The benefit of diagnostic hypotheses in clinical reasoning: Experimental study of an instructional intervention for forward and backward reasoning

Two approaches to electrocardiogram (ECG) diagnosis were examined in a seri es of 2 experiments. The first approach, based on forward reasoning, asked participants to carefully obtain all the data, then synthesize the data int o a diagnosis using provided rules. The second, based on backward reasoning , asked participants to try to work out the diagnosis then identify support ing features. Participants were undergraduate psychology students. In the f irst experiment, the forward reasoning group had the ECG removed after list ing features. Accuracy of the forward reasoning: group was 41.9% and accura cy of the backward reasoning group was 61.3%. In the second experiment, the forward reasoning group was permitted to retain the EGG; this time accurac y rose to 49.4% versus 61.9% for the backward reasoning group. The differen ce remained statistically significant. Thus, the results showed a consisten t advantage for holistic, backward reasoning in an ECG diagnostic task with novices.