Experimental Psychology Volume 2, No. 1; A Manual of Laboratory Practice

by Edward Bradford Titchener

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 ... amount may vary, quite considerably, from stage to stage of a long series of experiments. If our own constant error c has varied in this way, its variation must evidently have affected the value of em as determined above. To-free em of any influence of this sort, we must 'fractionate' the results. We determine 2e, not for the whole group of 100 observations, but for quarter-groups of 25 observations apiece; and we 2e determine em, not as-, but as 100 100 This value is more accurate than the value-. On the other hand, it is 100 indifferent for the determination of the c of each group whether we work from the group as a whole, or separately from the quarter-groups. We come now to the consideration of the constant error, in the interest of which we increased our original 100 to 200 determinations. How are we to analyse it? We have already suggested that c is made up, in part at least, of the regular space error, q. The q errors are, by hypothesis, equal and opposite; they increase or diminish r, according as the two stimuli are disposed in this way or in that; but they increase and diminish it by equal amounts. If, then, these were the only errors involved in c, we ought to find----"=r. As a rule, the equation, does not hold; the average of the two rm turns out to be distinctly or r. Where this is the case, c must have a second component, the sign of which remains unchanged throughout the experiment. We will term it s. Then we rmu-r=+q + s; where the subscript i and u have the same meaning as on p. 65 above (1'=n to the left, n = n to the right), and the signs of q are so chosen that a positive or negative q, as found by the equations, corresponds to a positive or negative space error in Fechner's sense (p. 65). From these equations we Simp...

78 pages, Paperback

Published January 1, 2012