Augmenting Scalable Communication-Based Role Allocation for a Three-Role Task

In evolutionary robotics role allocation studies, it is common that the role assumed by each robot is strongly associated with specific local conditions, which may compromise scalability and robustness because of the dependency on those conditions. To increase scalability, communication has been proposed as a means for robots to exchange signals that represent roles. This idea was successfully applied to evolve communication-based role allocation for a two-role task. However, it was necessary to reward signal differentiation in the fitness function, which is a serious limitation as it does not generalize to tasks where the number of roles is unknown a priori. In this paper, we show that rewarding signal differentiation is not necessary to evolve communication-based role allocation strategies for the given task, and we improve reported scalability, while requiring less a priori knowledge. Our approach for the two-role task puts fewer constrains on the evolutionary process and enhances the potential of evolving communication-based role allocation for more complex tasks. Furthermore, we conduct experiments for a three-role task where we compare two different cognitive architectures and several fitness functions and we show how scalable controllers might be evolved.

Evolving flocking in embodied agents based on local and global application of Reynolds' rules

In large scale systems of embodied agents, such as robot swarms, the ability to flock is essential in many tasks. However, the conditions necessary to artificially evolve self-organised flocking behaviours remain unknown. In this paper, we study and demonstrate how evolutionary techniques can be used to synthesise flocking behaviours, in particular, how fitness functions should be designed to evolve high-performing controllers. We start by considering Reynolds' seminal work on flocking, the boids model, and design three components of a fitness function that are directly based on his three local rules to enforce local separation, cohesion and alignment. Results show that embedding Reynolds' rules in the fitness function can lead to the successful evolution of flocking behaviours. However, only local, fragmented flocking behaviours tend to evolve when fitness scores are based on the individuals' conformity to Reynolds' rules. We therefore modify the components of the fitness function so that they consider the entire group of agents simultaneously, and find that the resulting behaviours lead to global flocking. Furthermore, the results show that alignment need not be explicitly rewarded to successfully evolve flocking. Our study thus represents a significant step towards the use of evolutionary techniques to synthesise collective behaviours for tasks in which embodied agents need to move as a single, cohesive group.

Evolutionary online behaviour learning and adaptation in real robots

Online evolution of behavioural control on real robots is an open-ended approach to autonomous learning and adaptation: robots have the potential to automatically learn new tasks and to adapt to changes in environmental conditions, or to failures in sensors and/or actuators. However, studies have so far almost exclusively been carried out in simulation because evolution in real hardware has required several days or weeks to produce capable robots. In this article, we successfully evolve neural network-based controllers in real robotic hardware to solve two single-robot tasks and one collective robotics task. Controllers are evolved either from random solutions or from solutions pre-evolved in simulation. In all cases, capable solutions are found in a timely manner (1 h or less). Results show that more accurate simulations may lead to higher-performing controllers, and that completing the optimization process in real robots is meaningful, even if solutions found in simulation differ from solutions in reality. We furthermore demonstrate for the first time the adaptive capabilities of online evolution in real robotic hardware, including robots able to overcome faults injected in the motors of multiple units simultaneously, and to modify their behaviour in response to changes in the task requirements. We conclude by assessing the contribution of each algorithmic component on the performance of the underlying evolutionary algorithm.

Evolution of Collective Behaviors for a Real Swarm of Aquatic Surface Robots

Swarm robotics is a promising approach for the coordination of large numbers of robots. While previous studies have shown that evolutionary robotics techniques can be applied to obtain robust and efficient self-organized behaviors for robot swarms, most studies have been conducted in simulation, and the few that have been conducted on real robots have been confined to laboratory environments. In this paper, we demonstrate for the first time a swarm robotics system with evolved control successfully operating in a real and uncontrolled environment. We evolve neural network-based controllers in simulation for canonical swarm robotics tasks, namely homing, dispersion, clustering, and monitoring. We then assess the performance of the controllers on a real swarm of up to ten aquatic surface robots. Our results show that the evolved controllers transfer successfully to real robots and achieve a performance similar to the performance obtained in simulation. We validate that the evolved controllers display key properties of swarm intelligence-based control, namely scalability, flexibility, and robustness on the real swarm. We conclude with a proof-of-concept experiment in which the swarm performs a complete environmental monitoring task by combining multiple evolved controllers.

