The authors also report findings from a longitudinal survey in 1998-99 of 406 new computer and television purchasers. Over 90 % of people who used the Internet during a typical day in 2000, sent or received email ( Pew Internet Report, 2000 ), far more than used any other online application or information source. Some survey research indicates that online social relationships are weaker than off-line relationships ( Parks & Roberts, 1998 ), that people who use email regard it as less valuable than other modes of communication for Paradox revisted Page 5 maintaining social relationships ( Cummings et al., in press ; Kraut & Attewell, 1996 ), that people who use email heavily have weaker social relationships than those who do not ( Riphagen & Kanfer, 1997 ) and that people who use the Internet heavily report spending less time communicating with their families ( Cole, 2000 ). In contrast, other survey research shows that people who use the Internet heavily report more social support and more in-person visits with family and friends than those who use it less ( Pew Internet Report, 2000 ). Because this research has been conducted with different samples in different years, it is difficult to identify central tendencies and changes in these tendencies with time. A longitudinal study by Kraut, Patterson, Lundmark, Kiesler, Mukophadhyay and Scherlis ( 1998 ) was one of the first to assess the causal direction of the relationship between Internet use and social involvement and psychological well-being. The HomeNet field trial followed 93 households in their first 12-18 months online. The authors had predicted that the Internet would increase users ’ social networks and the amount of social support to which they had access. The sample as a whole reported high well-being at the start of the study. Contrary to predictions, however, the association of Internet use with changes in the social and psychological variables showed that participants who used the Internet more heavily became less socially involved and more lonely than light users and reported an increase in depressive Paradox revisted Page 6 symptoms. A more pertinent problem noted in the original HomeNet report is the unknown generalizability of the results over people and time. In 1995 and 1996, when they began the study, they initially had higher community involvement and more social ties than the population at large. Had the study begun with a more socially deprived sample or more recently, when more of the population was online, the group ’ s use of the Internet for social interaction might have led to more positive effects. In addition, some critics questioned the particular measures of social involvement and well-being deployed in this study ( e. g., Shapiro, 1999 ). The present article addresses these issues of generalizability through a follow up of the original HomeNet sample and a new longitudinal study. The follow-up study examined the longer-term impact of Internet use on those in the original HomeNet sample, providing a second look at a group for whom initial Internet use had poor effects. The second study followed a new sample in the Pittsburgh area, from 1998 and 1999. It also examines the impact of the Internet on a broader variety of social and psychological outcome measures than did the original HomeNet study. In particular, the research examines whether using the Internet had different consequences for people differing in extraversion and in social support. The data are from 208 members of 93 Pittsburgh families, to whom the authors provided a computer and access to the Internet in 1995 or 1996. The analyses of social impact reported in Kraut et al. ( 1998 ) were drawn from Internet usage records and from surveys given just before participants began the study and again in May 1997. However, the sample was too small to examine statistical interaction involving the extraversion measure. The follow-up study re-examines the impact of use of the Internet by adding a third survey, administered in February 1998 ( Time 3 ). Their research was especially vulnerable because the authors had not planned initially to follow the participants for more than one year. Further, technology changed rapidly during this period, and some participants changed Internet providers, ending their ability to monitor their Internet use. Because this research is fundamentally about changes in social and psychological outcomes, the authors limit analysis to 208 participants who completed a minimum of 2 out of 3 surveys. The authors used a longitudinal panel design to examine the variables that influenced changes in social involvement and psychological well-being from Time 1 to Time 2, and from Time 2 to Time 3. The main effect of Internet use assesses the cumulative impact of Internet use over the two or three years of the study, and the interaction of Internet use with time period assesses whether this impact is the same in the early period ( previously reported in Kraut et al., 1998 ) and in the more recent period. Whether these differences in results over time reflect participants ’ learning how to use the Internet as they gain more experience or whether they reflect changes in the Internet itself over this period is a topic the authors will return to in the discussion. Insert Table 2 about here Paradox