Cognitive Neuropsychology

Generative Oscillation - A Cognitive Model for the Emergence of Language

by Thorold (Thor) May

Research Material for a discontinued PhD

DRAFT COPY ONLY

NOT READY FOR PRINT PUBLICATION

The GO model proposes a co-generative view of the emergence of language. Most conventional linguistics models conceive... more The GO model proposes a co-generative view of the emergence of language. Most conventional linguistics models conceive of language as a representational system of symbols which refer to events, either mental or external to the organism. This representational function is said to motivate the linguistic system and (depending upon the linguistic model) largely control its form. The GO (Generative Oscillation) model proposed here recognizes the representational role of language. However it notes that as the mental linguistic system itself becomes efficiently organized, it creates an internal logic and drive of its own. To some extent this internally motivated linguistic system is conceived to override the external motivation to represent another reality. Since the internal linguistic system is dynamic and generative, it may give rise to linguistic output which seems strange in an inter-human communicative context (or even within the reflective mind of the creator). Thus while the external communicative context can become a constraint on unmotivated non-representational "internal language", it might not eliminate it. The Generative Oscillation model proposes that actual language production is an oscillating compromise between the representational function of language and the mental "language bot" itself (i.e. an internal self-organizing system) which is generating language strings just because that is what language language bots do. As far as I know, the Generative Oscillation Model, or anything like it, had not been suggested before in linguistics at the time of writing. Some conventional linguists may find it a bit "off the wall".

Effects of Brain- Improvers on Learning and Learners' Attitude

by Ahmet Özalp

How does attention training work in social phobia: Disengagement from threat or re-engagement to non-threat?

by Alexandre Heeren

Heeren, A., Lievens, L., & Philippot, P. (2011). How does attention training work in social phobia: Disengagement from threat or reengagement to non-threat? Journal of Anxiety Disorders, 25, 1108-1115.

Impaired orientation discrimination and localisation following parietal damage: On the interplay between dorsal and ventral processes in visual perception

by Graham Pluck

The Genetics of Creativity A Serendipitous Assemblage of Madness

by Andrea Kuszewski

Diagnosable: Mothering at the Threshold of Disability

by Julia Miele Rodas

in Disability and Mothering. Disability and Mothering: Liminal Spaces of Embodied Knowledge. Eds. Cynthia Lewiecki-Wilson and Jen Cellio. Syracuse Univ Press, 2011. Print.

This is an essay about a hotly contested issue in the experience and theory of disability: The question of how to... more This is an essay about a hotly contested issue in the experience and theory of disability: The question of how to locate, talk about, and live with an ambiguous disability identity. Because many disabilities are not immediately evident, because many are progressive or create erratic episodes of impairment, and because cultural and political considerations factor largely into competing definitions of disability historically and globally, scholars and activists have been keenly attentive to how individuals locate themselves in relation to disability. While I identify with disability identity in broader terms, however, I do not want to reduce myself to a label for the social convenience of my peers. And, while my desire for medical definition offers the possibility of affirmation, it also facilitates a greater threat. For the labeling of disability effectively generates exclusion and misunderstanding, leading to the dismissal of the person as an individual; bias abounds. There are strong competing concerns in this liminal space: unless we self-identify, we participate in the rampant oppression of and discrimination against disability, but I feel stronger and better acting out my resistance from the margin of what Tobin Siebers has called the disability “masquerade” than I do by potentially acting collectively with friends and colleagues who self-identify. My desire to remain in the indefinite, occupying the “diagnosable” space, is not so much an unwillingness to stand up politically as it is a desire to challenge the disciplinary and diagnostic boundaries of the conventional order. For my own sake, certainly, for the sake of my children, but also for the sake of my colleagues, my neighbors, and my fellow parents, I embrace this undisciplined space, rejecting the confinement of diagnosis and thus choosing to challenge the narrowing definition of human “normalcy.”

