11)What confounding variable occurs when the researchers gradually change their observation criteria over the course of the study? A)Regression toward the mean.  B)Instrumentation. C)Maturation. D)History. 12)Confounding due to instrumentation refers to A)changes in measuring instruments. B)changes in the dependent variable. C)changes in the participants behaviour. D)changes in the participants’ abilities over time. 13)If a human observer becomes more proficient in the course of a study, the type of threat to internal validity is called a change in A)proficiency. B)instrumentation. C)research bias. D)regression to the mean. 14)The concept of regression to the mean suggests A)participants with extreme scores will score more extreme on a second test. B)scores of participants on a second test would be the same or similar to the first test. C)scores of participants on a second test would be less extreme on average on a second test. D)the performance of particpants becomes worse and worse over time. 15)If we select participants on the basis of extremely high or low scores on a test, the most likely threat to validity is A)testing bias. B)diffusion of treatment. C)attrition. D)regression to the mean. 16)Which confounding factor is most likely to occur when participants are selected because their pretest measures were unusually high? A)Regression to the mean. B)Testing. C)Attrition. D)Selection. 17)Because any behaviour varies in frequency, intensity, and duration, a researcher must be careful to control for A)researcher bias. B)sampling error. C)measurement error. D)regression to the mean. 18)The concept of regression to the mean is particularly important when A)doing research involving children. B)selecting research participants on the basis of sex or some other categorical variable. C)selecting research participants on the basis of extreme scores on some measure. D)doing research during daylight savings time. 19)If some of the top scorers on an exam don’t perform as well on a second exam, this could be explained by the phenomenon known as A)poor motivation. B)equilibration. C)attrition. D)regression to the mean. 20)The inability to assign participants randomly to groups gives rise to which of the following confounding variables? A)Diffusion of treatment. B)Selection. C)Attrition. D)Sequence effects. Â