(10) Determine the range of attention (a) by help of an ordinary metronome, set at various rates. You must not count the beats, since every count would mean a separate attention. Determine the range also (b) by help of the letter-diagram and cardboard screen figured by W. Wundt, An Introduction to Psychology, 1912, 19. Notice the remark (p. 23) that the experimenter must practise covering and uncovering the diagram.
(11) Paint or paste a small disc of light grey on a white cardboard ground. Move so far away that the spot is only just distinguishable. Call out Gone! and Back! as it disappears and reappears, and have the times noted on the seconds-dial of a watch. Explain the fluctuation, in your own words, as due to adaptation and eye-movement. Can you devise a simple method of showing (by means of the negative after-image) that unnoticed eye-movements really occur?
(12) St. Thomas asks whether the mind can grasp more than one thing at a time; and replies that it can, if the various things are regarded as making up a single whole, but that it cannot, if they are regarded in their variety and particularity. Can you put all this into psychological language? And can you find any difference between St. Thomas’ question and our own question as to the range of attention?
Sir W. Hamilton, Lectures on Metaphysics, i., 1859, 254; W. B. Carpenter, Principles of Mental Physiology, 1888, ch. iii.; W. James, Principles of Psychology, i., 1890, ch. xi.; W. Wundt, Lectures on Human and Animal Psychology, 1896, Lect. xvii.; Outlines of Psychology, 1907, § 15; W. B. Pillsbury, Attention, 1908; E. B. Titchener, Lectures on the Elementary Psychology of Feeling and Attention, 1908, Lects. v.-viii.; Text-book of Psychology, 1910, 265 ff.
[CHAPTER V]
Perception and Idea
If we cross the fingers, a single object beneath them appears to be two; and yet we do not say that there are two, for sight is more decisive than touch; but if touch were our only sense, our judgment would declare that the single object is two.—Aristotle