Younger adults were sensitive to differences between enjoyment
and nonenjoyment smiles, consistent with previous research
(Frank et al., 1993; Miles & Johnston, 2007). Older adults were
found to be as sensitive as younger adults when discriminating
between these two types of smile, indicating that there were
age-related similarities in the perception of happiness. However,
the current findings also revealed age differences in the interpretation
of subtle but meaningful differences in positive facial expressions;
older adults had a greater tendency (i.e., response bias)
to categorize the target as feeling happy regardless of the type of
smile displayed