The Theory of Planned Behavior


The theory of planned behavior, developed by Icek Ajzen, is a social cognitive theory that has guided a large majority of theory-based research on physical activity. The theory of planned behavior is an extension  of  the  theory  of  reasoned  action  developed by Martin Fishbein and Icek Ajzen in 1975. Since its introduction over 25 years ago, the theory of planned behavior has become one of the most frequently cited and influential models for predicting human behavior.

The  theory  of  planned  behavior  specifies  that some  or  all  of  the  following  four  main  psychological variables influence our behavior: intention, attitude, subjective norm, and perceived behavioral control. The combination of an individual’s expectations about performing a behavior and the value attached to that behavior form the conceptual basis of this theory. Figure 1 displays the main variables of the theory of planned behavior, and each of these main variables is described in more detail below.the-theory-of-planned-behavior-sports-psychologyFigure 1    Main Variables of the Theory of Planned Behavior

Theory of Planned Behavior Variables

Intention to perform a behavior is the central determinant of whether or not an individual engages in that  behavior.  Intention  is  reflected  in  a  person’s willingness  and  how  much  effort  that  individual is  planning  to  exert  to  perform  the  behavior.  The stronger a one’s intention to perform a behavior, the more likely one will be to engage in that behavior. Thus,  if  someone  has  a  strong  intent  to  go  for  a walk this afternoon, that person is likely to go for that walk.

As might be expected, a person’s intention can weaken  over  time.  The  longer  the  time  between intention  and  behavior,  the  greater  the  likelihood that  unforeseen  events  will  produce  changes  in people’s intention. For example, a young adult may intend  to  be  a  regular  lifetime  runner.  However, after  running  for  a  few  years,  this  person  may become bored with the activity and start to swim instead.  The  runner  did  not  expect  boredom  to affect  the  intention  to  run.  A  person’s  behavioral intentions  are  influenced  by  personal  attitudes about the behavior, the perceived social pressures to perform the behavior (subjective norm), and the amount  of  perceived  control  over  performing  the behavior (perceived behavioral control).

Attitude  represents  an  individual’s  positive  or negative evaluation of performing a behavior. Do you find regular exercise useless or useful, harmful  or  beneficial,  boring  or  interesting?  An  older adult may have a negative attitude toward engaging  in  a  vigorous  physical  activity  such  as  running,  but  rather  have  a  positive  attitude  toward walking   in   the   neighborhood.   Our   attitude toward  a  specific  behavior  is  a  function  of  our behavioral  beliefs,  which  refer  to  the  perceived consequences  of  carrying  out  a  specific  action and our evaluation of each of these consequences. A college student’s beliefs about playing doubles tennis  could  be  represented  by  both  positive expectations  (e.g.,  it  will  improve  my  social  life because  I  will  meet  lots  of  people)  and  negative  expectations  (e.g.,  it  will  reduce  my  time  to study).  In  shaping  a  physical  activity  behavior, the person evaluates the consequences attached to each of these beliefs. Common behavioral beliefs for  physical  activity  include  that  it  improves  fitness  or  health,  improves  physical  appearance,  is fun  and  enjoyable,  increases  social  interactions, and improves psychological health.

Subjective  norm  reflects  the  perceived  social pressure  that  individuals  feel  to  perform  or  not perform a behavior. Subjective norm is believed to be a function of normative beliefs, which are determined by the perceived expectations of important significant  others,  such  as  family,  friends,  physician,  or  priest,  or  groups  like  classmates,  teammates, or church members, and by the individual’s motivation  to  comply  with  the  expectations  of these  important  significant  others.  For  example, an  individual  may  feel  that  his  wife  thinks  he should exercise three times a week. The husband, however,  may  not  be  inclined  to  act  according to  these  perceived  beliefs.  Common  normative beliefs for physical activity include those of family members, friends, and health care professionals.

