Task design

a, Virtual Tools task. The participants were required to click on one out of the three tools depicted in the upper right corner of the figure (second panel from the left) and to place it with another click on the screen to get the red ball into the green area (third panel from the left). As soon as the tool is released (panel on the right), the laws of physics/gravity are applied, and the tool interacts with the other objects. b, Galvanic Vestibular Stimulation set up with two pairs of electrodes shown on a head model. The upper electrodes deliver the Galvanic Vestibular Stimulation and the ones below are used as a Sham stimulation to control for non-vestibular specific effects. c, Procedure. After a series of practice games followed by baseline games designed under terrestrial gravity, participants played two sets of games designed under terrestrial gravity (in study 1) and hypo or hyper gravities (in study 2), with concurrent stimulation (either GVS or Sham during a given set).

Means, Standard Deviations and t test Statistics for Study 1 measures

Study 1 - Subset of games with a significant impact of the GVS

a, on the success rate. The games significantly impacted by the GVS are displayed on the left with their name below the illustration. The bar chart on the right shows the average success rate for the game when played under the Sham stimulation (blue bar) and the GVS stimulation (orange bar). The colour of the borders indicates the impact of gravity in the game. High-gravity-dependent games: turquoise box; Medium-gravity-dependent-games: magenta box. b, on the number of attempts. c, on the distance between placements. d, on the tool switching across attempts. Independent t-tests * p < .05

Clustering analysis

a, Illustration of results of the Dirichlet Process Gaussian Mixture Model by stimulation type for a selection of games. Each dot represents an individual placement, the ellipses represent the different clusters or strategies b, Strategy switch. Probability of strategy switch on overall games played under GVS versus Sham. c, Leave-one-out Kernel density analysis. This figure shows the distribution of accuracies obtained from 1000 iterations with randomly shuffled group labels and their corresponding 95% Equally-Tailed Intervals (ETIs). The black curve represents the null distribution obtained by randomizing group labels; red dashed lines mark its 95% credible interval. The blue bar marks the observed accuracy, which exceeds this range—indicating that tool placement patterns reliably distinguish between groups.

Study 2 - Subset of games with a significant impact of the GVS

a, on the success rate. The games significantly impacted by the GVS are displayed on the left with their name below the illustration. The bar chart on the right shows the average success rate for the game when played under the Sham stimulation (blue bar) and the GVS stimulation (orange bar). The colour of the borders indicates the impact of gravity in the game. High-gravity-dependent games: turquoise box; Medium-gravity-dependent-games: magenta box; Low-gravity-dependent-games: dark orange box. b, on the number of attempts. c, on the time per attempt. d, on the tool switching across attempts. Independent t-tests, * p < .05

Means, Standard Deviations and t test Statistics for Study 2

Gravity-weighted indexes in terrestrial gravity and altered gravity.

a, Success rate. The plot shows the gravity-weighted index averaged across conditions (black dots), as well as the individual participant gravity-weighted index data (transparent dots). An independent one-sided t-test: t(82) = 1.70; p = .046, Cohen’s d = 0.37 showed that gravity-weighted index for SR in altered gravity was significantly higher than in terrestrial gravity. b, Number of attempts. c, Time per attempt. d, Distance between tool placements. e, Tool Switching between attempts Independent t-tests, * p < .05.

Details of the games played under concomitant stimulation in study 1 and study 2.

The gravity dependency column indicates the level of reliance on gravity to solve each game. The difficulty column indicates the level of difficulty to solve the game. The two columns on the right indicate the gravitational accelerations used in each of the two study for a given game.

Left panel Games in Study 1

a, Baseline games. b, Games in Set 1. c, Games in Set 2. The colour of the borders indicates the impact of gravity in the game. High-gravity-dependent games: turquoise box; Medium-gravity-dependent-games: magenta box; Low-gravity-dependent games: orange box. Right panel Games in Study 2