1. The Role of Arousal in Mood Mediation: A Closer Look at Mood Congruent Memory
Ben Fox, Janna Kost, Sabette Thompson, Michelle Fung, Dawn Macaulay, Eric Eich
               
      
Method
Participants
207 student and community participants (60 males, 147 females), ranging in age from 17 to 40 years (mean = 21.61).
Procedure
Each subject participated in two 1hour sessions. For the purpose of our analysis we will be looking at the data from the first session.
Each subject was screened for depression using the Beck Depression Inventory (Beck, 1967).
A modified version of the Affect Grid (Russell, Weiss, & Mendelsohn, 1989) was explained and demonstrated to the subject and a baseline measurement was recorded.
Appropriate mood induction music was played and the subject was asked to think of a real or imagined experience that would recreate the designated mood: happy, calm, sad or anxious. The subject was given a mood grid every five minutes until the pleasure and arousal criterion were reached. The criteria were set at moderate intensity as demonstrated in Figure 1.
Once criteria were reached the subject performed the Autobiographical Memory Generation (AMG) task. Twelve neutral words were presented to the subject one word at a time. For each word they were asked to recall aloud a related past event, and to rate its valence, significance and vividness at the time that it occurred.
Subjects were selected on the basis of maintaining mood and at least moderate genuineness, rating mood at least 5 on a scale with 0 being not at all genuine and 10 being extremely genuine.
Results
 Mood Ratings
 Pleasure ratings were significantly different than baseline measures for both pleasant (P) and unpleasant (U) mood subjects pre- and post-task. (P means = 2.92 and 2.52; U means = and -1.41). See Figure 2.
 Arousal ratings were significantly different than baseline measures for both high arousal (H) and low arousal (L) mood subjects pre- and post-task. (H means = 2.45 and 2.06; L means = and -1.65). See Figure 3.
These measures indicate that relatively intense and stable moods were reported by our subjects.
 Mood Congruent Effects
 For the current investigation the dependent measure of interest was the number of positive and negative events that were described. We analyzed the number of positive and negative events produced by our subjects (event-type) according to the assigned level of pleasure and arousal.
 As is seen in Figure 4, our participants tended to describe more positive than negative events (F(1,203) = 100.5, p < .001, means of 0.56 and 0.32 respectively), but this tendency was much stronger for P than U mood subjects (F(1,203) = 115.8, p < .001, P mood subjects means = positive 0.70 vs. negative 0.19 and U mood subjects means = positive 0.43 vs. negative 0.44). These effects were qualified by a significant 3-way interaction, (F(1,203) = 5.38, p < .05).
 Though assigned arousal levels did not have a significant overall interaction with event-type (F<1), within unpleasant moods, it did influence the types of memories described. Specifically, post-hoc analyses revealed that while sad subjects recalled similar numbers of positive and negative events (means = 0.48 and 0.42) anxious subjects retrieved predominantly negative events (means = 0.38 and 0.48, F(1,203) p < .03)
Discussion
Overall, our results agree with the majority of other research which suggests that pleasure is critical to the production of MCM. The types of memories described are influenced much more by a change in pleasure than by a change in arousal. However, our data also support the idea that arousal's role should not be ignored.
In our study, subjects under conditions of unpleasant moods retrieved different proportions of positive and negative events according to their reported levels of arousal. In contrast, Varner and Ellis' (1998) study suggested arousal would not modify MCM. One reason our outcomes differ may reside with our methods. Whereas they used physical exercise to induce high arousal states, our induction required subjects to imagine different past and/or future events to experience moods that they would describe as being more or less energetic.
As answers to the arousal-affect debate remain uncertain, future studies should attempt to differentiate cognitive arousal from physiological arousal. Greater understanding of arousal's role is of importance to those studying emotion, memory and mood congruence alike.
Introduction
Mood Congruent Memory (MCM) has been defined as the enhanced encoding and retrieval of events with affective valences resembling one’s current mood (Blaney, 1986). Previous research has shown MCM to be stable and robust (Bower & Mayer, 1989; Salovey & Singer, 1989; Clark & Teasdale, 1982). Much MCM research rests on the assumption that pleasure is critical to moods (Blaney, 1986). However, theories of emotion exist that suggest there are 2 dimensions to mood (Watson & Tellegen, 1985; Russell, 1980). In particular, one suggestion is that both pleasure and arousal should be considered (Revelle & Loftus, 1990).  
Despite two-dimensional theories of mood, the relative contributions of arousal and pleasure to MCM have never been fully determined. One particular issue that researchers have yet to resolve is whether a change in arousal alone is sufficient to produce effects on memory. A recent study by Varner & Ellis (1998) investigated the roles of pleasure and arousal and found that the former produced MCM. Physiological arousal (heart-rate) was manipulated through a brief exercise technique that consisted of subjects stepping up and down on a cinder block for 5 minutes. However, physiological arousal was not implicated in producing MCM. Though emotion theory suggests that arousal may be critical to MCM, empirical corroboration is limited. 
In our study, we sought to further investigate the two-dimensional issue. Subjects, who had been randomly assigned to moods with moderate levels of pleasantness or unpleasantness, and arousal or calmness, were selected from an existing data set. These moods were induced prior to subjects describing autobiographical memories. This experimental protocol should improve our understanding of arousal’s role in MCM.
Figure 2
Figure 4
Figure 3
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Watson, D., & Tellegen, A. (1985). Toward a consensual structure of mood. Psychological Bulletin, 98,
Figure 1