Can anyone check my code. My serial monitor is blank that's the main problem.

/* Sweep
by BARRAGAN http://barraganstudio.com
This example code is in the public domain.

modified 8 Nov 2013
by Scott Fitzgerald

*/

#include <Servo.h>
#include <Brain.h>
// Set up the brain parser, pass it the hardware serial object you want to listen on.

Brain brain(Serial);

Servo Thumb;
Servo Index;
Servo Middel;
Servo Ring;
Servo Pink;// create servo object to control a servo
// twelve servo objects can be created on most boards

int pos = 0; // variable to store the servo position
long attention;

void setup() {
Serial.begin(9600);
Thumb.attach(2); // attaches the servo on pin 9 to the servo object
Index.attach(3);// attaches the servo on pin 9 to the servo object
Middel.attach(4);
Ring.attach(5);
Pink.attach(6);
}

void loop() {
if (brain.update()) {

attention = brain.readAttention();// Retrieve Attention Value 0 - 100
Serial.println(attention);
}
if (attention > 30) {

for (pos >= 0; pos <= 180; pos += 1) { // goes from 180 degrees to 0 degrees
// waits 15ms for the servo to reach the position
Index.write(pos);
delay(15);
Middel.write(pos);
delay(15);
Ring.write(pos);
delay(15);
Pink.write(pos);
delay(15);
Thumb.write(pos); // tell servo to go to position in variable 'pos'
delay(15);
}
}
else {
for (pos = 180; pos >= 0; pos -= 1) { // goes from 180 degrees to 0 degrees
// waits 15ms for the servo to reach the position
Index.write(pos);
delay(15);
Middel.write(pos);
delay(15);
Ring.write(pos);
delay(15);
Pink.write(pos);
delay(15);
Thumb.write(pos); // tell servo to go to position in variable 'pos'
delay(15);
}
}

}

Your only serial output is:

    if (brain.update()) {
        attention = brain.readAttention();  // Retrieve Attention Value 0 - 100
        Serial.println(attention);
    }

My guess is that brain.update() is never returning 'true'. Is there a brain.begin() you are supposed to call? If not, check your wiring.

Why does 'attention' have to be a 'long int' when the range is only 0 to 100?!?

Why do you pass Serial to brain when you declare it?!? If it is a serial device connected to Serial you can't also use Serial for serial monitor. If you need both you should either use SoftwareSerial to talk to the device or use an Arduino Leonardo/Micro that has both Serial (for serial monitor) and Serial1 (for communicating with a serial device).