When two targets are presented close together in a rapid visual stream, the second target is often missed. Psychologists call this phenomenon the attentional blink (AB). A study published in Advances in Cognitive Psychology (July 2013) investigated whether simultaneous or preceding sounds could reduce AB. Twenty subjects were presented a rapid visual stream of symbols and letters on a computer screen and asked to identify the first and second letters (the targets). After several trials, the subject's AB magnitude was measured as the difference between the percentages of first target and second target letters correctly identified. Each subject performed the task under each of three conditions. In the Simultaneous condition, a sound (tone) was presented simultaneously with the second target; in the Alert condition, a sound was presented prior to the coming of the second target; and in the No-Tone condition, no sound was presented with the second target. Scatter plots of AB magnitude for each possible pair of conditions are shown below as well as the least squares line for each.
a. Which pair of conditions produces the least squares line with the steepest estimated slope?
b. Which pair of conditions produces the least squares line with the largest SSE?
c. Which pair of conditions produces the least squares line with the smallest estimate of (?

60 % 60 % 40 60 % 40 40 20 20 20 -20 -20 -20 -40 40 -20 -40 40 -20 AB Magnitude No-Tone -40 40 -20 O 20 40 60% AB Magnitude No-Tone O 20 40 60% 20 40 60% AB Magnitude Alert