up to 50 per cent of the variance remains unexplained. Some new variables have been
developed to improve the effectiveness of the models.Expanded norms
The theory of reasoned action and the theory of planned behaviour include measures
of social pressures to behave in a particular way – the subjective norms variable.
However, it has been suggested that they should also assess other forms of norms. For
example, the intention to carry out behaviours that have an ethical or moral dimen-
sion such as donating blood, donating organs for transplant, committing driving
offences or eating genetically produced food may result from not only general social
norms but also moral norms. Some research has shown the usefulness of including a
moral norms variable (e.g. Sparks 1994; Parker et al. 1995; Légaré et al. 2003).
However, moral norms may only be relevant to a limited range of behaviours (Norman
and Conner 1996). The concept of social norms has also been further expanded to
include ‘descriptive norms’ which reflect the person’s perception of whether other
people carry out the behaviour (i.e. ‘Do you think doctors eat healthily’) and
‘injunctive norms’ which reflect that other people might approve or disapprove of the
behaviour (e.g. Povey et al. 2000).Anticipated regret
The protection motivation theory explicitly includes a role for emotion in the form of
fear. Researchers have argued that behavioural intentions may be related to anticipated
emotions. For example, the intention to practise safer sex ‘I intend to use a condom’
may be predicted by the anticipated feeling ‘If I do not use a condom I will feel guilty’.
Some research has shown that anticipated regret is important for predicting behavioural
intentions (Richard and van der Pligt 1991).Self-identity
Another variable which has been presented as a means to improve the model’s ability
to predict behavioural intentions is self-identity. It has been argued that individuals
will only intend to carry out a behaviour if that behaviour fits with their own image of
themselves. For example, the identity ‘I am a healthy eater’ should relate to the intention
to eat healthily. Further, the identity ‘I am a fit person’ should relate to the intention to
carry out exercise. Some research has supported the usefulness of this variable (Sparks
and Shepherd 1992). However, Norman and Conner (1996) suggested that this variable
may also only have limited relevance.Ambivalence
Most models contain a measure of attitude towards the behaviour which conceptual-
izes individuals as holding either positive or negative views towards a given object.38 HEALTH PSYCHOLOGY