IV. Results
4.5 Discussion
Ajzen fully developed the theory of planned behavior in 1991. There are over 2400 articles citing his article in the past 17 years. More and More disciplines are integrating his theory and apply it to other fields. This study examines present articles of the theory of planned behavior (TPB) by using co-citation analysis. The analysis subjectively takes account of co-citation times of these papers. Co-citation analysis is different from subjectively finding core paper and analyzing its reference to determine the co-citation data. Articles with over than 50 cited times will be considered in this study, which are strictest standard adopted to understand full-view of these studies.
The factor analysis diminishes 75 articles into 4 components, and it can also help to determine most important documents with highest loading, furthermore, integrate cluster and multidimensional scaling (MDS) to a map. In the y-axis, there are two domains with health issues which are condom use for safety sex (Albarracin et al., 2001; White et al., 1994; Sheeran and Taylor, 1999; Chan and Fishbein, 1993;
Kashima et al., 1993; Morrison, et al., 1995; Boldero et al., 1992) and intensions of receiving cancer treatments (Sheeran and Orbell, 2000; Courneya and Friedenreich, 1999; Courneya et al., 1999). In the x-axis, three clusters from right to left according to the degree of extensions can be identified as basic theory and health issue, physical activities with mediators, and integration with another theory- the technology acceptance model (TAM). There are two domains, basic (or core) theory group and extensions health issues, within the first identified cluster. The basic
domain with no or little extension at all, including all the documents of the initial the theory of planned behavior (TPB) core papers (Ajzen, 1991; Ajzen,2002,Godin and Kok, 1996;Conner and Armitage,1998, etc.), review papers with meta-analysis (Armitage and Conner,2001; Sutton, 1998; Hausenblas et al., 1997), and more specific constructs comparison (Conner and Armitage,1998; Ajzen,2001;
Madden,1992, etc.). Another domain within the first group is health issues with two topics in condom usage and cancer treatment as mentioned above, shown in Figure 8. Other “extensions” groups comprise physical activities and the technology acceptance model (TAM). All these works were published after 1990, some years after the first paper on the theory of planned behavior (TPB), and can be understood as attempts to extend this theory with additional variables such as mediators or integration with other current theories such as the technology acceptance model (TAM). From a more dynamic perspective, the theory of planned behavior (TPB) has developed in two clear directions. The first is discerned by moving along the x-axis of the graph reflecting the trends of theory development. For the group on the right side in figure 8, C1 represents the “core” perspective of the theory of planned behavior (TPB) with little extension. Two sub-groups from right to left according to the degree of their extensions are “core” theory termed C1 and simple application in health issues termed C2. The former discusses the major works of Ajzen’ works (Ajzen,2001,2002;Ajzen and Driver, 1991), the meta-analysis papers in the theory of planned behavior (TPB) (Armitage and Conner,2001; Sutton, 1998; Hausenblas et al., 1997), and more specific discussion in the theory of planned behavior (TPB) construct and related constructs, such as self-efficacy (Ajzen, 2002, White et al.,
1994, Sparks et al., 1997) and self-identity (Sparks and Shepherd, 1992, Conner and McMillan, 1999, Conner and Armitage, 1998). The latter discussed two topics in health issues. One is related to condom use for safe-sex behaviors, and the other is about personal physical health issues, such as caner treatments (Sheeran and Orbell, 2000; Courneya and Friedenreich, 1999; Courneya et al., 1999), low-fat diet (Raats et al., 1995), smoking and drinking (Norman et al., 1999; Parker et al., 1996, 1995;
Schlegel et al., 1992;) and drug usage (Beale et al., 1991). The second group C2 appearing on the upper left part of the diagram is related to physical activity engaging, more than that, most of them are dealing with mediators, such as behavioral processes of change, cognitive processes of change, self-efficacy, decisional balance, social support, and enjoyment, etc.(Baranowski, 1998; Lewis, 2002; Baranowski, 1997). According to the results, we can find the trend of the theory of planned behavior (TPB) not only applied to a certain area but also adopted a mediator to provide a more systematic approach to increase the effectiveness of physical activity interventions. Finally, with greater extension, C3 group on the lower left section taking the perspective of technology information was incorporated with the theory of planned behavior (TPB). From the multidimensional analysis, we can find the trend or application of the theory of planned behavior (TPB) along with the development of current issues such as safe sex for preventing from AIDS, cancer treatments, intensions to engage in physical activities for the threat of chronicle disease and obesity, finally to the application of technology acceptance.
