Table 1.

Contents of levels of training activities in CATS

Level	Training
1	In each trial in a given session, a red light flashes and the trainee needs to respond to the stimulus in time by pressing the number key of the block in which the light flashes. Only one block is used in a session, so only one number key is used in a session.
2	This level is the same as Level 1, except that all blocks are used in a session, so the trainee needs to choose the right number key to press.
3	As illustrated in Figure 1, in each trial, nearby red lights appear one after another and extend into a line. The trainee needs to track the extension and press the number key of the block in which the line stops extending.
4	As opposed to the extending in Level 3, a red light moves here (i.e. it extends with no trace). The trainee’s task is the same as in Level 3.
5	This level is the same as Level 1, expect that now a red light might be accompanied by a green light. If so, the trainee needs to inhibit key pressing and not respond. There are, therefore, two behaviors in the level: responding to the red light and not responding to the paired light.
6	The level is the same as Level 2, except that now the rule of paired-light inhibitory control is added in.
7	This level is the same as Level 3, except that some red lights might be accompanied by their green lights when the line is extending. If so, the trainee needs to inhibit key pressing when the line stops extending.
8	This level is the moving version (cf. Level 4) of Level 7. The trainee therefore needs not only inhibitory control ability, but also working memory for remembering green lights have shown (or not) to make the right response in the end of each light movement.
9	This level is the same as Level 1, except that now the stimuli might be red lights only or green lights only. The trainee needs to press a left-hand key to respond to a red light and a right-hand key to respond to a green light. Unlike Level 1, this level therefore uses two, but not one, keys in a given session.
10	This level is the same as Level 9, except that now stimuli can appear in any block (cf. Level 2).
11	This level is the same as Level 9, except that now the stimuli might be red lights only, green lights only, or paired red and green lights. If a pair of lights flash, the trainee needs to inhibit responding.
12	This level is the same as Level 11, except that now stimuli can appear in any block (cf. Level 2).