How to change the internal logic of an IR sensor module?

Other Hardware Sensors
6

Also please go back and edit your code to place it in code tags after removing the unnecessary blank lines.

As stated, sensor states are arbitrary. "0=off 1=on" is only a convention. So you can also:

#define IR_ON 0
#define IR_OFF 1

void setup() {
pinMode(8, INPUT);
Serial.begin(9600);
}
void loop() {
int ir_reading = digitalRead(8);
if ( ir_reading == IR_ON ) {
  Serial.println(1);
else {
  Serial.println(0);
}
delay(1000);
}