Factors affecting the accommodative response to sustained visual tasks

In the absence of adequate visual stimulation accommodation adopts an intermediate resting position, appropriately termed tonic accommodation (TA). A period of sustained fixation can modify the tonic resting position, and indicate the adaptation properties of TA. This thesis investigates various factors contributing to the accommodative response during sustained visual tasks, in particular the adaptation of TA. Objective infra-red optometry was chosen as the most effective method of measurement of accommodation. This technique was compared with other methods of measuring TA and the results found to be well correlated. The inhibitory sympathetic input to the ciliary muscle provides the facility to attenuate the magnitude and duration of adaptive changes in TA. This facility is, however, restricted to those individuals having relatively high levels of pre-task TA. Furthermore, the facility is augmented by substantial levels of concurrent parasympathetic activity. The imposition of mental effort can induce concurrent changes in TA which are predominantly positive and largely the result of an increase in parasympathetic innervation of the ciliary muscle although there is some evidence for sympathetic attentuation at higher levels of TA. In emmetropes sympathetic inhibition can modify the effect of mental effort on the steady-state accommodative response at near. Late-onset myopes (onset after the age of 15 years) have significantlylower values of TA then emmetropes. Similarly, late-onset myopes show lower values of steady-state accommodative response for nearstimuli. The imposition of mental effort induces concurrent increases in TA and steady-state accommodative response in the myopic group which are significantly greater than those for emmetropes. Estimates of TA made under bright empty-field conditions are well correlated with those made under darkroom conditions. The method by which the accommodative loop is opened has no significant effect on the magnitude and duration of post-task shifts in TA induced by a near vision task. Significant differences in the post-task shifts in TA induced by a near vision task exist between emmetropes and late-onset myopes, the post-task shifts being more sustained for the myopic group.

Investigations into visual hyperacuity

Visual hyperacuities.are a group of thresholds whose values surpass that expected by the anatomical and optical constraints of the eye. There are many variables which affect hyperacuities of which this thesis considers the following .. 1. The effect of contrast on displacement detection and bisection acuity. It is proposed that spatial summation may account for the different response of these two hyperacuities compared with the contrast response of vernier acuity. 2. The effect of references on displacement detection. These were shown to greatly enhance performance when present. Their effect was, however, dependent upon the temporal characteristics of the displacement. 3. The effect of spatial frequency on vernier acuity. Evidence from this experiment suggests that vernier performance can be explained on the basis of the output of orientationally selective spatial frequency filters. 4. Evidence for a weighting function for visual location using random dot clusters. The weighting attached to different parts of the retinal light distribution was found to alter non-linearly with increasing offset from the geometric center of the cluster. A relationship between dot density and peak amplitude of the weighting function was found. 5. Spatial scaling of vernier acuity in the peripheral field. With careful choice of a technique which did not allow separation and eccentricity to co-vary it was found possible to scale vernier acuity both for two lines and two separated dots. 6. The effect of increasing age on hyperacuity. No change in vernier acuity with age was found which contrasted with displacement detection and bisection acuity both of which showed a significant decline with increasing age.

Abnormal visual habituation in pediatric photosensitive epilepsy

Objective - To investigate visual habituation – a measure of visual cortical excitability – in photosensitive patients in pediatric age and compare the findings with a matched sample with idiopathic generalized epilepsies without photosensitivity and with normally developing children. Methods - We presented a full-field black-and-white checkerboard pattern, at 3 reversal/s with 100% contrast binocularly for 600 consecutive trials and measured the N75–P100 and P100–N145 pattern-reversal visual evoked potential inter-peak amplitudes and N75, P100, N145 latencies for the six blocks of 100 responses. As a measure of habituation we used the slope of the linear regression line of the N75–P100 and P100–N145 peak-to-peak amplitudes. The slope of the linear regression line of the N75–P100 and P100–N145 latencies was also analyzed. Results - Statistical analysis revealed significant differences between the three groups in the slope index of N75–P100 PR-VEP amplitude, with increased or constant amplitude in the PS group compare to the IGE and ND across the six blocks. Conclusions - Our results support the notion that photosensitivity is associated with altered control of excitatory and inhibitory cortical processes. The causal relationship between habituation deficit and photo-paroxysmal response needs to be further investigated with longitudinal studies. Significance This study supports the hypothesis that suppression of PR-VEP is a sensitive intermediate phenotype, which discriminates patients with photosensitivity from those with generalized epilepsies in pediatric age.

