Final answer:
The researcher cannot conclude that the supplement has a significant effect on cognitive skill.
Step-by-step explanation:
The researcher cannot conclude that the supplement has a significant effect on cognitive skill based on the information provided. The question is asking about the conclusion of a researcher, which typically comes from a well-designed scientific study.
The information provided, such as games improving cognitive skills and the power of suggestion in experiments, is not directly related to the supplement being discussed.
To determine if the supplement has a significant effect on cognitive skill, specific studies need to be conducted that specifically analyze the supplement's effects on cognitive skill.