Directed Forgetting of Emotionally Arousing Stimuli and Divided Attention

1. Directed Forgetting of Emotionally Arousing Stimuli and Divided Attention Hajime Otani, OlesyaSenkova, Abby R. Knoll, Tyler Foster, and Terry M. Libkuman Central Michigan University • Introduction • Emotion enhances memory, a phenomenon referred to as emotionally enhanced memory (Talmi, Schimmack, Paterson, & Moscovitch, 2007). • The present experiment investigated directed forgetting (DF) of emotionally arousing stimuli. • DF is a phenomenon that people intentionally forget information when they are instructed to forget (MacLeod, 1998) • This phenomenon has been studied by asking participants to remember some items (R items) and forget the other items (F items). They are then asked to recall both R and F items. If participants recall more R than F items, the DF effect is observed. • Two paradigms have been used to study the DF effect: item and list method. In the item method, each item is followed by an R (remember) or F (forget) instruction. In the list method, an R or F instruction is given after participants studied a list of items (List 1). After the instruction, participants receive another list (List 2) to study. • The DF effect is smaller or sometimes eliminated altogether for emotionally arousing stimuli (Minnema and Knowlton, 2008; Otani et al., 2012; Payne and Corrigan, 2007). The goal of the present experiment investigated the reason that the DF effect is smaller for emotionally arousing stimuli. • According to Christianson (1992), two types of processing are responsible for emotionally enhanced memory: preattentive processing and poststimulus elaboration. • Preattentive processing is fast and automatic processing of stimuli whereas poststimulus elaboration is slow and effortful processing of stimuli. • Hypothesis 1: It is possible that the DF effect is smaller for emotionally arousing than for neutral stimuli because emotional to-be-forgotten items (F items) are preattentively processed. • Hypothesis 2: It is also possible that the DF effect is smaller for emotionally arousing than for neutral stimuli because participants have a tendency of elaborating emotional to-be-forgotten items (F items). • We tested these possibilities using a divided attention task. If participants have a tendency of elaborating emotionally arousing F items, asking participants to engage in a divided attention task would eliminate the difference in recall of F items between emotionally arousing and neutral stimuli. • For half of the participants, an instruction slide (R or F) preceded a picture (the before condition) whereas for the other half, an instruction slide followed a picture (the after condition). • Each picture and instruction slide was presented for 5 s. • For half of the participants, each slide was presented with three single digits, presented at the second, third, and fourth second of the slide presentation. • These digits were randomly selected and presented via wav files. • Procedure • Participants were individually tested. • They were told to remember R items and forget F items. • In the divided attention condition, participants were asked to report the second largest digit among the three (e.g., 7, 2, 4 – report 4). • After viewing all slides, they performed a 2-min filler task (a simple arithmetic task). • They were asked to recall both R and F items and write a word or a short description of each recalled item. • They were asked to go back to the recall test and indicate which items were R items and which items were F items. • Design – a 2 (divided attention condition: divided and undivided) x 2 (instruction timing: before and after) x 3 (valence: negative, positive, and neutral) x 2 (instruction: R and F) mixed-design. The first two variables were between-subjects variables and the last two were within-subjects variables. • F items (Figure 3) - A 2 (divided attention condition: divided and undivided) x 2 (instruction timing: before and after) x 3 (valence: negative, positive, and neutral) ANOVA showed that valence was significant, F(2, 184) = 75.21, p < .001. The valence x divided attention condition interaction was not significant, F(2, 184) < 1.00. Recallwas lower in the divided than in the undivided condition, F(1, 92) = 23.84, p < .001, and for the before than for the after condition, F(1, 92) = 4.60, p = .04. • Divided attention performance was 90%. • The proportion of participants who made at least one misattribution error was higher for the negative picture (65%) than for the positive (28%) or neutral (41%) pictures. • Results • The proportion of correctly recalled pictures was the dependent measure. • As shown in Figure 1, the DF effect (R minus F) was smaller for the negative pictures than for the neutral pictures for both the divided and undivided conditions. However, the instruction timing x valence interaction was significant, indicating that the difference was only significant when the instruction slide was presented before the picture slide (due to insufficient power). • Figure 2 shows the mean proportion correct across valence, instruction type, and divided attention condition. Performance was higher for the negative pictures than for the positive or neutral pictures for both R and F items. • R items (Figure 3) – A 2 (divided attention condition: divided and undivided) x 2 (instruction timing: before and after) x 3 (valence: negative, positive, and neutral) ANOVA showed that valence was significant, F(2, 184) = 24.83, p < .001. The valence x divided attention condition interaction was not significant, F(2, 184) < 1.00. The valence x instruction timing was significant, F(2, 184) = 3.33, p = .04; however, for both the before and after conditions, recall was higher for the negative pictures than for the positive or neutral pictures. Not surprisingly, recall was lower in the divided than in the undivided condition, F(1, 92) = 86.68, p < .001. • Discussion and Conclusion • The DF effect was smaller for the negative pictures than for the positive and neutral pictures. • Importantly, for both R and F items, recall was greater for the negative pictures than for the positive or neutral pictures. Asking participants to engage in a divided attention task did not alter the results. • Superior recall of the negative F pictures was not based on post stimulus elaboration. Even when post stimulus elaboration was prevented, participants showed enhanced recall of negative F pictures. • Negative pictures may be processed preattentively or at least based on processing that does not require elaboration. • Implication – These results showed how difficult it is to forget negative pictures. Even when participants were told to forget the pictures and prevented from engaging in post stimulus elaboration, the negative pictures were remembered better than the positive or neutral pictures. • Method • Participants: 96 college students • Materials • Two sets of 10 negative arousing, 10 positive arousing, and 10 neutral pictures from IAPS (Lang, Bradley, & Cuthbert, 2001) were used. These pictures were the same as those used in Experiment 2 of Kern et al. (2005), used because of the ease in describing these pictures using one word or a short phrase. • For each set, half of the pictures from each valence category were designated as R items and the other half were designated as F items. R and F items were counterbalanced across lists. • The pictures in each list were randomly ordered but the same order was used across participants.