Impact of senescence and disease on the structural and functional performance of the visual pathway

The diagnosis and monitoring of ocular disease presents considerable clinical difficulties for two main reasons i) the substantial physiological variation of anatomical structure of the visual pathway and ii) constraints due to technical limitations of diagnostic hardware. These are further confounded by difficulties in detecting early loss or change in visual function due to the masking of disease effects, for example, due to a high degree of redundancy in terms of nerve fibre number along the visual pathway. This thesis addresses these issues across three areas of study: 1. Factors influencing retinal thickness measures and their clinical interpretation As the retina is the principal anatomical site for damage associated with visual loss, objective measures of retinal thickness and retinal nerve fibre layer thickness are key to the detection of pathology. In this thesis the ability of optical coherence tomography (OCT) to provide repeatable and reproducible measures of retinal structure at the macula and optic nerve head is investigated. In addition, the normal physiological variations in retinal thickness and retinal nerve fibre layer thickness are explored. Principal findings were: • Macular retinal thickness and optic nerve head measurements are repeatable and reproducible for normal subjects and diseased eyes • Macular and retinal nerve fibre layer thickness around the optic nerve correlate negatively with axial length, suggesting that larger eyes have thinner retinae, potentially making them more susceptible to damage or disease • Foveola retinal thickness increases with age while retinal nerve fibre layer thickness around the optic nerve head decreases with age. Such findings should be considered during examination of the eye with suspect pathology or in long-term disease monitoring 2. Impact of glucose control on retinal anatomy and function in diabetes Diabetes is a major health concern in the UK and worldwide and diabetic retinopathy is a major cause of blindness in the working population. Objective, quantitative measurements of retinal thickness. particularly at the macula provide essential information regarding disease progression and the efficacy of treatment. Functional vision loss in diabetic patients is commonly observed in clinical and experimental studies and is thought to be affected by blood glucose levels. In the first study of its kind, the short term impact of fluctuations in blood glucose levels on retinal structure and function over a 12 hour period in patients with diabetes are investigated. Principal findings were: • Acute fluctuations in blood glucose levels are greater in diabetic patients than normal subjects • The fluctuations in blood glucose levels impact contrast sensitivity scores. SWAP visual fields, intraocular pressure and diastolic pressure. This effect is similar for type 1 and type 2 diabetic patients despite the differences in their physiological status. • Long-term metabolic control in the diabetic patient is a useful predictor in the fluctuation of contrast sensitivity scores. • Large fluctuations in blood glucose levels and/or visual function and structure may be indicative of an increased risk of development or progression of retinopathy 3. Structural and functional damage of the visual pathway in glaucomatous optic neuropathy The glaucomatous eye undergoes a number of well documented pathological changes including retinal nerve fibre loss and optic nerve head damage which is correlated with loss of functional vision. In experimental glaucoma there is evidence that glaucomatous damage extends from retinal ganglion cells in the eye, along the visual pathway, to vision centres in the brain. This thesis explores the effects of glaucoma on retinal nerve fibre layer thickness, ocular anterior anatomy and cortical structure, and its correlates with visual function in humans. Principal findings were: • In the retina, glaucomatous retinal nerve fibre layer loss is less marked with increasing distance from the optic nerve head, suggesting that RNFL examination at a greater distance than traditionally employed may provide invaluable early indicators of glaucomatous damage • Neuroretinal rim area and retrobulbar optic nerve diameter are strong indicators of visual field loss • Grey matter density decreases at a rate of 3.85% per decade. There was no clear evidence of a disease effect • Cortical activation as measured by fMRI was a strong indicator of functional damage in patients with significant neuroretinal rim loss despite relatively modest visual field defects These investigations have shown that the effects of senescence are evident in both the anterior and posterior visual pathway. A variety of anatomical and functional diagnostic protocols for the investigation of damage to the visual pathway in ocular disease are required to maximise understanding of the disease processes and thereby optimising patient care.

