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Max Coltheart

Publications and source records attributed to Max Coltheart.

At least 19 recordsLinked to original sources
PubMed2006

Cumulative semantic inhibition in picture naming: experimental and computational studies.

We report an experiment in which subjects named 120 pictures, consisting of series of five pictures drawn from each of 24 semantic categories (and intermixed with 45 fillers). The number of intervening trials (lag) between successive presentations of members of the same category varied from two to eight. Subjects' naming latencies were slowed by 30 ms for each preceding member of the category. This effect was both cumulative and linear, and unrelated to the lag elapsing since the previous presentation of a category member. These results definitively demonstrate the occurrence of cumulative interference for word retrieval by prior retrieval of other exemplars of the same semantic category-cumulative semantic inhibition. We claim that this inhibition effect could only occur if the spoken word production system possesses three specific properties (competition, priming, and sharing of semantic activation). We provide computational-modelling evidence in support of this claim. We show that no current theory of spoken word production has all of these properties. In their current form, all these theories are falsified by these results. We briefly discuss the obstacles that may be encountered by current models were they modified to account for our findings.

Adolescent↗
PubMed2006

Empathetic perspective-taking is impaired in schizophrenia: evidence from a study of emotion attribution and theory of mind.

INTRODUCTION: Schizophrenia and autism are clinically distinct yet both disorders are characterised by theory of mind (ToM) deficits. Autistic individuals fail to appreciate false beliefs, yet understand the causal connections between behavioural events and simple emotions. Findings of this type have promoted the view that ToM deficits in autism reflect a domain-specific difficulty with appreciating the representational nature of epistemic mental states (i.e., beliefs and intentions and not emotions). This study examines whether the same holds true for schizophrenia. METHODS: A picture-sequencing task assessed capacity to infer false beliefs in patients with schizophrenia and healthy controls. To assess emotion attribution, participants were shown cartoon strips of events likely to elicit strong emotional reactions in story characters. Characters' faces were blanked out. Participants were instructed to think about how the characters would be feeling in order to match up the cards depicting facial affect appropriately. Participants later named emotions depicted in facial affect cards. RESULTS: Patients were as capable as controls of identifying cartoon facial expressions, yet had greater difficulties with: (a) attributing emotions based on circumstances; and (b) inferring false beliefs. CONCLUSIONS: Schizophrenia patients, unlike autistic individuals, suffer a domain-general difficulty with empathetic perspective-taking that affects equally their appreciation of other people's beliefs, percepts, and emotions.

Adult↗
PubMed2005

Paranoia, persecutory delusions and attributional biases.

An influential model of persecutory delusions put forward by Bentall and colleagues hypothesizes that persecutory-deluded patients avoid the activation of negative self-beliefs by making externalising, personalising attributions for negative events. The first study reported here used a new instrument for the measurement of persecutory ideation, the Paranoid, Persecutory and Delusion-Proneness Questionnaire, to investigate whether attributional biases are associated with subclinical persecutory ideation. The second study extended this investigation by re-examining associations between attributional biases and persecutory delusions. Both studies used the Internal, Personal and Situational Attributions Questionnaire to measure attributional style. No evidence was found for a connection between attributional biases and subclinical persecutory ideation. Furthermore, there was no support for an association between persecutory delusions and an externalising bias, and only marginal support for the hypothesized relationship between persecutory delusions and a personalising bias. These results suggest that the putative link between persecutory ideation and attributional biases only manifests (if at all) when persecutory ideation is of delusional intensity, and that it is confined to a personalising bias.

Adolescent↗
PubMed2005

Externalizing and personalizing biases in persecutory delusions: the relationship with poor insight and theory-of-mind.

The presence of externalizing bias (EB) for negative events together with personalizing bias (PB) (a bias to blame others rather than circumstances) may jointly constitute a vulnerability to develop persecutory delusions (PDs). Whereas EB purportedly serves to defend a vulnerable self-concept by avoiding negative self-attributions and might therefore exacerbate poor insight, PB may reflect cognitive deficits, including theory-of-mind impairment. We investigated these proposals in 34 schizophrenic patients with a history of PDs and 21 healthy controls. Patients with moderate- to severe-PDs and patients without a current PD showed excessive EB which was, surprisingly, absent in patients with mild persecutory delusions (mild-PDs). That EB might wax and wane with fluctuating delusional intensity was interpreted in accord with a new dynamic model of attribution self-representation cycles. As predicted, EB exacerbated poor insight. However, counter to predictions, theory-of-mind impairment did not increase PB, which was marked in all participants, whether clinical or non-clinical; instead, theory-of-mind impairment was also correlated with poor insight. Our findings indicate multiple pathways to poor insight, one of which is a theory-of-mind difficulty, impairing the capacity to simulate other perspectives for the purpose of critically evaluating one's own beliefs and circumstances.

