ECVP 2014
ECVP 2014

Illusion night

Following ‘Illusoriamente’ in Alghero and ‘Show time’ in Bremen, the Belgrade ECVP hosts asimilar manifestation, the ‘Illusion Night’.Like the previous events, this is an opportunity for attendees to present a demonstration or exhibit related to their research, including a novel illusion, a variant of an old one, or any imaginative, educational or attractive visual effect, in an informal and interactive environment.The event will take place Monday, August 25th from 18:00 to 19:30 at the Gallery. You are invited to come and participate in the following demonstrations and activities:

Images of Leonardo da Vinci as Artist’s Model: Analysis of Age-Appropriate Paintings and Sculptures Attributable as Portraits of da Vinci
Christopher Tyler (Optometry, City University, London)

There are only two known portraits of Leonardo da Vinci by his contemporaries, both at an older age. It is generally understood that we don’t know what he looked like when young, although Vasari says he was be “a man of outstanding physical beauty” and “infinite grace” who had posed as the model for the sculpture of David by his master, Verrocchio, and other works. Taking this as a cue that he may have been a popular artist’s model when young, I have unearthed several dozen sculptures and paintings by his contemporaries that suggest the evolution of his appearance through age-appropriate depictions as he matured. Integrating this sequence of putative portraits gives us a vivid perceptual image of the young Leonardo da Vinci when he was the chief apprentice and collaborator in the most important artistic studio in the Florence of his era.

Is age related to the color-dependent Fraser-Wilcox illusion?
Akiyoshi Kitaoka (Department of Psychology, Ritsumeikan University, Kyoto)

The color-dependent Fraser-Wilcox illusion is a mysterious phenomenonthat shows dimorphism of illusory motion depending on luminance orilluminance. I will distribute images of highest quality to visitors askinghow they perceive them and their ages because informal observationssuggested a possible correlation.

Dynamic features of 3D illusory surfaces observed in binocular viewing
Masanori Idesawa (UEC Museum of Communications, University of Electro-Communications, Tokyo)

Dynamic features of 3 D Illusory Surfaces with binocular viewing will be demonstrated. By using the anaglyph glasses, stereoscopic observations were realized and dynamic features of 3D illusory surfaces (opaque and/or transparent) can be observed vividly. Contents of demonstrations are as follows:1. Fusion and separation of illusory surfaces. 2. Rotational variation illusions (expansion and shrinking of illusory square, eccentric motion of illusory square, distortion of illusory hexagon, expansion and shrinking of illusory hexagon). 3. Interaction between triangular illusory surfaces: 3D arrangement of two triangular surfaces is changed dynamically. 4. Interaction between rectangular illusory surfaces: depth relations between two rectangular surfaces are changed dynamically. 5. Detecting probe for opaque surface perception: depth relation between the illusory surface and the Poggendorff probe line segments are changed dynamically.

Polygonization Effect
Kenzo Sakurai (Tohoku Gakuin University, Sendai)

Prolonged viewing of a circular shape in peripheral vision produces polygonal shape perception of the circle itself.  I demonstrate the shape distortion illusion can be induced in a short period by alternately presenting a circle and its inward gradation pattern when its temporal frequency is between 2 ~ 4 Hz.  Alternation of a circle and its inward gradation pattern seems to promote adaptation of cortical process responsive to curvatures and induce shape distortion illusion instantly.

The Beuchet Chair
Peter Thompson & Mladen Sormaz (Department of Psychology, University of York)

The Beuchet chair baffles because the two separate parts of the chair are seen as belonging together. Although at different distances, the two parts have appropriate sizes to create the retinal image of a single chair at some intermediate distance. The two figures are now perceived as being at the same distance away and therefore size constancy does not operate. Additionally the far figure must be tiny to fit on the big seat of the chair and the near figure must be huge.

Thatcherise Your Face
Tim Andrews& Andre Gouws (Department of Psychology,University of York)

The Thatcher illusion is one of the best-loved perceptual phenomena and one that continues to challenge models of face processing.  Here you will have the opportunity to see yourself ‘thatcherised’ in real time.   And you can have a photo of your thatcherised face as a souvenir.

A medley of illusion contests past
Arthur Shapiro (American University, Washington D.C.)

My lab frequently presents at the Best Illusion of the Year Contest; eleven entries have been in the top ten since 2005.  Here, I will give a retrospective of some of these presentations for an ECVP audience.  The illusions address ideas related to alternating contrast, spatial filtering, motion, color, vision in the periphery, and grouping. Many of the presentations are interactive and allow people the adjust parameters of the displays.

Exploring Mondrian in Space
Johannes M. Zanker & Jasmina Stevanov (Royal Holloway University of London   &   Kyoto University)

Mondrian unique style is recognised through his variation of paintings that embed rectangles of basic colours in rectangular grids of black lines. Whilst these iconic two-dimensional paintings are designed for fronto-parallel viewing, Mondrian placed them carefully in the three-dimensional space of his studio (e.g., Paris 1926), demonstrating his conviction that ‘a room should not be an empty space, limited by six empty planes which are merely opposite of each other’. Not only became his studio a theatrical stage with movable panels, which led him into deeper experiment with the geometric three-dimensional abstractions of De Stijl, but he also included an intriguing model of a theatre stage with exchangeable panels in the ensemble. His architectural experiments were concerned with cubistic spaces, such as the design plan for Ida Benert’s Library (1926), which we reconstructed previously (ECVP demo night 2012) to highlight compositional problems with perspective projections. One possibility to get around such ‘violations’ of rectangular composition in cubic space is the mounting of Mondrian compositions on a cylindrical 3D surface, and we will demonstrate this in the Virtual Reality of the ‘Mondrian-like’ studios. Just to explore the limits of different perspective interpretations, we furthermore constructed a Physical Reality model of a corridor covered with Mondrian patterns using inverse perspective – in the style of Robert Hughes – which takes the paradox of Mondrian composition in space to another level.

