Lecture
Illusion of Aristotle
| If you cross the middle and index fingers on your hand and touch the pads of these fingers to the tip of the nose with eyes closed at the same time, you get the illusion of doubling it. |  |
Weber's illusion
Cold objects seem heavier than warm objects of the same weight.
Illusion of sound contrast
The sound of the same power against a background of quieter sounds seems louder than against a background of louder ones.
Illusion of the moon
| The apparent (apparent) size of a celestial body - the Moon or the Sun - is about 1.5 times larger when it is low above the horizon than when it is high in the sky. This is really an illusion. You can make sure of it if you try to close the moon with your thumb at arm's length. It will equally hide both the ascending lunar disk and the planet at its zenith. |  |
Illusion of Muller-Schumann
After repeatedly lifting a heavy load, the lighter load seems lighter than it actually is and, conversely, after lifting a light load, the heavier load seems even heavier.
Illusion Charpentier
If you lift two of the same in weight and appearance, but different in volume of the object, then the smaller one will be perceived by the person as more severe.
Shepard's Illusion
When you increase the volume, the tone is perceived as higher. To check this illusion on yourself, download the wav file (56 Kb).
Bezold-Brücke effect
The effect is to change the shade of light as its intensity changes. If you increase the intensity of relatively long-wave light, such as, for example, yellow-green or yellow-red, it will seem not only brighter, but also "more yellow." Similarly, shortwave light, perceived as blue-green and violet, begins to appear bluer with increasing intensity.
MacGurk effect
| This effect is manifested in the fact that the auditory and visual information, which carries the speech, interact with each other and affect what we hear. Conducting their original research, MacGurk and MacDonald created such conditions under which the auditory signals of the pronounced syllable did not correspond to the corresponding lip movements (McGurk & MacDonald, 1976). The subjects were shown a video of a man who repeatedly pronounced the syllables ga-ga with his lips alone, while the phonogram reproduced the syllables ba-ba. When the subjects closed their eyes and only listened to the soundtrack, they accurately recognized the syllables. Moreover, when they saw only the movements of the lips of the person who spoke, and the phonogram was turned off, they rather accurately identified the pronounced sounds as ga-ga (confirming that if necessary we can read lips and that, perhaps, we do it more often what it seems to us). However, when auditory and visual stimuli conflicting with each other were simultaneously presented to the subjects, they heard sounds that were not found in any of them. For example, when the subjects saw a person on the screen, whose lip articulation corresponded to the ga-ga syllables, and the ba-ba sounded at the same time, most of them heard a completely different sound — da-da ! An interesting detail: most of the subjects did not realize the discrepancy between auditory and visual stimulations. |
You can check the MacGurk effect on yourself by downloading a video file (147 Kb). (A QuickTime player is required to view it) |
Purkinje effect
Purkinje in 1825 noticed that the brightness of blue and red road signs at different times of day was different: during the day both colors are equally bright, and at sunset the blue seems brighter than red. At the onset of deeper twilight colors completely fade and, in general, begin to be perceived in gray tones. Red is perceived as black, and blue as white. This phenomenon is associated with the transition from cone vision to rod with a decrease in light.
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Psychology of errors and illusions
Terms: Psychology of errors and illusions