According to Glanz, Rimer and Lewis (2002), the Theory of Planned Behavior (TPB) is an addition to the Theory of Reasoned Action (TRA). The TRA was first introduced in 1967 by Fishbein and suggests that the most important determinant of behavior is behavioral intention, or the intent to follow a specific course of action. In 1986 Ajzen and Madden incorporated another element to the TRA, perceived behavioral control and proposed the TPB. One of the greatest values of this theory has been its ability to explain the course of voluntary behaviors in specific individuals, groups, and populations. This paper describes the TPB and analyzes its ability to predict health behaviors in observational studies. Lastly, it reviews interventions …show more content…
Several studies have demonstrated that constructs within the TPB can predict a wide variety of behaviors in different populations. Observational studies have verified the link between intentions and behaviors, with a meta-analysis showing a correlation coefficient of 0.53 between these constructs (Sheeran, 2002). Additionally, a recent meta-analysis of 15 observational studies showed that attitudes are an independent predictor of behavioral intentions (Conner, et.al. 2014).
The constructs within the TPB also predict nutrition related behaviors. A cross-sectional study of 5th-7th grade students in New York, Texas and California found that positive intentions, subjective norms, and PBC increased the likelihood of eating family meals (Eto, Contento & Adachi, 2011). Another cross-sectional study used the TPB to investigate why women consume more fruit and vegetables than men (Emanuel, McCully, Gallagher & Updegraff, 2012). It analyzed responses of 3,397 participants to a national survey and found that constructs within the TPB (attitudes, perceived norms, and PBC) accounted for 87% of the difference in fruit and vegetable intake between men and …show more content…
It was designed to modify attitudes via nutrition instruction, subjective norms by including older children who completed the previous YFMP, and PBC by including cooking and gardening lessons. Surveys based on the TPB and 24 hour recalls were conducted before and after the intervention. The pre-intervention survey showed that attitudes were the primary predictor of behavioral intentions. The 24 hour recalls revealed that boys significantly increased their fruit and vegetable intake after the intervention. However, there was no significant change in fruit and vegetable consumption in girls. This may be because girls had greater consumption of fruit and vegetables prior to the intervention, creating less room for improvement. There was also gender differences on the associations between TPB constructs. PBC was associated with behavior in girls, but none of the constructs were associated with behavior in boys. This study shows that educational interventions based on the TPB can change behavior in certain groups, but further research is