Cannot set placeholder information
It appears that when using Chosen::* to load the widget that specifying placeholder, placeholderSingle, data-placeholder or any other variant in the htmlOptions has no effect on the actual placeholder that is going to be used. I suspect this is due to
// Chosen.php, lines 54 c.f. if (isset($this->placeholderMultiple)) // … if (isset($this->placeholderSingle))
and not actually looking for placeholder in the htmlOptions?