Abstract The availability of signals from multiple senses is often beneficial for perceptual decisions. To study such benefits, models of multisensory decision-making are typically fed with the behavioural performance as measured separately with unisensory component signals. Critically, by doing so, the approach implicitly makes the so-called context invariance assumption, which states that processing of a signal is independent of the experimental context in which it is embedded. However, context invariance is not necessarily true and is difficult to test directly. Here, we aim to assess context invariance indirectly in two testable scenarios. First, to consider the role of stimulus context, we compared unisensory performance in trials that either included a task-irrelevant signal in another modality, or not (unisensory vs. multisensory signal trials). We found that performance was faster but less sensitive in trials that contained a task-irrelevant signal. Hence, stimulus context invariance was violated. Second, to consider the role of instruction context, we compared unisensory performance when participants were asked to detect targets from either one or two modalities (unisensory vs. multisensory instructions). We found that performance was deteriorated in multi- compared to unisensory instructions, which was largely due to modality switch costs in multisensory instructions. Hence, instruction context invariance did not hold either. As performance was variant in both scenarios, context invariance cannot generally assumed to be true. We conclude that models of multisensory decision making should critically consider potential violations of the context invariance assumption as a potentially confounding factor.

中文翻译：

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情境在多感官决策实验和模型中的作用

摘要 来自多种感官的信号的可用性通常有利于感知决策。为了研究这些好处，多感官决策模型通常会输入行为表现，这些行为表现是用单感觉成分信号单独测量的。至关重要的是，通过这样做，该方法隐含地做出了所谓的上下文不变性假设，即信号的处理独立于其嵌入的实验上下文。然而，上下文不变性不一定正确，并且难以直接测试。在这里，我们的目标是在两个可测试的场景中间接评估上下文不变性。首先，为了考虑刺激上下文的作用，我们比较了在另一种模式中包含与任务无关的信号的试验中的单感觉表现，或者不包括（单感觉 vs 单感觉）。多感官信号试验）。我们发现，在包含与任务无关的信号的试验中，性能更快但不那么敏感。因此，违反了刺激上下文不变性。其次，为了考虑教学环境的作用，我们比较了当参与者被要求从一种或两种模式（单感与多感指令）中检测目标时的单感表现。我们发现与单感官指令相比，多感官指令的性能下降，这主要是由于多感官指令的模态转换成本。因此，指令上下文不变性也不成立。由于两种情况下的性能各不相同，因此通常不能假设上下文不变性是正确的。