Search results for "illusion"
showing 10 items of 110 documents
Paradox lost: variable colour-pattern geometry is associated with differences in movement in aposematic frogs
2014
Aposematic signal variation is a paradox: predators are better at learning and retaining the association between conspicuousness and unprofitability when signal variation is low. Movement patterns and variable colour patterns are linked in non-aposematic species: striped patterns generate illusions of altered speed and direction when moving linearly, affecting predators' tracking ability; blotched patterns benefit instead from unpredictable pauses and random movement. We tested whether the extensive colour-pattern variation in an aposematic frog is linked to movement, and found that individuals moving directionally and faster have more elongated patterns than individuals moving randomly and…
Perception of illusory surfaces and contours in goldfish
2007
Goldfish(Carassius auratus)were trained to discriminate triangles and squares using a two choice procedure. In the first experiment, three goldfish were trained with food reward on a black outline triangle on a white background, while a black outline square was shown for comparison. In transfer tests, a Kanizsa triangle and a Kanizsa square were presented, perceived by humans as an illusory triangle- or square-shaped surface of slightly higher brightness than the background. The choice behavior in this situation indicates that goldfish are able to discriminate between both figures in almost the same way as in the training situation. In control experiments goldfish did not discriminate betwe…
A Fuzzy Approach to the Role of Symmetry in Shape Formation: The Illusion of the Scalene Triangle
2009
The main purposes of this work are to demonstrate the role of directional symmetry as a second order principle that polarizes the perception of the shape and to show how this preference can be easily encoded in an algorithm using a fuzzy operator for symmetry detection. The role of grouping in influencing shape perception and the role of directional symmetry was demonstrated through small triangles that create a large triangle. The specific questions answered in the psychophysical experiments were the following: Can the grouping by similarity influence both the pointing and the shape of the small and the large isosceles triangles? Conversely, can the shape of the large triangle influence th…
Sobre De somniís liber de Augerius Ferrerius
2004
E-mail @uv.es: privado (a solicitud del interesado) En este libro Ferrer, en plena época renacentista, hace compatibles las teorías oníricas de los autores griegos con sus principios y punto de vista cristianos. Niega tajantemente que existan ensueños vanos y se interesa por los ensueños naturales, cuya génesis está en el estado psicofísico del individuo. Pero, sobre todo, presta su máxima atención a los ensueños divinos. Establece normas para distinguir éstos de los enviados por los malos espíritus. Afirma que ha descubierto mediante la razón y la propia experiencia claves para la interpretación de los ensueños que los filósofos anteriores no llegaron a descubrir. In this book, published d…
Impairment of Temporal Binding Window in Migraine Patients
Why are out-of-body experiences interesting for philosophers?
2009
After decades of only sparse scientific interest, we are currently witnessing a renaissance of empirical research into out-of-body experiences (OBEs) and full-body illusions. Being a philosopher of mind, I obviously have only a limited judgment of how good this research actually is from a purely scientific point of view. What I can do, however, is to draw attention to a series of theoretical aspects that make OBEs a particularly relevant target of investigation in the ongoing search for the neural correlate of self-consciousness and in the wider context of an empirically grounded theory of the human mind. Firstly, and most basically, this type of research has a great potential for conceptua…
Sensorimotor aspects of high-speed artificial gravity: I. Sensory conflict in vestibular adaptation
2003
Short-radius centrifugation offers a promising and affordable countermeasure to the adverse effects of prolonged weightlessness. However, head movements made in a fast rotating environment elicit Coriolis effects, which seriously compromise sensory and motor processes. We found that participants can adapt to these Coriolis effects when exposed intermittently to high rotation rates and, at the same time, can maintain their perceptual-motor coordination in stationary environments. In this paper, we explore the role of inter-sensory conflict in this adaptation process. Different measures (vertical nystagmus, illusory body tilt, motion sickness) react differently to visual-vestibular conflict a…
2021
In the early 19th century, William H. Wollaston impressed the Royal Society of London with engravings of portraits. He manipulated facial features, such as the nose, and thereby dramatically changed the perceived gaze direction, although the eye region with iris and eye socket had remained unaltered. This Wollaston illusion can be thought of as head orientation attracting perceived gaze direction when the eye region is unchanged. In naturalistic viewing, the eye region changes with head orientation and typically produces a repulsion effect. Here we explore if there is a flip side to the illusion. Does the gaze direction also alter the perceived direction of the head? We used copies of the …
webAppOS: Creating the Illusion of a Single Computer for Web Application Developers
2020
Unlike traditional single-PC applications, which have access to directly attached computational resources (CPUs, memory, and I/O devices), web applications have to deal with the resources scattered across the network. Besides, web applications are intended to be accessed by multiple users simultaneously. That not only requires a more sophisticated infrastructure but also brings new challenges to web application developers.