Novelty-Driven Cooperative Coevolution

Cooperative coevolutionary algorithms (CCEAs) rely on multiple coevolving populations for the evolution of solutions composed of coadapted components. CCEAs enable, for instance, the evolution of cooperative multiagent systems composed of heterogeneous agents, where each agent is modelled as a component of the solution. Previous works have, however, shown that CCEAs are biased toward stability: the evolutionary process tends to converge prematurely to stable states instead of (near-)optimal solutions. In this study, we show how novelty search can be used to avoid the counterproductive attraction to stable states in coevolution. Novelty search is an evolutionary technique that drives evolution toward behavioural novelty and diversity rather than exclusively pursuing a static objective. We evaluate three novelty-based approaches that rely on, respectively (1) the novelty of the team as a whole, (2) the novelty of the agents' individual behaviour, and (3) the combination of the two. We compare the proposed approaches with traditional fitness-driven cooperative coevolution in three simulated multirobot tasks. Our results show that team-level novelty scoring is the most effective approach, significantly outperforming fitness-driven coevolution at multiple levels. Novelty-driven cooperative coevolution can substantially increase the potential of CCEAs while maintaining a computational complexity that scales well with the number of populations.

Open Issues in Evolutionary Robotics

One of the long-term goals in evolutionary robotics is to be able to automatically synthesize controllers for real autonomous robots based only on a task specification. While a number of studies have shown the applicability of evolutionary robotics techniques for the synthesis of behavioral control, researchers have consistently been faced with a number of issues preventing the widespread adoption of evolutionary robotics for engineering purposes. In this article, we review and discuss the open issues in evolutionary robotics. First, we analyze the benefits and challenges of simulation-based evolution and subsequent deployment of controllers versus evolution on real robotic hardware. Second, we discuss specific evolutionary computation issues that have plagued evolutionary robotics: (1) the bootstrap problem, (2) deception, and (3) the role of genomic encoding and genotype-phenotype mapping in the evolution of controllers for complex tasks. Finally, we address the absence of standard research practices in the field. We also discuss promising avenues of research. Our underlying motivation is the reduction of the current gap between evolutionary robotics and mainstream robotics, and the establishment of evolutionary robotics as a canonical approach for the engineering of autonomous robots.

To err is robotic, to tolerate immunological: fault detection in multirobot systems

Fault detection and fault tolerance represent two of the most important and largely unsolved issues in the field of multirobot systems (MRS). Efficient, long-term operation requires an accurate, timely detection, and accommodation of abnormally behaving robots. Most existing approaches to fault-tolerance prescribe a characterization of normal robot behaviours, and train a model to recognize these behaviours. Behaviours unrecognized by the model are consequently labelled abnormal or faulty. MRS employing these models do not transition well to scenarios involving temporal variations in behaviour (e.g., online learning of new behaviours, or in response to environment perturbations). The vertebrate immune system is a complex distributed system capable of learning to tolerate the organism's tissues even when they change during puberty or metamorphosis, and to mount specific responses to invading pathogens, all without the need of a genetically hardwired characterization of normality. We present a generic abnormality detection approach based on a model of the adaptive immune system, and evaluate the approach in a swarm of robots. Our results reveal the robust detection of abnormal robots simulating common electro-mechanical and software faults, irrespective of temporal changes in swarm behaviour. Abnormality detection is shown to be scalable in terms of the number of robots in the swarm, and in terms of the size of the behaviour classification space.

