Long-haul truck drivers are often asked to drive while fatigued. Can a secondary task-such as a word association task-improve the performance of a fatigued driver? This was the question of interest in a Human Factors (May 2014) study. The researchers used a driving simulator to obtain their data. Each of 40 college students was assigned to drive a long distance in the simulator. However, the student-drivers were divided into four groups of 10 drivers each. Group 1 performed the verbal task continuously (continuous verbal condition); Group 2 performed the task only at the end of the drive (late verbal condition); Group 3 did not perform the task at all (no verbal condition); and, Group 4 listened to a program on the car radio (radio show condition). At the end of the simulated drive, drivers were asked to recall billboards that they saw along the way. The percentage of billboards recalled by each student-driver is provided in the next table. Use the information in the accompanying SPSS printout to determine if the mean recall percentage differs for student-drivers in the four groups. Test using a = .01.

Data for Exercise 9.31 Continuous Verbal Late Verbal No Verbal Radio Show 14 63 10 29 37 60 43 57 64 66 18 95 52 64 83 54 59 60 39 37 45 87 62 14 46 58 92 85 47 56 73 78 73 59 45 45 50 4 36 47 SPSS Output for Exercise 9.31 ANOVA RECAL Sum af Soares Mean Sauare Sig Between Orous 5921.700 1973.900 004 .372 Wihin Groups 131S AD0 Total 30 0111.100