Dependence and Independence in Responding to Double Stimulation: A Comparison of Stop, Change, and Dual-Task Paradigms

When a letter and a tone are presented in rapid succession, there is substantial interference if both require an overt response (the dual-task paradigm), but there is very little interference if the tone is a signal to inhibit the response to the letter (the slopping paradigm). These effects were replicated under common stimulus conditions in two experiments, and they were compared with effects in a change paradigm, in which the tone required an overt response, like the dual-task paradigm, but was also a signal to inhibit the response to the letter, like the stopping paradigm. In the change paradigm, the overt response to the tone suffered interference only if subjects failed to inhibit the concurrent response to the letter; inhibiting the response to the letter virtually eliminated the interference. The results suggest that differences in response competition are primarily responsible for differences in interference between the dual-task and stopping paradigms. More generally, the results support response-competition interpretations of dual-task interference.