Many of the decisions and actions in everyday life result from implicit learning processes. Impor... more Many of the decisions and actions in everyday life result from implicit learning processes. Important to psychopathology are, for example, implicit reward-seeking and punishment-avoidant learning processes. It is known that when specific actions get associated with a rewarding experience, such as positive emotions, that this will increase the likelihood that an organism will engage in similar actions in the future. Similarly, when actions get associated with punishing experiences, such as negative emotions, this may reduce the likelihood that the organism will engage in similar actions in the future. This study examines whether we can observe these implicit processes prospectively in the flow of daily life. If such processes take place then we expect that current behaviour can be predicted by how similar behaviour was experienced (in terms of positive and negative affect) at previous measurement moments. This was examined in a sample of 621 female individuals that had participated i...
This study investigates the basic assumption of homogeneity of monozygotic (MZ) twins: are there ... more This study investigates the basic assumption of homogeneity of monozygotic (MZ) twins: are there differences according to the timing of the zygotic splitting, early in dichorionic (DC) and later in monochorionic (MC) pairs? We assessed the IQ of 451 same-sexed twin pairs of known zygosity and chorion type with the Wechsler Intelligence Scale for Children-Revised (WISC-R). The variances of within-pair differences were compared for monochorionic (MC), dichorionic monozygotic (DC-MZ) and dizygotic same-sexed (DZ) twins and structural equation modeling was applied. High heritability estimates were found for almost all subscales and IQ-scores. A significant effect of chorion type was found: the MC twins resembled each other more than the DC-MZ twins on the subscales Arithmetic and Vocabulary. The effect accounts for respectively 14% and 10% of the total variance.
Previous work has examined the structure of subclinical positive psychotic experiences. The curre... more Previous work has examined the structure of subclinical positive psychotic experiences. The current study, using confirmatory factor analysis in a general population sample of young adult females, replicated a five-dimensional model, which showed excellent model fit. The results suggest stability of the five-dimensional model across adolescent and young adult life.
Subclinical psychotic experiences at the level of the general population are common, forming an e... more Subclinical psychotic experiences at the level of the general population are common, forming an extended psychosis phenotype with clinical psychosis. Persistence of subclinical experiences is associated with transition to later mental disorder. Increased daily life stress reactivity is considered an endophenotype for psychotic disorders. We examined, in a longitudinal framework, whether baseline momentary assessment markers of stress reactivity would predict persistence of subclinical psychotic experiences over time. In a general population sample of female twins (N = 566), the Experience Sampling Method (ESM; repetitive random sampling of momentary emotions, psychotic experiences and context) was used to assess (emotional and psychotic) daily life stress reactivity. Persistence of subclinical psychotic experiences was based on the Community Assessment of Psychic Experiences (CAPE), assessed three times over 14 months post-baseline. It was investigated whether baseline daily life emotional and psychotic stress reactivity predicted persistence of psychotic experiences over time. Higher levels of emotional stress reactivity (a decrease in positive and an increase in negative affect in response to stress), and increased psychotic reactivity to daily stress was found in individuals with persistent psychotic experiences over time compared to individuals with transient psychotic experiences. The results suggest that markers of daily life stress reactivity may predict…
Mental disorders may be reducible to sets of symptoms, connected through systems of causal relati... more Mental disorders may be reducible to sets of symptoms, connected through systems of causal relations. A clinical staging model predicts that in earlier stages of illness, symptom expression is both non-specific and diffuse. With illness progression, more specific syndromes emerge. This paper addressed the hypothesis that connection strength and connection variability between mental states differ in the hypothesized direction across different stages of psychopathology. In a general population sample of female siblings (mostly twins), the Experience Sampling Method was used to collect repeated measures of three momentary mental states (positive affect, negative affect and paranoia). Staging was operationalized across four levels of increasing severity of psychopathology, based on the total score of the Symptom Check List. Multilevel random regression was used to calculate inter- and intra-mental state connection strength and connection variability over time by modelling each momentary mental state at t as a function of the three momentary states at t-1, and by examining moderation by SCL-severity. Mental states impacted dynamically on each other over time, in interaction with SCL-severity groups. Thus, SCL-90 severity groups were characterized by progressively greater inter- and intra-mental state connection strength, and greater inter- and intra-mental state connection variability. Diagnosis in psychiatry can be described as stages of growing dynamic causal impact of mental states over time. This system achieves a mode of psychiatric diagnosis that combines nomothetic (group-based classification across stages) and idiographic (individual-specific psychopathological profiles) components of psychopathology at the level of momentary mental states impacting on each other over time.