Adult↗
PubMed2005

Attentional orienting triggered by gaze in schizophrenia.

The ability to detect the direction of another person's gaze and to shift our own attention reflexively in the same direction facilitates the sharing of attention with other people. Such sharing of attention would seem critical for the maintenance of normal social cognition. Social cognition is severely impaired in people with schizophrenia. So, we used spatial cuing paradigms to investigate reflexive (Experiment 1) and controlled (Experiment 2) attentional orienting triggered by gaze in schizophrenia. In Experiment 1, 30 patients and 24 controls detected targets appearing right or left of a central image of a head turned right, left, or straight-ahead. These gaze-cues were non-predictive. Patients, but not controls, showed a significant congruency advantage at 100 ms SOA. The congruency advantage was similar in patients and controls at 300-800 ms SOA. In Experiment 2, 20 patients and 24 controls detected targets 300-800 ms after a central gaze-cue that pointed away from the target on 80% of trials. Controls, but not patients, were able to reverse the reflexive congruency advantage at 800 ms SOA. This study provides the first evidence that people with schizophrenia show abnormally sensitive gaze-triggered reflexive orienting. Findings are discussed in light of recent neuroimaging work investigating the neural basis of social orienting and social cognition.

Adult↗
PubMed2005

Characterizing the motor execution stage of speech production: consonantal effects on delayed naming latency and onset duration.

The research described in this article had 2 aims: to permit greater precision in the conduct of naming experiments and to contribute to a characterization of the motor execution stage of speech production. The authors report an exhaustive inventory of consonantal and postconsonantal influences on delayed naming latency and onset acoustic duration, derived from a hand-labeled corpus of single-syllable consonant-vowel utterances. Five talkers produced 6 repetitions each of a set of 168 prepared monosyllables, a set that comprised each of the consonantal onsets of English in 3 vowel contexts. Strong and significant effects associated with phonetic characteristics of initial and noninitial phonemes were observed on both delayed naming latency and onset acoustic duration. Results are discussed in terms of the biomechanical properties of the articulatory system that may give rise to these effects and in terms of their methodological implications for naming experiments.

Humans↗
PubMed2005

"Sleights of mind": delusions, defences, and self-deception.

Two different modes of theorising about delusions are explored. On the one hand is the motivational approach, which regards delusions as serving a defensive, palliative, even potentially adaptive function. On the other, is the cognitive deficit approach, which conceptualises delusions as explicitly pathological, involving abnormalities in ordinary cognitive processes. The former approach, prominently exemplified by the psychoanalytic tradition, was predominant historically, but has been challenged in recent years by the latter. Some grievances against psychoanalytic theory are briefly discussed, and it is argued that although the reasons for psychoanalysis falling into scientific disrepute are partly justified, the psychodynamic notion that motivation has access to the mechanisms of belief formation is of potentially crucial theoretical utility. A variety of possible syntheses of the two theoretical modes are therefore explored, in the belief that the most comprehensive account of delusions will involve a theoretical unification of both styles of explanation. Along the way, an attempt is made to locate the notions delusion, defence, and self-deception in a shared theoretical space.

Journal Article↗
PubMed2005

Cognitive heterogeneity in Williams syndrome.

This study used the Woodcock-Johnson Tests of Cognitive Ability-Revised to investigate a wide range of cognitive abilities in people with Williams syndrome (WS). It involved a comparatively large sample of 31 people with WS, but took a case-series approach. The study addressed the widespread claims of a characteristic "WS cognitive profile" by looking for heterogeneity rather than homogeneity. People with WS showed a variety of preserved (significantly above mental age [MA]), expected (at MA), and significantly impaired (significantly below MA) levels of functioning. Such results provide clear evidence for heterogeneity in cognitive functions within WS. We found the most homogeneity on a test of phonological processing and a test of phonological short-term memory, with half of the WS sample performing at MA levels on these tests. Interestingly, no WS individual showed a weakness on a test of nonverbal reasoning, and only one WS individual showed a weakness on a test of verbal comprehension. In addition, we found that strengths on analysis-synthesis and verbal analogies occurred only for WS individuals with an MA less than 5.5 years (our sample median MA); people with an MA greater than 5.5 years performed at MA level on these 2 tests. Results also provided preliminary evidence for distinct subgroups of WS people based on their cognitive strengths and weaknesses on a broad range of cognitive functions. On the basis of the findings, caution should be made in declaring a single cognitive profile that is characteristic of all individuals with WS. Just as there is heterogeneity in genetic and physical anomalies within WS, not all WS individuals share the same cognitive strengths and weaknesses. Also, not all WS individuals show the profile of a strength in verbal abilities and a weakness in spatial functions.

