Abstract
PURPOSE: Running on a treadmill results in systematic errors in non-visual self-motion perception. For example, several research groups have shown that after only 1 min of running, participants will drift forward unintentionally when attempting to jog in place without vision. Here, we aimed to: (1) Replicate the basic finding using a less strenuous methodology (walking, then marching in place instead of running, then jogging in place); (2) Determine whether focused attention during adaptation (by reading) might ameliorate the self-motion aftereffect. This is a realistic exercise scenario, and promises to shed light on the stage of cognitive processing at which visual and motor sensory mismatches are registered. METHOD: Block 1: (1) Calibration: Participants first walked to pre-viewed targets (1–4 m distant, 0.5 m increments) without vision. Targets were binocularly viewed in a well-lit room; after walking, participants opened their eyes to obtain error feedback. (2) Baseline: Participants attempted to march in place for 20 s (blindfolded and wearing ear plugs). (3) Adaptation: Participants walked on a treadmill (2.5 mph) for 5 min (eyes open). During adaptation, they either read aloud (N=10) or did not read (N=11). (4) Test: Participants again attempted to march in place for 20 s. Block 2: Participants repeated steps 1–4; during Adaptation (step 3), the “reading” conditions were switched, so that all subjects were exposed to both conditions across the two blocks. RESULTS: Before adaptation, participants unintentionally drifted forward 75 cm, on average. After adaptation, they drifted forward reliably more (110 cm; p <.005). This aftereffect was not influenced by reading vs. no reading during adaptation (p = .31). CONCLUSION: The basic self-motion aftereffect is detectable even in a low-impact paradigm. Also, the aftereffect does not seem to rely on sustained, explicit awareness of mismatches between visual and motor self-motion signals.