Modern psychologists rely most heavily on to evaluate and understand theories of human behavior.

Scientific observation

Explanation:

Modern psychologists rely most heavily on scientific observation in order to evaluate and understand theories of human behaviour. Scientific observation is one of the most basic and most important processes of science. It consists of receiving knowledge of the outside world through our senses. Modern psychologists rely on scientific observation because this allows them to carefully examine the behaviour of human beings, thus providing better understanding and treatment.

answer; utilitarian;

answer; motor learning;