Therefore, one might find no deviation from chance in horizontal axis trials despite high within-trial persistence if there were arbitrary initial choices across trials (N.B. vertical axis trials were always separated by horizontal axis trials).
Therefore it is not the case that there is a within-trial perceptual persistence masked by inter-trial randomness of initial percept in the horizontal axis trials.
In contrast, in the horizontal axis trials the individual observers appear to show random scatter about 50% — there was no appreciable bias in favor of either a leftward or rightward viewing position, or for upward or downward rotation (Fig. 2A).
The results, shown in Figure 4, demonstrate a striking modulation of perceived left/right orientation in the horizontal axis trials: objects on the left side of the array are twice as likely to be seen as viewed from the right as objects on the right side of the array (50% more likely for the single cube condition).
Second, because we are at the mercy of air currents for horizontal movement, small trial balloons are sent up periodically to determine whether winds aloft are suitable.
On the horizontal axis, the trials are aligned to the time of the 'dip' measured for each neuron (see Methods).
Later in the experiment, vertical and horizontal rotation probe trials were introduced for both groups.
Two practice trials (one horizontal, then one vertical) were followed by six trials of sinusoidal pursuit, three horizontal and three vertical.
Due to stimulation across the horizontal meridian in a trial in Experiment 2, the ROIs coding for the upper and lower visual field were analyzed separately (see the Methods part).
Pursuit was controlled by moving the fixation task within a third of width and height of the screen with an unequal number of cycles of sinusoidal displacement per trial in horizontal and vertical axes, respectively (randomly assigned 3 or 4 cycles, each with random initial phases).
