In everyday perception, we combine incoming sensory information with prior expectations. Expectations can be induced by cues that indicate the probability of following sensory events. The information provided by cues may differ and hence lead to different levels of uncertainty about which event will follow. In this experiment, we employed pupillometry to investigate whether the pupil dilation response to visual cues varies depending on the level of cue‐associated uncertainty about a following auditory outcome. Also, we tested whether the pupil dilation response reflects the amount of surprise about the subsequently presented auditory stimulus. In each trial, participants were presented with a visual cue (face image) which was followed by an auditory outcome (spoken vowel). After the face cue, participants had to indicate by keypress which of three auditory vowels they expected to hear next. We manipulated the cue‐associated uncertainty by varying the probabilistic cue‐outcome contingencies: One face was most likely followed by one specific vowel (low cue uncertainty), another face was equally likely followed by either of two vowels (intermediate cue uncertainty) and the third face was followed by all three vowels (high cue uncertainty). Our results suggest that pupil dilation in response to task‐relevant cues depends on the associated uncertainty, but only for large differences in the cue‐associated uncertainty. Additionally, in response to the auditory outcomes, the pupil dilation scaled negatively with the cue‐dependent probabilities, likely signalling the amount of surprise.

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瞳孔扩张反应作为视觉线索不确定性和听觉结果惊喜的指标

在日常感知中，我们将传入的感官信息与先前的期望结合起来。可以通过指示后续感官事件概率的线索来诱发期望。线索提供的信息可能有所不同，因此导致对接下来发生的事件产生不同程度的不确定性。在本实验中，我们采用瞳孔测量法来研究瞳孔扩张对视觉线索的反应是否会根据后续听觉结果的线索相关不确定性水平而变化。此外，我们还测试了瞳孔扩张反应是否反映了随后呈现的听觉刺激的惊讶程度。在每次试验中，参与者都会看到视觉提示（面部图像），然后是听觉结果（口语元音）。在面部提示之后，参与者必须通过按键来表明他们接下来会听到三个听觉元音中的哪一个。我们通过改变概率提示结果意外事件来操纵与提示相关的不确定性：一张脸最有可能后面跟着一个特定的元音（低提示不确定性），另一张脸同样可能后面跟着两个元音中的任何一个（中间提示不确定性）和第三张脸后​​面跟着所有三个元音（提示不确定性高）。我们的结果表明，对任务相关线索的瞳孔扩张取决于相关的不确定性，但仅限于与线索相关的不确定性的巨大差异。此外，为了响应听觉结果，瞳孔扩张与线索相关概率呈负相关，这可能表明了惊喜的程度。