The dimensionality of reasoning: Inductive and deductive inference can be explained by a single process.

Area of Science:

• Cognitive Psychology
• Cognitive Science
• Human Reasoning

Background:

• Dual-processing theories propose distinct heuristic and analytic systems for reasoning.
• Empirical dissociations in reasoning tasks have traditionally supported these dual-process models.

Purpose of the Study:

• To investigate the number of processing dimensions underlying inductive and deductive reasoning.
• To test whether observed dissociations support dual-processing or single-process models.

Main Methods:

• Three experiments evaluated arguments based on logical validity and believability under inductive and deductive criteria.
• Factors manipulated included working memory load, working memory capacity, and decision time.
• State-trace analysis was used to determine the dimensionality of reasoning processes.

Main Results:

• Argument validity impacted deduction more than induction; believability impacted induction more than deduction.
• Lower working memory capacity and reduced decision time affected sensitivity to argument validity.
• State-trace analyses revealed a single underlying dimension for both inductive and deductive judgments.

Conclusions:

• Observed dissociations in reasoning are compatible with a single-process model.
• A common evidentiary scale may underlie both inductive and deductive reasoning.
• Findings challenge the necessity of dual-processing models for explaining these reasoning patterns.