Firstly, the reader is told that, as someone who does not want high blood pressure, they should be choosing a low salt diet. This utilises a manded altercast in order to invoke consistency in the reader, as people have been shown to behave in ways that are consistent with their perceived self image (Miller, Brickman & Bolen, 1975).
Secondly, the reader is told that they are advised to adhere to the behaviour change by the National Health Service. This technique utilises messenger attributes, as people have been shown to be more susceptible to persuasion when the source is trustworthy (Hovland & Weiss, 1951) and an authority (Bickman, 1974), both of which apply to the NHS.
Finally, the advert makes reference to the potential negative impact ingesting excessive salt may have on the reader themselves, as well as their family if they become ill. This is an emotional tactic, and has been shown to motivate behaviour due to the person wanting to avoid the negative feelings associated with the behaviour (Festinger, 1957).
Bickman, L. (1974). The social power of a uniform. Journal of Applied Social Psychology, 4(1), 47-61.
Festinger, L. (1957). A theory of cognitive dissonance Stanford University Press.
Hovland, C. I., & Weiss, W. (1951). The influence of source credibility on communication effectiveness. Public Opinion Quarterly, 15, 635-650.
Miller, R. L., Brickman, P., & Bolen, D. (1975). Attribution versus persuasion as a means for modifying behavior. Journal of Personality and Social Psychology,31(3), 430-441