Hockenbury Discovering Psychology 5th txtbk

26 CHAPTER 1 Introduction and Research MethodsJazzing Up Your Love Life with CorrelationCoefficients Using data from the Universityof Chicago’s ongoing General SocialSurvey, res earchers John Robinson and GeoffreyGodbey (1998) discovered that adultsexual behavior was positively correlatedwith certain musical preferences. Aftercontrolling for age and race, the researchersfound that people who have astrong preference for jazz are 30 percentmore sexually active than the averageAmerican. Liking other types of music, suchas rock or rap, was unrelated to sexual activity.Does this mean that listening to jazzcauses an increase in sexual activity? Notnecessarily. Remember, a correlation betweentwo factors does not necessarily indicatecausality—only that the two factorsco-vary in a systematic way.negative correlationA finding that two factors vary sys -tematically in opposite directions, one increasingas the other decreases.A Perfect Positive Correlation: The Clockand the Bell Tower If a +1.00 correlationoccurred between two variables, it wouldbe termed a perfect positive correlation.This means that every time Factor A occurred,Factor B would also occur. Thismight seem to suggest that Factor A iscausing Factor B to occur, but that’s notnecessarily the case. For example, everytime the big hand on the clock tower getsto 12, two miles away the bell starts ringing.The two events are perfectly correlatedyet, in this case, one does not causethe other.as the amount of time spent playing violentvideo games increased, aggression scores onpersonality tests increased.In contrast, a negative correlation is one inwhich the two variables move in opposite directions:As one factor decreases, the other increases.In analyzing their results, Anderson andDill found that there was a negative correlationof .20 between the amount of time spent playingvideo games and academic achievement, asmeasured by cumulative college grade point average.Thus, as the amount of time spent playingvideo games increased, college grade point averagedecreased.Given this basic information about correlationcoefficients, what can we conclude aboutthe relationship between the time spent playingvideo games and academic achievement? Orabout exposure to violent video games and aggressive personality characteristics?Does the evidence allow us to conclude that playing video games causes a decreasein grade point average? Or that playing violent video games causes people to developmore aggressive personalities?Not necessarily. For example, even if playing video games and getting poorgrades were very strongly correlated, it’s completely possible that some other factoris involved. For example, it could be that students who lack academic motivationtend to spend their free time playing video games rather than studying. Thus, itmight be that a lack of academic motivation, rather than video games, is responsiblefor lower grades.Similarly, consider the positive correlation between aggressive personality andamount of time spent playing violent video games. We cannot conclude that playing violentvideo games causes an increase in aggression. It’s entirely possible that people whoare more aggressive are attracted to violent video games or enjoy playing them. Thus,it could be that people with aggressive personalities are more likely to spend more timeplaying violent video games than people who are less aggressive.Here is the critical point: Even if two factors are very strongly correlated, correlationdoes not necessarily indicate causality. A correlation tells you only that two factorsseem to be related or that they co-vary in a systematic way. Although two factorsmay be very strongly correlated, correlational studies cannot be used todemonstrate a true cause-and-effect relationship. As you’ll see in the next section,the experimental method is the only scientific strategy that can provide compellingevidence of a cause-and-effect relationship between two variables.Even though you can’t draw conclusions about causality from it, correlational researchcan be very valuable. First, correlational research can be used to rule outsome factors and identify others that merit more intensive study. Second, the resultsof correlational research can sometimes allow you to make meaningfulpredictions. For example, when Anderson and Dill (2000)analyzed data from their survey, they discovered that there was amoderately strong correlation of .46 between the amount oftime spent playing violent video games and aggressive delinquentbehavior, such as damaging public or private property. That is, themore time that was spent playing violent video games, the higherwas the incidence of aggressive delinquent behavior. Looking atthe overall results of their survey, Anderson and Dill concludedthat there were legitimate reasons to be concerned about the potentialnegative consequences of long-term or excessive exposureto video games, especially violent video games. In Chapter 5, onlearning, we’ll take a critical look at the relationship between exposureto violent media and aggressive behavior.