Comparison of subjective and objective methods to determine the retinal arterio-venous ratio using fundus photography

Purpose: To assess the inter and intra observer variability of subjective grading of the retinal arterio-venous ratio (AVR) using a visual grading and to compare the subjectively derived grades to an objective method using a semi-automated computer program. Methods: Following intraocular pressure and blood pressure measurements all subjects underwent dilated fundus photography. 86 monochromatic retinal images with the optic nerve head centred (52 healthy volunteers) were obtained using a Zeiss FF450+ fundus camera. Arterio-venous ratios (AVR), central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE) were calculated on three separate occasions by one single observer semi-automatically using the software VesselMap (ImedosSystems, Jena, Germany). Following the automated grading, three examiners graded the AVR visually on three separate occasions in order to assess their agreement. Results: Reproducibility of the semi-automatic parameters was excellent (ICCs: 0.97 (CRAE); 0.985 (CRVE) and 0.952 (AVR)). However, visual grading of AVR showed inter grader differences as well as discrepancies between subjectively derived and objectively calculated AVR (all p < 0.000001). Conclusion: Grader education and experience leads to inter-grader differences but more importantly, subjective grading is not capable to pick up subtle differences across healthy individuals and does not represent true AVR when compared with an objective assessment method. Technology advancements mean we no longer rely on opthalmoscopic evaluation but can capture and store fundus images with retinal cameras, enabling us to measure vessel calibre more accurately compared to visual estimation; hence it should be integrated in optometric practise for improved accuracy and reliability of clinical assessments of retinal vessel calibres. © 2014 Spanish General Council of Optometry.

Self-organising zooms for decentralised redundancy management in visual sensor networks

When visual sensor networks are composed of cameras which can adjust the zoom factor of their own lens, one must determine the optimal zoom levels for the cameras, for a given task. This gives rise to an important trade-off between the overlap of the different cameras’ fields of view, providing redundancy, and image quality. In an object tracking task, having multiple cameras observe the same area allows for quicker recovery, when a camera fails. In contrast having narrow zooms allow for a higher pixel count on regions of interest, leading to increased tracking confidence. In this paper we propose an approach for the self-organisation of redundancy in a distributed visual sensor network, based on decentralised multi-objective online learning using only local information to approximate the global state. We explore the impact of different zoom levels on these trade-offs, when tasking omnidirectional cameras, having perfect 360-degree view, with keeping track of a varying number of moving objects. We further show how employing decentralised reinforcement learning enables zoom configurations to be achieved dynamically at runtime according to an operator’s preference for maximising either the proportion of objects tracked, confidence associated with tracking, or redundancy in expectation of camera failure. We show that explicitly taking account of the level of overlap, even based only on local knowledge, improves resilience when cameras fail. Our results illustrate the trade-off between maintaining high confidence and object coverage, and maintaining redundancy, in anticipation of future failure. Our approach provides a fully tunable decentralised method for the self-organisation of redundancy in a changing environment, according to an operator’s preferences.

The association between glycated haemoglobin levels and P100 visual evoked potentials in diabetes mellitus

Diabetes mellitus (DM) is a metabolic disorder which is characterised by hyperglycaemia resulting from defects in insulin secretion, insulin action or both. The long-term specific effects of DM include the development of retinopathy, nephropathy and neuropathy. Cardiac disease, peripheral arterial and cerebrovascular disease are also known to be linked with DM. Type 1 diabetes mellitus (T1DM) accounts for approximately 10% of all individuals with DM, and insulin therapy is the only available treatment. Type 2 diabetes mellitus (T2DM) accounts for 90% of all individuals with DM. Diet, exercise, oral hypoglycaemic agents and occasionally exogenous insulin are used to manage T2DM. The diagnosis of DM is made where the glycated haemoglobin (HbA1c) percentage is greater than 6.5%. Pattern-reversal visual evoked potential (PVEP) testing is an objective means of evaluating impulse conduction along the central nervous pathways. Increased peak time of the visual P100 waveform is an expression of structural damage at the level of myelinated optic nerve fibres. This was an observational cross sectional study. The participants were grouped into two phases. Phase 1, the control group, consisted of 30 healthy non-diabetic participants. Phase 2 comprised of 104 diabetic participants of whom 52 had an HbA1c greater than 10% (poorly controlled DM) and 52 whose HbA1c was 10% and less (moderately controlled DM). The aim of this study was to firstly observe the possible association between glycated haemoglobin levels and P100 peak time of pattern-reversal visual evoked potentials (PVEPs) in DM. Secondly, to assess whether the central nervous system (CNS) and in particular visual function is affected by type and/or duration of DM. The cut-off values to define P100 peak time delay was calculated as the mean P100 peak time plus 2.5 X standard deviations as measured for the non-diabetic control group, and were 110.64 ms for the right eye. The proportion of delayed P100 peak time amounted to 38.5% for both diabetic groups, thus the poorly controlled group (HbA1c > 10%) did not pose an increased risk for delayed P100 peak time, relative to the moderately controlled group (HbA1c ≤ 10%). The P100 PVEP results for this study, do however, reflect significant delay (p < 0.001) of the DM group as compared to the non-diabetic group; thus, subclincal neuropathy of the CNS occurs in 38.5% of cases. The duration of DM and type of DM had no influence on the P100 peak time measurements.

