关键词: 负数, 数字-空间联结, SNARC效应, 心理数字线

Abstract: The SNARC effect (Spatial-Numerical Association of Response Codes) refers to the fact that the left hand responds to small numbers faster than the right hand, while the right hand responds to large numbers faster than the left hand when participants performs a parity judgment task. At present, most studies on the SNARC effect focus on the positive numbers, but few researches have explored the negative numbers. However, there is still a debate among the interpreters of the SNARC effect of negative numbers that the spatial representation of negative numbers is affected by the absolute value and cannot extend to the leftward of the mental number line, or by the magnitude value and can extend to the leftward of the mental number line.Although studies have explored the SNARC effect of negative numbers, there are still some issues to be explored. First, some researchers used a way of independently presented negative numbers to observe the spatial representation of negative numbers, and found the inverted SNARC effect of negative numbers. However, some researchers have used a way of positive and negative numbers mixed presentation to explore the connection between negative and space, and the traditional SNARC effect of negative numbers was discovered. So, does the negative numbers alone or mixed with positive numbers presented have different effects on the SNARC effect of negative numbers? Second, in the existing studies, some researches used a way of the positive numbers with no plus sign mixed with negative numbers, and the reversed SNARC effect of negative numbers was found. However, others have used a way of the positive numbers with plus sign mixed with negative numbers, but not found the SNARC effect of negative numbers. Then, does the positive numbers without plus sign and the positive numbers which have plus sign mixed with negative numbers have different effects on the SNARC effect of negative numbers? Finally, some researchers asked the participants to respond only to negative numbers under the positive numbers and negative numbers mixed conditions, and the inverted SNARC effect appeared in negative numbers. However, other researchers told the participants to respond to both positive and negative numbers, but found a traditional SNARC effect of negative numbers. So, does respond only to negative numbers and respond to both positive and negative numbers have a different effect on the SNARC effect of negative numbers? Therefore, these issues are worthy of further discussion.In the current study, we use a magnitude judgment task to investigate the effect of positive and negative numbers mixed presentation on the negative SNARC effect. The results show that under the condition of negative number alone presented, the reversed SNARC effect which the left hand responds to small numbers faster than the right hand, while the right hand responds to large numbers faster than the left hand when participants performs a button reaction，was found; under the condition that the negative number mixed with the positive without plus sign and only reacted to the negative number, the negative number has the inverse SNARC effect; under the condition that the negatives number mixed with the positive numbers which have plus sign and only reacted to the negative number, the negative number has the inverse SNARC effect; under the condition that the negatives number mixed with the positive numbers without plus sign and respond to both positive and negative numbers, the negative number has the inverted SNARC effect, while the positive number appears a traditional SNARC effect.In general, the spatial representation of negative numbers is affected by the absolute values, which is negative numbers with smaller absolute values (-1, -2) are represented on the left side of the mental number line, while negative numbers with larger absolute values (-8, -9) are represented on the right side of the mental number line, and does not extend to the leftward of the mental number line.

Key words: negative numbers, Spatial-Numerical Associations, SNARC effect, mental number line