“…In respect to the other ground rules researchers have demonstrated some positive effects of using ground rules (Mulder & Vrij, 1996), but have also found limitations in the benefits of their implementation (Teoh & Lamb, 2010). For example, explaining to children that they should say "I don't know" or "I don't understand" does not necessarily have a positive impact on a child's conversational behaviour (Beuscher & Roebers, 2005;Blades, Waterman, & Gibson, 2003;Ellis, Powell, Thomson, & Jones, 2003;Waterman, Blades, & Spencer, 2004).…”