Figure 2.

Schematic illustration of the training game task design and composition. For details, please see Materials and Methods section: Training paradigm. In short, the training program comprised seven different games, Games 1–7, that tapped primarily on visual acuity and contrast sensitivity in multiple attentional and working memory tasks. Subjects were presented with a pre-determined selection of games for each training day. The total training duration per week was ~3.5 h, excluding the time spent on game parameter adaptation. In all tasks, the subject responded with a single keyboard-button press or withheld the response. Games 1 and 2 were single- or multi-object visual tracking tasks where complex shaped objects moved along curved paths on screen and the subjects’ task was to respond whenever they observed a feature-change in any of the objects. Different game segments exhibited different numbers of to-be attended objects (attentional loads 1, 2, 3, and 4). Prior to each game, there was a calibration period with one (Game 1) or two (Game 2) objects during which the magnitude of the feature change (C) was adjusted to yield a detection rate (HR) of 64−73%. Games 3 and 4 were visual-tracking games like Games 1 and 2 and had an identical calibration procedure and object mobility, but involved only attentional loads of 1 and 2, and exhibited in two out of four conditions six feature-wise distinct distractor objects to impose visual crowding. Game 5 was a continuous single-object tracking task where the subjects reported the feature changes of a single object (as in Games 1−4). Game 5 had no calibration but rather started with very salient feature changes that in each of the 12 game segments decreased by a factor of 1.6 so that the subjects on average were able to reach segments 7−8 at a detection rate of >25%. Game 6 was a Go/No-Go 1-back working memory task where the subject was presented stimuli with an object in one quadrant lasting ~1 s at a rate of one stimulus in ~2.5 s. The subjects task was to indicate whether the object in the current stimulus was different from the one in the previous stimulus regardless of quadrant and object rotation. Game 7 was a threshold-stimulus-detection task where semi-transparent complex visual objects were presented randomly for 0.1 s and the subjects’ task was to report perceived stimuli. The object transparency was calibrated so that for an alpha-level A, detection rate of 0.5 was obtained at 0.5 A. During the games, objects were at five equiprobable levels of A so that A were 0, 0.25, 0.5, 0.75, and 1.0.