Chapter Concept Check Answers

Concept Check 1

• Both of these research perspectives emphasize internal causes in their explanations of human behavior and mental processing. The biological perspective emphasizes the role of our actual physiological hardware, especially the brain and nervous system, while the cognitive perspective emphasizes the role of our mental processes, the “programs” of the brain. For example, biological explanations will involve actual parts of the brain or chemicals in the brain. Cognitive explanations, however, will involve mental processes such as perception and memory without specifying the parts of the brain or chemicals involved in these processes. Thus, the biological and cognitive perspectives propose explanations at two different levels of internal factors, the actual physiological mechanisms and the mental processes resulting from these mechanisms, respectively.
• Both of these research perspectives emphasize external causes in their explanations of human behavior and mental processing. The behavioral perspective emphasizes conditioning of our behavior by external environmental events while the sociocultural perspective emphasizes the impact of other people and our culture on our behavior and mental processing. Thus, these two perspectives emphasize different types of external causes. In addition, the behavioral perspective emphasizes the conditioning of observable behavior while the sociocultural perspective focuses just as much on mental processing as observable behavior and on other types of learning in addition to conditioning.

Concept Check 2

• The results of a case study cannot be generalized to a population because they are specific to the individual who has been studied. To generalize to a population, you need to include a representative sample of the population in the study. However, the results of a case study do allow the researcher to develop hypotheses about cause—effect relationships that can be tested in experimental research to see if they apply to the population.
• Random sampling is a method for obtaining a representative sample from a population. Random assignment is a control measure for assigning the members of a sample to groups or conditions in an experiment. Random sampling allows the researcher to generalize the results from the sample to the population; random assignment controls for individual characteristics across the groups in an experiment. Random assignment is used only in experiments, but random sampling is used in experiments and some other research methods such as correlational studies and surveys.
• There would be the same amount of scatter of the data points in each of the two scatterplots because they are equal in strength (.90). In addition, because they are strong correlations, there would not be much scatter. However, the scatter of data points in the scatterplot for +.90 would go from the bottom left of the plot to the top right; the scatter for -.90 would go from the top left of the plot to the bottom right. Thus, the direction of the scatter would be different in the two scatterplots.
• Some possible third variables that could serve as environmental triggers for autism among genetically vulnerable children stem from the children being in the house more and spending less time outdoors because of the high rates of precipitation. According to the authors of the study, such variables would include increased television and video viewing, decreased vitamin D levels because of less exposure to sunlight, and increased exposure to household chemicals. In addition, there may be chemicals in the atmosphere that are transported to the surface by the precipitation. All of these variables could serve as third variables and possibly account for the correlation.
• The double-blind procedure is necessary in experiments with placebo groups for two reasons. First, the participants in the placebo group must think that they are receiving a treatment that will help, or a placebo effect would be negatively impacted. Thus, they cannot be told that they received a placebo. Second, the experimenter must be blind in order to control for the effects of experimenter expectation (e.g., unintentionally judging the behavior of participants in the experimental and placebo groups differently because of knowing their group assignments).

Concept Check 3

• Measures of central tendency tell us what a “typical” score is for the distribution of scores. The three central tendency measures give us different definitions of “typical.” The mean is the average score; the median is the middle score when all of the scores are ordered by value; and the mode is the most frequently occurring score. Measures of variability tell us how much the scores vary from one another, the variability between scores. The range is the difference between the highest and lowest scores, and the standard deviation is the average extent that the scores vary from the mean for the set of scores.
• It has a bell shape because the scores are distributed symmetrically about the mean with the majority of the scores (about 68 percent) close to the mean (from -1 standard deviation to +1 standard deviation). As the scores diverge from the mean, they become symmetrically less frequent, giving the distribution the shape of a bell.
• In a right-skewed distribution, the mean is greater than the median because the unusually high scores in the distribution distort it. The opposite is true for the left-skewed distribution. The mean is less than the median because the unusually low scores in the distribution distort it.