Arquitecturas cognitivas y cerebro: hacia una teoría unificada de la cognición

by José María Ruiz Sánchez de León

Ruiz-Sánchez de León, J.M. y Fernández Blázquez, M.A. (2011). Cognitive architectures and brain: towards an unified theory of cognition [In Spanish]. International Journal of Psychological Research, 4(2), 38-47

Las arquitecturas cognitivas se definen como el conjunto de componentes esenciales de un sistema que permite el... more Las arquitecturas cognitivas se definen como el conjunto de componentes esenciales de un sistema que permite el análisis de sus cogniciones y sus conductas. El objetivo de este trabajo es revisar una de las arquitecturas cognitivas que resulta más plausible desde el punto de vista neuroanatómico: ACT-R es una teoría sobre el funcionamiento de la mente humana. Tras un acercamiento inicial a sus conceptos básicos, se describen sus dos niveles de computación: un nivel simbólico que contiene toda la información declarativa del sistema, y un nivel subsimbólico que está representado como un juego de procesos en paralelo. A su vez, se relacionan los módulos que componen la arquitectura con la neuroanatomía funcional del cerebro, describiendo el funcionamiento del circuito córtico-estriado-talámico.

Palabras clave: Modelos computacionales; arquitecturas cognitivas; simulación; psicología cognitiva; neuropsicología cognitiva.

Cognitive architectures are defined as the group of essential components belonging to a system which allows the analysis of its cognitions and behaviors. The aim of this study is to review one of the most plausible cognitive architectures from the neuroanatomic perspective: The Adaptive Control of Thought-Rational (ACT-R) is a theory about how human mind works. Following an initial approach to its basic concepts its two computational levels are described, these are: a symbolic level, which includes declarative information; and a sub-symbolic level which is represented as a parallel set of processes. At the same time, architecture’s modules are related to brain’s functional neuroanatomy describing how cortico-striatal-thalamic circuit works.

Key words: Computational models; cognitive architectures; simulation; cognitive psychology; cognitive neuropsychology.

Caracterización neuropsicológica de la impulsividad funcional y disfuncional en adictos a sustancias: implicaciones clínicas

by José María Ruiz Sánchez de León

Pedrero-Pérez, E.J., Ruiz-Sánchez de León, J.M., Rojo Mota, G., Llanero Luque, M. y Puerta-García, C. (2012). Neuropsychological characterization of functional and dysfunctional impulsivity in drug addicts: clinical implications [In Spanish]. Adicciones, 24(1), 51-58.

La impulsividad es una de las variables más consistentemente vinculadas a las distintas fases del proceso adictivo.... more La impulsividad es una de las variables más consistentemente vinculadas a las distintas fases del proceso adictivo. Sin embargo, casi siempre se ha estudiado como una condición negativa, vinculada a psicopatología. Dickman (1990) propuso dos tipos de impulsividad, una disfuncional (ID) y otra funcional (IF). A ésta última la definió como la tendencia a tomar decisiones rápidas, orientadas a metas, mediante un proceso de toma de decisiones con riesgo calculado. Pocos estudios han abordado la caracterización neuropsicológica de ambas variantes, relacionándolas con el rendimiento en pruebas clásicas. Una muestra de 52 sujetos adictos en tratamiento cumplimentó el Dickman Impulsivity Inventory y una batería de pruebas neuropsicológicas clásicas. Se observaron correlaciones de débiles a moderadas entre la IF e indicadores de éxito en las tareas neuropsicológicas, mientras que la ID mostró una relación difusa y débiles correlaciones con indicadores de mal rendimiento en todas las tareas. La ID se mostró como una disposición que dificulta la realización de las tareas de forma global, sin interferencia específica, en tanto que la IF se relacionó consistentemente con mayor precisión, menor número de errores y mejor mantenimiento de los planes, y ello a partir de una mejor gestión atencional y una mayor resistencia al ruido. Se sugieren las implicaciones de cara a los tratamientos de las adicciones.

Palabras clave: Impulsividad funcional, impulsividad disfuncional, evaluación neuropsicológica, adicción, tratamiento, atención, funciones ejecutivas.

