Assimilation and contrast effects

The assimilation effect, assimilation bias or biased assimilation is a bias in evaluative judgments towards the position of a context stimulus, while contrast effects describe a negative correlation between a judgment and contextual information. The assimilation effect, assimilation bias or biased assimilation is a bias in evaluative judgments towards the position of a context stimulus, while contrast effects describe a negative correlation between a judgment and contextual information. Francis Bacon (1561 – 1626) is quoted to have written 'The human understanding when it has once adopted an opinion ... draws all things else to support and agree with it.' In 1979, psychologists speculated about the mechanisms of biased assimilation in that one gives 'any information that suggests less damaging ‘alternative interpretations’' such importance to use it as proof for one´s belief. The classic Stanford University experiment involved supporters and opponents of the death penalty. After showing participants a study that concluded it deterred crime and another suggesting the opposite, they rated the study contradicting their beliefs as poor quality and not persuasive, so that the information resulted in more attitude polarization. In 2004 it has been defined as a bias in evaluative judgments towards the position of a context stimulus. In an assimilation effect, judgment and contextual information are correlated positively, i.e. a positive context stimulus results in a positive judgment, whereas a negative context stimulus results in a negative judgment. Assimilation effects are more likely, when the context stimulus and the target stimulus have characteristics that are quite close to each other. It is the power of narratives in fueling a certain belief. In priming experiments published in 1983, Herr, Sherman and Fazio found assimilation effects when subjects were primed with moderate context stimuli. Depending on how the individual categorizes information, contrast effects can occur as well. The more specific or extreme the context stimuli were in comparison to the target stimulus, the more likely contrast effects were to occur. The term assimilation effect appears in the field of social comparison theory as well. Complementary to the stated definition, it describes the effect of a felt psychological closeness of social surroundings that influence the current self-representation and self-knowledge. A more specific model to predict assimilation and contrast effects with differences in categorizing information is the inclusion/exclusion model developed 1992 by Norbert Schwarz and Herbert Bless.It explains the mechanism through which effects occur. The model assumes that in feature-based evaluative judgments of a target stimulus, people have to form two mental representations: One representation of the target stimulus and one representation of a standard of comparison to evaluate the target stimulus. Accessible information, i.e. information that comes to mind in that specific moment and draws attention, is the crucial context. The same accessible information can result in assimilation or contrast effects, depending on how it is categorized. When the accessible information to construct the representation of the target is used, an assimilation effect results, whereas accessible information used to construct the standard of comparison leads to contrast effects. By way of illustration, in their research on the perceived trustworthiness of politicians, Schwarz & Bless either primed their subjects with info on scandal-ridden politicians (e.g. Richard Nixon) or did not prime them. When subsequently asked for the evaluation of politicians' trustworthiness in general, primed subjects evaluated politicians in general as less trustworthy than subjects without priming. This shows how access to the information of politicians' scandals was included in the representation of the target stimulus, i.e. an assimilation effect.