AFFECT, AROUSAL, AND SELECTIVE PROCESSING

Two general issues are important to consider when evaluating emotions and memory. These include selective attention to emotion-congruent in- formation and selective attention to emotion-eliciting information. Each is discussed in turn.

Research on different factors influencing memory has shown interest- ing effects of affect-congruent processing at the stages of encoding and re- trieval (e.g., Bower, 1981; Isen, Shalker, Clark, & Carp, 1987; Mogg, Mathews, & Weinman, 1987). In one study, adults completed the Beck De- pression Inventory, a widely used, self-report questionnaire that meas- ures depression. The adults were asked to rate to what extent each of a se- ries of positive or negative adjectives was descriptive of themselves. At a later session, they were asked to recall the adjectives and then recognize them from a larger set of positive and negative items. Results showed that individuals with high scores on the Beck Depression Inventory had a bias to encode information with negative associations (Zuroff, Colussy, & Wielgus, 1983). Other studies that have employed similar designs reveal similar types of biases, for instance, an encoding bias among clinically anxious patients for anxiety-relevant adjectives (Greenberg & Beck, 1989) and panic-disordered patients for threat-related words (McNally, Foa, & Donnell, 1989).

Bower (1981) reported that negative information is preferentially proc- essed in an emotion congruent fashion when negative moods are induced. Adults were hypnotized into a happy or a sad mood and then asked to read a story about two men. One of the men was described as a happy and sucessful individual, and the other as a sad person with many prob- lems in life. After reading the story, participants were asked with whom they had identified the most, and their answers were congruent with the valence of the hypnotically induced mood. Further, during a recall test the following day, participants previously hypnotized into a happy mood re- membered approximately half of the facts pertaining to both characters. Thus, they did not exhibit a bias toward either individual. In contrast, par- ticipants previously hypnotized into a sad mood remembered almost ex- clusively the facts pertaining to the sad character of the story. This result suggests that we, to some extent, are predisposed to memorize nega- tively valenced emotional information, especially when that information

is consistent with our own feeling state. Indeed, research has similar- ly shown that an angry face in a crowd of neutral looking faces is per- ceived faster than a happy looking one (Hansen & Hansen, 1988), and that pictures with blood or physical injuries are retained in memory better than neutral pictures (e.g., Öhman, Dimberg, & Esteves, 1989). Together, the studies show that depression and the inducement of sadness may al- ter cognitive processsing in a congruent manner and that exposure to aversive or threatening stimuli may even alter moods into an arousal-like state.

Research on the effects of arousal on memory has, however, uncovered mixed results. Although a few studies have shown no differential effects of arousal (e.g., Hosch & Bothwell, 1990), most findings reveal either a decremental or enhancing effect on memory performance. A negative ef- fect of arousal has been demonstrated with regard to retrograde or anterograde amnesia for information not related to the gist of the event or the critical target (e.g., Christianson & Nilsson, 1984; Loftus & Burns, 1982). Studies that include an emotion-laden or divergent stimulus, such as a loud sound or a nude or injured person, presented in a series of neu- tral and homogoneous items, strongly suggest that anterograde and retro- grade amnesias are caused by heightened attention and processing allo- cated to unique items at the expense of other information (e.g., Detterman, 1975; Kramer, Buckhout, Widerman, & Tusche, 1991). These studies may indicate a problem of initial retrieval, as inhibitory effects of this kind have been shown to recede with recognition. By contrast, studies more specifically focused on memory of details that pertain to the gist or the critical target have shown that arousal enhances recall (e.g., Christianson & Loftus, 1987). In laboratory studies, a rather consistent pattern of encod- ing and memory under emotional stress has been revealed (e.g., Chris- tianson, 1984; Christianson & Loftus, 1990, 1991; Heuer & Reisberg, 1990, 1992; Kebeck & Lohaus, 1986). Specifically, details that are central or criti- cal to the cause of the stress are better retained in memory than details that are peripheral or noncritical. There is, in other words, a preponderance for remembering the details that gave rise to the emotional reactions and thoughts during the event. Heightened arousal focuses attention auto- matically to emotion-laden details which are therefore more thoroughly processed than are details in the periphery of attentional resources (cf. Easterbrook, 1959). The encoding of emotion-laden detail information will not, however, be enhanced in cases in which arousal arises by means of manipulation that is independent of (i.e., unrelated to) the content of the to-be-remembered stimuli (e.g., Christianson & Mjörndal, 1985; Christianson, Nilsson, Mjörndal, Perris, & Tjellden, 1986). Nonethe- less, because emotion-laden details are most often intrinsically related to emotional stress experienced during the event, arousal should be posi-

tively related to recall of details of crimes and other emotionally stressful experiences.

Children and adults alike have shown the same pattern of enhanced memory retention for central details. In one study of children’s memory for a medical checkup, children received either a vaccination on their arm or a pretend tattoo sticker placed on the same location. After 3 or 4 days, children were questioned about what had happened during the checkup. Children who received the inoculation remembered more central detail information, whereas children who received the tatoo remembered more peripheral details (Goodman, Hepps, & Reed, 1986; but see Vandermaas, Hess, & Baker-Ward, 1993). In a study by Maass and Kohnken (1989), the effect of exposure to a syringe and the possible threat of an injection was investigated in adults as a parallel to the phenomenon of weapon focusing (e.g., Cutler, Penrod, & Martens, 1987; Loftus, Loftus, & Messo, 1987). Adults were approached by the experimenter who either had a syringe or a pen in her hand. Results showed that recall of details of the experi- menter’s hand was better among adults exposed to the syringe than adults exposed the pen. The difference was even larger when adults ex- posed to the syringe were told that they might get an injection.

Outside the laboratory, what may be perceived as central or critical de- tails of a stressful real-life event is of course less evident. However, recur- rent details imbued with special traumatic meaning are usually revealed in play and drawings when children process a trauma. A clinical interpre- tation of symbolic activity of this kind is that it may reflect what is consid- ered central, that is, the critical details of the trauma, to a child who experi- ences such an event. For instance, a boy who saw a jet of water eviscerate his younger sister, constantly played with yarn by stretching it and tying it between pieces of furniture (Terr, 1990). The yarn may have been remi- niscent of intestines that he had seen. Another boy, who saw his mother being killed with a two-pronged pitchfork, drew two-pronged buildings and abstract images (Nader & Pynoos, 1990). As suggested by Wessel and Merckelbach (1994), it may be possible that the retention of central detail accounts for the reexperiencing of traumatic symptoms often found in in- dividuals diagnosed with posttraumatic stress disorder (PTSD).