Anderson (1974) reported an experiment in which subjects studied sentences either in the active voice or passive voice and then had to judge whether active or passive test probes followed from these sentences. The foils switched the roles of the agent and object. Thus, the original test sentence might be either
The-sailor shot the-painter.
or
The-painter was shot by the-sailor.
and the subjects would later be asked to recognize a test probe. For either of the above sentences foils could either be active or passive as in:
The-painter shot the-sailor.
or
The-sailor was shot by the-painter.
Thus, the trials could be classified by the voice of the study sentence (active or passive), the voice of the probe sentence (active or passive), and whether the probe sentence was a target or foil (yes or no). Also, subjects were tested either immediately after reading the study sentence or at a 2 minute delay.