IST is a task designed to measure
Display
The subject is presented with a 5x5 array of grey boxes on the screen, and two larger coloured panels below these boxes. The subject is instructed that they are playing a game for points, which they can win by making a correct decision about which colour is in the majority under the grey boxes. They must touch the grey boxes one at a time, which open up to reveal one of the two colours shown at the bottom of the screen. Once a box has been touched, it remains open. When the subject has made their decision about which colour is in the majority, they must touch the panel of that colour at the bottom of the screen to indicate their choice. After the subject has indicated their choice, all the remaining grey boxes on the screen reveal their colours and a message is displayed to inform the subject whether or not they were correct. The colours change from trial to trial.
The boxes always open up in the same order – for example, if the order of opening in the first trial is blue, yellow, yellow, yellow, blue, blue, yellow, yellow, then the first five boxes that the subject touches will reveal colours in that order, regardless of the spatial location of the boxes the subject touches.
There are two conditions – the fixed win condition, in which the subject is awarded 100 points for a correct decision regardless of the number of boxes opened, and the decreasing win condition, in which the number of points that can be won for a correct decision starts at 250 and decreases by 10 points for every box touched. In either condition an incorrect decision costs 100 points.
Task
The task begins with a single practice trial in the
IST test modes
The IST test has 2 modes:
Fixed
Decreasing
! If you have a group of subjects to whom you wish to administer this test, you should counterbalance both modes within this group. If you are administering this test as part of a battery, this will require setting up two
IST administration script (fixed