Lambrechts Anna, Walsh Vincent, van Wassenhove Virginie
Department of Psychology, City University London, London, United Kingdom ; Institute of Cognitive Neuroscience, University College London, London, United Kingdom ; INSERM U992, Cognitive Neuroimaging Unit, Gif/Yvette, France ; CEA, DSV/I2BM, NeuroSpin Center, Gif/Yvette, France ; Université Paris-Sud, Gif/Yvette, France.
PLoS One. 2013 Dec 5;8(12):e82122. doi: 10.1371/journal.pone.0082122. eCollection 2013.
Perceptual interferences in the estimation of quantities (time, space and numbers) have been interpreted as evidence for a common magnitude system. However, if duration estimation has appears sensitive to spatial and numerical interferences, space and number estimation tend to be resilient to temporal manipulations. These observations question the relative contribution of each quantity in the elaboration of a representation in a common mental metric. Here, we elaborated a task in which perceptual evidence accumulated over time for all tested quantities (space, time and number) in order to match the natural requirement for building a duration percept. For this, we used a bisection task. Experimental trials consisted of dynamic dots of different sizes appearing progressively on the screen. Participants were asked to judge the duration, the cumulative surface or the number of dots in the display while the two non-target dimensions varied independently. In a prospective experiment, participants were informed before the trial which dimension was the target; in a retrospective experiment, participants had to attend to all dimensions and were informed only after a given trial which dimension was the target. Surprisingly, we found that duration was resilient to spatial and numerical interferences whereas space and number estimation were affected by time. Specifically, and counter-intuitively, results revealed that longer durations lead to smaller number and space estimates whether participants knew before (prospectively) or after (retrospectively) a given trial which quantity they had to estimate. Altogether, our results support a magnitude system in which perceptual evidence for time, space and numbers integrate following Bayesian cue-combination rules.
数量（时间、空间和数字）估计中的感知干扰已被解释为存在一个通用量级系统的证据。然而，如果持续时间估计似乎对空间和数字干扰敏感，那么空间和数字估计往往对时间操纵具有抗性。这些观察结果对每个数量在构建一个通用心理度量的表征过程中的相对贡献提出了质疑。在此，我们设计了一项任务，其中针对所有测试数量（空间、时间和数字）随时间积累感知证据，以符合构建持续时间感知的自然要求。为此，我们使用了一种二分任务。实验试验包括不同大小的动态点在屏幕上逐渐出现。参与者被要求在显示中判断点的持续时间、累积面积或数量，同时另外两个非目标维度独立变化。在前瞻性实验中，参与者在试验前被告知哪个维度是目标；在回顾性实验中，参与者必须关注所有维度，并且仅在给定试验后才被告知哪个维度是目标。令人惊讶的是，我们发现持续时间对空间和数字干扰具有抗性，而空间和数字估计受时间影响。具体而言，且与直觉相反的是，结果显示无论参与者在给定试验之前（前瞻性地）还是之后（回顾性地）知道他们必须估计哪个数量，更长的持续时间都会导致更小的数字和空间估计。总之，我们的结果支持一个量级系统，其中时间、空间和数字的感知证据按照贝叶斯线索组合规则进行整合。
