Getting a tool gives wings: overestimation of tool-related benefits in a motor imagery task and a decision task

The difference between the Hand condition and the Tool condition in the Real situation is particularly important for Experiment 2, so we report here the differences (in s) between the Hand condition minus the Tool condition in the Real situation. Note that a positive difference reflects a gain in favor of the Hand condition, and a negative difference a gain in favor of the Tool condition: Quantity 4 (M = 10, SD = 1.39, range: 8:17), Quantity 8 (M = 6, SD = 3.52, range: 4:13), Quantity 12 (M = 0, SD = 3.38, range: −8:5), Quantity 16 (M = −6, SD = 4.44, range: −18:−1), Quantity 20 (M = −10, SD = 5.05, range: −19:−5), and Quantity 24 (M = −16; SD = 6.35, range: −29:−11). Importantly, these descriptive results indicate that the gain in favor of the Hand condition was present for all the participants for the quantities 4 and 8.

Another possibility to collect the choices could have been, for each trial, to present the participants with a quantity of rolls, to ask them to choose the condition in which they would move the rolls and to actually move the rolls. However, as explained in Experiment 1, moving the rolls in the Real situation required a substantial amount of time. So this procedure would have taken too much time, preventing the collection of several trials for each quantity. Moreover, we did not decide to ask the participants to actually move the rolls after the decision task for each quantity and in each condition (Tool and Hand). This procedure could have been interesting to compare the choices made by the participants with the time taken to actually move the rolls. Nevertheless, we thought that the participants might have modified their way to move the rolls to be consistent with the choices made during the decision task. We posited that the time taken by the participants of Experiment 2 to actually move the rolls for each quantity and in each condition (Tool and Hand) should be similar to that of the participants of Experiment 1. This assumption is based on the results of Experiment 1 indicating that the time-based benefit between the two conditions was globally constant among the participants of Experiment 1 (see Footnote 1).