Path Integration from Optic Flow and Body Senses in a Homing Task

Abstract

We examined the roles of information from optic flow and body senses (eg vestibular and proprioceptive information) for path integration, using a triangle completion task in a virtual environment. In two experiments, the contribution of optic flow was isolated by using a joystick control. Five circular arenas were used for testing: (B) both floor and wall texture; (F) floor texture only, reducing information for rotation; (W) wall texture only, reducing information for translation; (N) a no texture control condition, and (P) an array of posts. The results indicate that humans can use optic flow for path integration and are differentially influenced by rotational and translational flow. In a third experiment, participants actively walked in arenas B, F, and N, so body senses were also available. Performance shifted from a pattern of underturning to overturning and exhibited decreased variability, similar responses with and without optic flow, and no attrition. The results indicate that path integration can be performed by integrating optic flow, but when information from body senses is available it appears to dominate.

Human spatial navigation deficits after traumatic brain injury shown in the arena maze, a virtual Morris water maze

“…Although it is difficult to know whether the larger effect sizes observed in the present study were due to differences in the virtual environment tasks or to differences in the degree of underlying impairments, the fact remains that the impairments did not disappear when the environment became more realistic. This is important because a more realistic environment is presumably more amenable to path integration [61] and other processes necessary to the development of allocentric representations [65].…”

“…Thus, the N-S direction was distinguishable only by the direction in which the land sloped (viz., left-to-right or right-to-left). All surfaces were textured to optimize 'optic flow' [61,62] and all but the ceiling were textured like marble, to avoid local cues to location (specific features or number of pattern repetitions). The sound of footsteps and a slight 'head bob' during movement were added to heighten the sense of reality or 'presence' in the environment.…”

As the world turns: Short-term human spatial memory in egocentric and allocentric coordinates

“…In a virtual reality study by Kearns et al [27], although subjects wearing virtual reality goggles were able to use optical flow alone to complete a path integration task (i.e., moving through the virtual environment using a joystick and return to their starting point after a right triangle outward journey), the subjects' responses became more consistent if they were actively walking. Indeed, they exhibited a decreased variability in performance when self-generated movement information (generated by the subjects moving simultaneously in the real environment) was consistent with the visual information displayed via the virtual reality goggles.…”

“…Recent experiments on path integration in humans also suggest that multiple sources of redundant spatial information are weighted and integrated based on their respective reliability to support behavior [26,27]. In a virtual reality study by Kearns et al [27], although subjects wearing virtual reality goggles were able to use optical flow alone to complete a path integration task (i.e., moving through the virtual environment using a joystick and return to their starting point after a right triangle outward journey), the subjects' responses became more consistent if they were actively walking.…”

Environmental stability modulates the role of path integration in human navigation

“…Similarly, humans update their current position relative to a starting point or goal location during blindfolded walking, implicating an analogous path integration system (Loomis et al, 1993;Kearns et al, 2002). Furthermore, it appears that human navigators cannot ignore their own movements during navigation (Klatzky, Loomis, Beall, Chance, & Golledge, 1998;May, 2004;May & Klatzky, 2000), suggesting that the integration of self-motion information is obligatory.…”