Dr Parvin Abedi Assistant Professor in Community Nutrition Ahvaz Jundishapur University of Medical Sciences Nursing & Midwifery School
Dr Parvin Abedi
Assistant Professor in Community Nutrition
Ahvaz Jundishapur University of Medical
Sciences
Nursing & Midwifery School
Definition
The Theory of Reasoned Action (TRA)
and the Theory of Planned Behavior
(TPB) focus on theoretical constructs
concerned with individual motivational
factors as determinants of the likelihood
of performing a specific behavior.
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Definition
TRA(استدلال عملی ) and TPB ( رفتار )ریزی شده برنامه both assume the best predictor of a behavior is behavioral intention, which in turn is determined by attitude toward the behavior and social normative perceptions regarding it.
TPB is an extension of the TRA and includes an additional construct: perceived control over performance of the behavior.
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DEFINITION
The TRA and TPB, which focus on the
constructs of attitude, subjective norm,
and perceived control, explain a large
proportion of the variance in behavioral
intention and predict a number of
different behaviors, including health
behaviors.
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Application of TRA and TPB
TRA and TPB have been used
successfully to predict and explain a
wide range of health behaviors and
intentions, including smoking, drinking,
health services utilization, exercise, sun
protection, breastfeeding, substance
use, HIV/STD-prevention behaviors and
use of contraceptives, mammography,
safety helmets, and seatbelts.
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ORIGINS AND HISTORICAL
DEVELOPMENT TRA was developed to better
understand relationships between attitudes, intentions, and behaviors (Fishbein, 1967).
Many previous studies of these relationships found relatively low correspondence between attitudes and behavior, and some theorists proposed eliminating attitude as a factor underlying behavior
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تئوری رفتار برنامه ریزی شده
نگرش فرد نسبت به يك رفتار 2 ) نظر افرادي كه برايشان اهميت قايل است در باره آن
رفتار 3 ) برداشت فرد از سختي يا آساني به انجام رساندن آن
.رفتار براي مثال، بر اساس اين نظريه، امكان ترك سيگار در
: فردي كه ويژگي هاي زيررا داشته باشد بيشتر است1 ) نگرش )نگرش مثبت در مورد ترك سيگار داشته باشد
(نسبت به رفتار2 ) تصور كند ديگراني كه برايشان ارزش قايل است ترك
و; (هنجارهاي انتزاعي)سيگار او را تاييد مي كنند 3 ) احساس )احساس كند ترك سيگار در اختيار اوست
(. كارآيي فردي
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In the work that led to development of the TRA, Fishbein distinguished between attitude toward an object and attitude toward a behavior with respect to that object.
For example, most attitude theorists were measuring attitude toward an object (such as an attitude toward cancer) in trying to predict a behavior (such as mammography or breast cancer screening).
Fishbein demonstrated that attitude toward the behavior (for example, attitude toward Mammography) is a much better predictor of that behavior (obtaining mammography) than attitude toward the object (cancer) at which the behavior is directed
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Fishbein and Ajzen,1975; and 1991, clearly defined underlying beliefs (behavioral and normative), intentions, and behavior and their measurement.
They have shown that it is critical to have a high degree of correspondence between measures of attitude, norm, perceived control, intention, and behavior in terms of action (for example, go get), target (for example, a mammogram), context (for example, at the breast screening center), and time (for example, in the next twelve months).
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A change in any of these factors results
in a different behavior being explained.
Low correspondence between model
construct measures on any of these
factors will result in low correlations
between TRA/TPB variables, while high
correspondence will result in high
correlations
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Behavioral intention
TRA asserts that the most important determinant of behavior is behavioral intention.
Direct determinants of individuals’ behavioral
intention are their attitude toward performing the behavior and their subjective norm associated with the behavior.
TPB adds perceived control over the behavior, taking into account situations where one may
not have complete volitional control over a behavior
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Theory External variables
Demographic variables
Attitude towards targets
Personality traits
Other individual difference variables
Behavioral beliefs
Evaluations of behavioral outcomes
Normative beliefs
Motivation to comply
Control beliefs
Perceived power
Attitude
Subjective
norms
Perceived
control
Intention
to perform
behavior
behavior
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Theory of Reasoned
Action and Theory of
Planned Behavior.*
Attitude
Attitude is determined by the individual’s beliefs about outcomes or attributes of performing the behavior (behavioral beliefs), weighted by evaluations of those outcomes or attributes.
Thus, a person who holds strong beliefs that positively valued outcomes will result from performing the behavior will have a positive attitude toward the behavior.
Conversely, a person who holds strong beliefs that negatively valued outcomes will result from the behavior will have a negative attitude.
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Normative behavior
Similarly, a person’s subjective norm is
determined by his or her normative beliefs, that is, whether important
referent individuals approve or
disapprove of performing the behavior,
weighted by his or her motivation to
comply with those referents.