The Journal of Thoracic and Cardiovascular Surgery, 2007
Although it is known that pediatric cardiac surgery holds risks for later development, few studie... more Although it is known that pediatric cardiac surgery holds risks for later development, few studies investigated the long-term development in children with tetralogy of Fallot. The purpose of this study was to define their intellectual capacities, neuropsychological profile, and behavioral functioning 6 to 12 years postoperatively. Patients (n = 18; age, 8 years, 3 months +/- 1 year, 6 months) were examined with a short-form intelligence scale (Wechsler Intelligence Scale for Children, 3rd edition, Dutch version) and a neuropsychological assessment battery (NEPSY). Their parents completed a behavioral questionnaire. The patient group was compared with an acyanotic congenital heart disease group and a healthy control group. No significant differences between the patient group and the acyanotic group emerged. Compared with the healthy control group, children with tetralogy of Fallot showed significantly lower scores on the estimated Full Scale IQ (P < .05) and on the NEPSY domains Language (P < .01) and Sensorimotor Functioning (P < .01). Also, the subtests Tower (P < .05), Memory for Names (P < .05), Narrative Memory (P < .05), and Design Copy (P < .05) elicited group differences. Parental reports revealed significantly higher scores on attention problems (P < .05) and the total problem scale (P < .05), as well as significantly lower school performances than those of healthy peers (P < .01). In children with tetralogy of Fallot, we identified a lower estimated full-scale intelligence than in healthy peers and a neuropsychological profile characterized by primarily mild motor deficits and difficulties with language tasks. Parents of the children with tetralogy of Fallot indicated attention problems and rated the child's school competencies to be lower than in healthy control subjects.
The purpose of this study was to examine the role of background texture on an interception task d... more The purpose of this study was to examine the role of background texture on an interception task during self-motion. Twenty-six participants modulated tricycle speed along one arm of a V-shaped track so as to intercept a ball approaching horizontally on the other arm of the V. Either a plain or a textured background (consisting of contrasting vertical stripes) was used. Velocity modulations occurred so as to keep the angle beta between the direction of heading and the line head-ball constant (constant bearing angle, or CBA strategy), indicating that this observer-environment relation might regulate the approach phase. In the textured condition, participants initially drove faster than predicted by the CBA model and compensated by slowing down in the second half. This is in line with the texture-induced overestimation of the ball velocity and implies that absolute velocity information is also used.
The authors ran 3 experiments to investigate how catchers deal with the horizontal component of t... more The authors ran 3 experiments to investigate how catchers deal with the horizontal component of the ball's trajectory in an interception task during locomotion. The experiments were built upon the finding that velocity adaptations are based upon changes in the horizontal angular position or velocity of the ball with respect to the observer (M. Lenoir, M. Janssens, E. Musch, E. Thiery, J. Uyttenhove, 1999) a potential underlying information source for that strategy is described. In Experiment 1, actor (N = 10 participants)and ball approached each other along the legs of a V-shaped track. When the velocity and the initial angular bearing of the ball were varied, the observed behavior fitted with nulling the horizontal angular velocity of the ball: A positive or negative angular velocity was compensated by a velocity change. Evidence was obtained that those adaptations are modulated by a critical change in, rather than by a critical state of, the environment-actor system. In Experiment 2, the distance between the head and an artificial end-effector was varied. Irrespective of that distance, participants (N = 7) accelerated and decelerated in order to keep the angular velocity of the ball with respect to the end-effector close to constant. The ecological relevance of that constant bearing angle strategy was confirmed in Experiment 3: Participants (N = 7) in that experiment freely ran to catch fly balls. The present results support the concept that one can explain with a limited number of control variables an actor's behavior in an interception task during self-motion.
