Abstract: | The primary objective of this study was to test the validity of the here labelled ‘suppression-time’ assumption which contends that the more difficult the response suppression operation, the longer the time required for its successful implementation. A secondary interest addressed the possibility that output suppression difficulty would be influenced by the level of response-response (R-R) compatibility existing between retrieved response tendencies. Two basic requirements confronted subjects within an experimental session: (a) dual-initiation (Dual-I) of paired arm movements, (b) initiation/suppression (I/S) of retrieved outputs, the irrelevant response being suppressed, the relevant output initiated. RT(I/S) magnitude and failure-to-inhibit error frequency increased as response probability increased, thereby providing support for the ‘suppression-time’ assumption. But R-R compatibility degree variations, when realized, did not consistently affect response suppression difficulty. |