Visual driver support system for traffic signs

It has been well documented that traffic accidents that can be avoided occur when the motorists miss or ignore traffic signs. With the attention of drivers getting diverted due to distractions like cell phone conversations, missing traffic signs has become more prevalent. Also, poor weather and other unfriendly driving conditions sometimes makes the motorists not to be alert all the time and see every traffic sign on the road. Besides, most cars do not have any form of traffic assistance. Because of heavy traffic and proliferation of traffic signs on the roads, there is a need for a system that assists the driver not to miss a traffic sign to reduce the probability of an accident. Since visual information is critical for driving, processed video signals from cameras have been chosen to assist drivers. These inexpensive cameras can be easily mounted on the automobile. The objective of the present investigation and the traffic system development is to recognize the traffic signs electronically and alert drivers. For the case study and the system development, five important and critical traffic signs have been selected. They are: STOP, NO ENTER, NO RIGHT TURN, NO LEFT TURN, and YIELD. The system was evaluated processing still pictures taken from the public roads, and the recognition results were presented in an analysis table to indicate the correct identifications and the false ones. The system reached the acceptable recognition rate of 80% for all five traffic signs. The processing rate was about three seconds. The capabilities of MATLAB, VLSI design platforms and coding have been used to generate a visual warning to complement the visual driver support system with a Field Programmable Gate Array (FPGA) on a XUP Virtex-II Pro Development System.

Dynamic image precompensation for improving visual performance of computer users with ocular aberrations

With the progress of computer technology, computers are expected to be more intelligent in the interaction with humans, presenting information according to the user's psychological and physiological characteristics. However, computer users with visual problems may encounter difficulties on the perception of icons, menus, and other graphical information displayed on the screen, limiting the efficiency of their interaction with computers. In this dissertation, a personalized and dynamic image precompensation method was developed to improve the visual performance of the computer users with ocular aberrations. The precompensation was applied on the graphical targets before presenting them on the screen, aiming to counteract the visual blurring caused by the ocular aberration of the user's eye. A complete and systematic modeling approach to describe the retinal image formation of the computer user was presented, taking advantage of modeling tools, such as Zernike polynomials, wavefront aberration, Point Spread Function and Modulation Transfer Function. The ocular aberration of the computer user was originally measured by a wavefront aberrometer, as a reference for the precompensation model. The dynamic precompensation was generated based on the resized aberration, with the real-time pupil diameter monitored. The potential visual benefit of the dynamic precompensation method was explored through software simulation, with the aberration data from a real human subject. An "artificial eye'' experiment was conducted by simulating the human eye with a high-definition camera, providing objective evaluation to the image quality after precompensation. In addition, an empirical evaluation with 20 human participants was also designed and implemented, involving image recognition tests performed under a more realistic viewing environment of computer use. The statistical analysis results of the empirical experiment confirmed the effectiveness of the dynamic precompensation method, by showing significant improvement on the recognition accuracy. The merit and necessity of the dynamic precompensation were also substantiated by comparing it with the static precompensation. The visual benefit of the dynamic precompensation was further confirmed by the subjective assessments collected from the evaluation participants.

