76 Mood, Cognition, and Memory
implement the ideal combination, the chances of demon-
strating MDM would be slim in the absence of an effective
manipulation of mood. So what makes a mood manipulation
effective?
One consideration is mood strength. By definition, mood
dependence demands a statistically significant loss of mem-
ory when target events are encoded in one mood and retrieved
in another. As Ucros (1989) has remarked, it is doubtful
whether anything less than a substantial shift in mood, be-
tween the occasions of event encoding and event retrieval,
could produce such an impairment. Bower (1992) has argued
a similar point, proposing that MDM reflects a failure of in-
formation acquired in one state to generalize to the other, and
that generalization is more apt to fail the more dissimilar the
two moods are.
No less important than mood strength is mood stability
over time and across tasks. In terms of demonstrating MDM,
it does no good to engender a mood that evaporates as soon
as the subject is given something to do, like memorize a list
of words or recall a previously studied story. It is likely that
some studies failed to find mood dependence simply because
they relied on moods that were potent initially but that paled
rapidly (see Eich & Metcalfe, 1989).
Yet a third element of an effective mood is its authenticity
or emotional realism. Using the autobiographical event gen-
eration and recall tasks described earlier, Eich and Macaulay
(2000) found no sign whatsoever of MDM when undergradu-
ates simulated feeling happy or sad, when in fact their mood
had remained neutral throughout testing. Moreover, in sev-
eral studies involving the intentional induction of specific
moods, subjects have been asked to candidly assess (post-
experimentally) how authentic or real these moods felt. Those
who claim to have been most genuinely moved tend to show
the strongest mood-dependent effects (see Eich, 1995a; Eich
et al., 1994).
Thus it appears that the prospects of demonstrating MDM
are improved by instilling affective states that have three im-
portant properties: strength, stability, and sincerity. In princi-
ple, such states could be induced in a number of different
ways; for instance, subjects might (a) read and internalize a
series of self-referential statements (e.g., I’m feeling on top of
the worldvs.Lately I’ve been really down), (b) obtain false
feedback on an ostensibly unrelated task, (c) receive a post-
hypnotic suggestion to experience a specified mood, or, as
noted earlier, (d) contemplate mood-appropriate thoughts
while listening to mood-appropriate music (see Martin,
1990). In practice, however, it is possible that some meth-
ods are better suited than others for inducing strong, stable,
and sincere moods. Just how real or remote this possibly is
remains to be seen through close, comparative analysis of
the strengths and shortcomings of different mood-induction
techniques.SynopsisThe preceding sections summarized recent efforts to uncover
critical factors in the occurrence of mood-dependent mem-
ory. What conclusions can be drawn from this line of work?
The broadest and most basic conclusion is that the prob-
lem of unreliability that has long beset research on MDM
may not be as serious or stubborn as is commonly supposed.
More to the point, it now appears that robust and reliable ev-
idence of mood dependence can be realized under conditions
in which subjects (a) engage in open, constructive, affect-
infusing processing as they encode the to-be-remembered or
target targets; (b) rely on similarly high-infusion strategies as
they endeavor to retrieve these targets; and (c) experience
strong, stable, and sincere moods in the course of both event
encoding and event retrieval.
Taken together, these observations make a start toward de-
mystifying MDM, but only a start. To date, only a few factors
have been examined for their role in mood dependence; the
odds are that other factors of equal or greater significance
exist, awaiting discovery. Also, it remains to be seen whether
MDM occurs in conjunction with clinical conditions, such as
bipolar illness, and whether the results revealed through re-
search involving experimentally engendered moods can be
generalized to endogenous or natural shifts in affective state.
The next section reviews a recent study that relates to these
and other clinical issues.Clinical Perspectives on Mood DependenceEarlier it was remarked that mood dependence has been im-
plicated in a number of psychiatric disorders. Although the
MDM literature is replete with clinical conjectures, it is lack-
ing in hard clinical data. Worse, the few pertinent results that
have been reported are difficult to interpret.
Here we refer specifically to a seminal study by Wein-
gartner et al. (1977), in which five patients who cycled be-
tween states of mania and normal mood were observed over
several months. Periodically, the patients generated 20 dis-
crete free associations to each of two common nouns, such as
shipandstreet,and were tested for their recall of all 40 asso-
ciations four days later. Recall averaged 35% when the mood
at testing (either manic or normal) matched the mood at gen-
eration, but only 18% when there was a mismatch, a result
that Bower (1981) considered “the clearest early example of
mood-dependent memory” (p. 134).