Max Coltheart

Macquarie University, Sydney, New South Wales, Australia

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Publications (243)761.58 Total impact

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    ABSTRACT: Dual-route theories of reading posit that a sublexical reading mechanism that operates serially and from left to right is involved in the orthography-to-phonology computation. These theories attribute the Masked Onset Priming Effect (MOPE) and the Phonological Stroop Effect (PSE) to the serial left-to-right operation of this mechanism. However, both effects may arise during speech planning, in the phonological encoding process, which also occurs serially and from left to right. In the present paper, we sought to determine the locus of serial processing in reading aloud by testing the contrasting predictions that the dual-route and speech planning accounts make in relation to the MOPE and the PSE. The results from three experiments that used the MOPE and the PSE paradigms in English are inconsistent with the idea that these effects arise during speech planning, and consistent with the claim that a sublexical serially-operating reading mechanism is involved in the print-to-sound translation. Simulations of the empirical data on the MOPE with the DRC and CDP++ models, which are computational implementations of the dual-route theory of reading, provide further support for the dual-route account.
    Journal of Experimental Psychology Learning Memory and Cognition 10/2014; · 3.10 Impact Factor
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    ABSTRACT: Fregoli delusion is the mistaken belief that some person currently present in the deluded person's environment (typically a stranger) is a familiar person in disguise. The stranger is believed to be psychologically identical to this known person (who is not present) even though the deluded person perceives the physical appearance of the stranger as being different from the known person's typical appearance. To gain a deeper understanding of this contradictory error in the normal system for tracking and identifying known persons, we conducted a detailed survey of all the Fregoli cases reported in the literature since the seminal Courbon and Fail (1927) paper. Our preliminary reading of these cases revealed a notable lack of definitional clarity. So, we first formulated a classification scheme of different person misidentification delusions so as to identify those cases that qualified as instances of Fregoli according to the above characterization: the mistaken belief that a known person is present in the environment in a different guise to his or her typical appearance. We identified 38 clear cases of this type and set out to answer a series of questions motivated by current hypotheses about the origin of the Fregoli delusion. We asked whether the patients misidentified particular strangers, made reference to the misidentified known persons using wigs or plastic surgery (or other techniques to disguise their appearance), misidentified many different strangers or only one, showed other symptoms (in particular, other misidentification delusions), and made inferences about the motives of the known persons in disguise. We conclude by discussing the implications of our findings for current hypotheses concerning the origin of the Fregoli delusion.
    Topics in Cognitive Science 09/2014; · 2.88 Impact Factor
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    ABSTRACT: In this work, we develop an empirically driven model of visual attention to multiple words using the word-word interference (WWI) task. In this task, two words are simultaneously presented visually: a to-be-ignored distractor word at fixation, and a to-be-read-aloud target word above or below the distractor word. Experiment 1 showed that low-frequency distractor words interfere more than high-frequency distractor words. Experiment 2 showed that distractor frequency (high vs. low) and target frequency (high vs. low) exert additive effects. Experiment 3 showed that the effect of the case status of the target (same vs. AlTeRnAtEd) interacts with the type of distractor (word vs. string of # marks). Experiment 4 showed that targets are responded to faster in the presence of semantically related distractors than in presence of unrelated distractors. Our model of visual attention to multiple words borrows two principles governing processing dynamics from the dual-route cascaded model of reading: cascaded interactive activation and lateral inhibition. At the core of the model are three mechanisms aimed at dealing with the distinctive feature of the WWI task, which is that two words are presented simultaneously. These mechanisms are identification, tokenization, and deactivation.
    Memory & Cognition 07/2014; · 1.92 Impact Factor
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    ABSTRACT: Mirrored-self misidentification delusion is the belief that one's reflection in the mirror is not oneself. This experiment used hypnotic suggestion to impair normal face processing in healthy participants and recreate key aspects of the delusion in the laboratory. From a pool of 439 participants, 22 high hypnotisable participants ("highs") and 20 low hypnotisable participants were selected on the basis of their extreme scores on two separately administered measures of hypnotisability. These participants received a hypnotic induction and a suggestion for either impaired (i) self-face recognition or (ii) impaired recognition of all faces. Participants were tested on their ability to recognize themselves in a mirror and other visual media - including a photograph, live video, and handheld mirror - and their ability to recognize other people, including the experimenter and famous faces. Both suggestions produced impaired self-face recognition and recreated key aspects of the delusion in highs. However, only the suggestion for impaired other-face recognition disrupted recognition of other faces, albeit in a minority of highs. The findings confirm that hypnotic suggestion can disrupt face processing and recreate features of mirrored-self misidentification. The variability seen in participants' responses also corresponds to the heterogeneity seen in clinical patients. An important direction for future research will be to examine sources of this variability within both clinical patients and the hypnotic model.
    Frontiers in Human Neuroscience 06/2014; · 2.91 Impact Factor
