Contents

CHAPTER 2: The Scientific Method 51set of propositions (claims, statements, assertions) that serves to define events (concepts),describe relationships among these events, and explain the occurrence of these events.For example, a theory of flashbulb memory must state exactly what a flashbulbmemory is and how a flashbulb memory differs from typical memories. Thetheory would include descriptions of relationships, such as the relationshipbetween degree of emotional involvement and amount remembered. Finally,the theory would also have to explain why in some cases a person’s so-calledflashbulb memory is clearly wrong, even though the individual is very confidentabout the (inaccurate) memory (see Neisser & Harsch, 1992). Such was the casein Talarico and Rubin’s (2003) findings for students’ memories of the September11, 2001, terrorist attacks; despite a decrease in the accuracy of their memoriesover time, participants maintained confidence in their very vivid memories.The major functions of a theory are to organize empirical knowledge and toguide research (Marx, 1963). Even in relatively specific areas of research such asflashbulb memories, many studies have been done. As the scope of a research areaincreases, so does the number of relevant studies. Scientific theories are importantbecause they provide a logical organization of many research findings andidentify relationships among findings. This logical organization of findings guidesresearchers as they identify testable hypotheses for their future research.Theories frequently require that we propose intervening processes to accountfor observed behavior (Underwood & Shaughnessy, 1975). These interveningprocesses provide a link between the independent variables researchers manipulateand the dependent variables they subsequently measure. Because these processes“go between” the independent and dependent variables, they are calledintervening variables. You probably are familiar with what we mean by an interveningvariable if you think about your computer use. As you press keys on thekeyboard or click the mouse, you see (and hear) various outcomes on the monitor,printer, and from the speakers. Yet it isn’t your keystrokes and mouse clicksthat directly cause these outcomes; the intervening variable is the “invisible” softwarethat serves as a connection between your keystrokes and the outcome onyour monitor.Intervening variables are like computer software. Corresponding to the connectionbetween keystrokes and what you see on your monitor, intervening variablesconnect independent and dependent variables. Another familiar examplefrom psychology is the construct of “thirst.” For example, a researcher might manipulatethe number of hours participants are deprived of liquid and, after thespecified time, measure the amount of liquid consumed. Between the deprivationtime and the time participants are allowed to drink liquid, we may say that theparticipants are “thirsty”—the psychological experience of needing to replenishbody fluids. Thirst is a construct that allows theorists to connect variables suchas the number of hours deprived of liquid (the independent variable) and theamount of liquid consumed (the dependent variable). Intervening variables suchas thirst not only link independent and dependent variables; intervening variables alsoare used to explain why the variables are connected. Thus, intervening variables playan important role when researchers use theories to explain their findings.Intervening variables and theories are useful because they allow researchersto identify relationships among seemingly dissimilar variables. Other