odNEAT: An Algorithm for Decentralised Online Evolution of Robotic Controllers

Online evolution gives robots the capacity to learn new tasks and to adapt to changing environmental conditions during task execution. Previous approaches to online evolution of neural controllers are typically limited to the optimisation of weights in networks with a prespecified, fixed topology. In this article, we propose a novel approach to online learning in groups of autonomous robots called odNEAT. odNEAT is a distributed and decentralised neuroevolution algorithm that evolves both weights and network topology. We demonstrate odNEAT in three multirobot tasks: aggregation, integrated navigation and obstacle avoidance, and phototaxis. Results show that odNEAT approximates the performance of rtNEAT, an efficient centralised method, and outperforms IM-(μ + 1), a decentralised neuroevolution algorithm. Compared with rtNEAT and IM-(μ + 1), odNEAT's evolutionary dynamics lead to the synthesis of less complex neural controllers with superior generalisation capabilities. We show that robots executing odNEAT can display a high degree of fault tolerance as they are able to adapt and learn new behaviours in the presence of faults. We conclude with a series of ablation studies to analyse the impact of each algorithmic component on performance.

Online Evolution of Adaptive Robot Behaviour

The authors propose and evaluate a novel approach to the online synthesis of neural controllers for autonomous robots. The authors combine online evolution of weights and network topology with neuromodulated learning. The authors demonstrate our method through a series of simulation-based experiments in which an e-puck-like robot must perform a dynamic concurrent foraging task. In this task, scattered food items periodically change their nutritive value or become poisonous. The authors demonstrate that the online evolutionary process, both with and without neuromodulation, is capable of generating controllers well adapted to the periodic task changes. The authors show that when neuromodulated learning is combined with evolution, neural controllers are synthesised faster than by evolution alone. An analysis of the evolved solutions reveals that neuromodulation allows for a more effective expression of a given topology's potential due to the active modification of internal dynamics. Neuromodulated networks learn abstractions of the task and different modes of operation that are triggered by external stimulus.

PMCNS

Novelty search is an evolutionary approach in which the population is driven towards behavioural innovation instead of towards a fixed objective. The use of behavioural novelty to score candidate solutions precludes convergence to local optima. However, in novelty search, significant effort may be spent on exploration of novel, but unfit behaviours. We propose progressive minimal criteria novelty search (PMCNS) to overcome this issue. In PMCNS, novelty search can freely explore the behaviour space as long as the solutions meet a progressively stricter fitness criterion. We evaluate the performance of our approach by evolving neurocontrollers for swarms of robots in two distinct tasks. Our results show that PMCNS outperforms fitness-based evolution and pure novelty search, and that PMCNS is superior to linear scalarisation of novelty and fitness scores. An analysis of behaviour space exploration shows that the benefits of novelty search are conserved in PMCNS despite the evolutionary pressure towards progressively fitter behaviours.

Poisson regression models outperform the geometrical model in estimating the peak-to-trough ratio of seasonal variation: a simulation study

INTRODUCTION

Several statistical methods of assessing seasonal variation are available. Brookhart and Rothman [3] proposed a second-order moment-based estimator based on the geometrical model derived by Edwards [1], and reported that this estimator is superior in estimating the peak-to-trough ratio of seasonal variation compared with Edwards' estimator with respect to bias and mean squared error. Alternatively, seasonal variation may be modelled using a Poisson regression model, which provides flexibility in modelling the pattern of seasonal variation and adjustments for covariates.

METHOD

Based on a Monte Carlo simulation study three estimators, one based on the geometrical model, and two based on log-linear Poisson regression models, were evaluated in regards to bias and standard deviation (SD). We evaluated the estimators on data simulated according to schemes varying in seasonal variation and presence of a secular trend. All methods and analyses in this paper are available in the R package Peak2Trough[13].

RESULTS

Applying a Poisson regression model resulted in lower absolute bias and SD for data simulated according to the corresponding model assumptions. Poisson regression models had lower bias and SD for data simulated to deviate from the corresponding model assumptions than the geometrical model.

CONCLUSION

This simulation study encourages the use of Poisson regression models in estimating the peak-to-trough ratio of seasonal variation as opposed to the geometrical model.

