Masin S C, Fanton V
Percept Psychophys. 1989 Nov;46(5):483-6. doi: 10.3758/bf03210864.
The point of subjective equality obtained by the method of constant stimuli depends to a great extent on whether the standard (S) or the variable (V) stimulus occurs first. This presentation-order effect was studied using lines as stimuli. Successive S, V pairs were presented, with inter-stimulus and interpair intervals equal. Observers, who were not told which was S or V, reported whether a given line was longer or shorter than the immediately preceding line. Although the observers' subjective experience was of a train of lines that was not organized into pairs, the presentation-order effect still occurred. This implies that the effect does not depend on the order of presentation of the stimuli in an experienced pair. It was also shown that the observers could categorize line lengths, since they could identify stochastically the most frequent stimulus (S). We propose that the presentation-order effect depends on a decision process based on response probabilities inferred from length categories.
采用恒定刺激法所获得的主观相等点在很大程度上取决于标准刺激（S）或可变刺激（V）何者先出现。使用线段作为刺激来研究这种呈现顺序效应。相继呈现S、V对，刺激间间隔和对间间隔相等。未被告知何为S或V的观察者报告某一线段比紧接在前的线段长还是短。尽管观察者的主观体验是一系列未被组织成配对的线段，但呈现顺序效应仍然出现。这意味着该效应并不取决于在经验配对中刺激的呈现顺序。研究还表明观察者能够对线的长度进行分类，因为他们能够随机识别出最频繁出现的刺激（S）。我们提出呈现顺序效应取决于一个基于从长度类别推断出的反应概率的决策过程。
