Argument passed to function must be callable, array given

I'm trying to run a method on each element inside a collection. It's an object method residing in the same class:

protected function doSomething()
{
    $discoveries = $this->findSomething();
    $discoveries->each([$this, 'doSomethingElse']);
}

protected function doSomethingElse($element)
{
    $element->bar();
    // And some more
}

If I precede the call on Collection::each with the check is_callable([$this, 'doSomethingElse']) it returns true, so apparently it is callable. The call itself however throws an exception:

Type error: Argument 1 passed to Illuminate\Support\Collection::each() must be callable, array given, called in ---.php on line 46

The method trying to be called can be found here.

I'm bypassing this by just passing a closure that itself simply calls that function, but this would definitely a much cleaner solution and I can't find out why it throws the error.

via Padarom