Final answer:
The largest Stroop effect would occur when 20% of the trials are congruent and 80% are incongruent.
Step-by-step explanation:
The Stroop effect is a phenomenon in psychology where people experience difficulty in naming the color of a word if the word itself is the name of a different color. In this case, the question is asking which condition would lead to the largest Stroop effect. The Stroop effect is typically measured as the difference in response time between congruent and incongruent trials.
a) If 80% of the trials are congruent and 20% are incongruent, there would be a moderate Stroop effect. Since the majority of the trials are congruent, it would be easier for participants to name the colors accurately.
b) If 20% of the trials are congruent and 80% are incongruent, there would be a larger Stroop effect. The higher proportion of incongruent trials would make it more challenging for participants to accurately name the colors.
c) If 100% of the trials are congruent, there would be no Stroop effect. The word and its color would always match, making it easy for participants to name the colors.
d) If 50% of the trials are congruent and 50% are incongruent, there would be a moderate Stroop effect. Participants would experience interference from the incongruent trials, but also have some congruent trials to help them accurately name the colors.
Based on this information, option b) with 20% congruent trials and 80% incongruent trials is likely to lead to the largest Stroop effect.