Adolescent↗
PubMed2004

Recognition of metaphor and irony in young adults: the impact of schizotypal personality traits.

Patients with schizophrenia demonstrate two dissociable impairments of pragmatic language comprehension: (1) an insensitivity to irony, which is associated with poor theory-of-mind (i.e. a difficulty with inferring other people's thoughts); and (2) poor recognition of metaphors, which may reflect degraded semantics. This study investigated whether non-clinical high-schizotypal adults show similar impairments of pragmatic language. Thirty-six university students completed the Raine Schizotypal Personality Questionnaire, the Wechsler Memory Scale Logical-Memories subtest, Raven's Progressive Matrices and a story comprehension task that tested the ability to discriminate between incongruous statements and appropriate uses of ironical, metaphorical or literal speech. Counter to the pattern found for patients, high-schizotypal adults were just as capable as low-schizotypal adults of identifying appropriate metaphors, suggesting a discontinuity between schizophrenia and schizotypy for the metaphor-recognition problem. This study's finding of intact metaphor recognition in high-schizotypal adults contrasts with previous findings of poor proverb comprehension in these individuals and is interpreted in terms of different semantic processes required for recognizing and interpreting metaphors. Consistent with the pattern found for patients, high-schizotypal adults were significantly impaired in their ability to appreciate when a literally contradictory utterance could be interpreted as ironical, suggesting continuity between schizophrenia and schizotypy for the irony-appreciation problem.

Adolescent↗
PubMed2004

Is there a causal link from phonological awareness to success in learning to read?

In this review, we re-assess the evidence that phonological awareness represents a skill specific to spoken language that precedes and directly influences the process of reading acquisition. Longitudinal and experimental training studies are examined in detail, as these are considered most appropriate for exploring a causal hypothesis of this nature. A particular focus of our analysis is the degree to which studies to date have controlled for existing literacy skills in their participants and the influence that these skills might have on performance on phonological awareness tasks. We conclude that no study has provided unequivocal evidence that there is a causal link from competence in phonological awareness to success in reading and spelling acquisition. However, we believe that such a study is possible and outline some ideas for its design and implementation.

Awareness↗
PubMed2004

Are there lexicons?

Many models of the processing of printed or spoken words or objects or faces propose that systems of local representations of the forms of such stimuli--lexicons--exist. This is denied by partisans of the distributed-representation connectionist approach to cognitive modelling. An experimental paradigm of key theoretical importance here is lexical decision and its analogue in the domain of objects, object decision. How does each theoretical camp account for our ability to perform these two tasks? The localists say that the tasks are done by matching or failing to match a stimulus to a local representation in a lexicon. Advocates of distributed representations often do not seek to explain these two tasks; however, when they do, they propose that patterns of activation evoked in a semantic system can be used to discriminate between words and nonwords, or between real objects and false objects. Therefore the distributed-representation account of lexical and object decision tasks predicts that performance on these tasks can never be normal in patients with an impaired semantic system, nor in patients who cannot access semantics normally from the stimulus domain being tested. However, numerous such patients have been reported in the literature, indicating that semantic access is not needed for normal performance on these tasks. Such results support the localist form of modelling rather than the distributed-representation approach.

Agnosia↗
PubMed2004

Enlarged temporal lobes in Turner syndrome: an X-chromosome effect?

Gender differences in brain morphology have previously been reported in the temporal lobe and an 'X-chromosome dosage effect' has been described in Turner syndrome (45,X). To examine this further, we investigated temporal lobe morphology, metabolism and function in nine children with non-mosaic Turner syndrome using magnetic resonance imaging, (1)H magnetic resonance spectroscopy and neuropsychological testing and compared outcomes with results from nine age-matched control girls (46,XX). Turner subjects were found to have significantly larger superior temporal lobes (P = 0.004) and middle temporal lobes (P = 0.047) than controls. The size of the temporal lobe was found to correlate negatively with temporal lobe choline-containing compounds suggesting that increased temporal lobe size is associated with larger cells and/or decreased dendrites. This suggests a developmental failure to prune neurons. The degree of enlargement correlates negatively with functional performance on temporal-lobe associated tasks, suggesting that the enlargement may be a compensatory mechanism, or possibly causative in the case of semantic fluency performance. These temporal lobe abnormalities are discussed with reference to genes which are absent in Turner syndrome and to hormonal differences between Turner syndrome subjects and 46,XX controls.

