Suppression of Emotional and Nonemotional Content in Memory

Two experiments utilized a think/no-think paradigm to examine whether cognitive control of memories differs depending on whether they contain information with negative or neutral emotional content. During a training phase, participants learned face-word pairs (Experiment 1) or face-picture pairs (Experiment 2). In a subsequent experimental phase, participants were shown faces and told to think of the items paired with some of the faces and to try not to think of the items paired with other faces. Finally, in a test phase, participants were again shown each face and asked to recall the item with which it had been paired previously. Results for both verbal (Experiment 1) and nonverbal (Experiment 2) items indicated that the facilitatory and inhibitory influences of cognitive control were larger for negative than neutral items. Suppression of Emotional and Nonemotional Content in Memory Effects of Repetition on Cognitive Control Brendan E. Depue, Marie T. Banich, and Tim Curran Department of Psychology, University of Colorado at Boulder, and Department of Psychiatry, University of Colorado Health Science Center Cognitive control allows for the top-down selection and manipulation of task-relevant information. Research suggests that cognitive control mechanisms, such as top-down attention, can facilitate and enhance memory for certain information (Behrmann & Tipper, 1999; Kastner & Ungerleider, 2000). A less understood aspect of cognitive control that has been implicated as being dysfunctional in clinical disorders is the control mechanism used to suppress unwanted memories. Traditionally, suppressive mechanisms of cognitive control have been studied in the motor domain using the go/no-go task. In this task, individuals respond, or ‘‘go,’’ to certain frequently occurring stimuli and withhold response to other, rare stimuli (‘‘no go’’). Many populations with deficits in cognitive control, such as individuals with attention deficit hyperactivity disorder (Vaidya et al., 1998) and frontal lobe damage (Drewe, 1975), exhibit an impaired ability to suppress responding in the no-go condition. Recently, a modification of the go/no-go paradigm, aptly named the think/no-think paradigm, was designed to examine whether similar suppressive mechanisms can operate on memory representations (Anderson & Green, 2001). In the training phase, participants memorized cue-target word pairs, so they could accurately recall each target when presented with its cue. In the experimental phase, participants were shown only the cues. For some cues, participants had to suppress thinking about the associated target (no-think condition), whereas for other cues, they were to think of the associated target (think condition). These manipulations did not involve re-presentation of the targets, so cognitive control had to be applied to internal memory representations. In the final phase of the experiment, memory for each target item in response to its cue was assessed. Anderson and Green’s (2001) results indicated that cognitive control can extend to items in memory. Recall of target items in the think condition was superior to recall of items in a baseline condition. In the baseline condition, word pairs were presented only in the training phase, with no intervening presentation of the cue in the experimental phase. Conversely, recall for items in the no-think condition was worse than baseline. Moreover, the level of recall was directly related to the number of times cognitive control was exerted (Anderson & Green, 2001; Levy & Anderson, 2002). Recall of words whose cues were shown infrequently during the experimental phase deviated from baseline less than recall of words whose cues were shown often. The main focus of the present research was to investigate whether the efficacy of these control mechanisms differs for Address correspondence to Brendan Depue, 345 UCB, Boulder, CO 80309, e-mail: [email protected]. PSYCHOLOGICAL SCIENCE Volume 17—Number 5 441 Copyright r 2006 Association for Psychological Science emotional and nonemotional information. Previous research suggests that emotional information can automatically capture attention (Blaney, 1986), which enhances encoding (Cahill & McGaugh, 1998; Canli et al., 2001; Rolls, 2000) and retrieval (Hamann, 2001). Thus, memory representations of emotional material appear to be stronger than representations of nonemotional material, and if cognitive control mechanisms act similarly on emotional and nonemotional information, one would nonetheless observe differences in recall. More specifically, in the think condition, the recall of emotional information would be greater than the recall of nonemotional information. Furthermore, the reduction of recall in the no-think condition would be smaller for emotional than for nonemotional material (i.e., there would be better recall for emotional material). Both of these patterns would be a simple reflection of the heightened encoding of emotional information (see Fig. 1, top panel). Consistent with this possibility, studies have shown that individuals with posttraumatic stress disorder (PTSD) and obsessive-compulsive disorder (OCD) report that exerting suppressive control over uncontrolled intrusions of thoughts and images can be difficult (e.g., de Silva & Marks, 2001). Another possibility is that greater cognitive control can be exerted over emotional information than over nonemotional information. This is a possibility because evidence suggests that increased strength of a representation may make the memory more accessible to cognitive control mechanisms (Norman, Newman, Detre, & Polyn, 2004). In addition, research involving memory reconsolidation suggests that as a memory representation is accessed or recalled, it once again becomes labile. This allows for the possibility that the strength of the memory may be modified—either enhanced or reduced (Abel & Lattal, 2001; Dudai, 2002; Walker, Brakefield, Hobson, & Stickgold, 2003). Thus, if emotional memories are easier to recall than nonemotional memories are, they may be more susceptible to mechanisms of cognitive control. If this were the case, then one would expect greater recall for emotional than nonemotional material in the think condition, but more suppression (i.e., less recall) for emotional than nonemotional material in the no-think condition (see Fig. 1, bottom panel). A secondary focus of the present research was to examine whether the control mechanisms observed by Anderson and his colleagues (Anderson & Green, 2001) generalize to different types of material. Therefore, we utilized pairings of verbal and nonverbal information (Experiment 1) and of two types of nonverbal information (Experiment 2), rather than word-word pairs. This issue is significant because emotional events are experienced both verbally and nonverbally (Adolphs, Tranel, & Damasio, 2003; LeDoux, 1998a, 1998b).