The noise covariance matrices necessary for source localization were estimated per subject from a baseline of period of 500 ms prior to the start of each trial.
The target, a circular black dot (0.8° diameter), was presented in the centre of the screen (0°) for 1000 ms at the start of each trial.
Subjects were instructed to look at the fixation cross at the start of each trial and respond to the visual probe as quickly and accurately as possible.
The latency between the onset of the noncontingent stimulus at the start of each trial and a positive response was recorded as the response latency.
At the start of each trial, the mouse was lowered into the water in one of four start positions (located in the north, south, east and west, respectively), and the order of these start positions was varied pseudorandomly across trials.
The start of each trial was marked with a display (1000 ms duration) consisting of a central fixation cross and two peripheral boxes located 10° laterally to the fixation cross.
At the start of each trial, all items were stationary for 8 s and then started to move.
The images were presented in a random order and participants did not know if or when a case would be interrupted at the start of each trial.
At the start of each trial, all items would remain stationary for N s so that observers had sufficient time to encode both the identity and the state of each object.
To increase task difficulty, at the start of each trial the red target appeared at a randomly selected location along the semicircular path, whereas the cursor always began centered along the path.
Artifacts related to the motion of the arm at the start of each trial were removed.
