To navigate the world safely, we often need to rapidly 'change our mind' about decisions. Current models assume that initial decisions and change-of-mind decisions draw upon common sources of sensory evidence. In two-choice scenarios, this evidence may be 'relative' or 'absolute'. For example, when judging which of two objects is the brightest, the luminance difference and luminance ratio between the two objects are sources of 'relative' evidence, which are invariant across additive and multiplicative luminance changes. Conversely, the overall luminance of the two objects combined is a source of 'absolute' evidence, which necessarily varies across symmetric luminance manipulations. Previous studies have shown that initial decisions are sensitive to both relative and absolute evidence; however, it is unknown whether change-of-mind decisions are sensitive to absolute evidence. Here, we investigated this question across two experiments. In each experiment participants indicated which of two flickering greyscale squares was brightest. Following an initial decision, the stimuli remained on screen for a brief period and participants could change their response. To investigate the effect of absolute evidence, the overall luminance of the two squares was varied whilst either the luminance difference (Experiment 1) or luminance ratio (Experiment 2) was held constant. In both experiments we found that increases in absolute evidence led to faster, less accurate initial responses and slower changes of mind. Change-of-mind accuracy decreased when the luminance difference was held constant, but remained unchanged when the luminance ratio was fixed. We show that the three existing change-of-mind models cannot account for our findings. We then fit three alternative models, previously used to account for the effect of absolute evidence on one-off decisions, to the data. A leaky competing accumulator model best accounted for the changes in behaviour across absolute evidence conditions - suggesting an important role for input-dependent leak in explaining perceptual changes of mind.

中文翻译：

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感知改变主意的决定对绝对证据量级很敏感

为了安全地在世界上航行，我们经常需要迅速“改变主意”来做决定。当前的模型假设初始决策和改变主意的决策利用了共同的感官证据来源。在两种选择的情况下，该证据可能是“相对的”或“绝对的”。例如，在判断两个物体中哪一个最亮时，两个物体之间的亮度差和亮度比是“相对”证据的来源，它们在加法和乘法亮度变化中是不变的。相反，组合的两个对象的整体亮度是“绝对”证据的来源，这必然会随着对称亮度操作而变化。先前的研究表明，最初的决定对相对和绝对证据都很敏感；然而，不知道改变主意的决定是否对绝对证据敏感。在这里，我们通过两个实验研究了这个问题。在每个实验中，参与者都指出两个闪烁的灰度方块中哪个最亮。根据最初的决定，刺激物会在屏幕上停留一小段时间，参与者可以改变他们的反应。为了研究绝对证据的影响，两个方块的整体亮度发生变化，而亮度差异（实验 1）或亮度比（实验 2）保持不变。在这两个实验中，我们发现绝对证据的增加导致更快、更不准确的初始反应和更慢的思想变化。当亮度差保持恒定时，改变主意的准确度会降低，但当亮度比固定时保持不变。我们表明，三个现有的改变主意模型无法解释我们的发现。然后，我们将三个替代模型拟合到数据中，这些模型以前用于解释绝对证据对一次性决策的影响。一个泄漏的竞争累加器模型最好地解释了绝对证据条件下行为的变化——这表明依赖于输入的泄漏在解释心理感知变化方面发挥着重要作用。