Fernberger, S. W. (1920). Interdependence of judgments within the series for the method of constant stimuli. Journal of Experimental Psychology, 3(2), 126-150.
http://dx.doi.org/10.1037/h0065212
Examined whether there was operative, for the method of constant stimuli, any effect of one judgment upon another within the series; that is to say, whether the passing of a judgment of a certain category has any influence upon the succeeding judgment. In other words, we wish to ascertain if the order of the presentation of the series of stimuli has any effect upon the relative frequencies of the categories of judgment. In order to determine this matter experimentally, lifted weights were used as stimuli. Immediately after the lifting of each comparison weight, a judgment was given verbally in terms of the second weight. The subject employed the three categories of 'lighter,' 'equal' and 'heavier,' which were defined in the usual manner. The observed relative frequencies of the different categories of judgment upon each of the comparison pairs thus obtained were treated in accordance with the methods of calculation developed by Urban. Four observers took part in this investigation. In conclusion, there is present, in the method of constant stimuli as applied to lifted weights, a contrast effect between the pairs of stimuli. If a comparison stimulus, which is likely to fall within the interval of uncertainty, immediately follows the lightest pair, for which, of course, the judgment is usually 'lighter,' there is a strong tendency that it will be judged 'heavier.' If it follows the heaviest pair--which usually gives the judgment 'heavier'--there is an equally strong tendency that it will be judged 'lighter." The presence of this factor of contrast causes a distortion of the curves for the psychometric functions for the 'lighter' and 'heavier' judgments. It has a slight effect upon the size of the interval of uncertainty and a very marked effect upon the position of the thresholds and of the point of subjective equality. There seems to be a slight tendency for the effects of this factor of contrast to increase with practice. It seems doubtful if simple instructions given the observer will eliminate the effects of this factor of contrast--for the habituated subject at least. A method of eliminating the effects of the factor of contrast by handling the objective relations of the stimuli themselves is suggested. (PsycINFO Database Record (c) 2016 APA, all rights reserved)