身體周遭的數字與距離之映射關係

Abstract

在手可及的空間範圍內，我們與環境互動時，對物體相對於身體之距離估計是相當重要的。由於距離為一具備數量性質之空間概念，距離表徵與常用於數量估計之數字表徵很可能共享一個表徵系統(the ATOM theory, 2003)。本研究分別於矢狀軸(sagittal axis)和橫向軸(transverse axis)檢驗此假說，系統性地探討水平面上的數字與距離表徵。實驗一中，參與者被要求盡快且正確判斷單個數字的奇偶性，奇偶數反應鍵皆設置於身體前方，沿著矢狀軸，一個靠近身體，另一個遠離身體，結果顯示近鍵對小數反應快於大數，而遠鍵則反之。實驗二中，按鍵設置一樣沿著矢狀軸，一個按鍵設置於身體前方，另一個則在後方，結果顯示前後方按鍵的反應速度對數字大小沒有顯著差異。於實驗三按鍵設置平行於冠狀軸，兩個按鍵一近一遠，但皆置於身體右側或左側，結果顯示在右側有近小遠大的對應關係，而左側則無，推測此由於與過去發現的左小右大之SNARC效應方向互相抵銷所致。上述研究結果顯示，除了過去已知的SNARC效應之外，數字亦對應於整個身體周圍的水平面上，並且數字以近前方空間為中心從小到大向外映射，反映了我們在動作反應時所使用的參考座標系統的特性。

In the space within arms’ length that surrounds each individual, being able to estimate distance of objects relative to the body is important for interaction with the environment. Given that distance is an interval of magnitude one describing space, it is likely that distance and the commonly used estimations of magnitude, i.e., numbers, share a common representation system (the ATOM theory, Walsh, 2003). We test this hypothesis in the peripersonal space, on both the sagittal and transverse axes, to systematically explore the distance representations on the transverse plane. Participants in Experiment 1 were required to judge the parity of digits as quickly and correctly as possible by pressing one of two buttons (both were in front of participants): one set near the body and the other far away from it. We found that near responses were faster when paired with smaller numbers and far responses with larger numbers. When one button was set in front and the other in back in Experiment 2, no mapping was found. In Experiment 3, when both buttons were on the right side, one being near the body and the other being far aligned with the transverse axis, smaller numbers were also faster with near responses and larger numbers with far responses. However, no such effect was found on the left side, suggesting that this distance-number mapping and the left-to-right SNARC effect are counteracted. These results suggest that beyond the SNARC effect, numbers are also mapped onto the whole transverse plane of the peripersonal space, not only a left-to-right oriented number line.