protected function determineChoiceField()
    {
        $expanded = $this->options['expanded'];
        $multiple = $this->options['multiple'];

        if ($multiple) {
            $this->options['attr']['multiple'] = true;
        }

        if ($expanded && !$multiple) {
            return $this->choiceType = 'radio';
        }

        if ($expanded && $multiple) {
            return $this->choiceType = 'checkbox';
        }
    }