In a study on the effects of caffeine on memory, participants drank a bottle of tasteless water containing 100, 50, or 0 milligrams of caffeine. neither the researcher who handed out the bottled water nor the study participants knew whether the water contained caffeine or not. this is an example of a
1) correlational study
2) case study
3) single-blind procedure
4) double-blind procedure

The answer is double-blind procedure

Explanation: Double-blind procedure is a type of research study that neither the researcher nor participants knows the crucial aspects of the study. This study is used to prevent subconscious giveaway by the researcher and bias due to placebo effect by the participants. In this research study, participants are grouped randomly.

Research study given above is an example of double-blinded study because neither the researcher nor the participants are aware that the bottle water used in the experiment contains caffeine.

double-blind procedure

Explanation:

A double-blind study is one in which neither the participants nor the researchers know who is receiving a particular treatment. This procedure is designed to prevent bias in research results. Double-blind studies are particularly major functionis toprevent bias due to demand characteristics or the placebo effect.

For example, the researchers are investigating the effects of caffeine on the memory. In a double-blind study, the researchers who interact with the participants would not know who was receiving the caffeine in varying amounts or none at all (placebo), thereby they will be no bias.

lack of interest from state and local governments.