Paediatric arterial ischaemic stroke and cerebral sinovenous thrombosis in Denmark 1994-2006: a nationwide population-based study

AIM

To assess the incidence rates (IR), clinical characteristics, risk factors, treatment and outcomes of paediatric arterial ischaemic stroke (AIS) and cerebral sinovenous thrombosis (CSVT).

METHODS

Using population-based, nationwide medical registries, we identified all patients aged 0-18 years at the time of hospitalization with first-ever AIS and/or CSVT in Denmark between 1994 and 2006. Medical records were retrieved and reviewed.

RESULTS

We identified 211 patients with AIS and 40 patients with CSVT corresponding to IRs of 1.33 (95% CI 1.16-1.52) and 0.25 (95% CI 0.19-0.34) per 100,000 person-years, respectively. The IRs peaked in infancy (<1 year) for both AIS and CSVT with an additional peak among adolescents (15-18 years) for CSVT. The IR of AIS increased 3.9% per year (p=0.036), whereas no changes were found for CSVT. In total, 48.2% of the patients received antithrombotic treatment; no major complications were observed. All-cause and thrombosis-related 30-day case fatality ratios were 3.6% and 2.4%, respectively; neurological sequelae were found in 56.2% of patients.

CONCLUSION

The IR of AIS was highest in infants and had increased with 3.9% annually during the observation period. The IR of CSVT had an additional peak in adolescence and remained unchanged over time.

Evolving self-assembly in autonomous homogeneous robots: experiments with two physical robots

This research work illustrates an approach to the design of controllers for self-assembling robots in which the self-assembly is initiated and regulated by perceptual cues that are brought forth by the physical robots through their dynamical interactions. More specifically, we present a homogeneous control system that can achieve assembly between two modules (two fully autonomous robots) of a mobile self-reconfigurable system without a priori introduced behavioral or morphological heterogeneities. The controllers are dynamic neural networks evolved in simulation that directly control all the actuators of the two robots. The neurocontrollers cause the dynamic specialization of the robots by allocating roles between them based solely on their interaction. We show that the best evolved controller proves to be successful when tested on a real hardware platform, the swarm-bot. The performance achieved is similar to the one achieved by existing modular or behavior-based approaches, also due to the effect of an emergent recovery mechanism that was neither explicitly rewarded by the fitness function, nor observed during the evolutionary simulation. Our results suggest that direct access to the orientations or intentions of the other agents is not a necessary condition for robot coordination: Our robots coordinate without direct or explicit communication, contrary to what is assumed by most research works in collective robotics. This work also contributes to strengthening the evidence that evolutionary robotics is a design methodology that can tackle real-world tasks demanding fine sensory-motor coordination.

Neuropsychological experiences in neurotraumatology

My work in Neurotraumatology was initiated in 1961, when I as a neuropsychologist got a position in a neurosurgical University department. The tasks were to evaluate the mental state of patients, give advices to family members regarding the mental and social prognosis of the patients and to support nurses in the initial care of the patients. Initially the methods that were made use of were tests developed by the German neurologist Kurt Goldstein and traditional psychometric tests, but it was not until the theories of A. R. Luria and his investigation method were applied that a true position as a member of the treatment team was secured. Reading Luria's book "Higher Cortical Functions in Man" made me aware of his theories. The skill to perform the investigation was acquired during visits to Luria's laboratory at the Bourdenko Neurosurgical Institute in Moscow in the nineteen-seventies. Text and material to "Luria's Neuropsychological Investigation" was published in 1974. The early work was further stimulated by the development in the neurosciences regarding brain plasticity and brain repair and experiences from visits to rehabilitation centres in the US, Yehuda Ben-Yishay's center at New York Medical School, George Prigatano's centre at the time in Oklahoma, and Lance Trexler's center at Community Hospital, Indianapolis led in 1985 to the establishment of the first post acute rehabilitation center in Europe: the Center for Rehabilitation of Brain Injury (CRBI) at the University of Copenhagen, DK. The main program was a holistic day program, six hours a day for four months in accordance with the university semesters, and an eigth months follow-up. Groups of 15 persons started together, collaborating in smaller groups. The present director of the CRBI is neuropsychologist Frank Humle. A thorough follow-up of the patients' state and improvement through the course of treatment towards social integration, including getting back to work was performed, and studies have indicated that successful integration of the traumatized patient is possible, provided that an early intensive care is succeeded by a comprehensive, individualized post-acute rehabilitation program, of which follow-up is a part, all within the frame of multidisciplinary collaboration.

