Search results for "Illusio"

O047. The sound-induced flash illusions reveal visual cortex hyperexcitability in cluster headache

2015

Objectives Pathophysiology of cluster headache (CH) is not wellknown. Although posterior hypothalamus has been suggested to play a pivotal role, evidence exists of a more diffuse involvement of the central nervous system including brainstem and cerebral cortex. In this regard, we recently observed increased motor cortical excitability in episodic CH patients both outside and inside bout [1]. The sound-induced flash illusions (SIFI) represent an example of multisensory integration, and provide a tool to indirectly explore the excitability state of the visual cortex [2]. SIFI are classified as “fission” and “fusion” illusions. When one visual stimulus (flash) is accompanied by two or more aud…

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…

Film: kreowanie iluzji czy dialog? Irytująca widoczność narzędzi warsztatu filmowego

2012

Op art et roman virtuel : correspondances entre Escher et Perec

2012

Op art et roman virtuel : correspondances entre Escher et Perec Les structures mathématiques, la notion de réalité comme « humaine illusion », le défi à l’infini et la structure énigmatique qui donne aux œuvres eschériennes la même structure que celle d’un roman policier permettent d’établir des convergences significatives entre le graveur hollandais et Georges Perec. Dans certaines œuvres de Perec, en effet, il est possible de remarquer des références explicites au graveur bien qu’elles constituent la traduction visuelle de l’angoisse du « retour du semblable », du « retour involontaire au même point ». Mais Perec ne se limite pas seulement à citer Escher, puisque certaines de ses œuvres c…

Illusion of knowledge through Facebook news? Effects of snack news in a news feed on perceived knowledge, attitude strength, and willingness for disc…

2020

Abstract Research indicates that using social network sites as a source for news increases perceived knowledge even if, objectively, people fail to acquire knowledge. This might result from the frequent repetition of topics in news posts caused by multiple news outlets posting about the same news topics and the algorithm that favors similar postings. These repeated encounters can have a positive effect on the perception of knowing more, even if actual learning hardly occurs. An experiment (N = 810, representative of German Internet users) tested these assumptions. Participants were assigned to one of four groups and received a news feed with no information, few news posts, many news posts, …

A Functional Magnetic Resonance Imaging Assessment of Small Animals Phobia Using Virtual Reality as a Stimulus

2014

[EN] Background: To date, still images or videos of real animals have been used in functional magnetic resonance imaging protocols to evaluate the brain activations associated with small animals phobia. Objective: The objective of our study was to evaluate the brain activations associated with small animals phobia through the use of virtual environments. This context will have the added benefit of allowing the subject to move and interact with the environment, giving the subject the illusion of being there. Methods: We have analyzed the brain activation in a group of phobic people while they navigated in a virtual environment that included the small animals that were the object of their pho…

Decorative elements in the medical imaging area improve patients’ perception of pleasantness

2014

Abstract Objectives To evaluate the sensation of pleasantness perceived by patients attended in the radiology department in response to decorative elements hung on the walls in the waiting rooms and in the hallways of the imaging area. Material and methods The material resources comprised works of art in the form of “magic windows” representing scenes from nature installed on the ceilings and walls of the waiting area and hallways of the imaging area. Patients were given a brief questionnaire with general data and questions (sadness–cheerfulness, coldness–warmth, darkness–light, and pessimism–optimism) about their perception of the decorative elements. Results Of the 150 questionnaires coll…

O046. Color vision and visual cortex excitability are impaired in episodic migraine. Simply coexisting or pathophysiologically related dysfunctions?

2015

Background and objectives Evidence of abnormal color vision processing in migraine comes from observation of positive symptoms during visual aura, effects of strong color contrast triggering attacks and of colored-spectacles reducing migraine frequency. Although the central or peripheral basis of such color misperception remains unclear, several authors reported a selective deficit of shortwavelength cones (S-cones) [1]. Sound-induced flash illusions (SIFI) are a simple way to describe visual distorsion induced by acoustic perception. SIFI critically depend on excitability of primary visual cortex (V1) as they are reduced by facilitatory anodal transcranial direct current stimulation (tDCS)…

O069. Menstrual cycle affects cortical excitability differently in females with migraine and in healthy controls: a new perspective by cross modal so…

2015

The sound-induced flash illusions (SIFI) represent a valid tool to explore multimodal perception and are critically dependent on visual and acoustic cortical excitability [1, 2]. In a previous study [3], we observed a significant reduction of illusions in migraine patients with respect to healthy controls, probably due to a condition of visual cortex hyperexcitability. Aim of the present study was to evaluate SIFI perceptions in healthy women and patients with menstrual migraine and to describe the effects of cyclical change of steroid hormones and cortical responsiveness.