Assistant Professor in Community Nutrition Nursing

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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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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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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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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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:


scored −3 to +3 Belief that behavioral

performance

is associated with certain

positive or negative feelings

Indirect Measure:

Behavioral belief


scales:

for example, good-bad;

wisefoolish

Overall evaluation of the

behavior INSTRUMENTAL ATTITUDE ,

Direct measure


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:


scale;

scored −3 to +3


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


scale;

scored −3 to +3


most people perform

the behavior

Descriptive Norm Direct Measure:


scale;

scored −3 to +3


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


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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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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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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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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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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Documents

Assistant Professor in Community Nutrition Nursing