Abstract: Number is the crystallization of human wisdom. It is an important tool for human to understand the nature of things. The course and essence of number cognition have aroused the interest of researchers for decades. The discovering of mental number line and spatial-numerical association of response codes (SNARC) effect have provided evidence for understanding the cognitive process and representation types of number. Researchers have claimed that there was an imaginative and virtual number line in the human brain. It was used for people to work on operation and judgment task. Afterwards, the SNARC effect was found with the method of timed odd-even judgments task. That is, the left hand has faster reaction time to the smaller number, and the right hand has faster reaction time to the larger number. These results have verified that the direction of representation of mental number line was from left to right. Besides, some researchers have claimed that mental number line had good stability in horizontal dimension. The most representative number was positive number, whereas the spatial representation of negative number had the nature of dynamic and scene dependence. However, there was few study focusing on the representation of ordinal number so far. The impact of context on the representation of mental number line was still an open question. The present study aimed at investigating the influence of context on spatial representation of ordinal number with the timed odd-even judgment task. Three kinds of experimental stimulus were presented on the computer screen: only ordinal number, first, second, eighth, and ninth; floor context, the first floor, the second floor, the eighth floor, and the ninth floor; family tree context, the first generation, the second generation, the eighth generation, and the ninth generation. People were familiar with the floor context and had the experience of taking elevator or walking upstairs. In floor context, the higher floors, the larger numbers should be used to denote them. Family tree context was a relatively abstract context. Generally, the earlier forefathers located at the top of the family tree, and the nearer forefathers located at the bottom of the family tree. That is, the smaller number was on the top and the lager number was under below in family tree context. In the present study, subjects were asked to press the up key or the down key according to the odd-even property of numbers as soon as possible. Results of three experiments showed that, in only order number context, the reaction time was not significant different between up and down responses to small numbers and that to large numbers. In floor context, participants acted faster for down than up responses to small numbers and they acted faster for up than down responses to large numbers. In family tree context, the results were opposite to that in floor contexts. These results demonstrated that the spatial representation of ordinal number in vertical dimension affected by the contexts, providing support for the dynamic nature of the spatial representation of mental number line.

Key words: Mental number line, SNARC effect, Ordinal number, Context-dependent

摘要： 通过设置垂直维度上不同的情境，本研究采用“奇偶判断任务”探讨了情境对序数空间表征的影响。结果发现，只有序数的情况下，被试对小数的上键反应或下键反应、对大数的上键反应或下键反应都没有显著差异；在楼层情境下，被试对小数的下键反应更快，对大数的上键反应更快；在家谱情境下，被试对小数的上键反应更快，对大数的下键反应更快。以上结果表明，垂直维度上序数的空间表征受到情境的影响，这说明在垂直维度上数字的空间表征具有动态性，且受到具体和情境的调节。

关键词: 心理数字线, SNARC效应, 序数, 情境依存性