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Normative behavior
A person who believes that certain referents think she should perform a behavior and
is motivated to meet expectations of those referents will hold a positive subjective
norm.
Conversely, a person who believes these referents think she should not perform
the behavior will have a negative subjective norm, and a person who is less motivated
to comply with those referents will have a relatively neutral subjective norm.
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Behavioral Intention
TRA assumes that the most important direct determinant of behavior is behavioral intention.
Success of the theory in explaining behavior depends on the degree
to which the behavior is under volitional (the power to make your own decision)
control
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Perceived behavioral control
It is not clear that the TRA components
are sufficient to predict behaviors in which volitional control is reduced.
Thus, Ajzen and colleagues added perceived behavioral control to take account for factors outside individual control that may affect intentions and behaviors.
With this addition, they created the Theory
of Planned Behavior
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CONTROL BELIEFS
Perceived control is determined by
control beliefs concerning the presence or absence of facilitators and barriers to
behavioral performance, weighted by
their perceived power or the impact of
each control factor to facilitate or inhibit
the behavior.
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Motivation and ability
Ajzen’s inclusion of perceived control was based in part on the idea that behavioral performance is determined jointly by motivation (intention) and ability
(behavioral control).
A person’s perception of control over behavioral performance, together with intention, is expected to have a direct effect on behavior, particularly when perceived control is an accurate assessment of actual control over the behavior and when volitional control is not high.
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The role of perceived control
The effect of perceived control declines,
and intention is a sufficient behavioral predictor in situations in which volitional control over the behavior is high.
Thus, similar to Triandis’s (1980) conceptualization of facilitating conditions, perceived control is expected to moderate the effect of intention on behavior. However, this interaction hypothesis has received very little empirical support.
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The role of attitude and subjective norm in
intention
TPB also postulates that perceived control is an independent determinant of behavioral
intention, along with attitude toward the behavior and subjective norm.
Holding attitude and subjective norm constant, a person’s perception of the ease or difficulty
of behavioral performance will affect his behavioral intention.
Relative weights of these three factors in determining intentions should vary for different behaviors and populations.
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Intention and other variables
TRA and TPB assume a causal
chain that links behavioral beliefs,
normative beliefs, and control
beliefs to behavioral intentions
and behaviors via attitudes,
subjective norms, and perceived
control.
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Demographic factors
This is one of the major strengths of the
TRA/TPB approach.
Other factors, including demographic
and environmental characteristics, are
assumed to operate through model
constructs and do not independently
contribute to explain the likelihood of
performing a behavior.
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Measures of TRA and TPB
Constructs
TRA and TPB measures can use either
5- or 7-point scales.
A person’s behavioral beliefs about the
likelihood that performance of the
behavior will result in certain outcomes
are measured on bipolar “unlikely-likely”
or “disagree-agree” scales.
Evaluations of each outcome are
measured on bipolar “good-bad” scales.
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Measurements of TRA AND TPB
For example, one outcome of “my quitting
smoking” may be that this “will cause me to
gain weight.”
A person’s behavioral belief about this
outcome is measured by having him rate
the likelihood that “my quitting smoking will
cause me to gain weight.” The person’s
evaluation of this outcome is measured by
having him rate the degree to which “my
gaining weight” is good versus bad.
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MEASUREMENT OF TRA AND TPB
These behavioral belief and evaluation ratings are usually scored from −3 to +3, capturing the psychology of double negatives, where a belief
that a behavior will not result in a negative outcome contributes positively to the person’s attitude.
An “indirect measure” of the person’s attitude toward performing the behavior is computed by first multiplying her behavioral belief concerning each outcome by her corresponding outcome evaluation ratings and then summing these product scores across all outcomes of the behavior.
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MEASUREMENT OF TRA AND TPB
In the example, a person may believe that “quitting smoking” is very unlikely to result in “gaining weight” (belief scored as −3), and may evaluate gaining weight as very bad (evaluation scored as −3), resulting in a belief-evaluation product score of +9.
Thus, the strong belief that performing the behavior will not result in (will avoid) a negatively valued outcome contributes just as positively to the person’s attitude as would a strong belief that the action will result (+3) in a positively valued (+3) outcome (product = +9).
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MEASUREMENTS, continued…
Conversely, a strong belief that the behavior will not result (−3) in a positively valued outcome (+3) contributes negatively (product = −9) to the person’s attitude, because performance of the behavior will not achieve a highly valued outcome.
In the example of “quitting smoking,” beliefs and evaluations of all salient outcomes of this behavior will enter into the computation of an indirect measure of the person’s attitude.
