Ricci Matthew, Gallistel Randy
Brown University, Providence, RI, USA.
Rutgers University, New Brunswick, NJ, USA.
Atten Percept Psychophys. 2017 Jul;79(5):1480-1494. doi: 10.3758/s13414-017-1310-0.
Subjects observing many samples from a Bernoulli distribution are able to perceive an estimate of the generating parameter. A question of fundamental importance is how the current percept-what we think the probability now is-depends on the sequence of observed samples. Answers to this question are strongly constrained by the manner in which the current percept changes in response to changes in the hidden parameter. Subjects do not update their percept trial-by-trial when the hidden probability undergoes unpredictable and unsignaled step changes; instead, they update it only intermittently in a step-hold pattern. It could be that the step-hold pattern is not essential to the perception of probability and is only an artifact of step changes in the hidden parameter. However, we now report that the step-hold pattern obtains even when the parameter varies slowly and smoothly. It obtains even when the smooth variation is periodic (sinusoidal) and perceived as such. We elaborate on a previously published theory that accounts for: (i) the quantitative properties of the step-hold update pattern; (ii) subjects' quick and accurate reporting of changes; (iii) subjects' second thoughts about previously reported changes; (iv) subjects' detection of higher-order structure in patterns of change. We also call attention to the challenges these results pose for trial-by-trial updating theories.
观察来自伯努利分布的多个样本的受试者能够感知生成参数的估计值。一个至关重要的问题是当前的感知——我们现在认为的概率——如何取决于观察到的样本序列。这个问题的答案受到当前感知随隐藏参数变化而变化的方式的强烈限制。当隐藏概率经历不可预测且无信号的阶跃变化时，受试者不会逐次更新他们的感知；相反，他们只会以步进保持模式间歇性地更新它。可能步进保持模式对于概率感知并非必不可少，而只是隐藏参数阶跃变化的一种假象。然而，我们现在报告，即使参数缓慢且平稳地变化，步进保持模式仍然存在。即使平滑变化是周期性的（正弦波形式）且被感知为如此，它也依然存在。我们详细阐述了一个先前发表的理论，该理论解释了：（i）步进保持更新模式的定量属性；（ii）受试者对变化的快速准确报告；（iii）受试者对先前报告变化的重新思考；（iv）受试者对变化模式中高阶结构的检测。我们还提请注意这些结果对逐次更新理论提出的挑战。