Many of the decisions and actions in everyday life result from implicit learning processes. Impor... more Many of the decisions and actions in everyday life result from implicit learning processes. Important to psychopathology are, for example, implicit reward-seeking and punishment-avoidant learning processes. It is known that when specific actions get associated with a rewarding experience, such as positive emotions, that this will increase the likelihood that an organism will engage in similar actions in the future. Similarly, when actions get associated with punishing experiences, such as negative emotions, this may reduce the likelihood that the organism will engage in similar actions in the future. This study examines whether we can observe these implicit processes prospectively in the flow of daily life. If such processes take place then we expect that current behaviour can be predicted by how similar behaviour was experienced (in terms of positive and negative affect) at previous measurement moments. This was examined in a sample of 621 female individuals that had participated i...
This study investigates the basic assumption of homogeneity of monozygotic (MZ) twins: are there ... more This study investigates the basic assumption of homogeneity of monozygotic (MZ) twins: are there differences according to the timing of the zygotic splitting, early in dichorionic (DC) and later in monochorionic (MC) pairs? We assessed the IQ of 451 same-sexed twin pairs of known zygosity and chorion type with the Wechsler Intelligence Scale for Children-Revised (WISC-R). The variances of within-pair differences were compared for monochorionic (MC), dichorionic monozygotic (DC-MZ) and dizygotic same-sexed (DZ) twins and structural equation modeling was applied. High heritability estimates were found for almost all subscales and IQ-scores. A significant effect of chorion type was found: the MC twins resembled each other more than the DC-MZ twins on the subscales Arithmetic and Vocabulary. The effect accounts for respectively 14% and 10% of the total variance.
Previous work has examined the structure of subclinical positive psychotic experiences. The curre... more Previous work has examined the structure of subclinical positive psychotic experiences. The current study, using confirmatory factor analysis in a general population sample of young adult females, replicated a five-dimensional model, which showed excellent model fit. The results suggest stability of the five-dimensional model across adolescent and young adult life.
Subclinical psychotic experiences at the level of the general population are common, forming an e... more Subclinical psychotic experiences at the level of the general population are common, forming an extended psychosis phenotype with clinical psychosis. Persistence of subclinical experiences is associated with transition to later mental disorder. Increased daily life stress reactivity is considered an endophenotype for psychotic disorders. We examined, in a longitudinal framework, whether baseline momentary assessment markers of stress reactivity would predict persistence of subclinical psychotic experiences over time. In a general population sample of female twins (N = 566), the Experience Sampling Method (ESM; repetitive random sampling of momentary emotions, psychotic experiences and context) was used to assess (emotional and psychotic) daily life stress reactivity. Persistence of subclinical psychotic experiences was based on the Community Assessment of Psychic Experiences (CAPE), assessed three times over 14 months post-baseline. It was investigated whether baseline daily life emotional and psychotic stress reactivity predicted persistence of psychotic experiences over time. Higher levels of emotional stress reactivity (a decrease in positive and an increase in negative affect in response to stress), and increased psychotic reactivity to daily stress was found in individuals with persistent psychotic experiences over time compared to individuals with transient psychotic experiences. The results suggest that markers of daily life stress reactivity may predict…
Mental disorders may be reducible to sets of symptoms, connected through systems of causal relati... more Mental disorders may be reducible to sets of symptoms, connected through systems of causal relations. A clinical staging model predicts that in earlier stages of illness, symptom expression is both non-specific and diffuse. With illness progression, more specific syndromes emerge. This paper addressed the hypothesis that connection strength and connection variability between mental states differ in the hypothesized direction across different stages of psychopathology. In a general population sample of female siblings (mostly twins), the Experience Sampling Method was used to collect repeated measures of three momentary mental states (positive affect, negative affect and paranoia). Staging was operationalized across four levels of increasing severity of psychopathology, based on the total score of the Symptom Check List. Multilevel random regression was used to calculate inter- and intra-mental state connection strength and connection variability over time by modelling each momentary mental state at t as a function of the three momentary states at t-1, and by examining moderation by SCL-severity. Mental states impacted dynamically on each other over time, in interaction with SCL-severity groups. Thus, SCL-90 severity groups were characterized by progressively greater inter- and intra-mental state connection strength, and greater inter- and intra-mental state connection variability. Diagnosis in psychiatry can be described as stages of growing dynamic causal impact of mental states over time. This system achieves a mode of psychiatric diagnosis that combines nomothetic (group-based classification across stages) and idiographic (individual-specific psychopathological profiles) components of psychopathology at the level of momentary mental states impacting on each other over time.
