Search results for " illusion"

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

La chiesa di S. Spirito in Agrigento. Stucchi di Serpotta e illusionismo pittorico-architettonico

2009

Cognitive Impairment in Multiple Sclerosis Is Reflected by Increased Susceptibility to the Sound-Induced Flash Illusion

2019

Objective: To determine whether the performance of multiple sclerosis (MS) patients in the sound-induced flash illusion (SiFi), a multisensory perceptual illusion, would reflect their cognitive impairment.Methods: We performed the SiFi task as well as an extensive neuropsychological testing in 95 subjects [39 patients with relapse-remitting MS (RRMS), 16 subjects with progressive multiple sclerosis (PMS) and 40 healthy control subjects (HC)].Results: MS patients reported more frequently the multisensory SiFi than HC. In contrast, there were no group differences in the control conditions. Essentially, patients with progressive type of MS continued to perceive the illusion at stimulus onset a…

A Mission Impossible? Learning the Logic of Space with Impossible Figures in Experience-Based Mathematics Education

2016

Most visual effects based on mathematically and physically describable phenomena and formalizable processes. Creating visual illusions, paradox structures and ‘impossible’ figures through playful and artistic procedures, holds an exciting pedagogical opportunity for raising students’ interest towards mathematics and natural sciences and technical aspects of visual arts. The Experience Workshop Math-Art Movement has a number of pedagogical methods, which are connected to visual paradoxes and perspective illusions. In the first part of our article, we introduce classroom exercises connected to the Hungarian artist Tamás F. Farkas’s paradox structures and impossible figures. There are certain …

Cathodal occipital tDCS is unable to modulate the sound induced flash illusion in migraine

2019

Migraine is a highly disabling disease characterized by recurrent pain. Despite an intensive effort, mechanisms of migraine pathophysiology still represent an unsolved issue. Evidence from both animal and human studies suggests that migraine is characterized by hyperresponsivity or hyperexcitability of sensory cortices, especially the visual cortex. This phenomenon, in turn, may affect multisensory processing. Indeed, migraineurs present with an abnormal, reduced, perception of the Sound-induced Flash Illusion (SiFI), a crossmodal illusion that relies on optimal integration of visual and auditory stimuli by the occipital visual cortex. Decreasing visual cortical excitability with transcrani…

Color induction via non-opponent lateral interactions in the human retina

1992

Retinal connections causing colors in Benham's top (pattern induced flicker colors, PIFCs) are investigated by psychophysical experiments. PIFCs are still seen when stimuli to different cones are demodulated selectively, indicating the involvement of non-opponent channels. PIFCs also occur on retinal areas next to those affected by modulated stimuli; further, both monochromat and dark-adapted trichromats perceive PIFCs which are achromatic. These additional findings point to horizontal cells as neuronal mediators of modulated excitation leading to PIFCs. The unspecifity of the postulated connection with respect to cone types agrees with anatomic findings of Boycott, B. B., Hopkins, J. M. an…

Optical illusions in scanning electron micrographs: the case of the eggshell of Acrosternum (Chinavia) marginatum (Hemiptera: Pentatomidae)

2003

Scanning electron microscopy revealed that-as is common in this family of the Hemiptera-the eggs of the green stink bug Acrosternum (Chinavia) marginatum are roughly barrel-shaped and possess at their apical pole a row of slender extensions, the aero-micropylar processes. The outer surface of the eggshell carries hexagonally arranged pits. The analysis of cross-fractured eggshells showed that the pits have slender basal extensions with transverse diaphragms. When scanning electron micrographs of the egg surface of A. marginatum are viewed upside down, the perception flips and the pits appear as elevations to all observers addressed. Thus, we are dealing with an optical illusion, which is kn…

Inverting the Wollaston Illusion: Gaze Direction Attracts Perceived Head Orientation

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 o…

100 Years of Benham's Top in Colour Science

1995

For 100 years Benham's top has been a popular device demonstrating pattern-induced flicker colours (PIFCs). Results of early and recent investigations on PIFCs are reported and show that the phenomenon originates in phase-sensitive lateral interactions of modulated neural activity in the retina followed by additional spatial interactions in the visual cortex behind the locus of binocular fusion. Colour matches with normal colour stimuli indicate that S/(M + L) opponent neurons are involved. Dichromats do not find matching stimuli for all PIFCs. PIFCs may become useful in medical diagnosis. The phenomenon is interpreted as a side effect of a neural mechanism providing colour constancy under…