See what your hands feel: Measuring the Uznadze aftereffect
Daniele Zavagno & Olga Daneyko (Psychology Department, University of Milano-Bicocca)

The demonstration is interactive and will allow to experience firsthand the strength of the Uznadze haptic size after effect, and to measure its magnitude using a visual scale. The demonstration consists of an adapting momentum that takes about 3-4 minutes, and the after effect experience. The effect is robust and pretty strong.

Making our retinal blood vessels visible
MariannHudák&JánosGeier (PázmányPéter Catholic University, Department of General Psychology, Budapest, Stereo Vision ltd, Budapest)

We aim to revive a known, but undeservingly rarely cited phenomenon. We show how to make the shadows of our retinal blood vessels visible by a spot lamp, after Ditchburn (1973).We take 10-12 spot lamps to the Showtime, which visitors can move in the corner of their eyes based on our instructions. The experience is fascinating and surprising: the pattern of our blood vessel is seen sharply and in full detail as their shadow slightly moves.This phenomenon is an example of stabilized retinal images. As already known, if it is provided that the retinal image is stationary relative to the retina by means of suitable equipment (not moved by the tremor of the eye), the image disappears within few seconds. If the image is moved, it reappears (Yarbus, 1967). The shadow of retinal blood vessels provides a perfect stabilized image phenomenon.Stabilized retinal images have an important theoretical relevance. Although physical change occurs only near the edges due to the tremor of the eye, colours are perceived in the entire inner area of large homogeneous fields (Cornsweet, 1974). This is straightforward evidence for the claim that filling-in mechanism starting from the edges is a necessary condition for seeing.

Rotating Columns
Vicky Froyen &Daglar Tanrikulu (Department of Psychology, Center for Cognitive Science, Rutgers University, New Brunswick)

Adding textural motion to classic figure-ground displays reveals complex interactions between accretion-deletion and geometric (static) figure-ground cues. Interestingly geometric cues can be found to overwrite the standard occlusion interpretation of accretion-deletion resulting in such regions to be perceived as figural, and rotating in 3D. Surprisingly, this occurs despite the textural motion being linear and therefore inconsistent with 3D rotation.

Autonomous Sensory Meridian Response (ASMR)
Funda Yildirim (University of Groningen)

If you browse for ASMR on Youtube, you will find thousands of videos that people watchto get themselves into a pleasant and relaxed state of mind. This is as a result of a ‘tingling’ sensation that is caused by certain visual and auditory triggers intentionally integrated in these videos. To name a few examples for these multisensory triggers, someone painting on a canvasor you being a subject in a visual science experiment can cause these ‘tingles’. The most common ASMR triggers received during personal attention, facial attention, observing hand gestures, tapping on objects and writing/drawing on paper.ASMR is often associated with synesthesia, sinceit is a sensation that not everyone experience. It also has similarities with hypnosis as the relaxation feeling isused for self-treatment of anxiety and depression.In the illusion night, people will get to experience ASMR andthey will begiven a chance to pick their personal favorites.

Color Motion Standstill and Capture Induced by Random Dot Luminance Masks
Max R. Dürsteler (University Hospital Zurich, Department of Neurology, Zurich)

According to current experimental evidence a common neuronal pathway analyses global motion and complex motion (e.g. global translation, rotation, expansion/contraction, and shearing). Conflicting inputs from different modalities such as the luminance system and the color system should result in motion capture (a physically moving stimulus appears as motionless) or motion standstill (a physically stationary stimulus is perceived as moving) illusions, if one of the conflicting inputs is suppressed. Otherwise, a percept of separate motion components arises (i.e. motion transparency). In the demonstration, the color system is probed with isoluminant red and green stimuli overlaid by a random-dot pattern. At low speeds, the perceived global motion appears dominated by the overlaying dot texture resulting either in color motion standstill with stationary dots or in color motion capture with moving dots. At higher speeds different outcomes for either smooth or sharp transitions between red and green can be observed. While the perceived motion of smooth color borders is still dominated by the dots’ motion, sharp color borders are perceived as moving separately from the overlying dots.

Secrets of ‘Witch Rings’
Priscilla Heard & David Phillips (University of the West of England, Bristol)

Experience the weird magic ring on your finger. Turn it round and see it expanding and contracting. These strange rings were known historically as ‘Witch Rings’ because of their baffling powers. We will show them small on your fingers and big with CCTV on a screen and present demonstrations of some novel proposals about what might be going on in the visual system.

Saccade Viewer (see your own saccades!)
Peter April (VPixx Technologies Inc.)

VPixx Technologies will use its PROPixx DLP projector running at a refresh rate of 1440Hz to generate a scanning spot on a projection screen. When you make a saccade while looking at the screen, the scanning spot will trace a perceptible ogive curve on your retina. The perception is a visible plot showing eye position as a function of time. Does saccade speed depend on saccade amplitude? Try it and see for yourself!

Make your own spectroradiometer
Caterina (Katia) Ripamonti and Jakob Thomassen (Cambridge Research Systems)

We will show you how to build your own spectrometer from a piece of black cardboard, a diffraction grating made from a DVD-R, and adhesive tape. This simple own-made device can be placed in front of a mobile phone camera or a webcam, to capture the diffracted light. We will also demonstrate how to calibrate such device, using reference light sources made from elements of Helium and Hydrogen. A spectroradiometer is a light measuring device which returns the spectral power distribution of the light as a function of wavelength. There are several factors that determine its accuracy, among which its optical components and its calibration. Our crafty activity offers an opportunity to come and talk about how to measure the properties of light that are crucial for your experiments.

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