Figure 8 Integrated Map
The difference between factor and the map made by cluster and multidimensional scaling (MDS) is that one focuses on the degree of loading and the other focuses on the distance between two points on that map. The point of the theory of planned behavior (TPB) of Ajzen developed in 1991 is first discovered in the middle of the map, which indicates other articles disseminate from first article without special applications. Furthermore, the evolution of the map is found by longitudinally, which from the evaluation of the theory of planned behavior (TPB) to the topics relative to health, such as the use of condom (AIDS is the most important issue in the 20th century), cancer, sport, healthy diet, and finally the integration with technology and physical activity, shown in table 10.
The development of theory is driven by the environmental concern. The fast evolution of technology affects the behaviors of human beings, and factor 3 (cluster 2) is highly negative correlated to the basic of the theory of planned behavior (TPB) because the construct of the theory of planned behavior (TPB) is changed. People started to discuss issues about technology, and developed the technology acceptance model (TAM). In the recent years, articles are mainly about the issue of technology.
After taking further investigation, we found that there are 17 articles out of articles developed after 2000. In the technology group, there were 9 articles in total, but seven of them are developed after 2000 accounted for 41% based on total 17 articles after 2000, in table 10-13. This indicates that the theory of planned behavior is highly applicable to the technology field. The other issue is about physical activity (cluster 3), which discuss the chronic disease prevention, healthy diet, exercise, etc.
Table 10 Comparison between Cluster and Factor in Journal
Impact Factor In 2006
C1 F1 2 Godin et al. 1996 American Journal of Health Promotion 1.703
C1 F1 3 Armitage et al. 2001 British Journal of Social Psychology 1.418 C1 F1 6 Conner et al. 1998 Journal of Applied Social Psychology 0.566
C1 F1 7 Ajzen 2001 Annual Review of Psychology 11.706
C1 F2 10 Madden et al. 1992 Personality and Social Psychology Bulletin 2.419
C1 F1 11 Albarracin et al. 2001 Psychological Bulletin 12.725
C1 F1 12 Sutton 1998 Journal of Applied Social Psychology 0.566
C1 F1 13 Hausenblas et al. 1997 Journal of Sport and Exercise Psychology 1.457
C1 F2 15 Beck et al. 1991 Journal of Research In Personality 1.912
C1 F1 16 Terry et al. 1996 Personality and Social Psychology Bulletin 2.419
C1 F2 17 Ajzen et al. 1992 Journal of Leisure Research 0.457
C1 F1 18 Terry et al. 1995 British Journal of Social Psychology 1.418 C1 F1 19 Bagozzi et al. 1995 British Journal of Social Psychology 1.418 C1 F1 20 Orbell et al. 1997 Personality and Social Psychology Bulletin 2.419
C1 F1 21 Sparks et al. 1992 Social Psychology Quarterly 1.298
C1 F1 22 Parker et al. 1995 British Journal of Social Psychology 1.418
C1 F1 23 Ajzen 2002 Journal of Applied Social Psychology 0.566
C1 F2 24 Parker et al. 1992 Journal of Applied Psychology 2.851
C1 F2 25 Dzewaltowski et al. 1990 Journal of Sport and Exercise Psychology 1.457 C1 F1 26 White et al. 1994 Journal of Applied Social Psychology 0.566
C1 F1 27 Ajzen 2002 Personality and Social Psychology Review 3.348
C1 F1 28 Sheeran et al. 2000 Health Psychology 3.693
C1 F1 29 Ajzen et al. 1991 Leisure Sciences 0.667
C1 F2 30 Godin et al. 1993 Journal of Behavioral Medicine 1.348
C1 F1 31 Armitage et al. 1999 Journal of Applied Social Psychology 0.566 C1 F1 32 Doll et al. 1992 Journal of Personality and Social Psychology 4.223
C1 F1 33 Courneya et al. 1995 Health Psychology 3.693
C1 F2 34 Godin et al. 1992 British Journal of Addiction NA
C1 F1 35 Sheeran et al. 1999 Journal of Applied Social Psychology 0.566
C1 F2 38 Chan et al. 1993 Journal of Applied Social Psychology 0.566
