Top-down control plays an important role in the selection of an optimal perceptual-decision strategy. However, in previous studies, inferences about the strategies have primarily been based on the participants' subjective reports after they completed all experiments, which can not reflect their trial-by-trial strategies. Hence, this study investigated whether participants can be consciously aware of and control their strategies. A double-dot detection task was conducted and Systems Factorial Technology (SFT) was used for the experimental design, data analysis, and inferences. In Experiment 1, participants were asked to report their strategy (serial or parallel strategy) immediately after each trial; in Experiment 2, participants were asked to pre-select a strategy before a trial started. The results of Experiment 1 showed that all participants utilized either parallel self-terminating processing or coactive processing regardless of their reported strategies. Similarly, the results of Experiment 2 showed that all participants adopted parallel self-terminating processing regardless of their chosen strategies. These findings suggest that participants fail to intentionally adopt serial processing to detect redundant targets. Moreover, these outcomes occurred perhaps because pre-attentive processing is not affected by top-down control; accordingly, our results could further help understandings of how top-down control affects the perceptual decision process.