In the double-blind procedure, both the participants and the research staff about whether the research participants have received the treatment or a placebo.

Both the participants and the research staff are unaware.

Explanation:

In a double-blind experiment, none of the people involved in the research are aware about which group has received the treatment. This is done in order to avoid biases from the participants due to the placebo effect, and to prevent the researchers from providing accidental cues about the effects of the treatment.

answer; collective security;

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