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The Stroop effect: why proportion congruent has nothing to do with congruency and everything to do with contingency
James R Schmidt1, Derek Besner
1Department of Psychology, University of Waterloo, Waterloo, ON, Canada. j4schmid@watarts.uwaterloo.ca
Summary
The item-specific proportion congruent (ISPC) effect is explained by participants predicting responses based on word cues, not by modulating attention. This contingency hypothesis sufficiently accounts for observed Stroop effect variations.
Area of Science:
- Cognitive Psychology
- Experimental Psychology
Background:
- The item-specific proportion congruent (ISPC) effect describes how the Stroop effect varies based on word-color presentation frequencies.
- Existing theories, such as the modulation and contingency hypotheses, attempt to explain this phenomenon.
Purpose of the Study:
- To test the validity of the modulation hypothesis versus the contingency hypothesis in explaining the ISPC effect.
- To determine the underlying mechanism driving the ISPC effect.
Main Methods:
- Reanalysis of existing data from Jacoby, Lindsay, and Hessels (2003).
- Conducting new experimental studies to gather further evidence.
- Analyzing response patterns in relation to word identity and color congruence.
Main Results:
- Data reanalyses and new experimental results were inconsistent with the modulation hypothesis.
- Findings strongly supported the contingency hypothesis, indicating participants use word cues to predict responses.
- A response threshold mechanism incorporating contingency information adequately explained the observed data.
Conclusions:
- The contingency hypothesis provides a more robust explanation for the ISPC effect than the modulation hypothesis.
- Participants appear to leverage response prediction based on word-color contingencies.
- Response threshold mechanisms are crucial for understanding how contingency information influences cognitive performance.
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