Studies show that praising children for perfect attendance makes their attendance worse. Montessorians avoid rewards and punishments of all kinds including praise because it can often have the opposite of the intended effect.
Why is it that giving children praise for being smart promotes dishonesty?
…Noting previous research which shows ability praise can undermine a child’s motivation to learn when they encounter difficulties, University of California San Diego Professor Gail Heyman, co-author of the studies, said, “Our findings show that the negative effects of ability praise extend beyond this to promoting dishonesty, and that this occurs in children as young as three years of age.”
Montessori discovered that besides having unpredictable effects, praise is an unnecessary distraction. The child is motivated from within.