Fig. 4

Virtual interface and environment. a From the user’s perspective, a cube could appear in one of four vertical positions (two on either side of the user), and four horizontal positions, some appearing above the user and some appearing below; b When the user was not aiming the crossbow at a cube, a non-descript image was displayed; c Once the user aimed the crossbow at the cube, the target posture was revealed; d Image shows the user beginning to interact with a cube. The target is ‘hand open’ (green) and the user is volitionally performing a hand open posture, which is resulting in green arrows being fired; e Image shows the moment just before the cube ‘breaks’. The cube has increased in size; however, the image shows the pattern recognition system mis-estimating, as the arrows fired are cyan (indicating a wrist flexion posture). Although arrows generated from incorrect postures did not increase the cube size, the information was added to the classifier in the adaptation group