C1 F1 39 Norman et al. 1995 European Journal of Social Psychology 1.287 C1 F2 40 Kimiecik et al. 1992 Journal of Sport and Exercise Psychology 1.457
C1 F1 42 Armitage et al. 2000 Psychology and Health 1.636
C1 F2 43 Kashima et al. 1993 British Journal of Social Psychology 1.418 C1 F2 44 Beale et al. 1991 Journal of Applied Social Psychology 0.566 C1 F1 45 Conner et al. 1999 British Journal of Social Psychology 1.418
C1 F1 46 Blue et al. 1995 Research In Nursing and Health 1.337
C1 F2 47 Morrison et al. 1995 Journal of Applied Social Psychology 0.566 C1 F1 48 Kaiser et al. 1999 Journal of Environmental Psychology 1.319 C1 F1 49 Sparks et al. 1997 Journal of Applied Social Psychology 0.566 C1 F1 50 Milne et al. 2000 Journal of Applied Social Psychology 0.566
C1 F1 51 Courneya et al. 1995 Journal of Behavioral Medicine 1.348
C1 F1 53 Sheeran et al. 1999 Journal of Applied Social Psychology 0.566 C1 F2 55 Boldero et al. 1992 Journal of Applied Social Psychology 0.566 C1 F2 56 Reinecke et al. 1996 Journal of Applied Social Psychology 0.566 C1 F1 58 Van Der Pligt 1998 British Journal of Health Psychology 1.218 C1 F1 59 Parker et al. 1996 Journal of Applied Social Psychology 0.566 C1 F2 61 Sparks et al. 1995 Basic and Applied Social Psychology 0.644
C1 F4 63 Craig et al. 1996 Preventive Medicine 2.39
C1 F1 64 Raats et al. 1995 Journal of Applied Social Psychology 0.566
C1 F2 66 Theodorakis 1994 Sport Psychologist 0.887
C1 F1 70 Norman et al. 1999 Health Psychology 3.693
C1 F1 71 Richard et al. 1996 Basic and Applied Social Psychology 0.644
C1 F2 73 Courneya et al. 1999 Psycho-Oncology 2.772
C1 F1 74 Courneya et al. 1999 Rehabilitation Psychology 0.851
C1 F2 75 Schlegel et al. 1992 Journal of Applied Social Psychology 0.566
C2 F3 4 Taylor et al. 1995 Information Systems Research 2.537
C2 F3 5 Venkatesh et al. 2000 Management Science 1.687
C2 F3 8 Venkatesh et al. 2003 Mis Quarterly 4.731
C2 F3 14 Venkatesh et al. 2000 Mis Quarterly 4.731
C2 F3 54 Harrison et al. 1997 Information Systems Research 2.537
C2 F3 60 Venkatesh et al. 2000 Organizational Behavior and Human Decision Process 1.514
C2 F3 68 Rai et al. 2002 Information Systems Research 2.537
C2 F3 69 Morris et al. 2000 Personnel Psychology 2.392
C2 F3 72 Bock et al. 2005 Mis Quarterly 4.731
C3 F1 1 Ajzen 1991 Organizational Behavior and Human Decision Process 1.514 C3 F4 9 Baranowski et al. 1998 American Journal of Preventive Medicine 3.497
C3 F4 36 Baranowski et al. 1997 Annals of Epidemiology 2.21
C3 F1 37 Kretzer et al. 1998 American Journal of Infection Control 2.489
C3 F4 41 Marshall et al. 2001 Annals of Behavioral Medicine 2.87
C3 F4 52 King et al. 2002 American Journal of Preventive Medicine 3.497 C3 F4 57 Lewis et al. 2002 American Journal of Preventive Medicine 3.497 C3 F4 62 Dishman et al. 1994 Medicine and Science In Sports and Exercise 2.909
C3 F1 65 Parker et al. 1992 Accident Analysis and Prevention 1.587
C3 F4 67 Baranowski et al. 2003 Obesity Research 3.491
Years Source
cluster Factor No. Author
Table 11 TPB Trends I (Before 2000 A.D.)
Impact Factor In 2006
1991 1 Ajzen C1 F1 Organizational Behavior and Human Decision Processes 1.514
1991 15 Beck et al. C1 F2 Journal of Research In Personality 1.912
1991 29 Ajzen et al. C1 F1 Leisure Sciences 0.667
1991 44 Beale et al. C1 F2 Journal of Applied Social Psychology 0.566
1992 10 Madden et al. C1 F2 Personality and Social Psychology Bulletin 2.419
1992 17 Ajzen et al. C1 F2 Journal of Leisure Research 0.457
1992 21 Sparks et al. C1 F1 Social Psychology Quarterly 1.298
1992 24 Parker et al. C1 F2 Journal of Applied Psychology 2.851
1992 32 Doll et al. C1 F1 Journal of Personality and Social Psychology 4.223
1992 34 Godin et al. C1 F2 British Journal of Addiction NA
1992 40 Kimiecik et al. C1 F2 Journal of Sport and Exercise Psychology 1.457
1992 55 Boldero et al. C1 F2 Journal of Applied Social Psychology 0.566
1992 75 Schlegel et al. C1 F2 Journal of Applied Social Psychology 0.566
1992 65 Parker et al. C3 F1 Accident Analysis and Prevention 1.587
