Figure 1.

The sequence of the CDL (Conditional Discrimination Learning) task. The sample stimulus was presented together with a sound and remained on the screen until the child responded by touching the stimulus on the touch screen. During the delay (if any), a blank screen was presented. Then, the choice stimuli were presented and remained on the screen until the child responded on the touch screen. Incorrect responses were followed by a red cross, whereas correct responses were followed by a red or green smiley face (random presentation of colors). After 2 s, the next trial was presented.