Semantic feature-based visual attention model for pedestrian detection

Objective
Pedestrian detection under video surveillance systems has always been a hot topic in computer vision research. These systems are widely used in train stations, airports, large commercial plazas, and other public places. However, pedestrian detection remains difficult because of complex backgrounds. Given its development in recent years, the visual attention mechanism has attracted increasing attention in object detection and tracking research, and previous studies have achieved substantial progress and breakthroughs. We propose a novel pedestrian detection method based on the semantic features under the visual attention mechanism.
Method
The proposed semantic feature-based visual attention model is a spatial-temporal model that consists of two parts: the static visual attention model and the motion visual attention model. The static visual attention model in the spatial domain is constructed by combining bottom-up with top-down attention guidance. Based on the characteristics of pedestrians, the bottom-up visual attention model of Itti is improved by intensifying the orientation vectors of elementary visual features to make the visual saliency map suitable for pedestrian detection. In terms of pedestrian attributes, skin color is selected as a semantic feature for pedestrian detection. The regional and Gaussian models are adopted to construct the skin color model. Skin feature-based visual attention guidance is then proposed to complete the top-down process. The bottom-up and top-down visual attentions are linearly combined using the proper weights obtained from experiments to construct the static visual attention model in the spatial domain. The spatial-temporal visual attention model is then constructed via the motion features in the temporal domain. Based on the static visual attention model in the spatial domain, the frame difference method is combined with optical flowing to detect motion vectors. Filtering is applied to process the field of motion vectors. The saliency of motion vectors can be evaluated via motion entropy to make the selected motion feature more suitable for the spatial-temporal visual attention model.
Result
Standard datasets and practical videos are selected for the experiments. The experiments are performed on a MATLAB R2012a platform. The experimental results show that our spatial-temporal visual attention model demonstrates favorable robustness under various scenes, including indoor train station surveillance videos and outdoor scenes with swaying leaves. Our proposed model outperforms the visual attention model of Itti, the graph-based visual saliency model, the phase spectrum of quaternion Fourier transform model, and the motion channel model of Liu in terms of pedestrian detection. The proposed model achieves a 93% accuracy rate on the test video.
Conclusion
This paper proposes a novel pedestrian method based on the visual attention mechanism. A spatial-temporal visual attention model that uses low-level and semantic features is proposed to calculate the saliency map. Based on this model, the pedestrian targets can be detected through focus of attention shifts. The experimental results verify the effectiveness of the proposed attention model for detecting pedestrians.

Évaluation objective de la séquence de récupération des fibres sensitives de la troisième division du nerf trijumeau suite à une ostéotomie sagittale mandibulaire bilatérale (OSMB)

Le projet de recherche est une étude prospective consistant à déterminer la séquence de récupération des fibres sensitives de la troisième division du nerf trijumeau (V3) suite à une ostéotomie sagittale mandibulaire bilatérale (OSMB). Dix-neuf sujets ont été recrutés entre les mois de mars et septembre 2008. Tous ont eu une chirurgie orthognathique d’OSMB afin de corriger une malocclusion. La sensibilité dans le territoire cutané innervé par V3 de chacun des sujets a été évaluée en pré-opératoire de même qu’à cinq autres reprises en post-opératoire (2, 4, 20, 36 et 52 semaines). Deux méthodes d’évaluation objectives de la récupération nerveuse sensitive ont été utilisées. La première consistait à utiliser un appareil nommé Neurometer afin de déterminer l’intensité minimale de courant électrique (Current Perception Threshold [CPT]) pouvant être ressentie spécifiquement par chacun des trois types de fibres nerveuses sensitives (A-Bêta, A-Delta et C) dans le territoire cutané de V3. La deuxième méthode consistait à utiliser les monofilaments de Semmes-Weinstein afin de déterminer le seuil minimal de pression (Von Frey) pouvant être ressenti dans le même territoire cutané. De plus, lors de chacun des rendez-vous post-opératoires, il a été demandé à chaque sujet de quantifier subjectivement sa sensibilité à l’aide d’une échelle visuelle analogue. Cela a permis de corréler les valeurs de CPT, les seuils de perception de la pression et l’évaluation subjective que le patient a de sa propre sensibilité. Il a été démontré que la séquence de récupération des fibres sensitives de V3 suite à une OSMB est la suivante : les fibres A-Delta récupèrent en premier, suivies des fibres C puis des fibres A-Bêta.

