Figure 1. Experimental setup, trial structure of the tasks, and stimulus conditions.

(a) The respiratory effort is converted into electronic signal changes using a respiratory transducer, amplified by BIOPAC, digitized using an A/D converter, and sent to the test computer for the final visual display as a dynamic breath curve, with or without a 400 ms delay. (b) This panel shows two trials for the breath detection task (BDT) and flash dot detection task (DDT) runs, respectively. Each trial begins with a 3 s blank display, followed by a 12 s display of respiratory curve presented with or without a 400 ms delay and with or without a 30 ms red dot flashed at a random position on the curve, and ends with a 3 s response window during which participants make a forced-choice button-press response to two alternative choices depending on the block type (BDT or DDT) to indicate whether the feedback curve is synchronous or delayed (for the BDT run) or whether a dot has appeared (for the DDT run). (c) The task represents a 2 × 2 × 2 factorial design with the factors of attention to breath or dot (block design), presence or absence of breath curve delay, and presence or absence of a dot flashed. The dashed line represents the actual breath curve, while the solid line represents the feedback breath curve displayed on the screen.

Figure 1—figure supplement 1. Raincloud plots visualizing the five-number summary (minimum, lower quartile, median, upper quartile, and maximum) for (a) accuracy, (b) reaction time, (c) d’, and (d) β for the BDT and DDT tasks in the first sample of the fMRI study.

Figure 1—figure supplement 2. Raincloud plots visualizing the five-number summary (minimum, lower quartile, median, upper quartile, and maximum) for (a) accuracy, (b) reaction time, (c) d’, and (d) β for the BDT and DDT tasks in the second sample of the fMRI study.