Title

Counteracting the base-rate fallacy: Effects of causal information and vivid presentation on news readers' issue perception

Date of Award

5-2000

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mass Communications

Advisor(s)

Fiona Chew

Keywords

Base-rate fallacy, Causal information, Vivid presentation, News readers, Issue perception

Subject Categories

Critical and Cultural Studies | Journalism Studies | Mass Communication

Abstract

This dissertation investigates the effects of causal information and vivid presentation in counteracting the base-rate fallacy and generating accurate issue perceptions in the context of news slant. Base-rate fallacy refers to the human tendency to neglect more valid (statistically based) base-rate information in favor of more colorful case-specific information when making decisions/judgments. Previous communication research showed that selective use of exemplars, that is an aggregation of exemplars inconsistent with the distribution of majority vs. minority positions in the base-rate information, in a news report misled news readers' issue perceptions. With the introduction of causal information and vivid presentation (i.e., use of an infographic), news readers were expected to (1) consider the base-rate information as more relevant to the judgment task, (2) pay more attention to such information, (3) utilize it more in their issue perceptions, (4) recall it more accurately, and (5) be more confident in the accuracy of their judgments.

An experiment with a 2 x 2 x 2 mixed factorial design was conducted to examine the effects of causal information (present vs. absent) and vivid presentation (present vs. absent) in counteracting the base-rate fallacy. Two news issues varying in the degree of relevance (high vs. low) to the experiment participants were employed to explore the possible influence of issue relevance on news readers' ability to counteract such a fallacy. One hundred and thirty-six undergraduates participated in the experiment. They were randomly assigned to one of the four experimental conditions. Each participant was requested to read both issues of high and low relevance, whose presentation order was counterbalanced, before answering questionnaires designed to measure his/her utilization, recall, assessed relevance of the base-rate information, as well as his/her attention level and confidence level in the accuracy of his/her response.

Partial support for the postulated predictions was observed in this experiment. First, the presence of causal information was found to increase news readers' utilization of the base-rate information. Second, vivid presentation of the base-rate information (i.e., use of an infographic) increased news readers' recall of such information. Both significant findings were evident in the issues of high relevance and of low relevance, with larger effect sizes observed for the issue of high relevance. However, little evidence of significant impact was found for the rest of the dependent variables. The presence of causal information did not make any difference to the assessed relevance level that news readers attributed to the base-rate information. Neither did it make a difference on people's perceived confidence in the accuracy of their judgment. Similarly, the presence of vivid presentation failed to increase news readers' utilization of the base-rate information and to increase their perceived attention level to such information.

The significant findings indicate that news readers can avoid committing the base-rate fallacy without much effort. Journalists can elicit a more accurate issue perception from the reader, even when it is impossible to feature cases of majority vs. minority exemplars in proportion to the distribution of the base-rate information. These will, in turn, result in a better and more accurately informed society, which is essential to produce more reliable and soundly grounded public opinions.

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