Table 4 The table gives out the NF EEG modulation conditions for users

Alatorre et al. [61]

/^a

Theta should be in between 60–80\(\%\) of previous power

Andrade et al. [58]

/

Gamma synchrony up-regulation

Azarpaikan and Torbati [47]

/

Theta power suppression and SMR power up-regulation

Becerra et al. [60]

/

Theta should be in between 60–80\(\%\) of previous power

Campos et al. [56]

Power bands related to motor was not controlled

SMR power in a 1-s window increases by 10\(\%\) for each baseline measured

Gomez et al. [59]

/

Modulation around 12Hz, 18Hz and 21 Hz

Jirayu et al. [46]

/

Beta/Alpha ratio exceeds the average of current value and its three previous epochs

Kober et al. [53]

Keep theta and beta below a certain threshold (eye blinks and movements)

Upper alpha power surpass mean power of baseline and previous run

Kober et al. [51]

Suppress power band 0.05–10 Hz (eye blinks) and 75–100 Hz (Muscle artefacts)

SMR and upper alpha power surpasses mean power value of the baseline run and previous feedback run

Lee et al. [49]

/

Attentive score above 50 lasting for 2 seconds. (No specific frequency band)

Marlats et al. [55]

Suppress beta band power

SMR and theta reach 50\(\%\) of the maximum amplitude of baseline measurement

Reichert et al. [52]

Suppress eye-blink artefacts (4-7Hz band power)

SMR power exceeds baseline mean +1 standard deviation for more than 250 ms

Reis et al. [54]

Suppress Fp1 or Fp2-Fp1 signal amplitude brought by eye movements

Real-time ratio of alpha or theta PSD to baseline PSD was visualised

Sanchez-Cifo et al. [48]

Muse 2 built-in preprocessing algorithm

calm/stressed states

Staufenbiel et al. [57]

/

Beta and Gamma power level surpass at 75\(\%\) of the power in the preceding 30 sec window

Wang and Hsieh [50]

Suppress 0.5–2 Hz (eye blinks) and 43–59 Hz (high frequency disturbance)

Theta (4–7 Hz) amplitude exceeds mean amplitude of the eye-open baseline