Estimates of genetic parameters for visual scores and their correlation with production and reproductive traits in Brahman cattle

The objective of this study was to evaluate the association of visual scores of body structure, precocity and muscularity with production (body weight at 18 months and average daily gain) and reproductive (scrotal circumference) traits in Brahman cattle in order to determine the possible use of these scores as selection criteria to improve carcass quality. Covariance components were estimated by the restricted maximum likelihood method using an animal model that included contemporary group as fixed effect. A total of 1,116 observations of body structure, precocity and muscularity were used. Heritability was 0.39, 043 and 0.40 for body structure, precocity and muscularity, respectively. The genetic correlations were 0.79 between body structure and precocity, 0.87 between body structure and muscularity, and 0.91 between precocity and muscularity. The genetic correlations between visual scores and body weight at 18 months were positive (0.77, 0.57 and 0.59 for body structure, precocity and muscularity, respectively). Similar genetic correlations were observed between average daily gain and visual scores (0.60, 0.57 and 0.48, respectively), whereas the genetic correlations between scrotal circumference and these scores were low (0.13, 0.02, and 0.13). The results indicate that visual scores can be used as selection criteria in Brahman breeding programs. Favorable correlated responses should be seen in average daily gain and body weight at 18 months. However, no correlated response is expected for scrotal circumference.

Integrated visual perception architecture for robotic clothes perception and manipulation

This thesis proposes a generic visual perception architecture for robotic clothes perception and manipulation. This proposed architecture is fully integrated with a stereo vision system and a dual-arm robot and is able to perform a number of autonomous laundering tasks. Clothes perception and manipulation is a novel research topic in robotics and has experienced rapid development in recent years. Compared to the task of perceiving and manipulating rigid objects, clothes perception and manipulation poses a greater challenge. This can be attributed to two reasons: firstly, deformable clothing requires precise (high-acuity) visual perception and dexterous manipulation; secondly, as clothing approximates a non-rigid 2-manifold in 3-space, that can adopt a quasi-infinite configuration space, the potential variability in the appearance of clothing items makes them difficult to understand, identify uniquely, and interact with by machine. From an applications perspective, and as part of EU CloPeMa project, the integrated visual perception architecture refines a pre-existing clothing manipulation pipeline by completing pre-wash clothes (category) sorting (using single-shot or interactive perception for garment categorisation and manipulation) and post-wash dual-arm flattening. To the best of the author’s knowledge, as investigated in this thesis, the autonomous clothing perception and manipulation solutions presented here were first proposed and reported by the author. All of the reported robot demonstrations in this work follow a perception-manipulation method- ology where visual and tactile feedback (in the form of surface wrinkledness captured by the high accuracy depth sensor i.e. CloPeMa stereo head or the predictive confidence modelled by Gaussian Processing) serve as the halting criteria in the flattening and sorting tasks, respectively. From scientific perspective, the proposed visual perception architecture addresses the above challenges by parsing and grouping 3D clothing configurations hierarchically from low-level curvatures, through mid-level surface shape representations (providing topological descriptions and 3D texture representations), to high-level semantic structures and statistical descriptions. A range of visual features such as Shape Index, Surface Topologies Analysis and Local Binary Patterns have been adapted within this work to parse clothing surfaces and textures and several novel features have been devised, including B-Spline Patches with Locality-Constrained Linear coding, and Topology Spatial Distance to describe and quantify generic landmarks (wrinkles and folds). The essence of this proposed architecture comprises 3D generic surface parsing and interpretation, which is critical to underpinning a number of laundering tasks and has the potential to be extended to other rigid and non-rigid object perception and manipulation tasks. The experimental results presented in this thesis demonstrate that: firstly, the proposed grasp- ing approach achieves on-average 84.7% accuracy; secondly, the proposed flattening approach is able to flatten towels, t-shirts and pants (shorts) within 9 iterations on-average; thirdly, the proposed clothes recognition pipeline can recognise clothes categories from highly wrinkled configurations and advances the state-of-the-art by 36% in terms of classification accuracy, achieving an 83.2% true-positive classification rate when discriminating between five categories of clothes; finally the Gaussian Process based interactive perception approach exhibits a substantial improvement over single-shot perception. Accordingly, this thesis has advanced the state-of-the-art of robot clothes perception and manipulation.

A busca visual da cor, como medida avaliadora do funcionamento do sistema visual: um estudo exploratório a propósito da objetividade da felicidade em crianças

Este estudo, procura explicar a modularidade da mente humana, como um conjunto de módulos, permitindo desta forma contribuir para o estudo das ciências cognitivas. Estes módulos da arquitetura mental, permitem que a nossa mente interprete a cor resultante do sistema visual e das longitudes de ondas do espetro eletromagnético refratado dos objetos. Tendo por base o estudo do sistema visual, as células sensíveis, designadas por fotorrecetores percorrem o nervo ótico até atingir o encéfalo, localizando-se aí o sistema percetivo, permitindo desta forma realizar o estudo sobre busca visual da cor, como medida avaliadora do funcionamento do sistema visual, um estudo exploratório a propósito da objetividade da felicidade em crianças, que visa explorar a busca visual disjuntiva da cor como medida objetiva do bom funcionamento mental, do bem-estar subjetivo, como construto da felicidade. A amostra foi constituída por um grupo de 49 crianças não institucionalizadas e por um grupo de 16 crianças institucionalizadas, de ambos os sexos. Para a concretização deste estudo, foi necessária a utilização de uma tarefa de busca visual disjuntiva, que utilizou as simetrias de cores pertencentes ao mesmo par oponente e cores pertencentes a diferentes pares oponentes. Os resultados sugerem que não há qualquer interferência da institucionalização no funcionamento mental, logo no bem-estar subjetivo nas crianças; ABSTRACT: This study seeks to explain the modularity of the human mind, as a set of modules, giving this way a contribution to the study of the cognitive sciences. These modules of the mental architecture, allow our mind to interpret the resulting color of the visual system and the wavelengths of the electromagnetic spectrum refracted from the objects. Based on the study of our visual system, sensitive cells known as photoreceptors, which run along the optic nerve to the encephalon, being the perceptive system located there, allowing in this way to carry out the study on visual search of colour, as an assessment measure of the functioning of the visual system, an exploratory study concerning the objectivity of happiness in children, which aims to explore the disjunctive visual search of color as an objective measure of good mental functioning, of subjective well-being, as a construct of happiness. The sample consisted of a group of 49 non institutionalized children and of a group of 16 institutionalized children from both sexes. For the implementation of this study it was necessary to use a disjunctive visual search task, which used the Symmetry of colours belonging to the same opponent pair, and colours belonging to different opponent pairs. The results suggest that there is no interference from the institutionalization in mental functioning, therefore in the children’s subjective well being.

PLAGUE. Un editor visual para PDDL

Plague es un editor de archivos escritos en lenguajes de planificación como STRIPS y PDDL, que permite lanzar el algoritmo GrahPlan a partir de los archivos de dominio y problema editados y encontrar una solución al problema planteado. El objetivo del editor es eminentemente pedagógico: su uso es muy simple y viene con variados ejemplos de ambos lenguajes de planificación, de modo que el usuario pueda aprenderlos de forma paulatina. Además, la salida de la ejecución permite ir viendo paso a paso el desarrollo del algoritmo GraphPlan: los operadores que se van ejecutando, los no-ops que se han seguido, los mutex que se han aplicado en cada nivel y el tiempo empleado, además de la solución final al problema si se alcanza. El programa hace uso de dos utilidades que permiten compilar el código STRIPS o PDDL que son JavaGP y PDDL4J. Una vez ejecutado el problema de planificación, se obtiene la salida en pantalla y también se puede imprimir el problema completo incluida la solución. El objetivo ha sido crear un programa que permita al usuario editar rápidamente archivos STRIPS y PDDL, los pueda compilar velozmente y obtener el resultado en un solo sitio, con una salida mucho más clara, organizada y entendible y se evite el problema de tener que usar editores externos y una ventana de línea de comando para ejecutar GraphPlan. Plague is a text editor for files written in action languages, such as STRIPS and PDDL, which allows running the GraphPlan algorithm from the domain archives and edited problems, and finding a solution to the proposed problem. The goal of the editor is primarily for pedagogical purposes: it is simple to use and comes equipped with a variety of examples in both action languages, so that the user can gradually learn. In addition, as the editor runs it allows the user to observe the step by step development of the GraphPlan algorithm: the operators being executed, the no-ops that have been followed, the mutex applied at each level and the time spent, as well as the final answer to the problem, if reached. The program uses two utilities allowing the STRIPS or PDDL code to be compiled: JavaGP and PDDL4J. Once the planning problem has been executed, the result is shown on screen and the complete problem can also be printed, including the solution. The objective has been to create a program that allows the user to quickly edit STRIPS and PDDL archives, to compile them swiftly and obtain the solution in a single place, with a result that is clear, organised and understandable, thus avoiding the problem of having to use external editors and command prompts to execute GraphPlan.