Department of Psychology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L 3G1, Canada.
Exp Brain Res. 2010 Dec;207(3-4):157-64. doi: 10.1007/s00221-010-2449-2. Epub 2010 Oct 16.
The line bisection task--commonly used as a clinical measure of unilateral neglect--requires participants to place a mark on a horizontal line to indicate where they think centre is. In general, results suggest that the allocation of attention mediates bisection. In addition, previous research shows that participants rarely explore the endpoints of lines, suggesting that peripheral visual information informs bisection. Here, we examined bisection performance under conditions in which differing levels of 'noise' were introduced to the line to examine the hypothesis that the fidelity and symmetry of peripheral information would inform performance. Contrary to our expectations, results showed that symmetrically introducing noise to the line biased bisection further leftward compared to a 'no-noise' condition. Furthermore, asymmetrical noise increased leftward bisection errors primarily when lines were presented in left space or when the greater amount of noise was on the left half of the line. These results indicate that the fidelity of peripheral visual information mediates bisection behaviour that is already biased leftwards probably due to right hemisphere attentional mechanisms.
线二分任务——通常用作单侧忽略的临床测量手段——要求参与者在一条水平线上做标记，以指示他们认为的中心位置。一般来说，结果表明注意力的分配调节了二分。此外，先前的研究表明，参与者很少探索线的端点，这表明周边视觉信息告知二分。在这里，我们在向线引入不同程度“噪声”的条件下检查二分表现，以检验周边信息的保真度和对称性会影响表现的假设。与我们的预期相反，结果表明，与“无噪声”条件相比，将对称性噪声引入线会使二分进一步偏向左侧。此外，当线呈现在左侧空间或线的左半部分有更多噪声时，不对称噪声会主要增加左侧的二分错误。这些结果表明，周边视觉信息的保真度调节了已经偏向左侧的二分行为，这可能是由于右半球注意力机制所致。
