Figure 1.
The robot arm JAHIR, which was used in the experiment, consisted of a base, upper arm and forearm connected though joints.
Figure 2.
Screenshots from the videos of the different agents presented to the subjects in the previous [13] and the current experiment. The participants were instructed to perform horizontal or vertical movements while viewing the videos and fixating on the right hand of A) a human agent (MH), B) the humanoid robot JAST [13], C) the industrial robot arm JAHIR and D) JAHIR rotated, which performed congruent or incongruent movements. The experimenter shown in A has given written informed consent (as outlined in the PLoS consent form) to publication of his photograph.
Figure 3.
Overview of all experimental conditions.
Summary of all conditions of the present (A, C, D) and the previous experiments (A, B) [13]. Left: experimental conditions (only vertical agent movement is shown). Right: examples of movement trajectories performed by the observing subjects.
Figure 4.
Illustration of the types of analysis.
Four types of analyses performed on the present experiment: standard analysis (SA), tilt analysis (TA), deviation analysis (DA), curvature analysis (CA). In the SA, we calculated the deviations of the individual movement from the horizontal or vertical axis. In the TA, we calculated the tilt (or shift) of the overall line fit from the horizontal or vertical axis. In the DA, the deviations of line fits for individual movements from the overall line fit have been calculated. Finally, in CA, we calculated the deviations of every single movement from the straight line fitting this movement.
Figure 5.
Results using the standard analysis.
Standard deviation (SD) of movement from the instructed movement plane during observation of incongruent and congruent movements of the human agent (A), humanoid robot JAST (B), industrial robot JAHIR (C) and rotated industrial robot JAHIR90° (D). Data from all subjects (including [13]), i.e., each graph represents a different number of subjects (see text). Error bars represent standard error of the mean. Stars denote significance (** p<0.01; * p<0.05).
Figure 6.
TA, DA and CA analyses for human agent observation.
A: Actual plane tilt of movement (mean line fit) with respect to the horizontal and vertical directions (TA). B: Standard deviation of individual line fit from the mean line fit (actual plane of movement) (DA). C: Curvature of single movements with respect to a straight line (individual line fit) (CA). Error bars represent standard error of the mean. Stars denote significance (** p<0.01).