Two processing modes
Chaiken (1980) noted that people do not always scrutinize messages carefully. When an issue was highly relevant to them, participants changed their attitudes according to argument quality, but when relevance was low they were more influenced by cues such as the communicator's likability. Chaiken explained this as the difference between effortful systematic processing and heuristic processing, which applies simple decision rules learned from experience. Typical rules include experts are usually right, if many people agree it must be true and longer arguments have more support. Such shortcuts resemble judgment heuristics such as the availability heuristic.
The sufficiency principle and co-occurrence
Chaiken and colleagues (1989) proposed the sufficiency principle: people exert effort only until they reach a level of confidence they consider sufficient. The larger the gap between actual and desired confidence, the more systematic processing they do. A distinctive feature of the model is that the two modes can co-occur. Their effects can be additive when both point the same way; systematic processing can attenuate the impact of heuristic cues; and heuristic cues can bias systematic processing itself. Chaiken and Maheswaran (1994) showed that when arguments are ambiguous, source credibility changes how people interpret the arguments themselves.
Processing motives and applications
Chen and colleagues (1999) argued that people process information not only under accuracy motivation, the desire for correct judgments, but also under defense motivation, to protect existing beliefs, and impression motivation, to make a good impression on others. Strong defense motivation can lead even careful scrutiny to biased, self-serving conclusions. The model has been widely applied in health and environmental risk communication: Griffin and colleagues (1999) built a model of risk information seeking and processing, and Trumbo (2002) showed that risk perception varies with processing mode. Critics note that it closely resembles the elaboration likelihood model, and unimodel advocates argue the two modes are a single process.
FAQ
- What is the heuristic-systematic model in simple terms?
- People sometimes judge persuasive messages quickly through cues, such as an expert said it so it must be right, and sometimes scrutinize the content carefully. The more they care and need confidence, the more carefully they think.
- How does it differ from the elaboration likelihood model?
- Both distinguish deep from shallow processing, but the elaboration likelihood model mainly treats one of the central and peripheral routes as dominant, whereas the heuristic-systematic model stresses that both modes can occur at once and add to, attenuate or bias each other.
Sources reviewed: 2026-10-26
References
- Chaiken, S. (1980). Heuristic versus systematic information processing and the use of source versus message cues in persuasion. Journal of Personality and Social Psychology, 39(5), 752–766. The original experiment distinguishing heuristic and systematic processing.
- Chaiken, S., Liberman, A., & Eagly, A. H. (1989). Heuristic and systematic information processing within and beyond the persuasion context. In J. S. Uleman & J. A. Bargh (Eds.), Unintended Thought (pp. 212–252). New York: Guilford Press. The sufficiency principle and accuracy, defense and impression motives.
- Bohner, G., Chaiken, S., & Hunyadi, P. (1994). The role of mood and message ambiguity in the interplay of heuristic and systematic processing. European Journal of Social Psychology, 24(1), 207–221. Mood, ambiguity and the interplay of the two modes.
- Chaiken, S., & Maheswaran, D. (1994). Heuristic processing can bias systematic processing: Effects of source credibility, argument ambiguity, and task importance on attitude judgment. Journal of Personality and Social Psychology, 66(3), 460–473. Heuristic cues can bias systematic processing.
- Chen, S., Duckworth, K., & Chaiken, S. (1999). Motivated heuristic and systematic processing. Psychological Inquiry, 10(1), 44–49. Motivated processing beyond accuracy.
- Griffin, R. J., Dunwoody, S., & Neuwirth, K. (1999). Proposed model of the relationship of risk information seeking and processing to the development of preventive behaviors. Environmental Research, 80(2), S230–S245. The RISP model applying HSM to risk information.
- Trumbo, C. W. (2002). Information processing and risk perception: An adaptation of the heuristic-systematic model. Journal of Communication, 52(2), 367–382. HSM adapted to risk perception.