revisted Page 12 Because teenagers use the Internet more than their parents and because teens and adults differed on several of the outcomes reported in Table 2, the authors tested the differential effects of Internet use with age. Study 2: A longitudinal study of computer and television purchasers Study 2 is a replication of the original HomeNet research design in a sample of households that had recently purchased new home technology—either a computer or TV. First, the authors attempted to manipulate Internet use to create a true experiment, with participants randomly assigned to condition. The addition of a TV-purchaser comparison group in Study 2 ( of whom just 29 % obtained Internet access after 12 months ) provides a sample that was unlikely to use the Internet and helps to rule out explanations of change based on external events. The authors also increased the number of dependent variables, to examine the generalizability of the effects of using the Internet across outcomes and measures. Finally, the authors extended the HomeNet study conceptually by examining the differential effects of individual differences in extraversion and perceived social support on the effects of Internet use. The perception of social support refers to feelings that others are available to Paradox revisted Page 14 provide comfort, esteem, assistance, and information or advice ; perceived social support buffers the effects of stress ( e. g., Cohen, 1988 ). The authors recruited participants through advertisements placed in local newspapers, soliciting people for a study of household technology who purchased a new computer or new television within the previous six months. Half of the computer purchaser households were randomly offered free Internet access to participate in the study ; the other participants were offered payments to complete surveys. Unlike the procedures used in Study 1, the authors did not encourage Internet use or provide technology support. The authors administered surveys three times during the study, in February 1998, 6 months later, and a year later, February 1999. Because the authors had automated measures of Internet usage only for the group randomly given Internet access, their main independent variable is an index of self-reported Internet use ( e. g., ” I use the world wide web very frequently ” ; “ Time per day spent using email ” ; “ Frequency per month of using a computer at home ”. Within the group randomly given Internet access, the Pearson correlations between the self report index of Internet use and the automated count of the number of sessions logged into the Internet in the 8 weeks surrounding the questionnaires was moderate ( r ( 112 ) =. 55 at Time 2 and r ( 104 ) =. 42 at Time 3 ). These correlations reflect moderate validity of the self-report measure, although they are far from perfect because there is error in both the self-reports and in the server data ( e. g., the usage records do not include Internet use at work and include cases where one family member uses another ’ s account ). The authors used self-report measures to assess demographic characteristics of the participants, and measures from the original HomeNet study, including perceived social support ( Cohen et al., 1984 ), size of local and distant social circles, and time talking with other family members. To assess well-being, the authors again used the CES-D to measure depressive symptoms ( Radloff, 1977 ), the daily life stresses scale ( Kanner, Coyne, Schaefer, & Lazarus, 1981 ), and the UCLA Loneliness Scale ( Russell, Peplau, & Cutrona, 1980 ) from the original HomeNet study. The authors included a self-report measure of skill using computers, expanded from the original HomeNet study ( e. g., “ I am very skilled at using computers ” ; “ I don ’ t know much about using computers ”, ( R ) ). The authors used Stata ’ s xtreg procedure, with participant as a random effect, ( StataCorp, 2001 ) to analyze the panel design. In the Study 2 models, social involvement, well-being, and knowledge outcomes at the second and third time period were regressed on self-reported Internet use during that period, controlling for demographic characteristics and the lagged dependent variables. Holding constant respondents ’ prior community involvement, extraverts who used the Internet extensively reported more community involvement than those who rarely used it ; on the other hand, introverts who used the Internet extensively reported less community involvement than those who rarely used it. In particular, extraverts who used the Internet more reported increased well-being, including decreased levels of loneliness, decreased negative affect, decreased time pressure, and increased self-esteem. Table 6 shows the effects of Internet use on self-reported computer skill and multiple choices tests of world knowledge. Because the way people choose to use the Internet could strongly influence its effects, the authors asked participants to report how often they used the Internet for various purposes. The authors conducted an exploratory factor analysis of these items to create four scales reflecting different uses of the Internet: ( a ) for communication with friends and family ; ( b ) for acquiring information for school, work, news, and other instrumental purposes such as shopping ; ( c ) for entertainment such as playing games, downloading music, and escape and ( d ) for meeting new people and socializing in chat rooms. Using the Internet for communication with family and friends ( r =. 