Here's the true story of how I approached your assignment:
(1) I looked at your textbook for broad ideas > I settled on learning and memory > I thought about what aspects of learning and/or memory are interesting to me (from textbooks, own experiences, news story, etc.) > I narrowed it down to concept of body memories.
i.e. memories that don't necessarily have a visual element but evoke an intense physical response, such as increased heart rate
(2) I did some googling on body memories and came across this brief article.
(3) I narrowed down my topic by picking just one aspect of body memories (e.g. How can they affect behavior? Where in the brain are they stored? Why isn't there a visual element? Does age at the time of the memory matter? Are there sex differences? If problematic, how can they be treated? etc.)
(4) I settled on this (tentative) research question: How can body memories from infancy affect behavior later in life?
NOTE: Your research question at this point doesn't have to be set in stone! After some searching and reading, you will likely identify gaps or weaknesses in the current research that you want to explore.
You are interested in how body memories from infancy can affect behavior later in life?
Step 1: Break up this research question into two or three main concepts. Ignore extraneous words.
Step 2: Conduct an initial search with these words, and quickly scan the results.
Step 3: Using information from your initial search, add synonyms, acronyms, and variant spellings.
(body memories OR somatic memories) AND (affect OR impact) AND (behavior OR mental health)