Cattaneo Zaira, Fantino Micaela, Silvanto Juha, Tinti Carla, Vecchi Tomaso
Department of Psychology, University of Milano-Bicocca, Piazza dell'Ateneo Nuovo, Milan, Italy.
Atten Percept Psychophys. 2011 May;73(4):1021-8. doi: 10.3758/s13414-011-0094-x.
Neurologically normal individuals typically show a leftward bias--known as pseudoneglect--in bisecting physical lines as well as numerical intervals. The latter bias may reflect the spatial nature in which numbers are represented (i.e., the mental number line). In previous studies, we found that congenitally blind individuals show such leftward bias in haptic bisection. Here, we demonstrate that blind individuals also show a consistent leftward bias in numerical bisection. The leftward bias was greater when numbers were presented in descending rather than ascending order, and the magnitude of the leftward bias was comparable to that shown by a control group of blindfolded sighted participants. Our findings thus support the view that pseudoneglect operates at a mental representational level rather than being perceptually based. Moreover, the consistent leftward bias shown by blind individuals in both line and numerical bisection suggests that the right hemisphere dominance in spatial processing, resulting in an overestimation of the left side of space, develops even in the absence of any visual input.
神经功能正常的个体在平分实物线段以及数字区间时通常会表现出向左的偏差——即所谓的假性忽视。后一种偏差可能反映了数字表征的空间性质（即心理数字线）。在先前的研究中，我们发现先天性盲人在触觉平分中表现出这种向左的偏差。在此，我们证明盲人在数字平分中也表现出一致的向左偏差。当数字按降序而非升序呈现时，向左的偏差更大，并且向左偏差的程度与蒙眼有视力参与者的对照组所表现出的偏差程度相当。因此，我们的研究结果支持这样一种观点，即假性忽视在心理表征层面起作用，而非基于感知。此外，盲人在直线和平分数字时都表现出一致的向左偏差，这表明即使在没有任何视觉输入的情况下，右半球在空间处理中的优势地位也会导致对空间左侧的高估。
