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Subjective Norm

Definition

A broad definition of perceived or subjective norm is "the perceived social pressure to perform or not to perform the behavior" in question (Ajzen, 1991, p. 188). But subjective norm is usually defined more precisely, as an individual's perception or "opinion about what important others [italics added] believe the individual should do" (Finlay, Trafimow, & Moroi, 1999, p. 2015) – i.e., perform or not perform the behavior in a specific situation. This perception or opinion has been labeled as that individual's normative belief, which is often then multiplied by motivation to comply (with this belief), as represented in the equation (NB×Mc) (Ajzen & Fishbein, 1972). When multiple, specified important others are included, the normative beliefs and motivation to comply for each would be summed, Σ(NBiMci). If the researcher is interested in relative influences of each specified other, regression weights can be calculated.

Subjective norms as represented by normative beliefs are located within, but not identical to, the broader construct of social norms. "While a social norm is usually meant to refer to a rather broad range of permissible, but not necessarily required behaviors, NB refers to a specific behavioral act the performance of which is expected or desired under the given circumstances" (Ajzen & Fishbein, 1972, p. 2).

Subjective norm is also measured as normative belief without including motivation to comply. Some research has concluded that it is not necessary to include motivation to comply, finding measures of Mc to be "unsatisfactory" (Ajzen & Fishbein, 1972, p. 4) or that including Mc may even attenuate the correlation between subjective norm and behavioral intention (Ajzen & Driver, 1992).

The theory of reasoned action (TRA) (Fishbein & Ajzen, 1975) includes subjective norms and attitude toward the behavior as both influencing behavioral intention, which then directly influences behavior. The theory of planned behavior (TPB) (Ajzen, 1991) adds to these the variable of perceived behavioral control, which, when lacking, can help to explain failure to perform the behavior even when attitude and subjective norms are positive.

Attitude has generally been found to be more predictive of behavior intention than has subjective norm (Trafimow & Fishbein, 1994). Lap and Rimal (2005) conclude that findings of the effects of social norms (which include subjective norms) on behavior are mixed. An number of studies have found that attitude and subjective norms, together, to be predictive of behavior (as cited in Park, 2000; Trafimow & Fishbein, 1994), including health behaviors (Finlay, Trafimow, & Moroi, 1999).

Miniard and Cohen (1979) found multicollinearity between normative and attitudinal measures, and that manipulation of either variable affected the other one. On the other hand, Fishbein and Ajzen (1981) argue that adequate discriminant validity exits between these variables, that in research "they correlated more strongly with the criterion than with each other" (p. 341). Moreover, Ajzen and Fishbein (1972) found that targeted manipulations of either variable had no significant effect on the other one.

Important others has been measured as a single construct, with subjects or respondents determining what this means or whom it includes. In a more precise approach, specific referents within important others are selected by the researcher based on their relative strength of influence on the behavior in question. Trafimow and Fishbein (1994) found that including behavior-specific referents – those having greater influence on specific behaviors – may be more effective. They go on to suggest that use of the general construct of important others, rather than behavior-specific referents, "may have resulted in an underestimation of the relative contribution of normative considerations as determinants of behavioral intentions" (p. 762). The latter, specific approach may be useful in campaign development, including selection of spokespersons.

Subjective norms have been measured by multiple items, with same single construct of important others. In this approach, differently worded statements measure the perceived expectations of important others, the responses to which are summed.

Example measures with reliability findings

The standard, single-item measure of subjective norm (Fishbein & Ajzen, 1975) is a version of:

"Most persons who are important to me think I should/should not

Should

[description of behavior.]"

Responses are often measured on a seven-point Likert scale, with scores from +3 (should, extremely) to -3 (should not, extremely).

If motivation to comply is included, it can be measured by the following statement and scale.

In general, I want to do what persons who are important to me think I should do:

who are important to me think I should do

Then, responses to each scale would be multiplied and summed if multiple specific referents were included.

Primack et al. (2007) provide an example using multiple, specified important others. Measures of subjective norm (as represented by normative belief) for cigarette smoking as perceived by adolescents included the following scale ( α = .82):

According to my parents, it is very important for me to not smoke cigarettes.
According to my friends, it is very important for me to not smoke cigarettes.
According to most people my age, it is very important for me to not smoke cigarettes.

