2. Applying an Extended Version of the Theory of Planned Behavior to Illicit Drug Use Among Students BRIANM CMILLAN2 AND MARKC ONNER University of Leeds School of Psydegreechology, University of Leeds,, England, England Journal of Applied Social Psychology, 2003, 33, 8, pp
Zohreh fathian
Candidate of health education & health promotion
Medical university of Esfahan

3. Introduce
drug use among young people has been on the increase in recent years. Data from various drug use surveys in the United Kingdom have founRecreationald that the use of cannabis and other non-opiates has been rising over the last 30 years.
Although many individuals use illicit drugs and experience few problems, there are potential risks involved. Aside from the issues of legality,the use of any drug can be a risk to health. Cannabis smoke contains 50% to70% more carcinogenic hydrocarbons than does tobacco smoke . LSD use may lead to long-lasting psychopathology in vulnerable individuals as may use of ecstasy,. Repeated use of amphetamines causes tolerance and dependence and may result in a condition known as amphetamine psychosis, which is similar to paranoid schizophrenia).
Thus, recreational drug use is a topic, particularly among young people, that is a matter of interest on health and legal grounds

4. Introduce
The present paper examines the usefulness of the theory of planned behavior (TPB; Ajzen, 1991; Ajzen & Madden, 1986) in understanding intentions to use and self-reported use of LSD, amphetamine, cannabis, and ecstasy in a sample of students.
The predictive role of three additional variables (descriptive norms,moral norms, and attitude variability) is also examined, along with several hypothesized interactions.

5. Theory of Planned Behavior
The TPB, which was developed from the theory of reasoned action (TRA;Ajzen & Fishbein, 1980; Fishbein & Ajzen, 1975), is one of the more widelyused frameworks for understanding and predicting behavior in social and health psychology.
The TPB postulates that behavior can be predicted by intentions to perform that behavior, which in turn can be predicted by the attitude toward performing
that behavior, the subjective norm (which refers to the perceived social pressure to perform or not to perform the behavior),
and finally the degree of perceived behavioral control (PBC; the perceived ease or difficulty in performing a behavior, thought to reflect past experience and anticipated barriers and facilitators)

6. Theory of Reasoned Action r
Behavioral Beliefs
Evaluation of
Behavioral Outcomes
Attitude toward
Behavior
Behavioral Intention
Normative Beliefs
Behavior
Subjective Norms
Motivation to Comply
TRA;Ajzen & Fishbein, 1980; Fishbein & Ajzen, 1975

7. Theory of planned behaviour (TPB)
Azjen (1991) suggested various factors combine to form an intention to act a certain way.
Hmm….How do
I use
this with
addiction?
Attitudes toward
behaviour
Subjective
norms
Intention to
behave in a
certain way
Behaviour
Perceived
behavioural
control
the perceived ease or difficulty in performing a behavior, thought to reflect past experience and anticipated barriers and facilitators

8. self-efficacy is one’s degree of confidence in the
INTEGRATED BEHAVIORAL MODEL
Knowledge
and skills o
Perform he
behavior
Experiential
attitude
if a person has a strong behavioral
intention, she needs knowledge and skill to carry out the behavior.
Feelings about
behavior
Feelings about
behavior
Feelings about
behavior
Feelings about
behavior
influencing
perceptions of behavioral outcome likelihood or evaluation of outcomes.
self-efficacy is one’s degree of confidence in the
ability to perform the behavior in the face of various obstacles or challenges. This is
measured by having respondents rate their behavioral confidence on bipolar “certain
I could not–certain I could” scales
Instrumental
attitude
Behavioral
beliefs
Behavioral
beliefs
Behavioral
beliefs
Salience
of the
behavior
Behavioral
beliefs
normative beliefs about what others think one
should do and motivation to comply
one’s perceived
amount of control over behavioral performance, determined by one’s perception of
the degree to which various environmental factors make it easy versus difficult to
carry out the behavior
Instrumental attitude is cognitively
based, determined by beliefs about outcomes of behavioral performance
Normative
beliefs—Others’
expectations
Normative
beliefs—Others’
expectations
Injunctive
norm
Normative
beliefs—Others’
expectations
Normative
beliefs—Others’
expectations
Other
Factor
Intention to perform the behavior
Behavior
Normative
beliefs—Others’
behavior
Normative
beliefs—Others’
behavior
Descriptive
norm
Normative
beliefs—Others’
behavior
Environmental constraint
there should be no or few environmental constraints that make behavioral performance
very difficult or impossible.
Control
beliefs
Perceived
control
Control
beliefs
what others in one’s social or personal networks are doing
(descriptive norm
Self-efficacy
Habit
Self-efficacy
Efficacy
beliefs
Efficacy
beliefs

9. Normative Influences in the TPB
Previous research suggests that normative influences play an important role in behaviors such as drug use. For example, Leitner et al. (1993) found that 90% of respondents in their survey saw peer pressure as a cause of drug use.
Despite this, studies employing the TPB generally report that subjective norms (the component of the model held to encapsulate normative influences) were the weakest predictor of intentions (Armitage & Conner, 2001).
Cialdini, Reno, and Kallgren (1990) refer to the normative beliefs used in the usual applications of the TPB as injunctive social norms as they concern others’ social approval or disapproval, and distinguish them from descriptive social norms (ie., perceptions of what others do) and moral or personal norms (i.e., personal rules of conduct).

