Figure 2

PSE graphs. A) Psychometric functions of color saturation and contrast sensitivity. Data from participants are combined with Weibull functions for each group. Data points are marked with symbols and fitted functions with lines. Each column presents each stimulus (blue, red, contrast). Top row presents psychometric functions for control group, and bottom row for the ADHD group. Horizontal axes represent test stimulus saturation/contrast sensitivity distances in DKL colorspace. Vertical axes are percent of trials for which the test stimulus was selected as more colourful (higher saturation level). Test cued conditions are represented by red lines with circles, neutral cued conditions by black lines with squares, and standard cued conditions by blue lines with triangles. Points of Subjective Equality (PSEs) for the Test shifts to the left for Blue and Contrast indicating that exogenous attention enhanced subjective saturation/contrast sensitivity to be more saturated or higher in contrast than the standard stimuli. Red psychometric functions indicate lack of exogenous attention influence on the stimuli as Test, and Standard psychometric functions are together with Neutral. B) Normalized PSE for color saturation and contrast sensitivity shown in a bar graph. Each participant’s PSEs were normalized by taking the ratio of any one PSE and the average of the test-cued, neutral, and standard-cued PSEs. Each column presents each stimulus (blue, red, contrast). In each bar graph, test cued conditions are represented by a red bar, neutral cued conditions are represented by a black bar, and standard cued conditions are represented by a blue bar. For blue and contrast, when the test stimuli were cued, participants chose the test stimuli when their saturation/contrast levels were lower than those of standard stimuli. This pattern of results indicates that cuing a stimulus increased its perceived blue saturation/ contrast sensitivity level.