The strategy works only if the subject doesn't know Lewis intends to tag along for months.

Neither the researchers nor the subjects knew which bottle was being presented.

Obviously, the subjects had not known they were under surveillance.

The subjects did not know to which group they had been assigned.

The only problem is that the subject cannot know what is happening to him.

Even the normal subjects in the study don't know the name of it or what it is about.

It's especially effective when the subject doesn't know where the tallow will fall next.

My subjects should always know that I am willing to do without so that they may live better.

What the subjects did not know is that they had previously been divided into two groups.

In the second, subjects knew ahead that they were guaranteed to win $1 with every fourth card.