In fact, the actual size of the moon remains constant as does its distance from the earth. Moon illusion Illusion in which the moon appears much larger at the horizon than when viewed high in the sky. Kundt's illusion Illusion occurring when one attempts to bisect a horizontal line with only one eye and the segment on the temporal side of the visual field is then larger than the other. Jastrow illusion Illusion in which two identical curved and tapering ring segments placed one above the other appear unequal in size, the band nearer the centres of curvature appearing to be the longest (Fig.
Horizontal-vertical visual illusion Illusion in which the vertical line appears longer than the horizontal line when two lines of equal length are placed with the vertical line at the midpoint of the horizontal. Hollow square illusion See café wall illusion. Hole in the hand illusion See hole in the hand test. Hermann's illusion See Hering-Hermann grid. In this case, the two parallel lines appear to bend away from each other (Fig. This illusion is most noticeable when radiating lines are crossing two parallel lines on opposite sides of the point of radiation. Hering's illusion Illusion in which a pair of parallel lines appear bent when placing diagonal lines across them. This type of stimulation is assumed to stimulate the non-linear mechanism within the magnocellular visual system. light bars become dark and vice versa) at a high temporal frequency (more than 15 Hz). This happens when a sinusoidal grating with a low spatial frequency (less than 4 c/deg) flickers in a counterphase fashion (i.e. I6).įrequency doubling illusion Illusion in which a grating pattern appears to have twice as many black and white bars as it actually has. It is a peculiar illustration of physiological diplopia (Fig. A small, disembodied finger with two tips appears floating in between and can be shortened or lengthened by varying the distance between the fingertips. I5).įloating-finger illusion Illusion noted when fixating a point in the distance while the forefingers of each hand are held horizontally about 30 centimetres in front of the eyes, with the fingertips nearly touching. I3).Įbbinghaus illusion Illusion in which a circle usually appears larger when surrounded by smaller circles than by larger circles (Fig.I4).Įhrenstein's brightness illusion Illusion in which the erased area at the intersection of radial (or horizontal and vertical) lines appears to be brighter than the background and with an illusory contour (Fig. I2).Ĭraik-Cornsweet illusion See Craik-O'Brien-Cornsweet effect.ĭelboeuf illusion Illusion in which a circle surrounded by a slightly larger concentric circle appears larger than another circle of the same size surrounded by a much larger concentric circle (Fig. The figure that seems further away appears larger than the one in the foreground (Fig. A variant of this illusion consists of hollow squares without alternating colour and is called a 'hollow square illusion'.Ĭornsweet illusion See Craik-O'Brien-Cornsweet effect.Ĭorridor illusion Illusion in which images of equal size in a perspective figure of a corridor, appear to be of different sizes. Illusion in which a dot placed halfway between a large disc and a smaller disc appears to be nearer the large one.Ĭafé wall illusion An illusion induced by a pattern of alternating columns of black and white rectangles (or squares) placed in such a way that the lines that they compose do not appear to be parallel. Illusion in which a line connecting two large squares appears shorter than a line connecting two smaller squares (Fig. It is not due to eye movements and the illusion disappears as soon as the ambient luminance increases so that other objects become visible. See ambiguous figure.Īutokinetic visual illusion The apparent motion of a luminous object fixated in the dark, or in a large blank field. Illusions can occur with each of the senses. A false interpretation of an object or figure presented to the eye ( visual illusion).
0 kommentar(er)