Impulsivity is a stable correlate throughout the course of drug addiction. However, it has always been studied as a negative condition, linked to psychopathology. Dickman (1990) proposed two subdimensions of impulsivity, dysfunctional (DI) and functional (FI). He defines the latter as the tendency for rapid, goal-oriented decision-making characterized by well calculated risks. Only a few studies have attempted to differentiate between these two subdimensions using classical neuropsychological tests. Fifty two drug addicts in treatment were tested using Dickman’s Impulsivity Inventory and a battery of classical neuropsychological tests. FI shows moderate to high correlations with many classical neuropsychological test scores in relation to enhanced executive functioning, whereas DI reveals surprisingly weak and scarce correlations with indicators of impaired executive functioning. DI appears to be a trait related to some difficulties in classical neuropsychological tests, while FI emerges as a consistent and much stronger predictor of higher attention capacity, lower distractibility, better precision, fewer errors, and better maintenance of goal-oriented strategies. Thus, functional impulsivity is related to positive conditions and more efficient cognitive functioning. Implications for the treatment of drug addictions are suggested.

Key words: Functional impulsivity, dysfunctional impulsivity, neuropsychological assessment, drug addiction, treatment, attention, executive functions.

Validación de un cuestionario de quejas cognitivas para adultos jóvenes: relación entre las quejas subjetivas de memoria, la sintomatología prefrontal y el estrés percibido

by José María Ruiz Sánchez de León

Lozoya-Delgado P, Ruiz-Sánchez de León JM, Pedrero-Pérez EJ. Validation of a cognitive complaints questionnaire for young adults: the relation between subjective memory complaints, prefrontal symptoms and perceived stress [In Spanish] Rev Neurol 2012; 54: 137-50.

Introducción. Las quejas subjetivas de memoria constituyen uno de los motivos de consulta más frecuentes a los... more Introducción. Las quejas subjetivas de memoria constituyen uno de los motivos de consulta más frecuentes a los servicios sanitarios, aunque apenas existen instrumentos validados en castellano para valorar su magnitud. Así como los cuestionarios de quejas de memoria habitualmente incluyen ítems referentes a aspectos atencionales y ejecutivos, se formulan hipótesis acerca de su relación con otros procesos dependientes de la integridad de la corteza prefrontal. Objetivo. Se trata de estudiar las propiedades psicométricas de un instrumento basado en el cuestionario de fallos de memoria de la vida cotidiana –Memory Failures Everyday (MFE)–, proporcionando una baremación sobre una amplia muestra de población española. Como objetivo secundario, se pretenden analizar las relaciones existentes entre la aparición de las quejas, la sintomatología de origen prefrontal y el estrés percibido. Sujetos y métodos. Se administran el MFE-30 (una modificación del MFE), el cuestionario disejecutivo y la escala de estrés percibido a una muestra de adultos jóvenes de población general no clínica (n = 900). Resultados. Los análisis muestran que el MFE-30 es un cuestionario unifactorial que valora un único constructo llamado ‘quejas cognitivas’. Además, se observa un intenso patrón de correlaciones entre dichas quejas, la sintomatología de origen prefrontal y el estrés percibido. Conclusiones. Los baremos aportados muestran que el MFE-30 es un instrumento útil en la práctica clínica. Los resultados encontrados están en consonancia con estudios anteriores, sugiriendo que existe una estrecha relación entre la aparición de quejas cognitivas, la presencia de sintomatología prefrontal y el estrés percibido.

Palabras clave. Atención. Corteza prefrontal. Cribado. DEX. Funciones ejecutivas. Lóbulos frontales. Memoria. Metamemoria. MFE. Neuropsicología. Quejas de memoria. Síndrome disejecutivo.

