Figure legends
Figure 1. Experimental design . A) Task Protocol: each
observer executed the task on a computer. The observers filled out a
questionnaire collecting personal and physical activity-related data.
Then a two-interval forced-choice (2IFC) task consisted of 84 trials.
Each trial contained two videos in sequence: one was the reference
stimulus (box weight: 7.5 kg) and the other was one of the seven
comparison stimuli (box weights: 0, 2.5, 5, 7.5, 10, 12.5, 15 kg). In
the end, a question asked in which video the box was heavier, and the
observers could choose between “first” or “second”. B) Frames of a
video proposed to observers for male and female.
Figure 2. Results of the Main experiment . A)
Discrimination sensitivity (d’) in Concentric (red) and Eccentric (blue)
condition at each weight. Circles represent median values, and error
bars represent interquartile intervals. Black asterisks indicate
significant differences between conditions (*p < 0.05, **p
< 0.01). Colored brackets and asterisks indicate significant
weight differences within each condition (Concentric: red, Eccentric:
blue; *p < 0.05). B) Mean d’ in Concentric and Eccentric
conditions for Heavy and Light weights (*p < 0.05, ***p
< 0.001. The box represents the inter-quartile ranges, and the
bars show the maximum and the minimum values. C) Psychometric functions
for Concentric (red) and Eccentric (blue) condition. Dots represent the
proportion of Heavier responses at each load for each group, obtained
from the average of the responses of all observers to each load. (D)
Asymptotes (AUP) and for Concentric (red) and Eccentric (blue)
conditions. The box represents the inter-quartile ranges, and the bars
show the maximum and the minimum. *p < 0.05.
Figure 3. Results of the Control experiment . A)
Estimated Effort in Concentric (red) and Eccentric (blue) condition at
each box weight. Circles represent the answer of each participant. The
square represents mean value at each weight and condition, error bars
represent the standard deviation. B) Δ (estimated) Effort in Concentric
(red) and Eccentric (blue) condition at each weight. Squares represent
mean values and error bars represent the standard error of means. Black
asterisks indicate significant differences between conditions (*p
< 0.05, ***p < 0.001). (C) ΔVAS Effort in Concentric
and Eccentric conditions for Heavy and Light weights. The box represents
the inter-quartile ranges, and the bars show the maximum and the minimum
values (*p < 0.05, **p < 0.01, ****p <
0.0001).