When fast logic meets slow belief: Evidence for a parallel-processing model of belief bias

Dries Trippas,Valerie A Thompson,Simon J Handley

doi:10.3758/s13421-016-0680-1

Dries Trippas, Valerie A Thompson + Show 1 more

Open Access

https://doi.org/10.3758/s13421-016-0680-1

Copy DOI

Abstract

Two experiments pitted the default-interventionist account of belief bias against a parallel-processing model. According to the former, belief bias occurs because a fast, belief-based evaluation of the conclusion pre-empts a working-memory demanding logical analysis. In contrast, according to the latter both belief-based and logic-based responding occur in parallel. Participants were given deductive reasoning problems of variable complexity and instructed to decide whether the conclusion was valid on half the trials or to decide whether the conclusion was believable on the other half. When belief and logic conflict, the default-interventionist view predicts that it should take less time to respond on the basis of belief than logic, and that the believability of a conclusion should interfere with judgments of validity, but not the reverse. The parallel-processing view predicts that beliefs should interfere with logic judgments only if the processing required to evaluate the logical structure exceeds that required to evaluate the knowledge necessary to make a belief-based judgment, and vice versa otherwise. Consistent with this latter view, for the simplest reasoning problems (modus ponens), judgments of belief resulted in lower accuracy than judgments of validity, and believability interfered more with judgments of validity than the converse. For problems of moderate complexity (modus tollens and single-model syllogisms), the interference was symmetrical, in that validity interfered with belief judgments to the same degree that believability interfered with validity judgments. For the most complex (three-term multiple-model syllogisms), conclusion believability interfered more with judgments of validity than vice versa, in spite of the significant interference from conclusion validity on judgments of belief.

Highlights

Two experiments pitted the default-interventionist account of belief bias against a parallel-processing model
We found that belief-logic conflict interferes more with belief judgments than with logic judgments for modus ponens, but not when reasoning about the more complex modus tollens
Do we assume that these decisions are based on two distributions of belief-strength, with a logic-based response criterion which shifts according to validity? For we argue it is safest to rely on the signal detection theory as an excellent measurement model until it is specified in a more dynamic way such that it can make predictions about the timecourse of processing (e.g., Pleskac & Busemeyer, 2010)

Summary

Introduction

Two experiments pitted the default-interventionist account of belief bias against a parallel-processing model. A review of the available evidence suggests that occasionally belief judgments may require considerable time and effort (cf., Handley & Trippas, 2015), suggesting that here too a pure classification in terms of Type 1 or Type 2 processing is overly simplistic Taken together, these data support models in which logical and belief-based processing is initiated simultaneously (De Neys, 2012, 2014; Handley & Trippas, 2015; Pennycook, Fugelsang, & Koehler, 2015; Sloman, 2014)

Objectives

Results

Discussion

Conclusion