1993 30 Godin et al. C1 F2 Journal of Behavioral Medicine 1.348
1993 38 Chan et al. C1 F2 Journal of Applied Social Psychology 0.566
1993 43 Kashima et al. C1 F2 British Journal of Social Psychology 1.418
1994 26 White et al. C1 F1 Journal of Applied Social Psychology 0.566
1994 66 Theodorakis C1 F2 Sport Psychologist 0.887
1994 62 Dishman et al. C3 F4 Medicine and Science In Sports and Exercise 2.909
1995 18 Terry et al. C1 F1 British Journal of Social Psychology 1.418
1995 19 Bagozzi et al. C1 F1 British Journal of Social Psychology 1.418
1995 22 Parker et al. C1 F1 British Journal of Social Psychology 1.418
1995 33 Courneya et al. C1 F1 Health Psychology 3.693
1995 39 Norman et al. C1 F1 European Journal of Social Psychology 1.287
1995 46 Blue et al. C1 F1 Research In Nursing and Health 1.337
1995 47 Morrison et al. C1 F2 Journal of Applied Social Psychology 0.566
1995 51 Courneya et al. C1 F1 Journal of Behavioral Medicine 1.348
1995 61 Sparks et al. C1 F2 Basic and Applied Social Psychology 0.644
1995 64 Raats et al. C1 F1 Journal of Applied Social Psychology 0.566
1995 4 Taylor et al. C2 F3 Information Systems Research 2.537
1996 2 Godin et al. C1 F1 American Journal of Health Promotion 1.703
1996 16 Terry et al. C1 F1 Personality and Social Psychology Bulletin 2.419
1996 56 Reinecke et al. C1 F2 Journal of Applied Social Psychology 0.566
1996 59 Parker et al. C1 F1 Journal of Applied Social Psychology 0.566
1996 63 Craig et al. C1 F4 Preventive Medicine 2.39
1996 71 Richard et al. C1 F1 Basic and Applied Social Psychology 0.644
1997 13 Hausenblas et al. C1 F1 Journal of Sport and Exercise Psychology 1.457
1997 20 Orbell et al. C1 F1 Personality and Social Psychology Bulletin 2.419
1997 49 Sparks et al. C1 F1 Journal of Applied Social Psychology 0.566
1997 54 Harrison et al. C2 F3 Information Systems Research 2.537
1997 36 Baranowski et al. C3 F4 Annals of Epidemiology 2.21
1998 6 Conner et al. C1 F1 Journal of Applied Social Psychology 0.566
1998 12 Sutton C1 F1 Journal of Applied Social Psychology 0.566
1998 58 Van Der Pligt C1 F1 British Journal of Health Psychology 1.218
1998 9 Baranowski et al. C3 F4 American Journal of Preventive Medicine 3.497
1998 37 Kretzer et al. C1 F1 American Journal of Infection Control 2.489
1999 31 Armitage et al. C1 F1 Journal of Applied Social Psychology 0.566
1999 35 Sheeran et al. C1 F1 Journal of Applied Social Psychology 0.566
1999 45 Conner et al. C1 F1 British Journal of Social Psychology 1.418
1999 48 Kaiser et al. C1 F1 Journal of Environmental Psychology 1.319
1999 53 Sheeran et al. C1 F1 Journal of Applied Social Psychology 0.566
1999 70 Norman et al. C1 F1 Health Psychology 3.693
1999 73 Courneya et al. C1 F2 Psycho-Oncology 2.772
1999 74 Courneya et al. C1 F1 Rehabilitation Psychology 0.851
cluster Factor
No. Author
Years Source
Table 12 TPB Trends II (After 2000 A.D.)
Impact Factor In 2006
2000 50 Milne et al. C1 F1 Journal of Applied Social Psychology 0.566
2000 5 Venkatesh et al. C2 F3 Management Science 1.687
2000 14 Venkatesh et al. C2 F3 Mis Quarterly 4.731
2000 60 Venkatesh et al. C2 F3 Organizational Behavior and Human Decision Processes 1.514
2000 69 Morris et al. C2 F3 Personnel Psychology 2.392
2001 3 Armitage et al. C1 F1 British Journal of Social Psychology 1.418
2001 7 Ajzen C1 F1 Annual Review of Psychology 11.706
2001 11 Albarracin et al. C1 F1 Psychological Bulletin 12.725
2001 41 Marshall et al. C3 F4 Annals of Behavioral Medicine 2.87
2002 23 Ajzen C1 F1 Journal of Applied Social Psychology 0.566
2002 27 Ajzen C1 F1 Personality and Social Psychology Review 3.348
2002 68 Rai et al. C2 F3 Information Systems Research 2.537
2002 52 King et al. C3 F4 American Journal of Preventive Medicine 3.497
2002 57 Lewis et al. C3 F4 American Journal of Preventive Medicine 3.497
2003 8 Venkatesh et al. C2 F3 Mis Quarterly 4.731
2003 67 Baranowski et al. C3 F4 Obesity Research 3.491
2005 72 Bock et al. C2 F3 Mis Quarterly 4.731
Years No. Author cluster Factor Source