The trial-by-trial analysis used to test the model also showed that even in magnitude-estimation studies, equal stimulus ratios do not result in equal response ratios, except on average.
Subsequently, the Delta 2 (second stimulus)/Delta 1 (first stimulus) ratios were calculated for each individual RGC.
The gap:no-gap stimulus presentation ratio remained at 1 1, with gap/no-gap stimulus type also determined on a pseudorandom trial-by-trial basis.
For the cells that responded maximally to one of the apex stimuli, the ratio between the averaged responses to the two other groups of stimuli and that of the best stimulus was plotted against the ratio between responses to the other stimuli that belonged to the same group as the best stimulus (Fig. 8).
In the example of Figure 2 the evaluation time window was set to 10 40 ms. We applied the following training protocol (slightly adapted from Shahaf and Marom [3]: We stimulated the culture until the evaluation electrode showed at least 2 responses to the last 10 stimuli (response ratio ≥0.2) or until the maximum stimulation time of 10 min was reached.
The yeast particles were resuspended in KRG, homogenized, and adjusted to a concentration to 5×107/mL, before added as stimuli at ratio 5∶1 (yeast/cell).
The flanker version of the task [ 23, 32] was identical to the original version in the sequence of presentation of stimuli and ratio of conditions but, in this version, each letter was flanked on each side by distractor letters.
For instance, if the participant with the highest percentage of correct responses in block 2 in the B+50 condition correctly identified 75% of the stimuli, whereas the participant with the lowest percentage correct in the same block identified only 50% of the stimuli, the ratio of highest to lowest was 1.5.
At any given stimulus size, this ratio is a measure of responsiveness, and responsiveness was indeed increased by locomotion.
To decrease stimulus discriminability, a ratio of 1.5 would produce center frequencies of 2 c/deg, 3 c/deg, and 4.5 c/deg.
