| Numbers have great influence on our daily life. It can be said that without numbers, the mathematical knowledge cannot really be set up. Research on human’s number cognition plays an important role on understanding the nature of human psyche as well as the development of artificial intelligence, so this topic has always been a focus in psychology. SNARC effect is one of the key phenomena in number cognition, through which researchers study the spatial representation of numbers.In the year1880, Galton assumed that digits have spatial characteristics, and in1970, Restle proposed the concept of mental number line, the research on number’s spatial representation has gone through a long journey.1993, Dehaene discovered a phenomenon in a digit parity judgment experiment:that was not relevant with the experimental task; the participants always responded fast towards the small numbers with left responds, while the big numbers was connected with the right hand responds. In a subsequent study, he found that this phenomenon was not connected with hands but with the left-right space. He named this phenomenon the effect of the spatial numerical association of response codes,(abbreviation for the SNARC effect), and use the concept of mental number line to explain it:small numbers were presented on the left side of the mental number line, and the big numbers were presented on the right side. Not until that point, the direction of number’s spatial representation was vivid. Now SNARC effect has become an important way to study the relationship between numbers and space, many scholars expand the SNARC effect in-depth study. But so far, most of the studies of SNARC effect concentrated in the horizontal direction, the SNARC effect found in the vertical direction is relatively less studied, and these studies got inconsistent results. To address this issue, four experiments focused on the influence of the horizontal direction towards the vertical direction on the single Arabic digit’s spatial representation were carried out.In experiment1, the researcher studied the SNARC effect in the horizontal direction. During the experiment, participants had to response to the single Arabic digit (from1to9, expect for5) which presented on the center of the computer screen using the index figure of their two hands, deciding that whether the presented digit was larger or smaller than5. The respond key was horizontally arranged; half of the participants had to cross their hands during the experiment, and the other half didn’t. Results show that SNARC effect appeared, the interaction between location and number was significant, F (1,11)=10.83, p<.01, small numbers were responded fast in the left side, big numbers on the right side.Experiment2investigated the impact of the placement of response hand on the spatial representation of the digit in vertical direction. The experiment procedure was similar with experimental1; except that the response keys were arranged vertically. The results did not show SNARC effect as Experiment1, the interaction of location and number was not significant, but the three way interaction of Number*Location*Response hand placement was significant, F (1,14)=10.54, P<.05. The result showed that vertical direction had impact on the vertical direction:when responded with left hand, participant’s reaction was shorter with small number; when responded with the right hand, participant’s reaction was shorter with big number.Experiments3A and3B, the responded key were arranged along diagonal directions, respectively,45degree and135degree horizontal direction. The specific direction of the keys, were upper-left, lower-right, lower-left and upper-right. The aim of the experiment3A and3B was to explore the results got in experiment2was associated with responding hand or with the responding direction. The results showed that when participants respond in the way that did not cross their hands, on both diagonal directions could get the same interaction as experiment2, the three way interaction Number*Location*Response hand placement was significant, F (1,14)=6.504, P<.05. But when participants responded with their hands crossed, the three way interaction of Number*Location*Response hand placement was insignificant.In the present study, the researcher draw a conclusion that horizontal direction did have impact on the digit’s spatial representation in vertical direction:when responded with both hands in the vertical direction, the spatial representation of numbers is linked with the reaction hand placement. Experiment results of the diagonal directions (45degrees and135degrees) further showed that both response hand and left and right direction could have influence to the vertical direction of the SNARC effect. |
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