(4) A child that has fallen and hurt itself stops crying if you offer it a toy; a soldier who in the heat of battle has received a serious wound may know nothing of it, and may go on fighting till he drops from exhaustion; many a martyr has suffered at the stake with calm serenity. How far are these cases explicable by the laws of attention? (5) Criticise Sir Wm. Hamilton’s experiment. Do not be satisfied till you have found several reasons for distrusting its result. (6) Do the lower animals ever give evidence of derived primary attention? (7) You can follow the movement of a single instrument in the orchestra better, when it has been playing a solo before, than when the whole group of instruments begin together. Why is this? Give other instances of the same law. (8) It has been proposed to measure the degree of attention by measuring the degree of effort which accompanies it. What have you to say to the proposal? (9) How could you tell, by outward observation, whether a child is attentive or inattentive? and whether it is adequate to its task or is in difficulties? Do not just list the symptoms; make your answer psychological. (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? References 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