It should be easy to run a controlled experiment to test this. Just come up with a few contacts that you have not been in touch with in the last few months, sep

It should be easy to run a controlled experiment to test this. Just come up with a few contacts that you have not been in touch with in the last few months, separate them into two groups, control and test. Say out the names of the people in test group to your phone and compare how often you see the names of people in test and control groups in auto complete suggestions and use a statistical test to confirm.