Parallel

You can mix a position parallel to a previous MP-command to produce two equivalent but random index assignments:

0 Do not mix parallel

1 Mix parallel to the previous MP-command

Note that both position definitions must consist of the same number of positions.

 Example for mixing indices of a position definition

POSITION Circle C
0 0 800 45 8

; This trial definition displays a position cue with a variable ISI
; before the onset of the search set which may contain a target at this place

TRIAL Trl
CS 500 1000          ; Clear screen and wait for 500 ms + RndMean(1000)
MP Circle          ; Permutate indices of Circle
SP Cue Circle 1 ?          ; Show position cue and wait for a variable time
RK ResKeys 1500          ; Prepare response registration (MaxRt 1500 ms)
FP ? Circle 1 120 Distractors          ; Show search set with variable target for 120 ms
CS 0 0 1          ; Clear screen and wait for response or MaxRt

 Example for moving pictures by rotating indices

POSITION Line L
-500 0 500 0 60           ;Define a horizontal line with 60 locations

TRIAL ShowPic          ;This trial is called 60 times by trial ‘move’
SP Picture Line 1 20          ;Show picture for 20 ms (rounded to next retrace)
MP Line 2          ;Rotate position indices by one place

TRIAL Move          ;This trial displays a picture on all 60 locations
SY 1          ;Synchronize each picture onset
RS ShowPic 60          ;Call 60 times trial definition ‘ShowPic’