Perceived behavioral control represents the perceived ease or difficulty of performing a behavior. Perceived  behavioral  control  influences  behavior either  directly  or  indirectly  through  intention. People  may  hold  positive  attitudes  toward  a behavior and believe that important others would approve  of  their  behavior.  However,  they  are  not likely  to  form  a  strong  intention  to  perform  that behavior if they believe they do not have either the resources or opportunities to do so. You may have a positive attitude and enjoy swimming; however, if you do not have access to a pool you will not be able to perform this behavior.

Perceived behavioral control is a function of control beliefs. Control beliefs represent the perceived presence  or  absence  of  required  resources  and opportunities (e.g., there is a road race this weekend),  the  anticipated  obstacles  or  impediments  to behavior (e.g., probability of rain on the weekend is  90%),  and  the  perceived  power  of  a  particular control  factor  to  facilitate  or  inhibit  performance of the behavior (e.g., even if it rains this weekend, I  can  still  participate  in  the  road  race).  The  most common control beliefs for physical activity include lack of time, lack of energy, and lack of motivation. Table  1  contains  sample  items  for  measuring  the theory  of  planned  behavior  constructs  in  relation to regularly exercising during the winter.

Theory of Planned Behavior and Physical Activity Research

Several  meta-analytic  reviews  have  supported  the theory of planned behavior for explaining and predicting a wide variety of physical activities in a wide variety of populations, including ethnic minorities, youth,  pregnant  women,  cancer  patients,  diabetic adults, cancer survivors, and older adults. In general, researchers found that intention is the strongest  determinant  of  behavior  followed  closely  by perceived  behavioral  control.  And  our  intention to perform a behavior is largely influenced by our attitude and perceived behavioral control followed to a lesser extent by subjective norm. It is important to note that the influence of each of the theory of planned behavior construct can vary from population and context.
the-theory-of-planned-behavior-sports-psychology-t1Table 1   
Theory of Planned Behavior Sample Items

Elicitation Studies

A main strength of the theory of planned behavior is that an elicitation study forms the basis for developing questions to assess the theory’s variables in a specific population. The elicitation study enables a practitioner  to  determine  the  specific  beliefs  for  a specific population. This is very important because we know that beliefs vary by population and even by  activity.  For  example,  the  main  behavioral beliefs  for  breast  cancers  survivors  are  that  exercise gets my mind off cancer and treatment, makes me feel better, improves my well-being, and helps me maintain a normal lifestyle. In comparison, the main  behavioral  beliefs  for  pregnant  women  are related to pregnancy-specific issues such as having a healthier pregnancy and easier labor and delivery.

Because  beliefs  vary  by  population,  researchers  and  practitioners  are  encouraged  to  refer  to research  that  has  determined  the  physical  activity beliefs  of  their  specific  intervention  population, for example postpartum women, cancer survivors, or high school students. If physical activity beliefs for a practitioner’s population of interest have not been  determined,  then  it  is  recommended  that  an elicitation study be conducted to determine the pertinent beliefs concerning a behavior for that specific population. Table 2 provides an example of open-ended items used to assess the beliefs of pregnant women during their first trimester. Women during their first trimester would be asked to list three to five  responses  for  each  of  the  items.  Then  a  content  analysis  (a  simple  frequency  count)  to  determine  which  beliefs  are  most  salient  and  finally  a structured belief questionnaire would be developed from the content analysis (see Table 2).

Structured  items  that  arise  from  the  elicitation study should be specific to the target at which the behavior is directed, the action or specificity of the behavior under study, and the context and time in which the behavior is being performed. For example,  when  developing  a  walking  intervention  for older  adults,  the  practitioner  should  ask  a  sample of older adults to list the main advantages of walking briskly three times a week for 30 minutes outside during the summer. This information will help researchers  develop  an  intervention  based  on  the salient behavioral beliefs of these older adults that is specific to the behavior. According to the theory of planned behavior, once beliefs are modified, intention will be altered and the desired behavior change will occur. The relative contribution of the theory of planned behavior constructs may fluctuate from context to context. Thus, before interventions using this  framework  are  implemented,  the  predictive ability of these constructs with the specific population and specific context should first be tested.

