Sometimes memories take a while to come back. One way to help jog a person’s memories is to show them pictures. But shuffling through a hundred family photos in a two hour interview is not possible. One option may be to create a picture book for the interviewee to write in at their leisure or for them to view before you actually interview them.
Digitize photographs you want to use to help the interviewee remember family members or long-forgotten stories. Put them in some sort of book format, leaving plenty of room for the person to write on the page next to the picture. There are numerous websites that allow you to publish such books of photographs or you could even simply put them in your favorite word processing program as a document and print them out, putting them in some sort of folder.
Your relative could leaf through the pages at their leisure and write down what they remembered, call you when they remembered something, or even make voice recordings when something popped into their mind.
The book, however it is created, should include page numbers or image numbers to make it easier to know which image is being referred to.