I have been looking for a MATLAB script for serial reaction time task. In SRT  four locations appear on screen with one of them having the stimuli. Participant's task is to press the spatially corresponding button to the stimuli location. This is a very famous task, and I know it is easy to design this using DMDX and Psychopy builder view using just four pictures. However, I am looking to improvise the task for my present study where I want to have  grids for each trial  with 5 rows and four columns. If any one has a basic script, I could alter further and use. Thank you for your help in advance.