PHP : false OR false OR true == false?

I don’t understand what’s going on here in PHP.
I’ve spent hours on this until I understood that it doen’t work normally, or that I dont understand something.

Here the few lines :

$test = false OR false OR true;
echo $test;

Here $test is false, nothing is printed.
Also, if I try:

if($test){
    echo "IT'S TRUE";
}

Nothing is printed.

BUT HERE :

if(false OR false OR true){
    echo "IT'S TRUE";
}

“IT’S TRUE” is printed.

So the statement “false OR false OR true” is false when assigned to a variable, but true when is a condition.
Does anyone know and can explain to me why ?