Thoughts that appear to come to us ‘out of the blue’ or ‘out of nowhere’ are a familiar aspect of mental experience. Such thoughts tend to elicit feelings of surprise and spontaneity. Although we are beginning to understand the neural processes that underlie the arising of such thoughts, little is known about what accounts for their peculiar phenomenology. Here, we focus on one central aspect of this phenomenology—the experience of surprise at their occurrence, as it relates to internal probabilistic predictions regarding mental states. We introduce a distinction between two phenomenologically different types of transitions in thought content: (i) abrupt transitions, which occur at surprising times but lead to unsurprising thought content, and (ii) wayward transitions, which occur at surprising times and also lead to surprising thought content. We examine these two types of transitions using a novel approach that combines probabilistic and predictive processing concepts and principles. We employ two different probability metrics—transition and occurrence probability—to characterize and differentiate between abrupt and wayward transitions. We close by discussing some potentially beneficial ways in which these two kinds of transitions in thought content may contribute to mental function, and how they may be implemented at the neural level.

This article is part of the theme issue ‘Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation’.

似乎“突然”或“突然”出现的想法是心理体验的一个熟悉方面。这样的想法往往会引起惊讶和自发的感觉。尽管我们开始了解这些想法产生背后的神经过程，但对其特殊现象学的原因知之甚少。在这里，我们关注这一现象学的一个核心方面——意外发生时的体验，因为它与关于心理状态的内部概率预测有关。我们在思想内容中引入了两种现象学上不同类型的转变之间的区别：（i）突然转变，发生在令人惊讶的时间但会导致意料之外的思想内容，以及（ii）任性的转变，这发生在令人惊讶的时间，也会导致令人惊讶的思想内容。我们使用一种结合了概率和预测处理概念和原理的新方法来检查这两种类型的转换。我们采用两种不同的概率指标——转变和发生概率——来表征和区分突然和任性的转变。我们最后讨论了一些潜在的有益方式，其中这两种思想内容的转变可能有助于心理功能，以及它们如何在神经层面上实施。

这篇文章是主题问题“离线感知：没有匹配外部刺激的自愿和自发的感知体验”的一部分。