the role of attention in normal visual processing

Behrmann, M., Black, S. E., & Bub, D. (1990). The evolution of pure alexia: a longitudinal study of recovery. Brain and Language, 39, 405-427.
Notes: Department of Psychology, University of Toronto, Ontario, Canada This case report documents the partial recovery, over a 12-month period, of pure alexia in an adult female following a left occipital infarction. Measures of speed and accuracy were obtained on an oral reading and a lexical decision task immediately postonset and then on 10 subsequent occasions. Explicit letter-by-letter reading was observed only during the first week poststroke but a significant effect of word length was seen in all testing sessions. Reading accuracy was relatively good at all stages and reading latency showed a remarkable decrease over time but did not reach normal reading rates. The inability to use higher-order orthographic knowledge, as manifest in the absence of a word superiority effect, was still noted at one year postonset. We therefore concluded that the change in behavior was attributable to increased proficiency in the use of the adaptive letter-by-letter procedure rather than to the resolution of the underlying deficit. It is suggested that longitudinal neurobehavioral studies add to our understanding of the alexic deficit and provide insight into the recovery process

Mozer, M. C. & Behrmann, M. (1990). On the interaction of selective attention and lexical knowledge: A connectionist account of neglect dyslexia. Journal of Cognitive Neuroscience, 2, 96-123.

Behrmann, M. (1987). The rites of righting writing: Homophone remediation in acquired dysgraphia. Cognitive Neuropsychology, 4, 365-384.
Notes: A homophone retraining program was implemented with a  surface dysgraphic patient. Extensive pretherapy testing suggested that lexical processing was impaired in writing but not in reading, resulting in difficulties in writing homophones and irregular words. The treatment procedure involved the pairing of the written homophone with its pictorial representation in order to link the orthography with the corresponding meaning and to enhance direct lexical access.  A series of exercises and practice techniques were introduced to strenghten this route. Results reveal significant improvement in writing treated homophones and untreated irregular words but minimal generalization to untreated homophones. Theoretical explanations for the changes are offered and the efficacy of the treatment program is demonstrated.

Anders Gade