Asymmetric Rod and Frame Effect on the Computerized Rod and Frame Test under Time Pressure

摘要

This study tested the effects of perceived time pressure on subjective visual vertical (SVV) perception in college healthy male students. Delayed down-weighting of inaccurate visual cues has been implicated in age-induced overreliance on visual information, which may be disruptive for postural control. Accordingly, I hypothesized that under time pressure, participants may not have enough time to downgrade the distracting visual input from the tilted frame and display larger rod-and-frame effects (RFE) on a computerized rod and frame test (CRAF), with a virtual line of two endpoints and a precision of 0.5°. All participants were right handed, with 31 in the normal time (NT) and 29 in the time pressure (TP) experimental conditions. Results showed that the feeling of acting under time pressure induced rightward SVV adjustments (counter clockwise (CCW) SVV estimates) in the nontilted frame context and an increased rod and frame effect (RFE), but only significantly with a right tilt of the frame. This indicates an increased tendency for CCW SVV estimates and marked asymmetries in the magnitude of the frame effects for left and right frame tilt under time pressure. In view of these findings I believe that quick actions may provoke abnormal weighting of cues mediating verticality perception due to an asymmetrical processing of visual information leading to an inefficient integration of sensory information in brain areas involved in SVV representation under time pressure. These findings may prove significant at a postural level for visually dependent individuals who may need to carry out postural orientation corrections quickly within environments rich with obliquely oriented visual cues.