1,721,123 research outputs found
Cognitive Biases and Gaze Direction: An Experimental Study
No full textThis paper investigates the validity of the model of dual processing by means of eyetracking methods. In this theoretical framework, gaze direction may be a revealing signal of how automatic detection is modified or sustained by controlled search. We performed an experiment by using a stylized decisional framework, i.e. informational cascade, proposed by economists to investigate the rationality of imitative behavior. Our main result is that automatic detection as revealed by gaze direction is driven by mechanisms that are dependent on cognitive biases. In particular, we find significant statistical correlation between overconfident subjects’ first fixation
and their revealed patterns of choice. This implies that gaze direction is driven by cognitive processes in a way that is not necessarily consistent with the efficient processing of informatio
Cerebrotendinous xanthomatosis.Heterogeneity of clinical phenotype with evidence of previosuly undescribed ophthalmological findings
No full textCerebrontendinous xanthomatosis (CTX) is a rare autosomal recessive neurometabolic disease involving lipid metabolism. The classical phenotype is characterized by neurological dysfunction, tendon xanthomas and juvenile cataracts. Other ophthalmological findings have occasionally been reported. To gain more insight into the type and frequency of ophthalmological alterations in this multisystem metabolic disorder, we examined 13 CTX patients. Besides cataracts, found in all cases, the second most frequent ocular abnormality was paleness of the optic disk, which was found in 6 patients and was probably previously underestimated. Signs of premature retinal senescence were also observed. We discuss the possible relation between these ocular manifestations and the metabolic defect
Evaluating the Influence of Motor Control on Selective Attention through a Stochastic Model: The Paradigm of Motor Control Dysfunction in Cerebellar Patient.
Full text linkAttention allows us to selectively process the vast amount of information with which we are confronted, prioritizing some aspects of information and ignoring others by focusing on a certain location or aspect of the visual scene. Selective attention is guided by two cognitive mechanisms: saliency of the image (bottom up) and endogenous mechanisms (top down). These two mechanisms interact to direct attention and plan eye movements; then, the movement profile is sent to the motor system, which must constantly update the command needed to produce the desired eye movement. A new approach is described here to study how the eye motor control could influence this selection mechanism in clinical behavior: two groups of patients (SCA2 and late onset cerebellar ataxia LOCA) with well-known problems of motor control were studied; patients performed a cognitively demanding task; the results were compared to a stochastic model based on Monte Carlo simulations and a group of healthy subjects. The analytical procedure evaluated some energy functions for understanding the process. The implemented model suggested that patients performed an optimal visual search, reducing intrinsic noise sources. Our findings theorize a strict correlation between the "optimal motor system" and the "optimal stimulus encoders.
Fast versus slow: different saccadic behavior in cerebellar ataxias
No full textSpinocerebellar ataxia type 2 (SCA2) is a genetic neurodegenerative disorder primarily characterized by involvement of the brainstem and cerebellum, basal ganglia, spinal cord, cerebral cortex, but white matter is also involved. In late-onset cerebellar ataxia (LOCA), the cerebellum is mainly involved, as demonstrated by clinical and neuroradiological findings. These neurodegenerative diseases are often associated with progressive abnormalities in eye movement control, particularly saccadic changes. We recorded saccadic eye movements in eight SCA2 patients and 10 LOCA patients. Here, we suggest that abnormalities in saccadic parameters differ in the two groups of patients according to specific anatomical substrates. The different saccadic behavior observed in these two clinically distinct degenerative cerebellar diseases offers the opportunity to simplify some general mechanisms of saccadic motor control. Like his mentor Fred Plum, John Leigh strongly encouraged younger neuroscientists to tackle neurological problems by investigating "pathological physiology." With this teaching in mind, we studied patients with rare neurometabolic and neurodegenerative diseases
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