A 4-point Likert scale was used (strongly agree, agree, disagree, strongly disagree).

Zhao et al. (2008) measured the subjective norm for marijuana use as perceived by adolescents. They also measured perceived approval by multiple, specified important others to represent subjective norm. Weighting each item for motivation to comply, measures for parents, teachers, and grandparents comprised a scale for authority approval (α = .83). Measures for close friends, boyfriend/girlfriend, and people in their age group comprised a scale for peer approval (α = .70). Aggregating authority and peer items yielded internal reliability of α = .83.

Park and Smith (2007) offer a multiple item example that does not include different specified others. They measured subjective norms for talking to one's family about organ donation. The differences between items are in the phrasing used to represent the social pressure.

Most people who are important to me think that I should talk with my family about organ donation.

Most people whose opinion I value consider that I should talk with my family about organ donation.

It is expected of me that I talk with my family about organ donation.

A 7-point response scale was used, from strongly disagree to strongly agree. Acceptable internal reliability was found (α = .73).

Rationale for Selection

These examples were chosen because they are thought to be representative of subjective norm as measured within theoretical frameworks commonly used in health communication (e.g., TPB, TRA). Examples of different scales were used, including single item and multiple items. Multiple item scales included those with different referents and those with different phrasing. This review concludes that use of behavior-specific referents may be the most fruitful approach. The following Additional Commentary locates subjective norms within the broader construct of social norms.

Additional Commentary

Social norms have been explicated by level and type. Lapinski and Rimal (2005) differentiate levels of collective norms to include those of a person's social network and those of an entire society. Subjective norms operate at the individual level as an individual's perception of collective norms. The commonly used subjective norms measures included above are at the low collective norm level of important others, and even at a lower level of specified referents within important others. If not measured as perceived at an individual, psychological level, collective norms should be measured through observational measures that include media environment and structural characteristics of the social system (Lapinski & Rimal, 2005).

Two types of social norms are injunctive and descriptive norms. Injunctive norms "refer to people's beliefs about what ought to be done" in a situation; and descriptive norms "refer to beliefs about what is actually done by most others in one's social group" (Lapinski & Rimal, 2005, p. 130). Cialdini, Reno, and Kallgren (1990) postulate that compliance with injunctive norms is motivated by social approval. Descriptive norms indicate to people the prevalence (Primack, Switzer, & Dalton, 2007) and popularity (Park & Smith, 2007) of a behavior. Bendor and Swistak (2001) argue that social norms affect behavior to the extent that violations of them are perceived to lead to some kind of social sanction. This is a reason that the distinction between injunctive and descriptive norms is important. While both types of norms are important to behavior (Reno, Cialdini, & Kallgren, 1993), "descriptive norms typically do not involve social sanctions for noncompliance" (Lapinski & Rimal, 2005, p. 130).

Lapinski and Rimal (2005) postulate that subjective norms as used in the TRA and TPB are a form of injunctive norms, in that they are "concerned with people's motivation to comply with the beliefs of important others" (p. 130). (These theories do not address descriptive norms (Lapinski & Rimal, 2005) On the other hand, Park and Smith (2007) found subjective norms, as measured by perceptions of important others' expectations (i.e., they "think that I should…."), and injunctive norms as measured perceptions of important others' approval (i.e., they "would approve of my…."), to be "separate dimensions across two different behaviors" related to organ donation (p. 209).

Differentiating types and levels of social norms, as subjectively perceived, should lead to more precise understanding of normative pressures influencing health behaviors.

References

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Relationship Among Attitudes And Subjective Norms: Testing The Theory Of Reasoned Action Across Cultures. [Article].
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Distinctiveness and Influence of Subjective Norms, Personal Descriptive and Injunctive Norms, and Societal Descriptive and Injunctive Norms on Behavioral Intent: A Case of Two Behaviors Critical to Organ Donation.
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Improving Measurement of Normative Beliefs Involving Smoking Among Adolescents.
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Targeting Norm-Related Beliefs About Marijuana Use in an Adolescent Population. [Article].
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