Measurement of transcobalamin by ELISA

BACKGROUND

Transcobalamin is essential for the cellular internalization of cobalamin. Methods to quantify the unsaturated protein are available, but few attempts have been made to develop methods to quantify the sum of unsaturated and cobalamin saturated transcobalamin.

METHODS

gamma-Globulins from two polyclonal rabbit antibodies against recombinant human transcobalamin were used as capture and detection antibodies, and recombinant human transcobalamin was used as calibrator in an ELISA design.

RESULTS

The ELISA is specific for transcobalamin and has a detection limit of <1.6 pmol/L. The imprecision (CV) is 4-6% for mean concentrations of 13-70 pmol/L. The central 95% interval for serum from healthy blood donors (n = 77) was approximately 600-1500 pmol/L and showed limited variation with age and sex. No correlation was observed between the marker of acute phase reaction, C-reactive protein, and transcobalamin in plasma.

CONCLUSIONS

The ELISA measures total transcobalamin in serum and thus can be used for measurement of transcobalamin in patients treated with cobalamin.

Luria's neuropsychological evaluation in the nordic countries

The publication of Luria's Neuropsychological Investigation (LNI) by Christensen in 1975 introduced Luria's evaluation procedures to worldwide neuropsychology. The LNI demonstrated the benefit of a thorough qualitative analysis of an individual patient's functioning as well as the usefulness of a comprehensive theory of brain functioning. This article reviews the experiences that led to the development of the LNI, discusses its use and extension in Scandinavian countries, and presents clinical and research applications of the LNI in diagnosis and rehabilitation. A series of case examples provides justification and validity for the continued use of the LNI and related procedures. Discussion of the advantages and disadvantages of the LNI and consideration of possible modifications of the procedures and interpretative methods provide the rationale for continued development of Luria's approach.

Sociological and cultural aspects in postacute neuropsychological rehabilitation

Various forms of postacute brain injury rehabilitation programs exist. Comprehensive day treatment programs are the most holistic, being neuropsychological in orientation. The importance of developing a trusting relationship and the use of inventive techniques in the individualization of treatment within a holistic rehabilitation program will be described via a case presentation, stressing the sociocultural aspects of the individual as central to treatment.

Subjective experience in brain-injured patients and their close relatives: a European Brain Injury Questionnaire study

Results are reported from an international project the aim of which has been to develop and validate a wide-ranging questionnaire suitable for administration to brain-injured patients and their relatives. A self-report questionnaire concerning subjective experience of cognitive, emotional and social difficulties (The European Brain Injury Questionnaire, EBIQ) was administered to a group of 905 brain-injured patients, and close relatives to these competed a parallel version of the questionnaire concerning the brain-injured person. The sample was drawn from seven European countries together with Brazil. The same questionnaire was also administered to a group of 203-non-brain-injured controls, similarly in self-report and relative-report versions. Scales relating to eight specific areas of functioning, together with a global scale, are derived from the questionnaire and their internal reliability was estimated in the present data. Analyses of the 63 items of the questionnaire showed consistently greater levels of problems for the brain-injured group, especially as indicated by relatives. This pattern was substantially replicated among the nine scales. The scales discriminated well between stroke patients and those who had suffered a traumatic brain injury. There was also a tendency for reported problems to be greater for patients who were surveyed later post-injury (> or = 19 months) rather than earlier. Comparison of sets of controls derived from two countries (France and Brazil) showed small but important differences. It is concluded that the questionnaire has an acceptable reliability and validity, but that it will be necessary to obtain culturally relevant non-brain-injured control data when employing it in different countries.