Introduction. Although subjective memory complaints are one of the most common causes behind visits to health services, there are hardly any validated instruments in Spanish for evaluating their magnitude. Since memory complaint questionnaires usually include items referring to attentional and executive aspects, it has been hypothesised that they may well be related with other processes that depend on the integrity of the prefrontal cortex. Aim. The purpose of this study was to examine the psychometric properties of an instrument based on the Memory Failures in Everyday (MFE) questionnaire, thus providing a valuation over a broad sample of the Spanish population. A second aim of the study was to analyse the relations that exist between the appearance of the complaints, the symptoms of a prefrontal origin and perceived stress. Subjects and methods. The MFE-30 (a modified version of the MFE), the dysexecutive questionnaire and the perceived stress scale were administered to a sample of young adults from a non-clinical general population (n = 900). Results. The analyses show that the MFE-30 is a single-factor questionnaire that evaluates a single construct called ‘cognitive complaints’. Moreover, an intense pattern of correlations among these complaints, the symptoms of a prefrontal origin and perceived stress is observed. Conclusions. The resulting scores show that the MFE-30 is a useful instrument in clinical practice. Findings are in line with those from previous studies, thus suggesting that there is a close relation among the appearance of cognitive complaints, the presence of prefrontal symptoms and perceived stress.

Key words. Attention. DEX. Dysexecutive syndrome. Executive functions. Frontal cortex. Frontal lobes. Memory complaints. Memory. Metamemory. MFE. Neuropsychology. Screening.

Propuesta de un protocolo para la evaluación neuropsicológica de las adicciones

by José María Ruiz Sánchez de León

A proposal for a protocol of neuropsychological assessment for use in addictions [In Spanish]. Revista de Neurología 2011; 53(8): 483-493.

Introducción. El interés por los procesos cerebrales implicados en la instauración, el mantenimiento y el abandono de... more Introducción. El interés por los procesos cerebrales implicados en la instauración, el mantenimiento y el abandono de las adicciones ha desencadenado que, en los últimos años, se hayan planteado algunos modelos neurocognitivos con un sustancial apoyo empírico. Sin embargo, existe la necesidad de un consenso en cuanto a las pruebas de valoración clínica que se pueden administrar y por qué hacerlo. El presente trabajo pretende recoger algunos de los tests neuropsicológicos más útiles para valorar a individuos adictos, así como las escalas de sintomatología cotidiana y pruebas de desempeño ocupacional que se han validado en castellano para esta población. Desarrollo. Los subprocesos cognitivos abordados en este trabajo, que han demostrado ser útiles en el diagnóstico sindrómico de las adicciones, son la velocidad de procesamiento, la atención selectiva y sostenida, la atención alternante y dividida, la amplitud atencional y el ejecutivo central, la memoria, la flexibilidad cognitiva y la fluidez, la inhibición de respuestas, la planificación, la abstracción, la toma de decisiones y, por último, la teoría de la mente. Se propone un protocolo en dos sesiones de 50 minutos, en el que la segunda sesión es opcional en función de la necesidad y la oportunidad en cada caso. Conclusión. El presente protocolo proporciona algunas ventajas importantes para los clínicos, como la sistematización, la posibilidad de replicación y convergencia entre evaluadores o la delimitación de los subprocesos susceptibles de evaluación compartiendo un mismo esquema, y, todo ello, en sesiones asequibles en cuanto a duración para casi todos los servicios que se dedican a atender a adictos que solicitan tratamiento.

Palabras clave. Abuso de drogas. Adicción. Amnesia. Atención. Corteza frontal. Déficit cognitivo. Deterioro cognitivo. Diagnóstico. Drogodependencias. Evaluación neuropsicológica. Funciones ejecutivas. Lóbulos frontales. Memoria. Neuropsicología. Síndrome disejecutivo. Trastorno cognitivo.