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    ABSTRACT: Introduction There is now significant evidence that prediction error signalling is mediated by dopamine in the midbrain, and that dopamine dysfunction is implicated in people experiencing psychotic symptoms, including delusions. There has also been significant theorizing and experimentation concerning the remaining link in this triad, namely that deviant prediction error signalling produces or maintains psychotic symptoms. Methods The research supporting the link between prediction error signalling and delusional symptoms was reviewed. Numerous studies indirectly support this link, but only one set of studies claim to directly test this hypothesis by combining three crucial elements: a patient sample, a manipulation of prediction error and neuroimaging. This particular set of studies were examined in detail. Results Important methodological limitations in these studies were observed, and a reinterpretation of their data was offered. Conclusions Methodological inconsistencies significantly weaken the claims made by these studies, but their data are consistent with current theorizing and they are instructive for future lines of inquiry in this field.
    Cognitive Neuropsychiatry 04/2014; · 1.68 Impact Factor
  • Max Coltheart
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    ABSTRACT: Are there universals of reading? There are three ways of construing this question. Is the region of the brain where reading is implemented identical regardless of what writing system the reader uses? Is the mental information-processing system used for reading the same regardless of what writing system the reader uses. Do the word's writing systems share certain universal features? Dehaene offers affirmative answers to all three questions in his book. Here I suggest instead that the answers should be negative. And I ask: if reading is not universal in any sense, what does this imply about Dehaene's Neuronal Recycling hypothesis for reading?
    Mind & Language 03/2014; 29(3). · 1.54 Impact Factor
  • Matthew Finkbeiner, Max Coltheart
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    ABSTRACT: Newell & Shanks (N&S) appeal to well-known problems in establishing subliminality to argue that there is little convincing evidence that subliminally presented stimuli can affect decision making. We discuss how recent studies have successfully addressed these well-known problems and, in turn, have revealed clear evidence that subliminally presented stimuli can affect decision making.
    Behavioral and Brain Sciences 01/2014; · 18.57 Impact Factor
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    Petroula Mousikou, Max Coltheart
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    ABSTRACT: Reading aloud is faster when target words/nonwords are preceded by masked prime words/nonwords that share their first sound with the target (e.g., s ave-SINK) compared to when primes and targets are unrelated to each other (e.g., farm-SINK). This empirical phenomenon is the masked onset priming effect (MOPE) and is known to be due to serial left-to-right processing of the prime by a sublexical reading mechanism. However, the literature in this domain lacks a critical experiment. It is possible that when primes are real words their orthographic/phonological representations are activated in parallel and holistically during prime presentation, so any phoneme overlap between primes and targets (and not just initial-phoneme overlap) could facilitate target reading aloud. This is the prediction made by the only computational models of reading aloud that are able to simulate the MOPE, namely the DRC1.2.1, CDP+, and CDP++ models. We tested this prediction in the present study and found that initial-phoneme overlap ( b lip-BEST), but not end-phoneme overlap (flat -BEST), facilitated target reading aloud compared to no phoneme overlap (junk-BEST). These results provide support for a reading mechanism that operates serially and from left to right, yet are inconsistent with all existing computational models of single-word reading aloud.
    The Quarterly Journal of Experimental Psychology 01/2014; 67(11):2239-2246,. · 4.67 Impact Factor
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    ABSTRACT: There is compelling evidence that hypnotic suggestions can be used to model clinical delusions in the laboratory. In two studies, we investigated the role that personality factors, delusion proneness and schizotypy, played in shaping such hypnotic models. In the first study, 398 participants were screened on measures of hypnotisability, delusion proneness, and schizotypy. Hypnotisability correlated with both delusion proneness and the cognitive–perceptual subscale of schizotypy. In the second study, 22 high and 20 low hypnotisable participants were given suggestions to model two content specific delusions: Frégoli (the belief that strangers are actually known people in disguise) and mirrored-self misidentification (the belief that one’s reflection in the mirror is a stranger). Whereas high delusion proneness predicted which high hypnotisable participants responded to the suggestion for Frégoli delusion, hypnotisability scores predicted which high hypnotisable participants responded to the suggestion for mirrored-self misidentification. No lows responded to either suggestion. We discuss the implications of these findings for hypnotic models of delusions.
    Personality and Individual Differences 01/2014; 57:48–53. · 1.88 Impact Factor
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    ABSTRACT: Mirrored-self misidentification is the delusional belief that one's own reflection in the mirror is a stranger. In two experiments, we tested the ability of hypnotic suggestion to model this condition. In Experiment 1, we compared two suggestions based on either the delusion's surface features (seeing a stranger in the mirror) or underlying processes (impaired face processing). Fifty-two high hypnotisable participants received one of these suggestions either with hypnosis or without in a wake control. In Experiment 2, we examined the extent to which social cues and role-playing could account for participants' behaviour by comparing the responses of 14 hypnotised participants to the suggestion for impaired face processing (reals) with those of 14 nonhypnotised participants instructed to fake their responses (simulators). Overall, results from both experiments confirm that we can use hypnotic suggestion to produce a compelling analogue of mirrored-self misidentification that cannot simply be attributed to social cues or role-playing.
    Consciousness and Cognition 11/2013; 22(4):1510-1522. · 2.31 Impact Factor
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  • Claudio Mulatti, Max Coltheart
    Cortex 09/2013; · 6.16 Impact Factor
