However, much of the research carried out into self-disclosure theory is correlational. Therefore, cause and effect cannot be established between self-disclosure and levels of attraction. For example, it may be the more satisfied the partners are, the more they disclose or there could be another intervening factor impacting how successful the romantic relationship is e.g. the amount of time partners spend together or physical attractiveness. Therefore, limiting the support and internal validity of the research into self-disclosure as a factor affecting attraction in romantic relationships.