Reasoning research has traditionally focused on cognitive biases to investigate the underlying processes. Tasks are often designed to induce conflict between two responses. We have designed a modification of the covariation-detection task. Participants were presented with a short description about the introduction of a new product, treatment or process (e.g. a new cure for a disease). They were told that, prior to implementation, the novel approach needed to be tested (e.g. trial vs. control group). After the description, participants were shown a matrix of results which indicated the pattern of positive and negative outcomes (e.g. 200 positive and 100 negative outcomes in the trial group ; 75 positive and 25 negative outcomes in the control group). The participants were then asked to decide (as fast as possible) whether the new treatment was better. In the prior example the correct answer is ‘NO’, because the positive to negative ratio was higher in the control group. Both the frequency of positive outcomes and the difference between positive and negative outcomes was larger in the treatment group, so there was a bias towards the answer ‘YES’. This is an example of an incongruent trial because the frequencies and ratios cue different solutions. By combining two levels of congruence and whether the novel or old approach was correct, we designed a 2×2 experiment consisting of twenty trials. Participants (N=36) made choices as described above, and after each trial gave a judgment of confidence on a six point scale. Three ANOVAs were conducted for accuracy, response times, and confidence judgments. In each of the analyses only the main effect of congruence was significant. Participants were more accurate, faster and more confident in the congruent versions of the task. Compared to previous research, extreme ratios reduced response times, increased confidence, and produced a larger effect of congruence. |