This line of investigation also suggests that there may be real problems in assuming that
self-report is a valid measure of SWB. For example if patients make judgements relative to
an internal criterion that is in some way adjusted to bring about a positive report (eg. by
making downward comparisons with patients even less well-off; Taylor 1983, cited Breetvelt
& Van Dam 1991; Diener 1984), then cognitive factors may lead to what Breetvelt and Van
Dam call `under reporting', ie. that `patients report less emotional distress, satisfaction or
the like than is actually present' (Breetvelt & Van Dam 1991, p. 983).