10. Ajzen (1991) suggested that moral norms also might directly influence intentions,and Beck and Ajzen (1991) found that the addition of moral norms significantly increased the amount of variance explained in intentions to perform dishonest behaviors by 3% to 6%.
Several other studies have reported that the inclusion of moral norms adds significantly to the prediction of intentions over and above the other components of the TPB (e.g., Kurland, 1995; Parker, Manstead, & Stradling, 1995; Raats, Shepherd, & Sparks, 1995; Randall & Gibson, 1991 ; for a review, see Manstead, 2000).
Conner and Armitage (1 998) found that in 9 out of 10 studies, moral norm was a significant predictor of intentions of 4% to the prediction of intentions..

11. Focus of the Present Study
The present study examines the application of the TPB to understanding intentions and actual use of LSD, amphetamine, cannabis, and ecstasy over a 6-month period in a sample of students.
We also examine the predictive power afforded by two additional measures reflecting normative pressures (descriptive and moral norms) and investigate interactions among attitude and PBC, attitude variability and attitude, and PBC and intentions
. The consideration of four different drugs allowed us to assess the generalizability across drugs of the proposed relationships

12. Method
Participants
A total of 494 undergraduate students (222 male, 272 female) aged 17 to 54 years (but mainly in the 19- to 22-year age range) at a university in England took part in the first round of the study (representing 62% of those approached). Of these, 461 provided complete data on all drugs and were used in the analysis. A
total of 146 of these undergraduates (95 female, 51 male) completed the second round of the study 6 months later, 136 of whom provided complete data on all drugs and were used in the analysis.3
Measures were assessed by means of an anonymous questionnaire. Participants were encouraged to complete and return the questionnaire, as it made them eligible for a cash prize.

13. :Material
Intention.
Intentions to use were measured with the items, “For each drug listed below, please indicate how often you intend to use that drug over the next 6-month period (if ever) by ticking the appropriate box.” The choices were rated on an 8-point scale ranging from 1 (never) through 4 (everyfew months) to 8 (every day). Higher scores indicate intention to use a drug more fiequently.4
Arritudes.
These were assessed by a pair of semantic differentials (two items;a = .76 for LSD, a = .72 for amphetamine, a = .81 for cannabis, a = .73 forecstasy). The statement “Using this drug over the next 6 months would be . . .”
was completed with the semantic differential choices of bad-good and unpleasant-pleasant. The items were scored on a 7-point scale ranging from -3 to +3,with higher scores indicating more positive attitude.5

14. :Material Injunctive norms.
These were measured in relation to best friend, other friends, family, health experts, partner, and people who use each of the drugs (groups identified in a pilot study). A sample item is “My best friend thinks I should not or should use this drug.” The items were rated on a 7-point scale ranging
from -3 (should not) to +3 (should).
Motivation to comply with each of the referent groups was measured with items for each group and each drug. A sampl item is “With regards to using this drug, I want to do what my best friend thinks I should.” The items were rated on a 7-point scale ranging from 1 (strongly disagree)
to 7 (strongly agree). These items were multiplicatively combined and
averaged (a = .80 for LSD, a = .80 for amphetamine, a = .81 for cannabis, a =
.80 for ecstasy).6

15. :Material Perceived behavioral control.
A belief-based measure of PBC was employed.Control beliefs were assessed in relation to expense, having important work to do, being in a bad mood, being in a good mood, “going out,” A sample item is “I am in a
bad mood . . ,,” which was rated on a 7-point scale ranging from 1 (infrequently)to 7 Vrequently). Power item measures were taken for each of the control beliefs.
For example, “Being in a bad mood makes my taking this drug . . .,” which was rated on a 7-point scale ranging from -3 (less likely) to +3 (more likely). These
measures were multiplicatively combined and averaged.

16. :Material Descriptive norms.
Descriptive norms were assessed in relation to best friend and partner with a single item: “Please indicate, by ticking the box beside each drug, which drugs your partner uses.” The item was scored either 0 (does not use this drug) or 1 (uses this drug). In relation to other friends, family, and health experts, a different single question was used. This item was “Please indicate, by ticking the appropriate box, how many (if any) of the people in your family use each drug” and was scored on a 6-point scale ranging from 1 (none) to 6 (all) The scores on each item were standardized and then averaged (a = .63 for LSD, a = .66 for amphetamine, a = .73 for cannabis, a= .64 for ecstasy).

