RndMode

The meaning of RndMode depends on it’s relationship to the value of RndTime. If the value of RndMode is zero or greater times greater than RndTime, an exponential random interval will be generated with RndTime as the estimated mean value. If RndMode is greater than zero and less or equal than RndTime, a random distribution of equi-distant intervals will be generated.

Exponential Distribution: RndMode = 0 or RndMode > RndTime:

RndTime Mean of exponential random time interval

RndMode Maximum of exponential random time interval
(if 0 then maximum value is 12.5 of RndTime)

Equi-distant Intervals: RndMode > 0 and RndMode <= RndTime:

RndTime Time range that should be varied

RndMode Divisor for creating equi-distant time intervals within that range

For example, if RndMode=5 and RndTime=4000 then the following five equidistant time intervals are drawn at random: 0,1000,2000,3000,4000. In other words, the number of intervals is RndMode minus one.

 Example for clearing screen image

TRIAL ShowItem
CS 300 500          ; Clear screen, wait for 300 ms + 500 ms (exp random)
RK ResKeys 2000          ; Record Key (MaxRT=2000 ms)

SP ? MidPos 1 200          ; Show variable stimulus for 200 ms
CS 0 0 1          ; Clear screen, wait until response or MaxRt