For
example, LePage and Stack (1993) found that mothers can elicit smiling from
their infants using only touch as the impetuous for the resultant behavior.
Moreover, touch alone was as effective as the combination of face, touch, and
voice for eliciting smiling in infants. In essence, touch expressions performed
like (and in some cases were superior to) facial or vocal expressions and thus
are used to carry on mutually reciprocal exchanges between parents and their
infants