17. :Material
Moral norms.
Moral norms were measured using a single item for each drug.
The item “It would be morally wrong for me to use this drug” was scored on a 7-point scale ranging from -3 (strongly agree) to +3 (strongly disagree). Negative scores indicated moral norms not to use a particular drug.
Attitude variability:
Attitude variability was assessed using a single item for each drug (“My attitude towards using this drug varies from time to time-sometimes my attitude is positive, sometimes negative”). The item was scored on a 7-point scale ranging from 1 (strongly disagree) to 7 (strongly agree), with higher scores indicating higher levels of attitude variability for a particular drug.

18. :Material
Behavior
Behavior was measured in the second questionnaire distributed 6 months after the first with the questions, “Over the last 6-month period, how often (if ever) have you been using each of the drugs listed below?” The item was scored on an 8-point scale ranging from 1 (never) to 4 (every few months) to 8 (every day). Higher scores indicated more frequent use.

19. Result:

20. Result

21. :Result
Attitudes, injunctive norms, and PBC were each significantly associated with intentions. Attitudes or PBC had the greatest influence on intentions compared to injunctive norms for all drugs. In each case, greater intention to use a drug was associated with holding a more positive attitude, perceiving greater pressure to use the drug, and perceiving factors to facilitate rather than inhibit drug use.
Descriptive norm was a positive significant predictor of
intention for each drug (p < .OOl). Moral norm was a significant predictor of ecstasy use intentions (p < .05) and a marginally significant predictor of cannabisuse intentions (p < .lo). The significant negative contribution of attitude variabil
The Attitude Variability x Attitude interaction had a marginally significant negative beta weight in the regression equations for LSD (p < .lo) and a significant negative beta weight for ecstasy (p < .05). The PBC x Attitude interactions were positive and significant
for all drugs (p < .001).8

22. Result: as PBC increased, the predictive power of intentions
increased. Thus, intentions became more predictive of frequency of drug use when individuals perceived factors to facilitate rather than inhibit performance of
the behavior.

23. :Discussion
The present findings suggest that the TPB can be used to predict intentions and use of LSD, amphetamine, cannabis, and ecstasy.
The data provide some additional support for the TPB, adding to a considerable body of literature supporting this model (Ajzen, 1996; Conner & Sparks, 1996; Godin & Kok, 1996).
In addition to providing further support for the TPB, the present findings demonstrate the role of additional normative variables and the importance of considering interactions among variables in the TPB. The findings also suggest that attitude variability can be an important consideration when examining the impact of attitudes on intentions.

24. :Discussion Interaction Eflects
We investigated three interaction effects in the TPB:
Two involved intentionas the dependent variable (Attitude Variability x Attitude, and PBC x Attitude),
and one involved behavior as the dependent variable (Intention x PBC).
Such interaction effects are of interest because they might indicate boundary conditions for the relationships between variables in the TPB.

25. :Discussion
Ajzen (1 991) predicted an interaction between intention and PBC in the TPB such that the relationship between intention and behavior varies as a function of levels of PBC.
It was predicted that as level of PBC increases, the predictive power of intention increases. A few studies have demonstrated such an effect in the context of the TPB (e.g., Terry & O’Leary, 1995; White, Terry, & Hogg,1994).
The present study confirms this effect in four drugs (although it was only marginally significant for amphetamine and ecstasy). However, this is the first study to confirm the effect using a belief-based measure of PBC

26. :Discussion
Thus, in the present case, it was perceiving there to be more facilitators than inhibitors to taking the drug that was associated with a stronger intention-behavior relationship

27. :Discussion
Norman and Smith (1 995) and Sparks et al. (1 992) hypothesized that attitude variability moderated the attitude-intention relationship.
The present findings with respect to attitude variability confirm this hypothesis when predicting LSD intentions. At higher levels of attitude variability, attitudes were less predictive of intention. However, attitudes remained significantly related to intention at all levels
of attitude variability

28. :Discussion
A final interaction that we examined was between PBC and attitude In the present study, we employed a belief-based measure of PBC.
As predicted, consistently across drugs, PBC was more strongly associated with intention when attitudes were more positive. In the case of cannabis and amphetamine, PBC was significantly positively associated with intention at all levels of attitude. However, for LSD and ecstasy, PBC was unrelated to intention when attitudes were negative. Thus, as predicted by Eagly and Chaiken, PBC becomes increasingly less important to
the formation of an intention about a behavior as attitude toward the behavior becomes more negative.`

29. شاد وسلامت باشید
:Discussion