In each experiment, the character displayed at trial start could involve a static (static trial) or a moving figure (dynamic trial), randomized on a trial-by-trial basis.
In all dynamic trials, the starting frame of the movie was chosen randomly, so that the movie segment displayed simultaneously with the fall of the ball also varied randomly from trial to trial, not to provide spatio-temporal cues for ball interception.
Using the 'calibrated anatomical system technique' (CAST) [8,10] allows the position of ASIS defined relative to the Cluster in a static trial and then during dynamic trial the position of the ASIS is linked to the Cluster and thus affected by the same skin movement artefact that affects the Cluster [11].
This was then used to compute the rotation of the shank segment marker plane required for placement of the ankle joint centre along a line between the malleoli in the dynamic trial data.
Dynamic trials are performed on a cracked specimen to demonstrate the capability of the new approach.
In the interception experiments, instead, we found a greater anticipation of the timed responses in dynamic trials than in static trials with animate characters (Fig. 4).
Crucially, default trials always depicting the same static character of a standing person were randomly intermingled with the dynamic trials in both animate and inanimate sessions, so as to assess persistent influences of the animate and inanimate contexts.
The relative size of the time bias in static versus dynamic trials was not constant, but varied as a function of the experiment type (interception or time discrimination) and character type.
During the dynamic trials, each participant was instructed to walk in a straight line at a self-selected pace along a 15-m laboratory walkway embedded with 4 AMTI BP400600 force plates (AMTI, MA, USA).
In a study by Douglas et al. [ 50], the 10-s trials of a dynamic balance test are questionable, and the subjects were tested exclusively with the open-eyes condition.
