Ruusuvirta Timo, Astikainen Piia
University of Turku, Faculty of Education, Department of Teacher Education in Rauma, Seminaarinkatu 1, FIN-26100 Rauma, Finland; University of Turku, Centre for Learning Research, University of Turku, Assistentinkatu 7, FIN-20500 Turku, Finland; Centre for Cognitive Neuroscience, University of Turku, Finland.
Department of Psychology, University of Jyväskylä, Ylistönmäentie 33, FIN-40014 Jyväskylä, Finland.
Brain Res. 2016 Mar 1;1634:68-74. doi: 10.1016/j.brainres.2015.12.047. Epub 2015 Dec 29.
The brain hosts a primitive number sense to non-symbolically represent numerosities of objects or events. Small exact numerosities (~4 or less) can be individuated in parallel. In contrast, large numerosities (more than ~4) can only be approximated. However, whether small numerosities can be approximated without their parallel individuation remains unclear. Parallel individuation is suggested to be an attentive process and numerical approximation an automatic process. We, therefore, tested whether small numerosities can be represented preattentively. We recorded adult humans׳ event-related potentials (ERPs) and behavioral responses to 300-ms sequences of six tones (each of either 440 Hz or 660 Hz in frequency). Mostly, a sequence was of 3 tones of each frequency. Occasionally (P=0.1), the numerosities were 4 and 2 (minor changes) or 5 and 1 (major changes). Mismatch negativity (MMN), but no later attention-related positive-polarity ERPs, was observed to the major but not to the minor changes during a visual non-numerical task. In a following attentive task, behavioral responses even to major changes resulted in a very low hit rates (0.11 for major and 0.023 for minor changes) and yet an above-zero false-alarm rate (0.052). The findings support a view that small numerosities of objects can be automatically approximated independently of their attentive individuation.
大脑拥有一种原始的数字感，用于非符号化地表征物体或事件的数量。少量精确的数量（约4个或更少）可以并行区分。相比之下，大量的数量（超过约4个）只能进行估算。然而，少量的数量在不进行并行区分的情况下是否可以估算仍不清楚。并行区分被认为是一个注意力过程，而数字估算则是一个自动过程。因此，我们测试了少量的数量是否可以在注意力之前得到表征。我们记录了成年人对300毫秒的六个音调序列（每个音调的频率为440赫兹或660赫兹）的事件相关电位（ERP）和行为反应。大多数情况下，一个序列包含每个频率的3个音调。偶尔（P = 0.1），数量为4和2（小变化）或5和1（大变化）。在视觉非数字任务中，观察到对大变化而非小变化出现了失匹配负波（MMN），但没有观察到后来与注意力相关的正性极性ERP。在随后的注意力任务中，即使对大变化的行为反应的命中率也非常低（大变化为0.11，小变化为0.023），但误报率高于零（0.052）。这些发现支持了这样一种观点，即少量物体的数量可以独立于其注意力区分而自动估算。
