When researchers conducted experiments to test whether ginkgo biloba improves memory and mental alertness, they found in before-and-after comparisons that scores on mental ability tests rose for both the experimental and the control group. The conclusion was that this was likely the result of effects, because the participants' experience with the tests was the most likely reason that test scores improved in both groups.

practice

Explanation:

Practice effect could be defined as focusing on and carrying out an act repeatedly based on feedback of the previous till the practice improves.

Several practise can influence the result of an analysis, when a practice is carried out often, there is tendency that the result won't turn out the same, especially when done over some handful number of times, this is what describes a practise effect, and what the researchers realized from the report.

think its caste system

explanation: