Improving Contact Tracing With Directed Recall

Contact tracing is a key strategy for slowing the spread of infectious diseases. We evaluated the effect of a directed recall manipulation on the quantity of names produced during contact tracing interviews. Participants reported close contacts over the last 4 days prior to the experiment. We found that people report more contacts when they are guided in directed recall (i.e., backward or forward in time) than when given the freedom to recall as they please. A second recall opportunity led to the retrieval of additional contacts, regardless of recall direction. Finally, the direction of recall instructions did not affect the overall number of names retrieved but did result in different patterns of retrieval density with respect to time. Backward recall elicited more recall of recent contacts, making it appropriate for public health officials engaging in forwardtracing protocols. Forward recall elicited more retrieval of distant contacts, making it appropriate for backward-tracing protocols.