Abstract: During the process of enumeration, researchers found that enumeration of three or fewer objects is very fast and accurate (often called “subitizing”), but gets slower and more error prone for more than three items (“counting”). Thereby they suggested that “subitizing” and “counting” are two qualitatively separable processes, a number of behavioral reaction time and accuracy supported their hypothesis. Moreover, recent neruoimage and electrophysiology results showed that “subitizing” and “counting” are also separable in attentional requirements. that is, “subitizing”can happen without attention, while “counting”must rely on attention. Based on these findings, many theories have been proposed to account for subitizing phenomenon

Key words: subitizing, counting, attention, FINST theory