Two choices good, four choices better: For measuring stereoacuity in children, a four-alternative forced-choice paradigm is more efficient than two
Fig 7
Average threshold estimates, uncertainty, precision and bias for the 2-AFC task (red full line) and the 4-AFC task (blue dotted line).
Error bars indicate 1 standard error above and below the average. Threshold uncertainty was calculated as the ratio between the simulated standard deviation and the threshold estimate. Bias and precision of threshold estimates were estimated by comparing the estimated thresholds after a subset of trials with the estimated threshold after the maximum number of trials (80). Bias is defined as the difference between both and precision as the absolute value of the bias.