The Story Around The Gefitinib Successes

The target images were created by randomly sampling a 225 �� 225 matrix of intensity values. Each pixel intensity was drawn from a uniform distribution between 0 and 98 cd/m2. A contour would be embedded in one of two target images. The contour was either a ��long�� contour (220 pixels, 5.25�� if the contour was entirely straight) or a ��short�� contour (110 pixels, 2.62�� if entirely straight). The contour was generated by sampling sequential turning angles (��) using a discretized approximation to a von Mises distribution. Continuing straight (�� = 0) is more common than a turning angle right or left (�� = Gefitinib ��/4 or �� = ?��/4). Once the contour was generated, it was dilated using the dilation mask [0 1 0;1 1 0;0 0 0], chosen so that a perfectly straight contour oriented horizontally or vertically was detected as easily as one oriented at an arbitrary angle in a pilot study involving author JDW as the observer. Next, to prevent the contour from appearing at a different scale from the random pixels in the image, the image was increased in size to 550 �� 550 pixels, using nearest-neighbor interpolation so that each pixel in the smaller image became a 2 �� 2 pixel area in the image. Finally, the contour was embedded in one of the target images. The contour was randomly rotated, and then placed at a random location in the image, with the restriction that the contour could not extend beyond the edge of Dasatinib supplier the image. The masks were random noise images consisting of black (0 cd/m2) and white pixels (98 cd/m2). The images were created by randomly sampling a binary matrix of size 225 �� 225, and then scaling the matrix to 550 �� 550 using nearest-neighbor interpolation, just as in the target images. The contours embedded in one of the target images were one of five different complexity levels and one of two lengths (110 pixels or 220 pixels; Oxygenase see Figure 2). Each contour was displayed at 17.5 cd/m2, or 64% contrast. Figure 1 shows a sample stimulus at the contrast used in the experiments; stimuli in Figure 2 show enhanced contrast. There were 40 images of each length and each complexity, resulting in a total of 40 �� 2 �� 5 = 400 trials. The luminance of the contour, image size, and contour lengths were chosen so that, in a pilot study, subjects performed near 75% correct. Results and discussion Every subject showed some level of decrease in detection as the complexity of the stimuli increased (see Figure 4); we used log odds of a correct response as a dependent measure to allow valid use of linear regression (see Zhang & Maloney, 2012). Using linear regression, all 20 subjects' slopes (20 out of 20) were negative, suggesting that complexity consistently and significantly affected performance (sign�Crank test, p = 1.9 �� 10?6). Five of 10 subjects showed a significant complexity effect (p