noun
experimental psychology
Academic field that studies psychological phenomena through controlled experiments.
彼は大学で実験心理学を専攻している。
He is majoring in experimental psychology at university.
心理学 is the broader field of psychology; 実験心理学 specifically refers to the subfield that uses experimental methods.
Compound of 実験 (experiment) and 心理学 (psychology), likely a calque from English 'experimental psychology'.