# Effects of Auditory Pre-Stimulation on Cognitive Task Performance in a Noisy Environment
## 2 Methods
### Experiment Variables
#### 2.3.1 STM/WM Tasks  
The current study employed three basic STM/WM tasks: the Corsi block-tapping [49], Digit span [50], and 3-back [51] tasks. The three STM/WM tasks differ in terms of how they load the WM system, as they involve different subsystems of [PERSON]'s WM model [40]. The Corsi block-tapping, the Digit span, and the 3-back tasks correspond to the visuospatial sketchpad, the phonological loop, and the central executive subsystem, respectively.  
The Corsi block-tapping task [49] was adopted to evaluate each participant's visuospatial STM performance, as this task has been widely used to test the function of the visuospatial sketchpad [58; 59; 60; 61; 62; 63; 64]. Here, twelve square frames were generated on a computer screen, and five visual stimuli (black circles) were sequentially flashed in five different square frames. The participants were instructed to memorize the sequence and location of the blinking black circle, wait for 15 s, and then reproduce them by pointing on the answer sheet presented on the monitor screen. Square frames and black circles were randomly  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Experiment** & **Condition** & **Pre-Stimulation** & **Environment** \\ \hline \multirow{2}{*}{1} & 1. \(P_{N}\,E_{Q}\) & \multirow{2}{*}{Non} & _Quiet-noise_ \\  & 2. \(P_{N}\,E_{F}\) & & _Field-noise_ \\ \hline \multirow{4}{*}{2} & 3. \(P_{Q}\,E_{F}\) & Quiet noise & \\  & 4. \(P_{W}\,E_{F}\) & White noise & \\  & 5. \(P_{F}\,E_{F}\) & Field noise & \\  & 6. \(P_{M}\,E_{F}\) & Mixed noise & \\ \hline \hline \end{tabular} \(P\) (Pre-stimulation): \(P_{N}\) (Non), \(P_{Q}\) (Quiet noise), \(P_{W}\) (White noise), \(P_{F}\) (Field noise), \(P_{M}\) (Mixed (White and Field) noise). \(E\) (Environments): \(E_{Q}\) (Quietnoise), \(E_{F}\) (Field-noise).  
\end{table}
Table 1: Experimental conditions for _Experiment 1_ and _Experiment 2_.  
presented for each condition. The number of correct matches was used as a performance measure; the score range for the task was 0 to 5 points.  
The Digit span task [50] was selected to evaluate the auditory-verbal STM performance, as this task has been used to test the phonological loop function in many previous studies [65; 66; 67; 68]. Participants were presented with ten single-digit numbers from 0 to 9 by voice in a random order, were instructed to memorize the ten numbers in the order presented, to wait for 15 s, and then to write the numbers on the provided answer sheet. The number of correct matches was used as a performance measure; the score range for this task was 0 to 10 points.  
The 3-back task (the \(N\)-back task with \(N=3\)) [51] was employed to evaluate the central executive WM performance, as this task has been widely used to test the central executive function [69; 70; 71; 72]. This task requires encoding the incoming stimuli, monitoring, maintaining and updating the material, and matching the current stimulus to the target stimulus [73; 74; 75]; decision, selection, inhibition, and interference resolution processes are also involved [71; 76]. In each 3-back task trial, the participants received a target number, which was a random number of 0 to 9. Then, a sequence of 16 single-digit numbers from 0 to 9 were presented auditorily; each sequence contained four target numbers at random positions. The participants were then instructed to write down the number that was presented three numbers earlier if the current number matched a predefined target number. As a performance measure, the number of correct matches was employed in this study; the score range for the task was 0 to 4 points. Figure 1 provides an example STM/WM task trial.  
Figure 1: _Cont._