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    ABSTRACT: Many studies have previously reported that the recognition of a stem target (e.g., teach) is facilitated by the prior masked presentation of a prime consisting of a derived form of it (e.g., teacher). We conducted two lexical decision experiments to investigate masked morphological priming in Spanish. Experiment 1 showed that equal magnitudes of masked stem-target priming are obtained for both morphologically complex word primes (e.g., doloroso-DOLOR [painful-PAIN]) and morphologically complex nonword primes that included letter transpositions within the stem (e.g., dlooroso-DOLOR). Experiment 2 used morphologically complex nonword primes comprising lexically illegal combinations of stems and suffixes (e.g., total + ito [a little total]). Priming was obtained for morphologically related nonword primes (e.g., totalito-TOTAL), but not for nonword primes that included letter transpositions within the pseudostem (e.g., ttoalito-TOTAL). Our data suggest that morphoorthographic parsing mechanisms benefit from semantic constraints at early stages in the reading system, which we discuss in the context of current morphological processing accounts.
    Applied Psycholinguistics 09/2013; 34(05). · 1.39 Impact Factor
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    ABSTRACT: The reach-to-touch paradigm has become an increasingly popular tool in the study of human cognition. It is widely held that reaching responses are able to reveal the moment-by-moment unfolding of decision processes by virtue of an assumed continuity between reaching trajectories and the underlying "cognitive trajectory." Yet the standard analysis of reaching trajectories aggregates the trajectories across stimulus viewing times, which yields ambiguous results. Here we introduce a new version of the reach-to-touch paradigm that incorporates the response-signal procedure to elicit reaching movements across a wide range of stimulus viewing times. We then analyze the direction of the initial movement by stimulus viewing time, which produces a sigmoidal growth pattern. Of note, we show how this sigmoidal relationship between stimulus viewing time and initial direction can be used to test and constrain the dynamical claims of computational models of basic cognitive processes. We introduce our new version of the reach-to-touch paradigm and analyses in the context of a lexical decision task and we compare our results with the dynamical claims of the dual-route cascaded model of reading. (PsycINFO Database Record (c) 2013 APA, all rights reserved).
    Journal of Experimental Psychology Human Perception & Performance 06/2013; · 3.11 Impact Factor
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    Australian and New Zealand Journal of Psychiatry 02/2013; · 3.29 Impact Factor
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    ABSTRACT: OBJECTIVE: Social cognition is profoundly impaired in patients with schizophrenia. This study describes 'Mental-State Reasoning Training for Social Cognitive Impairment' (SoCog-MSRT), a 5-week program developed to improve social cognition in patients with schizophrenia. We aimed to investigate the feasibility of implementing SoCog-MSRT in a rehabilitation setting and to evaluate whether our training methods produced improvements. METHOD The feasibility and benefits of SoCog-MSRT were evaluated in an open clinical trial with 14 participants with schizophrenia or schizoaffective disorder. Training comprised 10 twice-weekly sessions, for 5 weeks, with a pre- and post-training assessment. RESULTS: There were significant improvements on: (a) a classic false-belief test of Theory of Mind (ToM); (b) inferring complex mental states from the eyes; and (c) a self-reported measure of social understanding. Some of these improvements were associated with baseline levels of working memory and premorbid Intelligence Quotient (IQ). CONCLUSIONS SoCog-MSRT can improve ToM abilities and social understanding, but individuals with poorer working memory and lower premorbid IQ may be less able to benefit from this type of training.
    Australasian Psychiatry 02/2013; · 0.60 Impact Factor
  • Max Coltheart
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    ABSTRACT: Some delusional patients exhibit only a single delusional belief (or several delusional beliefs concerning a single theme): this is monothematic delusion. It contrasts with polythematic delusion, where the patient exhibits a variety of delusions concerning a variety of different themes. The neuropsychological bases of various monothematic delusions are rather well understood, and there is a well-worked-out general neuropsychological theory of monothematic delusion, the two-factor theory. Whether polythematic delusion might be explained in a similar way is an open question: I sketch some possible ways in which a comparable two-factor account might be developed for polythematic (‘psychiatric’) delusional conditions such as delusions of reference.
    Mind & Language 02/2013; 28(1). · 1.54 Impact Factor
  • Psychology of Consciousness: Theory, Research, and Practice. 01/2013;
  • Max Coltheart
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    ABSTRACT: Work on functional neuroimaging of cognition falls into two categories. The first aims at localizing specific cognitive subsystems in specific brain regions. In this research, the cognitive subsystems in question need to be defined independently of the neuroimaging data because the interpretation of the data requires such definition; so functional neuroimaging is informed by cognitive theories rather than informing them. The second category uses neuroimaging data to test cognitive theories. As cognitive theories are expressed in cognitive terms, such theories have to be embellished by explicit proposals about relationships between cognition and the brain if they are to become capable of generating predictions about the results of experiments that use functional neuroimaging. Whether functional neuroimaging can succeed in informing a cognitive theory depends critically upon the plausibility of such supplementary proposals. It is also critical to avoid the “consistency fallacy.” When neuroimaging data from an experiment are consistent with predictions from a particular cognitive theory, this cannot be offered as evidence in support of that theory unless it can be shown that there were possible other outcomes of the experiment that are inconsistent with the theory—outcomes that would have falsified predictions from the theory had they been obtained.
    Perspectives on Psychological Science 01/2013; 8(1):98-103. · 4.89 Impact Factor
  • Robyn Langdon, Max Coltheart
    Mind & Language 01/2013; 28(1). · 1.54 Impact Factor

