Psychology : an introductory manual for the use of students / by F. Ryland.

  • Ryland, Frederick, 1854-1902.
Date:
1900
Catalogue details

Licence: In copyright

Credit: Psychology : an introductory manual for the use of students / by F. Ryland. Source: Wellcome Collection.

    171/360 (page 155)
    posure, and exhibiting the colours complementary to those of the original. Some writers (Fechner) keep the name after-images for the second type; and call the former memory-after- images. To produce the latter, attention is necessary, and, as we have said, a very short fixation of the original. Something analogous to the visual after-image occurs in other orders of sensation. After knocking at a front door, we are often so acutely conscious of the sound that we can count the blows, although we did not do so when they actually fell on our ear. In the same way we often count the strokes of the church clock after it has ceased to sound. After-images of hearing also occur after noises of great intensity; a railway whistle continues for some seconds to ring in our ears. Negative after-images of taste have been noticed. After very sweet solutions, a sourish taste occurs (possibly due to the rapid formation of acids), and after very bitter ones, a sweetish taste. That tastes interfere with each other is well known; the palate is spoiled for wine after eating sweetmeats. There are temperature after-images, all positive, which can be experienced by pressing a cold coin to the forehead ; on removing it the sensation of cold remains though the temperature of the skin is rising. There are contact after-images, and these can be experienced by touching the back of the hand with the top of a penholder.