Subjective averaging of length with serial presentation

The 5s estimated the average of several lengths presented serially one at a time. In Exp. I, the judgment was made only at the end of the sequence. In Exp. II, 5 estimated a cumulative average as each new length was presented. The main phases of these experiments used sequences of six lengths. For the most part, each S's data could be described by a subjective averaging model as tested in single-5 analyses. There was a general recency effect, the later lengths in the sequence having greater influence. Recency was fairly uniform across .Ss with the end responding procedure of Exp. I, but large individual differences in the serial position curves appeared with the continuous responding procedure of Exp. II. In Exp. Ill, two hypotheses about the cause of recency were tested, but received little support. Functional measurement technique showed that subjective length differed from objective length, apparently by a constant error for each 5. It was noted that the present methods could be applied to psychophysical scaling of other stimulus dimensions. Suppose that you are shown several lines, one at a time, and asked to estimate their average length. Can your response be described as a mathematical average? If so, is it an arithmetic mean, geometric mean, weighted midpoint, or some other measure of central tendency? The present experiments were designed to consider this question. They test a subjective averaging model for length. Averaging model.—The basic assumption of the model is that the response (R) at Serial Position N is simply a weighted sum: Rff = L Wk.Sk[1]