Neuropsychological characteristics of Huntington's disease carriers: a double blind study

A cohort of 33 people at risk for Huntington's disease (HD), applying for genetic testing, were tested with a battery of neuropsychological tests covering attentional, visuospatial, learning, memory, and planning functions. A psychiatric rating scale, SCL-90R, was also applied, mainly as a control, since cognitive dysfunction could be ascribed to functional disorders as well as neurodegenerative processes. Self-rating did not indicate any psychiatric symptoms in carriers or non-carriers. However, significantly inferior cognitive functioning in the gene carriers was disclosed by the neuropsychological tests. Primarily, attentional, learning, and planning functions were affected. It is concluded that premorbid cognitive decline occurs in HD.

Neuropsychology in Denmark

The origins and development of neuropsychology in Denmark are briefly overviewed, as are the education and training opportunities for Danish neuropsychologists. Areas of application and research are presented, and the role of the rehabilitation of brain injury is emphasized, with specific reference being made to the Center for the Rehabilitation of Brain Injury at Copenhagen University, wherein the rehabilitation program and pertinent research ensuing from the center is presented. Future trends in Danish neuropsychology are also considered.

Psychosocial rehabilitation of cranial trauma and stroke patients

This paper presents the results of a longitudinal psychosocial study of 22 cranial trauma patients and 14 stroke patients from the time preceding injury (using retrospective data), through a 4-5 month intensive rehabilitation programme, to a follow-up 1 year after completion of the programme. Although the two groups of patients differed on several demographic and medical characteristics, essentially similar patterns for psychosocial decline following injury and improvement following rehabilitation could be observed. For both groups, the proportion in marital or cohabitational relationships returned to pre-injury levels, and for both groups the proportion requiring assistance in their living situation declined following rehabilitation, as did use of the health services. Virtually all patients in both groups had been in employment or undergoing education at the time of the injury, and although this percentage declined in practice to a small minority of both groups post-injury, there was a significant increase in the proportions working or in education following the rehabilitation programme. Similarly, the pattern of leisure-time activities in both groups declined post-injury and was restored following rehabilitation. Since both groups entered the programme at over 2.5 years post-injury, these generally encouraging results seem less likely to reflect spontaneous recovery than a beneficial effect of the programme itself.

Psychosocial outcome following individualized neuropsychological rehabilitation of brain damage

At the center for Rehabilitation of Brain Damage, University of Copenhagen, 46 consecutively admitted brain-damaged patients with varying pathologies and who were on average 2.9 years post-injury were treated in a daily four-month rehabilitation program in groups of about 10, followed by a six-month period of contact varying according to individual needs. An evaluation of psychosocial outcome is presented. The results, based on comparisons between pre-, post-treatment and follow-up questionnaire data, show continuing functional improvements in the areas of family life and living conditions. Dependence on health services declined. Over 70% of the patients returned to either work, further education or voluntary work activities. For the whole group, leisure activities returned to the pre-injury level. Follow-up at about two years revealed continuing improvements in all areas, suggesting social readaptation to a degree above expectations as judged from the existing literature.

[The risk of ornithosis among the staff of Copenhagen Zoo]

Because a keeper in Copenhagen ZOO had developed ornithosis, clinical and serological examination of the staff of the ZOO was instituted. The object was to demonstrate any possible threatening epidemic and also to demonstrate if the staff of the ZOO were particularly exposed to the risk of ornithosis. Neither of these could be confirmed.

