>> JND Radius
- Task: Discrimination
- Method: Forced choice with Staircase
Specifications
_Note that all CAPPED variables are constants taken from the excel sheets/data file._
- For a given subcondition, there are at minimum 24 trials and at maximum 52. Once a user has reached the 24th trial, we start computing for convergence by calculating an F-value to see if it is lower than the threshold.
- If the F-value is <
(1-CONVERGENCE_THRESHOLD), then the current subcondition ends, and proceeds to the next subcondition. - If the F-value is >=
(1-CONVERGENCE_THRESHOLD), then the trials continue.
- If the F-value is <
Test Procedure
- For a given subcondition's trial:
- The BASE_RADIUS for that subcondition will be used to calculate the distribution of one plot, but we need to calculate the adjusted radius on a trial-by-trial basis.
- At the first presentation of a trial, there is a need to compute the adjusted radius.
- If converging from above, we calculate it by:
BASE_RADIUS + INITIAL_DIFFERENCE - If converging from below, we calculate it by:
BASE_RADIUS - INITIAL_DIFFERENCE
- If converging from above, we calculate it by:
- If this is NOT the first presentation of a trial, then use the staircase method to calculate the adjusted radius.
- If converging from above:
- If the previous trial was correct, adjusted radius =
previous adjusted radius - 0.002 - If the previous trial was incorrect, adjusted correlation =
previous adjusted radius + 0.006
- If the previous trial was correct, adjusted radius =
- If converging from below:
- If the previous trial was correct, adjusted correlation =
previous adjusted radius + 0.002 - If the previous trial was incorrect, adjusted correlation =
previous adjusted radius - 0.006
- If the previous trial was correct, adjusted correlation =
- If converging from above:
- Generate the shape using the BASE_RADIUS and adjusted radius.
- Plot each shape side by side, and randomize whether the right/left areas get the base or adjusted shapes.
- A user can make keyboard inputs with the "z" or "m" keys. "z" corresponds to the left graph, "m" corresponds to the right graph.
- At the first presentation of a trial, there is a need to compute the adjusted radius.
- The BASE_RADIUS for that subcondition will be used to calculate the distribution of one plot, but we need to calculate the adjusted radius on a trial-by-trial basis.
Constants
These are the constants extracted from the input excel sheets. The values of these constants differ for each sub condition.
- BASE_RADIUS
- CONVERGE_FROM_ABOVE
- INITIAL_DIFFERENCE