"more" is the hypothesis prediction in this study. It is a statement about what the experimenters predict will happen as an educated guess (before the study occurred) OR a statement about what actually did happen (after the data are collected and analyzed). It is a little like you making the hypothesis prediction before you hear the album, "I think I will like this album because it was done by a musician I like." Then you listen to the album and your hypothesis prediction is either correct, if you do like it, or incorrect, if you don't like it.
The way psychologists use the term hypothesis when discussing the results
of a study is by saying either "The research hypothesis was confirmed." (when
the results came out the way they predicted) OR "The research hypothesis was
disconfirmed" (when the results don't come out the way they predicted.) So in
this example before the study was carried out the psychologists used previous
research (showing people estimate higher product values when credit card cues
are present) to develop their hypothesis prediction that credit card stimuli
would lead to higher tips. When the data was collected and they could determine
(using statistics) that chance could not explain the 4.29% higher tips in the
credit card condition they concluded that, "The hypothesis that credit card cues
lead to higher tips was confirmed." They then interpreted the data from their
tipping study within a social learning theory framework.
(See the double movement of
reflective thought link for the way science uses both inductive and
deductive reasoning to progress.)