Educational influences on consultation rates of house staff physicians in a primary care clinic

Consultation rates of medical house staff physicians were examined in a primary care setting in order to determine the factors that lead to the use of consultants. The factors that were studied in the regression analysis were clinical experience and teaching in medical school, intensity of use of services, residency year, Alpha Omega Alpha (AOA) membership, and future practice plans. The factors were marginally useful in predicting surgical consultations but were helpful in explaining the use of other consultations. House staff physicians with a pattern of intense ancillary service utilization also requested more consultations. Senior house staff physicians requested fewer consultations than junior house staff members. AOA members and future academic physicians used more consultations than other physicians. Consultation rates were highest for specialties requiring the lowest quantity of education in medical school. Consultation patterns reflect past educational experiences and future practice plans of medical house staff physicians and may be useful in the formulation of the curriculum of medical schools and residencies.

A neuropathological and neuropsychological study of Turner's syndrome

A neuropathological study was made in 2 women with Turner's syndrome. Neuropsychological investigation in one of them correlated with what has previously been found in Turner's syndrome as well as with the localization of the most pronounced neuropathological aberration which was of atherosclerotic nature, most pronounced in the right temporo-parietal area. These findings as well as the findings of acidophile hypoplasia of the pituitary gland are discussed.

Neurological, electroencephalographic and neuropsychological examination of 53 former amateur boxers

The purpose of the present study was to reveal possible neurological sequelae of amateur boxing after the introduction of modern medical supervision and safety precautions. Neurological, electroencephalographic and neuropsychological examinations were performed in a total of 53 former champion amateur boxers together with a control group consisting of 53 former football players. The football players were, on an average, better educated than the boxers, but otherwise the two groups were comparable. Complaints, neurological findings and electroencephalographic changes were identical in the boxers and control group. Only minor neuropsychological disturbances were found in the boxers most pronounced in impaired motor function of the left hand. This was further demonstrated by comparing 19 pairs, each consisting of one boxer and one football player, matched according to age, education and vocabulary. No relation between abnormal findings and "occupational exposure" during the boxing career could be demonstrated, not even by comparing three pairs of identical twins, although in each twin of the pairs there was a great difference in the number of fights. This study provides no basis for legislation against amateur boxing at the present time, as it indicates that the existing safety precautions protect the boxers against serious and permanent brain damage.

A psychiatric-psychological study of XYY males found in a general male population

The psychological test results of five XYY males from in a population study showed an intellectual level within the normal range but with a mean full scale IQ and educational level lower than expected. The cognitive as well as emotional function was characterized by immaturity, manifested in passivity, unreflectiveness and emotional liability, in three resulting in uncontrolled aggressive outbursts. Conflict material also appeared immaturely resolved, centering around unfulfilled needs of contact and insecure masculine identification. The defense mechanisms used were generally rather weak, but only in one subject did the anxiety level seem to be excessively low. All five males differed to a certain extent from their siblings; three of them were hyperactive, restless, hot-tempered and impulsive at school and four of them had difficulties at school. Three learned a trade, but only one stayed in his trade, and one was applying for disablement pension on account of personality deviation. Two of the five had a criminal record. It is concluded that the presence and degree of the above-mentioned characteristics of XYY males varied. It is evident that environmental factors play as great a role for the development of personality and behaviour in males with karyotype 47, XYY as in males with a normal chromosome constitution.

Thirty-five males with double Y chromosome

Thirty-five males with double Y chromosome were studied. Among the features observed in certain subgroups of these 35 were a more than average height, minor vertebral abnormalities, abnormal seminiferous epithelium, minor EEG abnormalities, and a mean intelligence level significantly below the expected. Fifteen of the 35 were found in institutions for criminals. The frequency of XYY males among 1,500 criminal males was 8·67 per 1,000 compared with 1·24 per 1,000 among 6,455 randomly selected males in the general population. Males with double Y chromosome tended to have more difficulties at school, to be more mentally immature, to be more impulsive than their siblings, and to have more difficulty in making relationships with others.

Psychological studies of ten patients with the XYY syndrome

The present study is the psychological part of a comprehensive study of male patients with the XYY syndrome from the Cytogenetic Laboratory, Risskov (Nielsen, 1968, 1969, 1971; Nielsen et al., 1969a, b; and Nielsen and Henriksen, 1972).