Optic flow can be used to detect various different properties of self-motion, including speed and distance (Frenz & Lappe,
2005,
2006; Harris, Jenkin, & Zikovitz,
2000; Lappe, Bremmer, & van den Berg,
1999; Redlick, Jenkin, & Harris,
2001; Sun, Campos, & Chan,
2004; Sun, Campos, Young, Chan, & Ellard,
2004; van den Berg,
1992; Wilkie & Wann,
2005). The capacity for observers to use optic flow to estimate heading has also been actively investigated. For instance, heading estimation based on optic flow has been studied using discrimination tasks (Britten & Van Wezel,
2002; Crowell & Banks,
1993; Fetsch, Turner, DeAngelis, & Angelaki,
2009a), magnitude estimation tasks using a pointer to indicate heading (Ohmi,
1996), and tasks that require an observer to select from a distribution of heading directions represented by oriented lines (Royden, Banks, & Crowell,
1992). The accuracy of heading judgments based on optic flow alone has also been shown to be contingent on factors such as heading eccentricities (i.e., the angle between the heading direction and the center of the stimulus; Crowell & Banks,
1993), the speed of simulated self-motion (Warren, Morris, & Kalish,
1988), the ability to compensate for eye movements using information from the extra-ocular muscles (Royden et al.,
1992), and the coherence of the dots presented in the display (Fetsch et al.,
2009a; Gu, Angelaki, & Deangelis,
2008; Gu, DeAngelis, & Angelaki,
2007).