Introduction. Interest in the brain processes involved in establishing, maintaining and overcoming addictions has led to the development, in recent years, of a number of neurocognitive models with a substantial amount of empirical support. However, agreement still needs to be reached regarding the clinical evaluation tests that can be administered and the reason for doing so. The aim of this work is to outline some of the most useful neuropsychological tests for evaluating addicts, as well as the scales of day-to-day symptoms and occupational performance tests that have been validated in Spanish for this population. Development. The cognitive sub-processes addressed in this work, which have proved to be useful in the syndromic diagnosis of addictions, are processing speed, selective and sustained attention, alternating and divided attention, attentional amplitude and central executive, memory, cognitive flexibility and fluency, response inhibition, planning, abstraction, decision-making and, lastly, theory of mind. A protocol involving two 50-minute sessions is proposed, where the second session is optional depending on the needs and suitability in each case. Conclusions. This protocol offers several important advantages for physicians, including systemisation, the possibility of replication and convergence among evaluators or delimitation of the sub-processes that can be evaluated by sharing the same scheme. Moreover, it can all be carried out in sessions that are short enough to allow them to be offered by nearly all services that attend to addicts who request treatment.

Key words. Addiction. Amnesia. Attention. Cognitive deficit. Cognitive disorder. Cognitive impairment. Diagnosis. Drug abuse. Drug addiction. Dysexecutive syndrome. Executive functions. Frontal cortex. Frontal lobes. Memory. Neuropsychological evaluation. Neuropsychology.

OxfordHandbookofConstructionGrammar_06March11

by Bert Cappelle

prepublished version of:
Friedemann Pulvermüller, Bert Cappelle and Yury Shtyrov. 2012. Brain basis of meaning, words, constructions and grammar. In: Thomas Hoffmann and Graeme Trousdale (eds.), Oxford Handbook of Construction Grammar. Oxford: Oxford University Press.

Heating up or cooling up the brain: MEG evidence that phrasal verbs are lexical units

by Bert Cappelle

The influence of contralesional targets on the cancellation of ipsilesional targets in unilateral neglect

by Alessio Toraldo

Bottini G., Toraldo A. (2003). Brain and Cognition 53, 117-120.

Neglect of contralesional stimuli and perseverative behavior on ipsilesional stimuli may co-occur on a target... more Neglect of contralesional stimuli and perseverative behavior on ipsilesional stimuli may co-occur on a target cancellation task. Our aim was to investigate whether the presence vs. absence of contralesional targets can modify perseveration on ipsilesional targets. We studied four right brain-damaged patients with left neglect and perseverative behavior on screening cancellation tasks. We compared their cancellation performance in two conditions: (i) targets equally distributed on both sides of space and (ii) targets confined to the right side. One patient showed no significant difference in perseveration between these two conditions; in contrast, three patients perseverated significantly more in condition (i) than in condition (ii). These results suggest that, at least in some patients, information from the 'neglected' targets is not completely lost, but rather it affects behavior in the ipsilesional side. The traditional dichotomy 'bad space-good space' would not apply here.

Two qualitatively different impairments in making rotation operations

by Alessio Toraldo

Buiatti T., Mussoni A., Toraldo A., Skrap M., Shallice T. (2011). Cortex, 47, 166-179.

It is widely recognized that mental rotation is a cognitive process which engages a distributed cortical network... more It is widely recognized that mental rotation is a cognitive process which engages a distributed cortical network including the frontal, premotor and parietal regions. Like other visual-spatial transformations it could require operations on both metric and categorical spatial representations. Previous reports have implicated respectively the right hemisphere being involved in the metric processing and the left hemisphere in the categorical processing. By using a modified version of the Bricolo et al.'s task (2000), we attempted to establish the cortical regions relevant for the categorical and metric aspects of mental rotation transformations. Two groups of patients were found to be impaired in our study, namely the left prefrontal and the right parietal. In particular, whereas the right parietal group made poor use of categorical information, the left prefrontal patients showed a broader mental rotation impairment with a significant number of metric errors. The results are discussed in terms of the model of Kosslyn et al. (1989) about the possible mental transformation impairments following brain lesions.

Omission vs. shift of details in spatial representations

by Alessio Toraldo

Toraldo A., Bottini G. (2006). Omission vs. shift of details in spatial representations. In: Vecchi T., Bottini G. (Curatori), Imagery and spatial cognition: Methods, models and clinical Assessment (Advances in Consciousness Research), Amsterdam, Benjamins, pp. 395-415.

