Brenna S. Adams and Dr. Michael J. Larson, Psychology Department

Main Text

Positive affect, or positive emotion, is associated with improvements in most cognitive abilities, such as creative problem solving (Isen, Daubman, & Nowicki, 1987), the integration of information for strategic decision-making (Estrada, Isen, & Young, 1997), and verbal fluency (Phillips, Bull, Adams, & Fraser, 2002). However, recent studies report that positive affect also fosters increased distractibility, impairing working memory (Dreisbach, 2006; Dreisbach & Goschke, 2004). Working memory refers to the neural system involved in “temporary maintenance and manipulation of information” (Baddeley, 2002, p. 85).

Given the competing findings from previous studies, the purpose of this project was to gain a better understanding of the influence of positive affect on cognitive capabilities, specifically working memory, and to reconcile a developing controversy in the literature as to whether positive affect has a beneficial or a detrimental effect on working memory. This project was tailored to overcome the major weakness of previous studies, sample size. Each of the previous studies assigned participants to affective groups, thereby dividing their already limited sample size into even smaller affective groups. By exposing each participant to positive, neutral, and negative affect-inducing pictures, this project utilized a within-subjects design to ensure equal representation across each affective condition. We hypothesized that participants would perform worse during a long delay condition where they had to maintain information in working memory when presented with a positive picture, as opposed to a negative or neutral picture or during short delay condition.

We collected data from 36 healthy undergraduate participants who are free from neurologic or psychiatric illness. These participants completed a modified version of the Stroop task. The task included the following three experimental manipulations: (1) word reading and color naming tasks, (2) long and short task instruction-stimulus delay (1s and 5s, respectively), and (3) congruent and incongruent color-word combinations in each of the two tasks (congruent example is RED written in red ink; incongruent example is RED written in green ink). In each trial, participants were presented with a pleasant, neutral, or unpleasant picture from the International Affective Picture System, which has been shown to reliably induce positive, negative, and neutral emotional states (Lang, Bradley, & Cuthbert, 1998). Participants were then presented with an instructional cue (“color” or “word”) and subsequently, one of two delay conditions. The short delay was one second in length and the long delay was five seconds in length. The probe was then presented and participants were instructed to respond as quickly and accurately as possible with a button press to one of three color-coded keys, as designated by the cue. We looked most closely at the more difficult color-naming condition, and our two dependent variables were accuracy and response time excluding error trials, which tend to be more impulsive and, thus, shorter. Following data collection, we ran 3-Emotion (Pleasant, Neutral, and Unpleasant) x 2-Delay (Short, Long) x 2-Congruency (Congruent, Incongruent) repeated measures analysis of variance (ANOVA) to test the hypothesis.

In looking at accuracy, there was a significant main effect of delay, F(1,36) = 5.43, p = .03, with improved accuracy at the long delay relative to the short delay. There was also a significant main effect of congruency, F(1,36) = 81.64, p < .001, with better accuracy for congruent than incongruent trials. For emotion-related findings, there was a significant Emotion x Congruency interaction, F(2,72) = 3.15, p < .05, with better accuracy for incongruent unpleasant relative to incongruent pleasant or neutral trials. The Emotion x Delay x Congruency interaction was significant at the trend level, F(2,72) = 2.59, p = .08, indicating better accuracy for unpleasant incongruent trials at the long delay. Considering response times, there was a significant main effect of congruency, F(1,36) = 281.03, p < .001, with longer RTs for incongruent than congruent trials, as would be expected. There were no significant main effects or interactions involving the emotion conditions or delays, Fs < .70, ps > .50.

As expected, accuracy was lower and response times were longer for incongruent trials than for congruent trials, and accuracy was higher during the long delay condition due to the extra rehearsal time, while response times showed no significant change across delay or valence. However, accuracy was higher for unpleasant incongruent trials than for pleasant or neutral incongruent trials, particularly at the long delay. So it appears that the higher arousal associated with the unpleasant pictures may have enhanced working memory rather than the pleasant pictures impairing it. It may be that positive affect does not increase distractibility as proposed by Dreisbach (2006), but that negative affect improves focus.

References

• Baddeley, A. D. (2002). Is working memory still working? European Psychologist, 7, 85-97. doi: 10.1027//1016-9040.7.2.85
• Dreisbach, G. (2006). How positive affect modulates cognitive control: The costs and benefits of reduced maintenance capability. Brain and Cognition, 60, 11-19. doi: 10.1016/j.bandc.2005.08.003
• Dreisbach, G., Goschke, T. (2004). How positive affect modulates cognitive control: Reduced perseveration at the cost of increased distractibility. Journal of Experimental Psychology: Learning, Memory, and Cognition, 30, 343-353. doi: 10.1037/0278-7393.30.2.343
• Estrada, C. A., Isen, A. M., & Young, M. J. (1997). Positive affect facilitates integration of information and decreases anchoring in reasoning among physicians. Organizational Behavior and Human Decision Processes, 72, 117-135. doi: 10.1006/obhd.1997.2734
• Isen, A. M., Daubman, K. A., & Nowicki, G. P. (1987). Positive affect facilitates creative problem solving. Journal of Personality and Social Psychology, 52, 1122-1131. doi: 10.1037/0022-3514.52.6.1122
• Lang, P.J., Bradley, M.M., & Cuthbert, B.N. (1998). International Affective Picture System (IAPS): Technical manual and affective ratings. Gainesville, Florida: University of Florida Center for Research in Psychophysiology.
• Phillips, L. H., Bull, R., Adams, E., & Fraser, L. (2002). Positive mood and executive function: Evidence from Stroop and fluency tasks. Emotion, 2, 12-22. doi: 10.1037//1528-3542.2.1.12