Example Scanpaths Showing the Effect of Lesion Condition and Bisection Task Bias on Line Scanning & Bisection.

<p>Each sub-plot shows the position of scanpath fixations (black dots) and point of line bisection (red asterisk) under various healthy and lesion conditions when the bisection bias weight was systematically raised, being set to the following values in order left to right: 3, 4, 4.5, 5. Axes refer to pixel position in the scene. a. Intact model. Raising the weight of the bisection task bias has the effect of concentrating the scanpath at the line centre. Bisection was consistently at line centre, position 500 (zero error). b. V1 lesion model. Raising the weight of the bisection task bias causes more fixations to be clustered around the location, offset contralesionally to line centre, which will later become the bisection point. As the task bias weight increases, less fixations are placed at the contralesional line end, but this is still where the majority of fixations are made. Bisection points were always contralesionally offset, in these simulations, from left to right, being: 455 (−4.1° offset, 9.1% of line length error), 468 (−2.9° offset, 6.5% error), 488 (−1.1° offset, 2.4% error), 482 (−1.6° offset, 3.6% error). c. Parietal lesion model using a step-function. If the weight of the bisection task bias is weak, the scanpath does not stay on the line. Bisection points were always highly ipsilesionally offset, in these simulations, from left to right, being: 688 (17.1° offset, 38.0% of line length error), 680 (16.4° offset, 36.4% error), 674 (15.8° offset, 35.2% error), 681 (16.5° offset, 36.6% error). d. Parietal lesion model using a gradient. Bisection points again were highly ipsilesionally offset, in these simulations, from left to right, being: 611 (10.1° offset, 22.4% of line length error), 669 (15.4° offset, 34.1% error), 652 (13.8° offset, 30.7% error), 644 (13.1° offset, 29.1% error).