tarleton.instructure.com C + 88 exam2.pdf & Download Info X Close Page 2 of 2 ZOOM + K7 PSYC 2317: Statistical Methods for Psychology Tarleton State University Exam 2 4. A variety of experiments suggest that visual images interfere with visual perception. In one study, Segal and Fusella (1970) had participants watch a screen, looking for brief presentations of a small blue arrow. On some trials, the participants were also asked to form a mental image (for example, imagine a volcano). The results for a sample of N = 36 show that participants made an average of 1.8 more errors while forming images than while not forming images. The difference scores had SS = 425. (a) Compute a 95% confidence interval for , the population mean difference score. (b) Perform a hypothesis test to decide whether people make significantly more errors on the task when forming visual images. 5. Downs and Abwender (2002) evaluated soccer players and swimmers to determine whether routine blows to the head experienced by soccer players produced long term neurological deficits. In the study, neurological tests were administered to mature soccer players and swimmers. In a similar study, a researcher obtained the following data Swimmers Soccer players N1 = 8 N2 = 5 X1 = 9 X2 = 6 SS1 = 52 SS2 = 44 (a) Compute a 95% confidence interval for #1 - /2, the population mean difference in neurological scores between the two groups. b) Compute an appropriate effect size (e.g., Cohen's d) to describe the mean difference in neurological scores between the two groups. (c) Perform a hypothesis test to decide whether the population mean neurological score for swimmers is significantly different from that of soccer players