Faculté des Sciences, Laboratoire de Psychologie et Neurosciences de la Cognition et de l'Affectivité (EA 4306), Université de Rouen, 76 821 Mont-Saint-Aignan Rouen Cedex, France.
Biol Psychol. 2011 Sep;88(1):94-103. doi: 10.1016/j.biopsycho.2011.06.013. Epub 2011 Jul 12.
Participants were exposed to a temporal generalization task where the duration of a small visual stimulus was judged. People received a 600ms standard duration, then had to judge whether other durations (longer than, shorter than, or equal to the standard) were or were not the standard (making a YES or NO response). In different experimental conditions, the spacing of non-standard durations around the standard was 150ms (Easy condition), or 75ms (Difficult condition), so the two conditions involved some judgements made with the same stimuli (450, 600, and 750ms). The experiment thus compared judgements of the same physical stimuli, when the basis of the judgement was the same, thus avoiding some problems of control that have been present in earlier electrophysiological studies of time judgements. As in previous work, fewer YES responses occurred in the Difficult condition and the 450ms duration was less confused with the 600ms standard than the 750ms one was. Computer modelling suggested that this (fewer YES responses) was due to a decrease in the decision threshold for the YES judgement. The electrophysiological results showed a distinction between the Easy and Difficult conditions observable by a change in the LCPt (Late Positive Component of Timing) measured after the stimulus presentations and by a change in the P1, the CNV (Contingent Negative Variation), and its positive counterpart during the presentation of the stimulus, which were larger when the discrimination was difficult. Our results therefore suggest that the increase in the difficulty of the generalization task not only changes decision processes but also alters attentional mechanisms. They also reveal that the decision does not seem to involve a unitary mechanism but depends on a group of sub-processes, notably attentional mechanisms which are altered from the moment of presentation of the stimulus.
被试者参与了一个时间泛化任务，在该任务中需要判断一个小视觉刺激的持续时间。他们首先接收到一个 600ms 的标准持续时间，然后必须判断其他持续时间（长于、短于或等于标准）是否与标准相同（做出是或否的反应）。在不同的实验条件下，非标准持续时间与标准持续时间的间隔为 150ms（简单条件）或 75ms（困难条件），因此两种条件下都包含了对相同刺激的一些判断（450、600 和 750ms）。因此，该实验比较了在判断基础相同时对相同物理刺激的判断，从而避免了先前时间判断的电生理研究中存在的一些控制问题。与之前的工作一样，在困难条件下，YES 反应较少，并且 450ms 的持续时间与 600ms 的标准相比，与 750ms 的标准混淆程度较低。计算机建模表明，这是由于 YES 判断的决策阈值降低所致。电生理结果显示，Easy 和 Difficult 条件之间存在区别，这可以通过刺激呈现后测量的 LCPt（时间的晚期正成分）的变化以及 P1、CNV（条件负变）及其在刺激呈现期间的正对应物的变化来观察，当辨别困难时，这些变化会更大。因此，我们的结果表明，泛化任务难度的增加不仅改变了决策过程，而且改变了注意力机制。它们还表明，决策似乎并不涉及单一机制，而是取决于一组子过程，特别是在刺激呈现时就会改变的注意力机制。
