Volume 1
A text-book of experimental psychology : with laboratory exercises / by Charles S. Myers.
- Charles Samuel Myers
- Date:
- 1911
Licence: Public Domain Mark
Credit: A text-book of experimental psychology : with laboratory exercises / by Charles S. Myers. Source: Wellcome Collection.
93/370 page 73
![chosen. Three such colours are called the ‘ primary5 colours. They may be represented as occupying the angles of a triangle (fig. I, page 77), along two of the sides of which may be marked off spectral colours that are inter¬ mediate in wave length between those at the angles. It is possible to produce any colour sensation, by mixing these three colours (if necessary, with black and white) in other proportions (exp. 49). Within this triangle a point W may be found, which will yield a white sensation when a straight line is drawn through that point between any points on opposite sides of the triangle. That is to say, every colour has a corre¬ sponding colour which, when presented simultaneously to the same retinal area, produces a colourless sensation. Such colours are called ‘ complementary ’ to one another (exps. 50, 5 0- [It might be expected that the hue of a colour stimulus would become more intense, the greater the intensity of the stimulus. But, beyond a certain limit, further increase of the intensity of the stimulus causes the corresponding colour sensation to pass over gradually into a colourless sensation. Indeed, any colour stimulus, if sufficiently intense, is seen as white. Intense spectral reds and orange, and greens up to a wave length of 517X9 acquire a yellow hue before they in this way become colourless. A green, of a somewhat shorter wave length than 517X, can be found, which passes over into white without change of colour tone. Intense colour stimuli, of still shorter wave length, become blue before they become colourless.] Under certain conditions, all colour stimuli, if sufficiently feeble, become reduced to the colourless (black-white) series. Conversely, all feeble colour stimuli produce, under suitable conditions, a colourless sensation, and as they become stronger, yield a colour (or * chromatic ’) sensation. The conditions of this so-called ‘ photochromatic ’ interval will be discussed later. The photochromatic interval appears upon diminution of 1 X signifies a millionth part of a millimeter.](https://iiif.wellcomecollection.org/image/b3135984x_0001_0093.jp2/full/800%2C/0/default.jpg)
