referred to as informational influence (Deutsch and Gerard, 1955) and is the basis of
expert power (French and Raven, 1960). If we believe that someone else is better
informed and better able to predict what will happen to us then they have the potential
to exert informational influence over us. Doctors are a good example of experts with
informational power in relation to health issues. Second, we are motivated to feel
positively about ourselves, that is, to maintain positive self-esteem. Third, we want to
have good relationships with other people (sometimes referred to as the ‘affiliation
motive’). Acceptance by other people is critical to our sense of self-worth so these
motivations combine to facilitate normative influence. For example, we are reluctant
to lose friends’ approval so we are willing to do what they want rather than following
our own preferences. In doing so we are subject to normative influence.
Research supports a series of principles concerning social influence processes
(Cialdini, 1995), which relate directly to these two types of influence (i.e. informational
and normative). First, as we have seen, ensuring that the message source is perceived
to be credible and expert enhances persuasive impact. Our perception of a message
source also depends on how we categorize ourselves in relation to the source (whether
this is an individual or group). People seen as similar to ourselves or belonging to the
same group are more likely to be liked, viewed positively and able to validate our
experiences (Turner, 1991). Therefore, such people have a greater potential to exert
normative influence. Consequently, it has been proposed that peers (people belonging
to the target audience) are the most persuasive communicators. However, evidence
indicates that this is only true if these communicators are also seen to be experts. Those
perceived to be expert and whose gender and ethnicity match the target group are
most persuasive and helpful (Durantini et al., 2006).
Cognitive dissonance theory (Festinger, 1957) proposes that we are motivated to
maintain a consistent view of the world because cognitive inconsistency creates
dissonance, which is inherently unpleasant. Consequently, when the opinions of others
or persuasive messages appear consistent with what we already know and believe, they
are more likely to be persuasive. Thus consistency, that is, ensuring that a health
message does not contradict existing beliefs, commitments or obligations (and thereby
generate cognitive dissonance) is an important second feature of communications likely
to persuade. See Focus 8.1 on how self-affirmation can be used to help increase the
effectiveness of persuasive messages that potentially challenge self-worth.
A third, and related, principle is the perception of consensus. If a proposed change
is supported by everyone (and this emphasizes the importance of not providing
contradictory advice) and is adopted by others we are more likely to want to join in.
Thus believing that others are performing an action that we are considering (that
is holding a positive descriptive norm – Rivis and Sheeran, 2003 – see Chapter 7) is
likely to facilitate persuasion and bolster motivation. This may be even more persuas -
ive if we categorize ourselves as belonging to the same group as those adopting
the change (e.g. ‘other people like you have already adopted this behaviour’) because
such identification is likely to enhance the self-worth/validation impact of the message.
Thus informational influence (and to some extent normative influence) can be
strengthened by three key features of persuasive messages: (1) source credibility and
expertise; (2) perceived consistency with current world view; and (3) perceived
consensus/identification.
CHANGING MOTIVATION 173