Using Theory for Practice

The theory of planned behavior is useful in identifying  psychosocial  determinants  of  physical activity.  Therefore,  it  has  been  useful  for  developing  community,  group,  and  individual  exercise  programs.  For  example,  people  intend  to exercise  when  they  hold  a  positive  evaluation of  exercise.  Exercise  programs  that  offer  a  positive experience would likely increase intention to exercise,  which  would  likely  positively  influence exercise behavior. Positive behavioral beliefs and their  evaluation  may  be  enhanced  if  people  are given  experiences  with  enjoyable  types  of  physical  activities  and  then  gradually  encouraged  to increase the intensity, duration, and frequency of those  activities.  Perceived  behavioral  control  is an  important  factor  in  intention  to  be  physically active. When individuals perceive physical activity as difficult to do, intention is low. Assisting people to  overcome  barriers,  such  as  time  involvement, other  obligations,  or  feelings  of  inability,  should enhance perceptions of control about carrying out exercise. We will now take a closer look at a physical  activity  intervention  called  Wheeling  Walks that was guided by the theory of planned behavior.


Table 2    Assessing the Theory of Planned Behavior Beliefs in Pregnant Women During Their First Trimester

Wheeling Walks was an 8-week mass media walking campaign developed by Bill Reger et al. (2001). The main goal of the intervention was to promote walking among sedentary adults ages 50 to 65 years old  in  the  city  of  Wheeling,  West  Virginia.  This “communication  intervention  used  the  theory  of planned behavior . . . constructs to change behavior by promoting 30 min[utes] of daily walking through paid media, public relations, and public health activities.” The impact of the campaign “was determined by pre and post-intervention telephone surveys with 719 adults in the intervention community and 753 adults  in  the  comparison  community  and  observations of walkers at 10 community sites” (p. 285).

To  develop  the  messages  to  be  used  in  the intervention,  the  theory  of  planned  behavior  was used  to  determine  the  salient  beliefs  that  should be targeted during the walking intervention. They found that sedentary and irregularly active people shared similar attitude and subjective norm beliefs with  regular  exercisers  but  showed  very  strong differences  on  perceived  control.  Sedentary  adults believed that they had less control over their time and  scheduling  of  exercise  compared  to  regular exercisers.  Wheeling  Walks  promoted  30  minutes or  more  of  moderate  intensity  walking  on  almost every day for better health and feeling more energetic.  To  address,  the  I-don’t-have-time  belief, which was identified as a primary barrier to physical  activity,  the  ads  suggested  “start  walking  ten minutes  a  day  at  first,  then  twenty  minutes  .  .  .” and  also  compared  the  30-minute  time  period  to that of “one TV program.” Each ad ended with the tagline, “Isn’t it time you started walking” (p. 287).

Behavioral observation showed a 23% increase in the number of walkers in the intervention community  versus  no  change  in  the  comparison  community. They also found that 32% of the baseline sedentary  population  in  the  intervention  community  reported  meeting  the  physical  activity  guidelines by walking at least 30 minutes at least 5 times per  week  versus  18%  in  the  comparison  community.  An  important  question  is  how  long  did  the increased  walking  last  by  the  adults  in  Wheeling, and can these results be replicated in other communities. The answer to both questions is yes. A follow-up study revealed that the campaign succeeded in  sustaining  the  increase  in  walking  12  months after  the  intervention.  As  well,  the  campaign  has been  successfully  replicated  in  other  communities including rural and larger communities.

Theory Limitations

Although the theory of planned behavior has been successful  in  explaining  and  predicting  physical activity  behavior,  limitations  of  the  theory  exist. Some  researchers  reject  the  theory  of  planned behavior  outright  as  an  adequate  explanation  of human  social  behavior.  Most  critics,  however, accept  the  theory’s  basic  assumptions  but  either question its sufficiency or inquire into its limiting conditions.  Some  of  the  theory’s  potential  limitations are briefly discussed below.

