Expository documentaries present a strong point of view through voiceovers and titles in an authoritative manner meant to persuade viewers. Examples include nature documentaries and profiles that deliver an unproblematic interpretation. Observational documentaries aim to simply observe with minimal intervention using portable cameras and equipment, often applying a "fly-on-the-wall" technique. Interactive documentaries show how the filmmaker's presence affects the situations being filmed, with the relationship between filmmaker and subject becoming central. Reflexive documentaries draw attention to their own construction and representation of reality in order to question notions of documentary truth.