Solving subtraction and addition problems is accompanied by spontaneous leftward and rightward gaze shifts, respectively. These shifts have been related to attentional processes involved in mental arithmetic, but whether these processes induce overt attentional shifts mediated by the activation of the motor programs underlying lateral eye movements or covert shifts only is still unknown. Here, we used the abducted eye paradigm to selectively disrupt activation of the oculomotor system and prevent oculomotor preparation, which affects overt but not covert attentional shifts. Participants had to mentally solve addition and subtraction problems while fixating a screen positioned either in front of them or laterally to their left or right such that they were physically unable to programme and execute saccades further into their temporal field while they still could do so in their nasal field. In comparison to the frontal condition, rightward eye abduction impaired additions (with carrying), and leftward eye abduction impaired subtractions (with borrowing) showing that at least some arithmetic problems rely on processes dedicated to overt attentional shifts. We propose that when solving arithmetic problems requires procedures such as carrying and borrowing, oculomotor mechanisms operating on a mental space transiently built in working memory are recruited to represent one numerical magnitude in relation to another (e.g. the first operand and the result).

解决减法和加法问题分别伴随着自发的向左和向右的注视转移。这些转移与心算中涉及的注意力过程有关，但这些过程是否会引起明显的注意力转移，这些转移是由激活横向眼球运动的运动程序介导的，还是仅引起隐蔽转移仍然未知。在这里，我们使用外展眼范式来选择性地破坏动眼神经系统的激活并防止动眼神经准备，这会影响明显但不影响隐蔽的注意力转移。参与者必须在脑力上解决加减法问题，同时将屏幕固定在他们面前或左右两侧，这样他们在身体上无法编程和执行更远的眼跳到他们的颞区，而他们仍然可以在他们的大脑中这样做鼻区。与正面条件相比，右眼外展损害加法（携带）和左眼外展损害减法（借用）表明至少一些算术问题依赖于专用于明显注意力转移的过程。我们提出，当解决算术问题需要诸如携带和借用等程序时，在瞬时建立在工作记忆中的心理空间上运行的动眼机制被招募来表示一个相对于另一个的数值大小（例如