Let us first fill in the gap in the question above. Note that the capitalized words are the missing words in the question.
''STRUCTURALISM involves using introspection to investigate the components of the mind, whereas FUNCTIONALISM involves the functions or purposes of the mind and behavior in the individual's adaptation to the environment.''
Functionalism is a concept that is been used by Psychologists to determine or how human brain especially the older ones or adult people behave that is it the concept deals about the analysis of adults' Behavior. This concept whose 'founding father'' is often refered to as Wilhelm Wundt used introspection for its investigation.
While FUNCTIONALISM deals with the reason behind a Behavior. It also about the purpose of a particular Behavior.
Explanation: Structuralism and functionalism are considered the first school of thought in psychology. Structuralism deals the study of human mind and the basic units that can be identified through introspection. Functionalism pays more objective forms of study and argues that it's important to study various aspects of the mind and behavior in terms of function