Two choices good, four choices better: For measuring stereoacuity in children, a four-alternative forced-choice paradigm is more efficient than two
Fig 5
Results for 2-AFC (in red) and 4-AFC (in blue) with half the number of trials as the 2-AFC task are superimposed in the same graph. Each panel depicts the difference between the estimated threshold and the model threshold as a function of number of trials. The model threshold increases from the left to the right panel. The average difference, plotted with open circles, is centred on zero, indicating no bias. Filled triangle symbols represent one standard deviation below and above the average difference.