Child↗
PubMed2004

Photographs of facial expression: accuracy, response times, and ratings of intensity.

Equal numbers of male and female participants judged which of seven facial expressions (anger, disgust, fear, happiness, neutrality, sadness, and surprise) were displayed by a set of 336 faces, and we measured both accuracy and response times. In addition, the participants rated how well the expression was displayed (i.e., the intensity of the expression). These three measures are reported for each face. Sex of the rater did not interact with any of the three measures. However, analyses revealed that some expressions were recognized more accurately in female than in male faces. The full set of these norms may be downloaded from www.psychonomic.org/archive/.

Facial Expression↗
PubMed2003

Modularity of music processing.

The music faculty is not a monolithic entity that a person either has or does not. Rather, it comprises a set of neurally isolable processing components, each having the potential to be specialized for music. Here we propose a functional architecture for music processing that captures the typical properties of modular organization. The model rests essentially on the analysis of music-related deficits in neurologically impaired individuals, but provides useful guidelines for exploring the music faculty in normal people, using methods such as neuroimaging.

Auditory Perception↗
PubMed2003

Electrophysiological correlates of anticipatory and poststimulus components of task switching.

Task-switching paradigms can shed light on cognitive and neural processes underlying attentional control mechanisms. An alternating runs task-switching paradigm (R. D. Rogers & S. Monsell, 1995) is used to identify ERP components associated with anticipatory and poststimulus components of task-switching processes. Subjects alternated between two tasks in a predictable series (AABB). Reaction time (RT) switch cost reduced with increasing response-stimulus (R-S) interval and a residual switch cost remained at the longest R-S interval. A switch-related positivity (D-Pos) developed in the R-S interval. D-Pos was time-locked to response onset, peaked around 400 ms post-response onset, and was unaffected by task-set interference. A switch-related negativity (D-Neg) emerged after stimulus onset. D-Neg peaked earlier with increasing R-S interval and its amplitude and latency were affected by task-set interference. D-Pos and D-Neg were interpreted within current models of task-switching.

Adolescent↗
PubMed2003

Cross-task strategic effects.

When easy and difficult items are mixed together, their reading aloud latencies become more homogeneous relative to their presentation in unmixed ("pure") conditions (Lupker, Brown, & Colombo, 1997). We report two experiments designed to investigate the nature of the mechanism that underlies this list composition, or blocking, effect. In Experiment 1, we replicated Lupker et al.'s (1997) blocking effect in the reading aloud task and extended these findings to the visual lexical decision task. In Experiment 2, we found that blocking effects generalized across tasks: The characteristics of stimuli in a visual lexical decision task influenced reading aloud latencies, and vice versa, when visual lexical decision and reading aloud trials were presented alternately in the same experiment. We discuss implications of these results within time-criterion (Lupker et al., 1997) and strength-of-processing (Kello & Plaut, 2000, 2003) theories of strategic processing in reading.

Decision Making↗
PubMed2003

When parallel processing in visual word recognition is not enough: new evidence from naming.

Low-frequency irregular words are named more slowly and are more error prone than low-frequency regular words (the regularity effect). Rastle and Coltheart (1999) reported that this irregularity cost is modulated by the serial position of the irregular grapheme-phoneme correspondence, such that words with early irregularities exhibit a larger cost than words with late ones. They argued that these data implicate rule-based serial processing, and they also reported a successful simulation with a model that has a rule-based serial component--the DRC model of reading aloud (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001). However, Zorzi (2000) also simulated these data with a model that operates solely in parallel. Furthermore, Kwantes and Mewhort (1999) simulated these data with a serial processing model that has no rules for converting orthography to phonology. The human data reported by Rastle and Coltheart therefore neither require a serial processing account, nor successfully discriminate among a number of computational models of reading aloud. New data are presented wherein an interaction between the effects of regularity and serial position of irregularity is again reported for human readers. The DRC model simulated this interaction; no other implemented computational model does so. The present results are thus consistent with rule-based serial processing in reading aloud.

Humans↗