First, factors such as personality, affect or mood, demographic variables (e.g., age, gender, socioeconomic  status),  past  exercise  behavior,  and  habit are  not  directly  taken  into  consideration  within the theory of planned behavior. This is a limitation because researchers examining the determinants of physical activity have consistently found, for example,  that  the  percentage  of  the  population  reporting  no  physical  activity  is  higher  among  female than  male  populations,  among  older  adults  than younger  adults,  among  extraverts  than  neurotics, and among the less affluent than the more affluent.

Second,  there  is  ambiguity  regarding  how  to define  perceived  behavioral  control,  and  this  creates measurement problems. Ajzen stated that the term  perceived  behavioral  control  may  be  misleading  and  to  avoid  misunderstanding,  he  suggested  that  perceived  behavioral  control  should be  read  as  “perceived  control  over  performance of a behavior.” Ajzen further noted that perceived behavioral  control  is  composed  of  two  components: self-efficacy (ease or difficulty of performing the behavior) and controllability (beliefs about the extent to which performing the behavior is up to the actor); and thus, measures of perceived behavioral control should contain items that assess both self-efficacy and controllability. Third, the longer the time interval between intention  and  behavior,  the  less  likely  the  behavior  will occur. Research reveals that the predictive power of intention will vary inversely with the time between the  measurement  of  intention  and  performance  of the behavior. The longer the time interval between intention and behavior, the more likely intention is to change with new available information. As time passes, an increasing number of intervening events can change people’s behavioral, normative, or control  beliefs  and  can  modify  attitudes,  subjective norms,  or  perceptions  of  control,  thus  generating revised  intentions.  Changes  of  this  kind  will  tend to  reduce  the  predictive  validity  of  intentions  that were  assessed  before  the  changes  took  place.  This new information would result in a diminished relationship between intention and behavior. Consistent with this argument, shorter intervals between assessment of intentions and behavior are associated with stronger correlations than are longer time intervals.

A  fourth  potential  limitation  pertains  to  the construct of subjective norm. Consistent throughout  the  physical  activity  literature,  the  theory  of planned  behavior  variables  of  attitude  and  perceived  behavioral  control  have  been  significant predictors of intention. Subjective norm, however, is  generally  a  weaker  predictor  of  intention.  One reason  for  the  inconsistent  usefulness  of  subjective norm is that the role of significant others may not  be  important  in  encouraging  participation  of physically active individuals. Support for this view comes from the fact that subjective norm is a stronger  predictor  of  intention  for  other  health  behaviors,  such  as  contraceptive  use,  where  the  role  of significant others is deemed to be more important for the decisions made, and thus cannot be ignored.


Changing  people’s  behavior  is  very  difficult  to  do, especially  when  dealing  with  a  complex  health behavior  such  as  physical  activity.  To  increase  the success  of  predicting,  understanding,  explaining, and  changing  physical  activity  behavior,  researchers and practitioners should use a theoretical framework such as the theory of planned behavior as a guide. Researchers have found support for the utility  of  attitudes,  perceived  behavioral  control,  and to  a  lesser  extent,  subjective  norms  in  explaining people’s  intention  to  becoming  physically  active. Also,  researchers  have  found  a  strong  relationship between someone’s intention to be active and one’s engaging in the behavior. Of importance, the size of the intention–behavior effect shrinks significantly  when  past  exercise  behavior  is  controlled. Furthermore, a person’s perception of the personal control  over  engaging  in  physical  activity  can  also directly predict behavior. In general, there is strong evidence  that  the  theory  of  planned  behavior  can explain and predict people’s physical activity intentions and behaviors. In summary, because of the success  of  the  theory  of  planned  behavior  to  explain and predict exercise behavior, intervention research reveals  that  it  is  also  a  useful  framework  to  guide physical activity interventions.


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