69 ) and for information ( r =. 62 ) had the highest association with the Internet use index in reported in Table 2, followed by use for entertainment ( r=. 51 ) and meeting new people ( r=. 38 ). To test whether particular ways of using the Internet were more beneficial than others, the authors conducted a mediation analysis, by adding the measures of specific Internet use to the models in Tables 3-6. The statistical interactions of loneliness and depressive symptoms with time period suggest that use of the Internet led to negative outcomes during the first phase of the study and more positive outcomes later. What accounts for the differences between the original HomeNet research, showing generally negative consequences of using the Internet, and the follow-ups, showing generally positive consequences ? However, the statistical interactions with extraversion and social support reported in Study 2 would lead one to expect that outcomes would be more positive in Study 1 than Study 2, but this was not the case. In addition to these changes to the online social environment, over the span of this research, the Internet provided a richer supply of information, with more news, health, financial, hobby, work, community, and consumer information available. Most studies show that people use the Internet more to keep up with relationships formed off line than to form new ones ( e. g, Kraut et al, 1996 ; Pew Internet and American Life Project, 2000 ). Gross, Juvonen, and Gable ( this issue ) also report that adolescents who feel socially anxious and/or lonely are especially likely to communicate online with people with whom they do not feel close. Across both studies, as people used the Internet more, they reported increases in daily life stress and hassles. The authors tried to conduct such an experiment on Internet use for Study 2, but in less than 12 months, 83 % of the households in the control group had acquired Internet access on their own. Although cross-sectional designs are most common in research on the impact of the Internet ( e. g., Cole, 2000 ; Parks, & Roberts, 1998l ; The Pew Internet & American Life Project, 2000 ; Riphagen & Kanfer, 1997 ), they can not distinguish pre-existing differences among people who use the Internet from consequences of using it. Surveying the digital future: The UCLA Internet report. The Pew Internet & American Life Project ( 2000, May 10 ). The CES-D Scale: A self-report depression scale for research in the general population, Applied Psychological Measurement, 1, 385-401. The plots show predictions from the models reported in Tables 4 and 5 as Internet use and extraversion move through the range appearing in the sample. Further, even if people use the Internet to talk with close friends and family, these online discussions might displace higher quality face-to-face and telephone conversation ( e. g., Cummings, Butler & Kraut, in press ; Thompson & Nadler, this issue ). Further, the cross-sectional nature of the research makes it impossible to distinguish self-selection ( in which socially engaged and disengaged people use the Internet differently ) from causation ( in which use of the Internet encourages or discourages social engagement ). As discussed further in the introduction to Study 2, people differing in extraversion and social support are likely use the Internet in different ways. All longitudinal research faces the potential of participant attrition. Two significant Internet use X time period interactions suggest that Internet use had different effects early and late in respondents ’ use of the Internet. Finally, interactions of age with Internet use suggest different positive effects for adults and teens. In addition, it was associated with declines in local knowledge, and declines in the desire to live in the local area, suggesting lowered commitment to the local area. Maturation of participants between the early and late phases of Study 1, differences in samples between Studies 1 and 2, and changes in the Internet itself are all potential explanations for this shift in results. Maturation of participants and changes in the way they used the Internet could potentially account for the shift in results between the early and later phases of Study 1. These sample differences make comparisons between the two studies problematic and could potentially account for differences in results between them. The similarity of findings comparing the early and later phases of Study 1 and comparing Studies 1 and 2 suggest that changes in the Internet environment itself might be more important to understanding the observed effects than maturation or differences between samples. However, research also suggests that strong relationships developed online are comparatively rare. As experience with television suggests, enjoyable uses of new technology may be Paradox revisted Page 26 harmful in the long term ( e. g., Huston et al, 1992 ; Putnam, 2000 ). Therefore, the authors believe longitudinal designs are essential to understanding the effects of Internet use and the differences in these effects as the Internet changes.