The Journal of Thoracic and Cardiovascular Surgery, 2007
Although it is known that pediatric cardiac surgery holds risks for later development, few studie... more Although it is known that pediatric cardiac surgery holds risks for later development, few studies investigated the long-term development in children with tetralogy of Fallot. The purpose of this study was to define their intellectual capacities, neuropsychological profile, and behavioral functioning 6 to 12 years postoperatively. Patients (n = 18; age, 8 years, 3 months +/- 1 year, 6 months) were examined with a short-form intelligence scale (Wechsler Intelligence Scale for Children, 3rd edition, Dutch version) and a neuropsychological assessment battery (NEPSY). Their parents completed a behavioral questionnaire. The patient group was compared with an acyanotic congenital heart disease group and a healthy control group. No significant differences between the patient group and the acyanotic group emerged. Compared with the healthy control group, children with tetralogy of Fallot showed significantly lower scores on the estimated Full Scale IQ (P < .05) and on the NEPSY domains Language (P < .01) and Sensorimotor Functioning (P < .01). Also, the subtests Tower (P < .05), Memory for Names (P < .05), Narrative Memory (P < .05), and Design Copy (P < .05) elicited group differences. Parental reports revealed significantly higher scores on attention problems (P < .05) and the total problem scale (P < .05), as well as significantly lower school performances than those of healthy peers (P < .01). In children with tetralogy of Fallot, we identified a lower estimated full-scale intelligence than in healthy peers and a neuropsychological profile characterized by primarily mild motor deficits and difficulties with language tasks. Parents of the children with tetralogy of Fallot indicated attention problems and rated the child's school competencies to be lower than in healthy control subjects.
The purpose of this study was to examine the role of background texture on an interception task d... more The purpose of this study was to examine the role of background texture on an interception task during self-motion. Twenty-six participants modulated tricycle speed along one arm of a V-shaped track so as to intercept a ball approaching horizontally on the other arm of the V. Either a plain or a textured background (consisting of contrasting vertical stripes) was used. Velocity modulations occurred so as to keep the angle beta between the direction of heading and the line head-ball constant (constant bearing angle, or CBA strategy), indicating that this observer-environment relation might regulate the approach phase. In the textured condition, participants initially drove faster than predicted by the CBA model and compensated by slowing down in the second half. This is in line with the texture-induced overestimation of the ball velocity and implies that absolute velocity information is also used.
The authors ran 3 experiments to investigate how catchers deal with the horizontal component of t... more The authors ran 3 experiments to investigate how catchers deal with the horizontal component of the ball's trajectory in an interception task during locomotion. The experiments were built upon the finding that velocity adaptations are based upon changes in the horizontal angular position or velocity of the ball with respect to the observer (M. Lenoir, M. Janssens, E. Musch, E. Thiery, J. Uyttenhove, 1999) a potential underlying information source for that strategy is described. In Experiment 1, actor (N = 10 participants)and ball approached each other along the legs of a V-shaped track. When the velocity and the initial angular bearing of the ball were varied, the observed behavior fitted with nulling the horizontal angular velocity of the ball: A positive or negative angular velocity was compensated by a velocity change. Evidence was obtained that those adaptations are modulated by a critical change in, rather than by a critical state of, the environment-actor system. In Experiment 2, the distance between the head and an artificial end-effector was varied. Irrespective of that distance, participants (N = 7) accelerated and decelerated in order to keep the angular velocity of the ball with respect to the end-effector close to constant. The ecological relevance of that constant bearing angle strategy was confirmed in Experiment 3: Participants (N = 7) in that experiment freely ran to catch fly balls. The present results support the concept that one can explain with a limited number of control variables an actor's behavior in an interception task during self-motion.
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