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For every behavioural outcome there are intermediate stages on the way to a particular action or practice. Making these stages explicit can help in specifying indicators to be measured in studies of interventions aimed at changing a practice or behaviour. Using concepts from social psychology and decision theory, CIET uses the acronym CASCADA to describe an unpredictable but broadly sequential flow through conscious knowledge, attitudes, subjective norms and positive deviation from subjective norms, the intention to change, the sense of agency (collective and individual) that change is possible, discussing it and, finally, making the behaviour change. Each stage may be illustrated with reference to HIV and AIDS prevention.


Conscious knowledge: In primary prevention, we might be concerned about knowledge about rights (for example, to say no), modes of transmission of sexually transmitted infections, prevention mechanisms including condoms, misconceptions and myths about HIV/AIDS. In secondary prevention, the value and nature of HIV testing and for tertiary prevention, we might focus on knowledge of antiviral therapy.


Attitudes: Attitudes of interest in primary prevention include the belief that, for example, women enjoy sexual abuse or that people with AIDS should live apart from others. In secondary or tertiary prevention, an example might be the belief that precautions like condoms are worth the effort.


Subjective norms: In primary prevention, the belief that friends or neighbours see things in a certain way (people around here believe that women enjoy sexual abuse) can be part of a negative cultural environment or, if modified, part of an incentive to change. The positive deviation from a negative social norm (in secondary prevention, my friends do not believe condoms are worth the effort, but I believe they are) can provide an early positive indicator of a behaviour change strategy.


Intention to change: The intention to go for HIV testing and, in tertiary prevention, intention to use a condom during intercourse, are useful markers of progress towards behaviour change.


Agency: Individual agency or sense of self-efficacy can be measured by the declared ability to insist on using a condom (secondary prevention). Also important is collective efficacy, the perception that a particular issue can be dealt with in the community.


Discussion or ability to talk about it: The ability to talk about an issue (refuse unwanted sex, use a condom, go for HIV testing or take up an ART offer) often precedes the actual practice. This also provides pointers for interventions in primary, secondary or tertiary prevention.


Actions/practices/behaviours: Prevention-related practices include sexual violence, going for HIV testing, using condoms, multiple concurrent partners, and uptake or adherence to ART. Like any prevention outcome, behaviour might be conditioned by factors like age or sex. A general concern is that of the social, cultural or economic factors supporting risk behaviour. The key to understanding preventive impact is to relate individual behaviour change to individual exposure to interventions.


Neither the steps in the cascade nor its slope are fixed. In a given situation, x% will have conscious knowledge of AIDS prevention, y% will have helpful attitudes and z% will have the agency to do something about it. The implication of the CASCADA model is that a positive attitude counts for more than conscious knowledge, and agency counts for more than a positive attitude. We do not know exactly how much more – this is probably situation and subgroup specific.


Initially developed in the context of HIV/AIDS prevention in South Africa, the CASCADA has also been applied in Nicaragua to community control of dengue, and is applicable to many other types of research involving human behaviour, such as suicide prevention among Aboriginal youth in Canada.