Data from: Decision-level adaptation in motion perception

Prolonged exposure to visual stimuli causes a bias in observers’ responses to subsequent stimuli. Such adaptation-induced biases are usually explained in terms of changes in the relative activity of sensory neurons in the visual system which respond selectively to the properties of visual stimuli. However, the bias could also be due to a shift in the observer’s criterion for selecting one response rather than the alternative; adaptation at the decision level of processing rather than the sensory level. We investigated whether adaptation to implied motion is best attributed to sensory-level or decision-level bias. Three experiments sought to isolate decision factors by changing the nature of the participants’ task while keeping the sensory stimulus unchanged. Results showed that adaptation-induced bias in reported stimulus direction only occurred when the participant’s task involved a directional judgement, and disappeared when adaptation was measured using a non-directional task (reporting where motion was present in the display, regardless of its direction). We conclude that adaptation to implied motion is due to decision-level bias, and that a propensity towards such biases may be widespread in sensory decision-making.

长期暴露于视觉刺激会导致观察者对后续刺激的反应出现偏差。这类适应诱导偏差通常被归因于视觉系统中对视觉刺激属性具有选择性响应的感觉神经元（sensory neurons）的相对活动变化。然而，此类偏差也可能源于观察者选择某一反应而非另一反应的判断标准发生偏移，即加工过程的决策层面而非感觉层面发生了适应。本研究旨在探究隐含运动（implied motion）适应效应究竟应归因于感觉层面还是决策层面的偏差。三项实验通过在保持感觉刺激不变的前提下调整被试的任务类型，以分离决策相关影响因素。结果表明，仅当被试任务涉及方向判断时，才会出现刺激方向报告中的适应诱导偏差；而当采用非方向任务（报告显示中运动出现的位置，不考虑其运动方向）测量适应效应时，该偏差便会消失。本研究得出结论：对隐含运动的适应源于决策层面的偏差，且产生这类偏差的倾向可能广泛存在于感觉决策过程中。