Reading Disorders In a Language With Shallow Orthography: A Multiple Single-Case Study In Italian

by Alessio Toraldo

Toraldo A., Cattani B., Zonca G., Saletta P., Luzzatti C. (2006). Aphasiology 20, 823-850.

Background: This study aimed (i) to verify whether the classical word-naming models developed for English-speaking... more Background: This study aimed (i) to verify whether the classical word-naming models developed for English-speaking participants also account for the performance of patients who speak a shallow-orthography language such as Italian, and (ii) to study the effects of word frequency, concreteness, and grammatical class on word naming. Methods & Procedures: A total of 90 Italian aphasic patients participated in two reading tasks. The first task contained four sets of items: (i) concrete nouns (natural objects and artefacts), (ii) abstract nouns, (iii) function words, (iv) morphologically simple legal nonwords. The second task (trisyllabic words with unpredictable stress position) was designed to test reading ability along the lexical route (the position of the major word stress is the only opaque variable in the Italian reading system). The patients' performances on the two tasks were analysed for strong dissociations, and to test the effect of grammatical class, concreteness, word frequency, and item length. The effect of age of acquisition was tested in a subsequent analysis. Outcomes & Results: Reading scores were pathological for all patients. The present sample reflected the entire spectrum of reading impairments: phonological (49), surface (4), undifferentiated (32), and letter-by-letter (5) dyslexia, which is in line with data reported for English-speaking aphasic patients. Only one of the phonological dyslexic patients made semantic errors (a reading impairment compatible with the diagnosis of deep dyslexia). The vast majority of Broca's aphasic patients suffered from phonological dyslexia (76%), while fluent aphasic patients were distributed more evenly across dyslexia types; all four surface dyslexic patients belonged to the fluent aphasia group. Overall, grammatical class (concrete nouns vs function words) had a significant effect on 14 patients (15.6%), concreteness (concrete vs abstract nouns) on 15 (16.7%), and word frequency on 5 (5.6%). Grammatical class and concreteness affected the performance of phonological and undifferentiated dyslexic patients, and seemed not to influence the scores of the surface dyslexic patients. Age of acquisition turned out to have a highly significant effect and may account for most of the lexical effects emerging from the first analysis. Conclusions: The entire spectrum of reading impairments was observed in this group of Italian aphasic patients, thus confirming the validity of contemporary reading models also for shallow-orthography languages. Concreteness and grammatical class effects, present in deep dyslexia, also affected the performance of patients suffering from other types of dyslexia, although both phenomena might derive from a confounding effect of age of acquisition.

Canceling out both the real and the spectral lines

by Alessio Toraldo

Toraldo A., Gandola M., Loffredo S., Rancati A., Zanardi G., Bottini G. (2005). Brain and Cognition 57, 226-235.

Neglect patients typically show motor perseveration while canceling targets on the ipsilesional side. This behavior... more Neglect patients typically show motor perseveration while canceling targets on the ipsilesional side. This behavior can be influenced by the presence vs. absence of targets on the (neglected) contralesional side (Bottini & Toraldo, 2003). As alternative explanations, the authors proposed (i) directional hypokinesia—the patient cannot perform reaching movements towards detected left-sided targets, and thus carries on canceling on the right side, and (ii) allochiria—the patient misperceives left-sided targets as located on the right side, and cancels them there. We report here data from a patient (EZ) that might confirm the second hypothesis. EZ was presented with 19 displays in which the number and position of cancellation targets on both sides were varied systematically. EZ showed motor perseveration while canceling, but this tendency did not vary across conditions. Interestingly though, EZ also drew cancellation marks in the empty space between the ipsilesional targets, and this phenomenon was significantly more intense when there were more targets on the neglected side. As EZ’s comments suggested, such a behavior might reflect the attempt to cancel out delusional targets. Our speculation is that those objects were generated by allochiria.