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Measurements, continued…
Similarly, a person’s normative beliefs about whether each referent thinks he should perform the behavior are measured on bipolar scales scored −3 to +3, while the person’s motivation to comply with each referent is measured on unipolar scales scored 1 to 7.
For example, one potential referent with regard to “quitting smoking” might be the person’s best friend. A person’s normative belief concerning his best friend is measured by asking him to rate the degree to which he believes his best friend thinks he should versus should not quit smoking.
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Measurements, continued…
Motivation to comply is measured
by having the person rate his agreement versus disagreement with the statement: “Generally, I want to do what my best friend thinks I should do.”
An indirect measure of the person’s subjective norm is computed by multiplying his normative belief about each referent by his motivation to comply with that referent and then summing these product scores across all referents.
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Measurements, continued…
Applications of TPB suggest that control
beliefs regarding each factor should
be measured on a bipolar likelihood of
occurrence scale scored −3 to +3.
Perceived power of each factor is
measured on a bipolar “easy-difficult”
scale
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Measurements, continued…
For example, some individuals might identify “restaurant smoking restrictions” as a factor that affects their perceived behavioral control over quitting smoking.
A person’s control belief regarding this factor is measured by having her rate her likelihood of encountering “a restaurant smoking restriction,” while perceived power is measured by having the person rate her perception of the effect of “restaurant smoking restrictions” in making it easier versus more difficult to quit smoking.
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Measurements, continued…
These measures are obtained for all factors identified as facilitating or impeding the behavior.
An “indirect measure” of the person’s perceived behavioral control is then computed by multiplying each control belief by the corresponding perceived power (impact) rating, and then summing these product scores across all control factors
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Direct measure of attitude
A direct measure of attitude toward performing the
behavior is obtained using semantic differential scale
items, such as “good-bad” and “pleasant-unpleasant,” and
summing them.
A direct measure of subjective norm uses a single item,
asking the person to rate “Most people important to me
think I should” perform the behavior.
This rating is made on a bipolar “unlikely-likely” or “agree-
disagree” scale.
The direct measure of perceived behavioral control
generally uses semantic (connected with the meaning of
the words) differential scale items such as “under my
control–not under my control” and “easy-difficult.” 5/25/2014 34
Direct measure
These direct measures are important for two reasons.
First, direct measures are usually more strongly associated with intentions and behaviors than indirect measures.
The associations between the “direct” measures and behavioral intention indicate
the relative importance of attitude, subjective norm, and perceived control in
explaining or predicting a given behavior
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Indirect measure
Second, indirect measures should be associated strongly with direct measures to be assured that appropriate beliefs were included in the indirect measures and that the composite beliefs (behavioral, normative, and control) are adequate measures of respective TRA/TPB constructs.
Once this is demonstrated, indirect measures are of most interest. Behavioral, normative, and control beliefs help us understand what drives behaviors and provide a focus for
intervention messages
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TRA, TPB, and IBM Constructs and Definitions
Measure Definition Construct
Bipolar unlikely-likely scale;
scored −3 to +3 Perceived likelihood of
performing the behavior Behavioral Intention
Semantic differential
scales: for example,
pleasant-unpleasant;
enjoyable-unenjoyable
Overall affective evaluation
of the behavior Experiential Attitude (Affect) Direct Measure:
Bipolar unlikely-likely scale;
scored −3 to +3 Belief that behavioral
performance
is associated with certain
positive or negative feelings
Indirect Measure:
Behavioral belief
Semantic differential
scales:
for example, good-bad;
wisefoolish
Overall evaluation of the
behavior INSTRUMENTAL ATTITUDE ,
Direct measure
Bipolar unlikely-likely scale;
scored −3 to +3 Belief that behavioral
performance is associated
with certain attributes or
outcomes
Indirect measure:
Behavioral belief
Bipolar bad-good scale;
scored −3 to +3 Value attached to a
behavioral outcome or
attribute
Evaluation
A
tt
it
u
d
e
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TRA, TPB, and IBM Constructs and Definitions
Measure Definition Construct
Bipolar disagree-agree
scale;
scored −3 to +3
Belief about whether
most people approve or
disapprove
of the behavior
Subjective (Injunctive) Norm Direct Measure:
Bipolar disagree-agree
scale;
scored −3 to +3
Belief about whether
each referent approves
or disapproves
of the behavior
Indirect Measure:
Normative belief
Unipolar unlikely-likely
scale;
scored 1 to 7
Motivation to do what
each referent thinks Motivation to comply
Bipolar disagree-agree
scale;
scored −3 to +3
Belief about whether
most people perform
the behavior
Descriptive Norm Direct Measure:
Bipolar disagree-agree
scale;
scored −3 to +3
Belief about whether
each referent performs
the behavior
Indirect Measure:
Normative belief
Per
ceiv
ed
Nor
m
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TRA, TPB, and IBM Constructs and Definitions Measures Definition Construct
Semantic differential
scales: for example,
under my control–not
under my control; easy-
difficult
Overall measure of
perceived control over
the behavior
Perceived Behavioral
Control
Direct Measure:
Unlikely-likely scale;
scored −3
to +3 or 1 to 7
Perceived likelihood of
occurrence of each
facilitating or
constraining condition
Indirect Measure:
Control belief
Bipolar difficult-easy
scale; scored −3 to +3 Perceived effect of each
condition in making
behavioral performance
difficult or easy
Perceived power
Certain I could not–
certain I could scale for
overall behavior;
scored −3 to +3 or 1 to 7
Overall measure of
ability to perform
behavior
Self-Efficacy
Direct Measure:
Certain I could not–
certain I could scale;
scored −3 to +3 or
Perceived ability to over-
come each facilitating or
constraining condition
Indirect Measure:
Self-efficacy belief
P
er
so
n
al
A
g
e
nc
y
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Research Designs and Analytical Approaches to
Testing TRA/TPB
A prospective study design is recommended to discern relationships between constructs, with attitudes, subjective norms, perceived control, and intentions measured at one time point and behavior measured following a time interval.
