“…Several researchers have studied the effects of the parent and child on each other during play interactions (e.g., Cohen & Tomlinson-Keasey, 1968;Cox & Campbell, 1968;Eckerman, Whatley, & Kutz, 1975;Vandell, 1979), and several have investigated training parents systematically in home settings as their youngster's most important teacher (e.g., Madden, Levenstein, & Levenstein, 1976;Schaefer, 1972).…”