A Ruler for Measuring Representational Space

by Alessio Toraldo

Toraldo A. (2003). Visual Cognition 10(5), 567-603.

In the last decade a number of theories have been formulated hypothesizing a “distortion” of representational space in... more In the last decade a number of theories have been formulated hypothesizing a “distortion” of representational space in neglect patients, in order to explain their impairment on tasks investigating the perception of horizontal extents. Trying to compensate for the relative lack of formalization in this field of research, a mathematical model of what a spatial distortion should be is formulated on the basis of theoretical considerations and of some neurophysiological evidence; furthermore, a psychophysical task is proposed that estimates the amount of distortion and is able to overcome some of the limits in the currently used methods. On this task, 32 normal subjects showed two different kinds of deviation from the ideal performance, neither of which is attributable to perceptual factors. Out of five neglect patients, two showed reliable distortion, another two showed a trend towards distortion (but in opposite directions with respect to one another), and one showed no sign of distortion. In conclusion, a new method for estimating distortion suggested that the explorative impairment—neglect—can dissociate from the metric one—distortion, as one would expect on grounds of a (evolutionarily plausible) separation between the two operations of exploring and measuring space.

A Revised Method for Analysing Neglect Using the Landmark Task

by Alessio Toraldo

Toraldo A., McIntosh R.D., Dijkerman H.C., Milner A.D. (2004). Cortex 40, 415-431.

In order to better disentangle 'perceptual' and 'response' biases in neglect patients, Bisiach and his co-workers... more In order to better disentangle 'perceptual' and 'response' biases in neglect patients, Bisiach and his co-workers developed a new version of the 'landmark task'. In their version, subjects are required to choose which is the longer (first condition) or the shorter (second condition) of the two portions of a pre-bisected horizontal line. Two indices were proposed, for the purpose of measuring perceptual and response bias respectively. The perceptual bias index (PB) is the constant error across conditions, while the response bias index (RB) is the degree of response consistency between conditions. Although valuable in a clinical context, these indices are not mathematically independent of one another. Furthermore, they do not exploit all of the information available in a given set of landmark data, since the responses made at the different landmark locations are all averaged together. To overcome these problems, we propose two new indices that can be derived from the revised landmark task. Our perceptual bias index is the Point of Subjective Equality (PSE)--the mean landmark location that appears to be halfway along the line. The response bias index, M, is the mean probability of making a response that opposes the patient's subjective midpoint. PSE and M are mathematically independent of each other and use most of the landmark information. The method and its theoretical foundation are summarized, and illustrative data obtained from brain damaged patients and control subjects are presented. Finally, computational procedures are provided for both PSE and M.

Critical dimensions affecting imitation performance of patients with ideomotor apraxia.

by Alessio Toraldo

Toraldo A., Reverberi C., Rumiati R.I. (2001). Critical dimensions affecting imitation performance of patients with ideomotor apraxia. Cortex 37, 737-740.

Examines the roles of long-term memory, a motor programming component, and a working memory component, including... more Examines the roles of long-term memory, a motor programming component, and a working memory component, including short-term memory and supervisory attentional system, in imitation of symbolic and nonsymbolic gestures in 86 patients (aged 75+ yrs) with ideomotor apraxia following a left-hemisphere vascular lesion. Results show that the programming of gestures is impaired in these patients, suggesting damage in the motor programming and working memory systems for hand/arm gestures but not for fingers gestures. Results also indicate that, by generating syntactic representations of gestures, the supervisory attentional system might alleviate the short-term memory load, and thereby compensate for the short-term memory deficit. A similar explanation might hold for the paradoxical results obtained by patients on symbolic vs. nonsymbolic sequences. Ss performed better on symbolic hand/arm sequences, but showed the opposite effect on fingers sequences. These findings might reflect differences in the possibility to be "syntactically encoded' among the various subsets of sequences. Results did not provide evidence that the meaning of a gesture can compensate for either a working memory or motor programming deficit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)