Cross-sectional studies are often used to test the TRA/TPB, but they may provide poor prediction and understanding of previous behavior because the time order of motivations and behavior cannot be discerned.
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Research Designs and Analytical Approaches to
Testing TRA/TPB
Relative weights of model constructs are determined empirically for the particular behavior and population under investigation.
This information provides guidance as to which constructs are most important to target for behavior change effort.
Some behaviors are entirely under attitudinal control, while others are under normative control or perceived control
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Research Designs and Analytical Approaches to
Testing TRA/TPB
For example, in a study of adults over age 40, McLallen and Fishbein found colonoscopy intention to be almost completely under normative control, whereas exercise intention was influenced by both attitudes and perceived control.
Similarly, a behavior may be under attitudinal control in one population but under normative control in another population
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Research Designs and Analytical Approaches to
Testing TRA/TPB
Our research found that condom use
with a main partner is primarily under
normative control for female injecting
drug users but influenced by attitude,
norm, and perceived control for females
who do not inject drugs
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Research Designs and Analytical Approaches to
Testing TRA/TPB
Once the significant constructs are
identified, analyses of the beliefs
underlying those constructs can
determine which specific behavioral,
normative, or control beliefs are
most strongly associated with intention
and behavior, thus providing empirically
identified targets for intervention efforts.
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Uses for and Evidence to Support
TRA/TPB
The name Theory of Reasoned Action has often led to the misrepresentation that the focus is purely on “rational behavior”.
This is far from correct. A fundamental assumption of TRA is that individuals are “rational actors” who process information and that underlying reasons determine motivation to perform a behavior.
These reasons, made up of a person’s behavioral, normative, and control beliefs, determine his attitudes, subjective norms, and perceived control, regardless of whether those beliefs are rational, logical, or correct by some objective standard.
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Strength A strength of TRA/TPB is that they provide a frame-
work to discern (diagnosis) those reasons and to decipher(Explore) individuals’ actions by identifying, measuring, and combining beliefs relevant to individuals or groups, allowing us to understand their own reasons that motivate the behavior of interest.
TRA and TPB do not specify particular beliefs about behavioral outcomes, normative referents, or control beliefs that should be measured. As noted in the examples, relevant behavioral outcomes, referents, and control beliefs will likely be different for different populations and behaviors.
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Strength
TRA and TPB provide a framework to
identify key behavioral, normative, and
control beliefs affecting behaviors.
Interventions can then be designed to
target and change these beliefs or the
value placed on them, thereby affecting
attitude, subjective norm, or perceived
control and leading to changes in
intentions and behaviors.
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Usage of TRA and TPB
TRA/TPB has been applied to explain a variety of health behaviors, including exercise, smoking and drug use, HIV/STD-prevention behaviors, mammography use,
clinicians’ recommendation of and provision of preventive services, and oral hygiene behaviors.
These studies generally have supported perceived control as a direct predictor of both intentions and behaviors.
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DIRECT MEASURE OF PERCEIVED
CONTROL However, most studies have used direct
measures of perceived control, rather than computing perceived control from measures of control beliefs and perceived power concerning specific facilitators and constraints.
The few studies that have measured control beliefs (indirect measure) found them to be important predictors of intentions and behaviors
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PERCEIVED BEHAVIORAL
CONTROL
Clearly, if perceived behavioral
control is an important
determinant of intentions or
behaviors, knowledge of the
effects of control beliefs
concerning each facilitator or
constraint would be useful in the
development of interventions.
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CONCLUSION
TRA is using to understand the relation
between attitude perceived norms and
intention.
TPB is the extension of TRA as the
perceived control was added.
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