Publication Stats

8k Citations
761.58 Total Impact Points

Institutions

  • 1993–2014
    • Macquarie University
      • • Department of Cognitive Science
      • • ARC Centre of Excellence for Cognition and its Disorders
      • • Department of Psychology
      • • Macquarie Centre for Cognitive Science (MACCS)
      Sydney, New South Wales, Australia
  • 2011–2013
    • University of Padova
      • Department of Developmental Psychology and Socialisation
      Padua, Veneto, Italy
    • Trent University
      • Department of Psychology
      Peterborough, Ontario, Canada
  • 2010
    • University College London
      • Institute of Cognitive Neuroscience
      London, ENG, United Kingdom
    • Karl-Franzens-Universität Graz
      • Sozialpsychologie
      Graz, Styria, Austria
  • 2009
    • Liverpool Hospital
      Liverpool, New South Wales, Australia
  • 2002–2009
    • Children's Hospital at Westmead
      • • Developmental Cognitive Neuropsychology Research Unit (DeCog)
      • • Department of Rehabilitation
      Sydney, New South Wales, Australia
  • 2008
    • University of Leeds
      Leeds, England, United Kingdom
    • University of New South Wales
      • School of Psychiatry
      Kensington, New South Wales, Australia
    • Charles Sturt University
      Уогга Уогга, New South Wales, Australia
  • 2006
    • Harvard University
      Cambridge, Massachusetts, United States
  • 2005
    • University of London
      Londinium, England, United Kingdom
  • 2004
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
    • University of Sydney
      Sydney, New South Wales, Australia
  • 2003
    • Royal Holloway, University of London
      • Department of Psychology
      London, ENG, United Kingdom
  • 2000–2002
    • Royal Prince Alfred Hospital
      Camperdown, New South Wales, Australia
    • University of Cambridge
      • Department of Psychology
      Cambridge, ENG, United Kingdom
  • 1998
    • Royal Brisbane Hospital
      Brisbane, Queensland, Australia
  • 1996
    • University of Exeter
      Exeter, England, United Kingdom
  • 1980–1988
    • Birkbeck, University of London
      Londinium, England, United Kingdom
  • 1975–1979
    • University of Reading
      • Department of Psychology
      Reading, ENG, United Kingdom