The relationship between systematic and heuristic processing

acceptable attitudes, such as ‘moderate positions minimise disagreement’, ‘people generally agree with people they like’, and ‘agreement facilitates liking’ (Chaiken et al., 1989). When processing systematically to achieve the goal of assessing whether an attitudinal position is socially acceptable, the individual gives more extensive consideration to the detail of the attitudinal messages, and whether they are socially-acceptable. Chen, Shechter and Chaiken (1996) found that when participants were instructed to have a pleasant interaction with another individual, impression-motivated individuals expressed attitudes that were similar to those of their partner, reflecting the use of the ‘go along to get along’ heuristic. It was also found that use of this heuristic biased subsequent systematic processing in impression- motivated participants.

2.5 The relationship between systematic and heuristic

processing

Systematic and heuristic processing are both susceptible to constraints that prevent their operation, for example a lack of motivation, or a lack of heuristic cues in the environment, respectively. Alternatively, there are some situations where both types of processing style are applicable, and the necessary requirements are met. The HSM considers two ways in which systematic and heuristic processing impact on one another: (1) interdependent, or interactive, effects, and (2) independent, or additive, effects (for a recent review, see Bohner & Dickel, 2011).

2.5.1 Interdependent co-occurrence

The interdependent relationship between systematic and heuristic processing suggests that there are conditions under which each processing style will influence the impact of the other processing style. Chaiken et al. (1989) highlight three main interdependent effects: (1) the attenuation hypothesis, (2) the bias hypothesis, and (3) the ability of each processing style to meet the sufficiency threshold.

The attenuation hypothesis.

The attenuation hypothesis captures the idea that the impact of heuristic cues can be weakened, or overridden, by systematic processing. Heuristic cues are more persuasive when motivation or ability to use systematic processing is low (Chaiken et al., 1989). Conversely, the impact of heuristic cues is much weaker when motivation and ability to systematically process is high (i.e. attenuation effects occur in these conditions). The attenuation effect may occur because systematic processing highlights information that questions the validity of heuristic processing. For example, an individual may have cues present regarding the length of the arguments presented. Based on the use of the simple decision rule ‘length implies strength’, longer arguments should be more persuasive. However, systematic processing of the content of the message may reveal that one long message contains many weak arguments, whereas a different, shorter message contains a small number of strong arguments. In such situations, the individual is less likely to use heuristic processing to form their judgement. Examples of heuristic cues’ impact being attenuated by systematic processing typically arise when the heuristic cue provides an interpretation that is incongruent with the interpretation derived from systematic processing (e.g., Maheswaran & Chaiken, 1991).

The bias hypothesis.

The bias hypothesis concerns the way in which heuristic cues can influence systematic processing. Such effects are most likely to occur when the message being processed is ambiguous, allowing for different interpretations to be made (Chaiken et al., 1989). Heuristic cues can disambiguate ambiguous sources, and Chaiken et al. (1989) suggest that the mechanism for this is through heuristic cues establishing expectancies about how valid the message is. In these instances, heuristic cues act to bias systematic processing. Chaiken and Maheswaran (1994) demonstrated that source credibility can bias subsequent systematic processing by shaping the appraisal of the message content (i.e. a message is systematically processed more favourably if it is from a credible source). They demonstrated this through the larger number of positive attributes recorded by individuals who had received a message from a credible source, compared to individuals who had not received a message from a credible source.

Meeting the sufficiency threshold.

As highlighted above (Section 2.5.1), the type of information processing style that is deployed is affected by each style’s ability to meet the sufficiency threshold. In instances

where heuristic processing does not instil adequate confidence, the individual is more likely to systematically process the information. Similarly, if systematic processing does not provide enough confidence (e.g., the individual lacks ability to successfully systematically process the information), the individual can increase their search for heuristic cues that may help in the attainment of the sufficiency threshold.

2.5.2 Independent co-occurrence

The HSM also assumes that there are conditions under which heuristic and systematic processing can proceed concurrently and relatively independent of one another. Chaiken et al. (1989) describe a situation in which support for the additive effects of heuristic and systematic processing could be obtained. They suggest that if a researcher manipulated a heuristic cue (e.g., source expertise) and an aspect of the message content (e.g., argument quality), and subsequently found main effects of both source expertise and argument quality on the individuals’ attitudes, a regression analysis could be conducted to confirm whether the impact of source expertise was mediated by the expertise heuristic and the impact of argument quality was mediated by the valence of thoughts about the message. Chaiken et al. (1989) argue that the reason that there is little empirical support for the additive hypothesis is that in conditions where the 2 × 2 design noted above is used, there are conflicts in conditions where there are strong arguments/non-experts and weak arguments/experts. If an individual is motivated to process systematically, then the heuristics will be invalidated in these two cells. Consequently, the likelihood of demonstrating a main effect of expertise is greatly reduced. The authors recommend comparing heuristic and systematic conditions to conditions where no heuristic cue is present, i.e. observing whether there is a greater effect of source expertise and strong arguments on positive post-message attitudes than strong arguments in the absence of the source expertise cue. Such experiments have yet to be conducted.