The Effects of Case Mixing on Word Recognition: Evidence from a PET Study

The early stages of visual word recognition were investigated by scanning participants using PET as they took part in implicit and explicit reading tasks with visually disrupted stimuli. CaSe MiXiNg has been shown in behavioral studies to increase reaction times (RTs) in naming and other word recognition tasks. In this study, we found that during both an implicit (feature detection) task and an explicit word-naming task, mixed-case words compared to same-case words produced increased activation in an area of the right parietal cortex previously associated with visual attention. No effect of case was found in this area for pseudowords or consonant strings. Further, lowering the contrast of the stimuli slowed RTs as much as case mixing, but did not lead to the same increase in right parietal activation. No significant effect of case mixing was observed in left-hemisphere language areas. The results suggest that reading mixed-case words requires increased attentional processing. However, later word recognition processes may be relatively unaffected by the disruption in presentation.

[1]  U. Frith,et al.  Explicit and implicit processing of words and pseudowords by adult developmental dyslexics: A search for Wernicke's Wortschatz? , 1999, Brain : a journal of neurology.

[2]  James L. McClelland,et al.  An interactive activation model of context effects in letter perception: I. An account of basic findings. , 1981 .

[3]  James T. Becker,et al.  Functional Neuroanatomy of Semantic Memory: Recognition of Semantic Associations , 1999, NeuroImage.

[4]  K. Mayall.  Case-mixing effects on children's word recognition: Lexical feedback and development , 2002, The Quarterly journal of experimental psychology. A, Human experimental psychology.

[5]  James L. McClelland,et al.  Understanding normal and impaired word reading: computational principles in quasi-regular domains. , 1996, Psychological review.

[6]  S. Bookheimer,et al.  Form and Content Dissociating Syntax and Semantics in Sentence Comprehension , 1999, Neuron.

[7]  Richard S. J. Frackowiak,et al.  The anatomy of phonological and semantic processing in normal subjects. , 1992, Brain : a journal of neurology.

[8]  H. Wimmer,et al.  Children with dyslexia and right parietal lobe dysfunction: event-related potentials in response to words and pseudowords , 2002, Neuroscience Letters.

[9]  R. Frackowiak,et al.  Demonstrating the implicit processing of visually presented words and pseudowords. , 1996, Cerebral cortex.

[10]  E. T. Possing,et al.  Human temporal lobe activation by speech and nonspeech sounds. , 2000, Cerebral cortex.

[11]  G W Humphreys,et al.  A peripheral reading deficit under conditions of diffuse visual attention , 2001, Cognitive neuropsychology.

[12]  Karl J. Friston,et al.  Hearing and saying. The functional neuro-anatomy of auditory word processing. , 1996, Brain : a journal of neurology.

[13]  G. Humphreys,et al.  Differential effects of word length and visual contrast in the fusiform and lingual gyri during , 2000, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[14]  Format distortion and word reading: The role of multiletter units , 1999 .

[15]  Karl J. Friston,et al.  A multimodal language region in the ventral visual pathway , 1998, Nature.

[16]  Kenneth R. Paap,et al.  Word shape's in poor shape for the race to the lexicon. , 1984, Journal of experimental psychology. Human perception and performance.

[17]  C D Frith,et al.  Neural mechanisms involved in the processing of global and local aspects of hierarchically organized visual stimuli. , 1997, Brain : a journal of neurology.

[18]  Gereon R Fink,et al.  ‘Where’ depends on ‘what’: A differential functional anatomy for position discrimination in one- versus two-dimensions , 2000, Neuropsychologia.

[19]  M. Corbetta,et al.  Human cortical mechanisms of visual attention during orienting and search. , 1998, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[20]  G. Humphreys,et al.  Segregating Semantic from Phonological Processes during Reading , 1997, Journal of Cognitive Neuroscience.

[21]  Karl J. Friston,et al.  Statistical parametric maps in functional imaging: A general linear approach , 1994 .

[22]  H. Kucera,et al.  Computational analysis of present-day American English , 1967 .

[23]  Glyn W. Humphreys,et al.  Neuropsychological evidence for case-specific reading: the role of multi-letter units in word recognition. , 2001 .

