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96 PART II: Descriptive MethodsKey ConceptResearchers can significantly increase the external validity of observationalfindings by using situation sampling. Situation sampling involves observingbehavior in as many different locations and under as many different circumstancesand conditions as possible. By sampling various situations, researchersreduce the chance that their results will be unique to specific circumstances orconditions. For example, animals do not behave the same way in zoos as theydo in the wild or, it seems, in different locales. This is seen in studies of mutualeye gaze between mother and infant chimpanzees. Mutual eye gaze occurs inchimps as it does in humans, but in one study of chimpanzees the frequencyof this behavior differed between animals observed in the United States andin Japan (Bard et al., 2005). Similarly, we can expect human behavior to differacross different settings.By sampling different situations, a researcher can also increase the diversityof the subject sample and, hence, achieve greater generality of findingsthan could be claimed if only particular types of individuals were observed.For example, LaFrance and Mayo (1976) investigated racial differencesin eye contact and sampled many different situations. Pairs of individualswere observed in college cafeterias, business-district fast-food outlets,hospital and airport waiting rooms, and restaurants. By using situation sampling,the investigators were able to include in their sample people whodiffered in age, socioeconomic status, sex, and race. Their observations ofcultural differences in eye contact have considerably greater external validitythan if they had studied only certain types of participants in only aspecific situation.There are many situations where there may be more behavior going onthan can be effectively observed. For example, if researchers observed students’food selections in the dining hall during peak hours, they would notbe able to observe all the students. In this case, and in others like it, the researcherwould use subject sampling to determine which students to observe.Similar to the procedures for time sampling, the researcher could either selectstudents systematically (e.g., every 10th student) or select students randomly.In what is likely by now a familiar refrain, the goal of subject sampling is toobtain a representative sample, in this example, of all students eating in thedining hall.OBSERVATIONAL METHODS• Observational methods can be classified as direct observation or indirectobservation.Researchers often observe behavior while it occurs—that is, through directobservation. However, observations also can be made indirectly, as when researchersexamine evidence of past behavior using physical traces or archivalrecords. This is indirect (or unobtrusive) observation. Figure 4.1 illustrates theorganization of observational methods. First we will discuss direct observationalmethods and then indirect (unobtrusive) methods.