OTHER INSTRUMENTS. Apparatus employed in the study of the more complicated mental proc esses have, as a rule, the special form given them by individual investigators. There are several forms of memory apparatus, the essential feature of which is the serial exposure of words, letters, etc., to be memorized by the observer. In work upon recognition. it is usual to adopt sonic one of the pieces given under the headings Psychologi cal Acoustics and Psychological Optics. Some thing has been done, in the study of imagination, IT aid of the symmetrical figures formed by folding upon itself a piece of paper upon which an ink-blot has been made; recourse is also had to the suggestions aroused by printed sentences or paragraphs. Individual psychology has its own materials, of specia113- prepared proof-sheets or pages of printer's pi. letter-patterns upon ruled cards. etc:, etc. Finally, it may be said that the apparatus described in the body of the article above are, in general, the simplest of their kind; many more elaborate instruments have been de vised, as e.g. for the study of rhythm.
Every laboratory must possess a good stock of general supplies, for u-se with the above-men tioned special apparatus. We may refer, in particular, to chemical and photographic ma terials; electrical appliances—motors, cells, storage batteries, switches, keys. wires; mechan ical supplies—tools, balances, materials for the construction and repair of simple instruments, standards, arms. clamps, etc., for the building up
of complex apparatus; projection lantern, and wall charts.
In the light of the above discussion, the figures of the plates will be largely self-explanatory. The sound pendulum was first invented by Vechner; it is figured in the form given it by Wundt. The combined color-mixer and campim eter was devised by Hering. Figs. 2, 3. 4, 6, 7, S of this Plate are taken from Titchenees Experi mental Psychology. The Appunn tonometer is a box containing reeds, differing by 4 complete vi brations; it is used for investigations of sensi ble discrimination, etc. The figure of Zwaarde maker's olfactometer shows the appliances used for the simultaneous record of the observer's breathing curve. The Deprez signal is a time marker, replacing the tuning-fork referred to in the text. Masson's disk is employed in experi ments on the fluctuation of visual attention. Figs. 2, 4, 5, 9, 10 of this Plate are taken from Titchen eels Experimental Psychology; Fig. 7 is from Sanford's Laboratory Course.
Consult the authorities referred to under LABORATORY, and especially the catalogues of in strument-makers listed in Titchener. Experi mental Psychology (New York, 1901). Sec DURA TION ; ILLCSION.