[24]  B. Horwitz,et al.  Phonological and orthographic components of word recognition. A PET-rCBF study. , 1997, Brain : a journal of neurology.

[25]  M. Corbetta,et al.  Superior Parietal Cortex Activation During Spatial Attention Shifts and Visual Feature Conjunction , 1995, Science.

[26]  Richard S. J. Frackowiak,et al.  Functional anatomy of a common semantic system for words and pictures , 1996, Nature.

[27]  L. Katz,et al.  Cerebral organization of component processes in reading. , 1996, Brain : a journal of neurology.

[28]  Paul W. B. Atkins,et al.  Models of reading aloud: Dual-route and parallel-distributed-processing approaches. , 1993 .

[29]  C. Price,et al.  Functional Neuroanatomy of the Semantic System: Divisible by What? , 1998, Journal of Cognitive Neuroscience.

[30]  G W Humphreys,et al.  Neuropsychological Evidence for Case-Specific Reading: Multi-Letter Units in Visual Word Recognition , 2001, The Quarterly journal of experimental psychology. A, Human experimental psychology.

[31]  Karl J. Friston,et al.  Cognitive Conjunction: A New Approach to Brain Activation Experiments , 1997, NeuroImage.

[32]  Richard S. J. Frackowiak,et al.  Brain activity during reading. The effects of exposure duration and task. , 1994, Brain : a journal of neurology.

[33]  Karl J. Friston,et al.  Subtractions, conjunctions, and interactions in experimental design of activation studies , 1997, Human brain mapping.

[34]  J. Stroop.  Studies of interference in serial verbal reactions. , 1992 .

[35]  C. Price,et al.  Three Distinct Ventral Occipitotemporal Regions for Reading and Object Naming , 1999, NeuroImage.

[36]  James L. McClelland,et al.  An interactive activation model of context effects in letter perception: part 1.: an account of basic findings , 1988 .

[37]  Karl J. Friston,et al.  The temporal dynamics of reading: a PET study , 1997, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[38]  Glyn W. Humphreys,et al.  CASE MIXING AND THE TASK-SENSITIVE DISRUPTION OF LEXICAL PROCESSING , 1996 .

[39]  K R Paap,et al.  Word shape's in poor shape for the race to the lexicon. , 1984, Journal of experimental psychology. Human perception and performance.

[40]  R S Frackowiak,et al.  A PET study of cognitive strategies in normal subjects during language tasks. Influence of phonetic ambiguity and sequence processing on phoneme monitoring. , 1994, Brain : a journal of neurology.

[41]  C. J. Price,et al.  The Effect of Varying Stimulus Rate and Duration on Brain Activity during Reading , 1996, NeuroImage.

[42]  Douglas J. K. Mewhort,et al.  Some tests of the interactive-activation model for word identification , 1988 .

[43]  G. C. Orden,et al.  Word identification in reading proceeds from spelling to sound to meaning. , 1988, Journal of experimental psychology. Learning, memory, and cognition.

[44]  M. Mintun,et al.  Regional cerebral blood flow during word and nonword reading , 1997, Human brain mapping.

[45]  C. Price.  The anatomy of language: contributions from functional neuroimaging , 2000, Journal of anatomy.

[46]  S. Bookheimer,et al.  Regional cerebral blood flow during object naming and word reading , 1995 .

[47]  S. Petersen,et al.  Activation of extrastriate and frontal cortical areas by visual words and word-like stimuli. , 1990, Science.

[48]  C. Price.  The functional anatomy of word comprehension and production , 1998, Trends in Cognitive Sciences.

[49]  The activation of multiletter units in visual word recognition , 1994 .

[50]  Richard S. J. Frackowiak,et al.  The role of the right hemisphere in the interpretation of figurative aspects of language. A positron emission tomography activation study. , 1994, Brain : a journal of neurology.

[51]  G. Humphreys,et al.  Disruption to word or letter processing? The origins of case-mixing effects. , 1997, Journal of experimental psychology. Learning, memory, and cognition.

[52]  Veronika Coltheart,et al.  When a ROWS is a ROSE: Phonological Effects in Written Word Comprehension , 1994 .

[53]  Derek Besner,et al.  Word frequency and pattern distortion in visual word identification and production: An examination of four classes of models. , 1987 .