coding fixed ISI in SRTT

Hey all

I am new to Psytoolkit and in the coding world. I am trying to code a fixed ISI (inter-stimulus interval) for my Serial Reaction Time Task in Psytoolkit.

Here my problem:
I want to create a Serial Reaction Time Task, where the Interstimulus interval (ISI) is fixed (500 ms) at each trial, while the response-stimulus interval (RSI) will change based on when the participants will answer to the stimulus presentation.

I need to record the participants' answers during the fixed ISI.

I tried to code the fixed ISI:

- here I tried to use many different readkey (like has been suggested in a post on the forum). However, if my answer is faster than 500 ms (and our hypothesis is that the RTs will be faster and faster after each trial) the stimulus disappears before 500 ms.


task training

table familiarization

keys t y g h

show bitmap p0

delay 100

show bitmap @1 @2 @3

readkey @4 100

clear -1

set $tmprt RT

set $total_rt RT

set $final_rt RT

set $tem_status STATUS

set $tem_status2 STATUS

if STATUS == TIMEOUT

readkey @4 200

clear -1

set $total_rt expression RT + $tmprt

fi

if STATUS == TIMEOUT

readkey @4 200

clear -1

set $final_rt expression RT + $total_rt

fi

save BLOCKNAME @1 @4 KEY $final_rt STATUS



- In this example, the RTs do not seem to be reliable.


task learning

table learning

keys t y g h

set &my_delay 500

show bitmap p0

timestamp begintime

timestamp now

set $remaining_time &my_delay

set $d timestamp-diff begintime now

while $d < &my_delay

show bitmap @1 @2 @3

readkey @4 $remaining_time

timestamp now

set $remaining_time expression &my_delay - $d

set $d timestamp-diff begintime now

save "RT = " RT "d = " $d " ; remaining_time = " $remaining_time

while-end

save BLOCKNAME @4 KEY STATUS RT


Someone can help? I would really appreciate any help