1. DEPARTMENT OF PSYCHOLOGY U N I V E R S I T Y O F C O P E N H A G E N Suppression of neutral but not emotional words Background Anderson & Green (2001) found that repeated attempts of memory suppression affected recall of neutral words negatively. Also, Anderson et al. (2004) reported that suppression was associated with increased dorsolateral prefrontal and decreased hippocampal activity. Such results has been related to the functioning of an “inhibitory control mechanism” which supposedly is active in “response-override situations” (Levy & Anderson, 2002). Furthermore, the results has been interpreted in relation to Freudian repression. The present study investigated forgetting / suppression in relation to emotional versus neutral material and tested the “long-term” effect of suppression. Emotional material (such as emotional words) is normally remembered better than neutral material (e.g. Altarriba & Bauer, 2004). Therefore it was hypothesized that emotional stimuli would be more difficult to forget / suppress than neutral stimuli. To test the “long-term” effect of suppression, we employed a retest after one week. Simon Nørby To what extent are we able to forget things we do not want to think about? It has been shown that memories of neutral material may be forgotten at will (Anderson & Green, 2001). The present study shows that memories of emotional material are much harder to forget. The data also suggest that the ability to forget verbal material is poor among good learners and much better among less efficient learners. Preliminary Results.................................. Anderson and Green’s (2001) results were confirmed. Overall, recall of neutral suppress items was inferior to recall of neutral baseline items. On the other hand, recall of emotional suppress items was not worse than recall of recall of emotional baseline items, i.e., emotional material was not as easily forgotten as neutral material. There was a negative correlation (.74) between the total amount of words remembered in the first try in phase 2 and the total amount of words forgotten in the suppression categories as measured in phase 4, i.e., good learners seemed to be bad at forgetting. I consider testing verbal memory of participants to obtain an independent measure which can be correlated with the individual ability to forget...................................... Emotional words elicited slightly lower GSR’s than the neutral words in the learning phase. The relatively high GSR for neutral words were probably due to the effort put into or frustration related to trying to learn those words. This interpretation fits with the observation that the words not learned in the first try in phase 2 led to a stronger GSR’s in the last sequence of the learning phase (regardless of emotionality)............................................. The result of the retest (of so far only 24 participants) is suggestive but not conclusive. There is a practice effect for both the neutral and emotional words. The effects of repeated attempts of suppression on neutral words seem to disappear. However, more subjects need to be tested before a clear conclusion can be reached. Concluding remarks................................. The result – that emotional words are harder to suppress than neutral words – is consistent with the outcome of a recent study which the “directed forgetting paradigm” and found that it is harder to forget the gist of emotional pictures compared to neutral pictures (Payne & Corrigan, 2006). Do the findings in this experiment apply to everyday memory? Anderson & Green (2001) proposed that their results implicate a mechanism similar to Freudian repression / suppression and that their results (on suppression of neutral verbal material) bears directly on clinical phenomena. While this interpretation may be questionable one way to improve ecological validity would be to expose subjects with anxiety to stimuli they fear and test the ease with which such stimuli could be suppressed. Altarriba, J. & Bauer, L.M. (2004): The distinctiveness of emotion concepts: a comparison between emotion, abstract, and concrete words, American Journal of Psychology, 117 (3), 389-410 Anderson, M.C. & Green, C. (2001): Suppressing unwanted memories by executive control, Nature, 410, 366-9 Anderson, M.C., Ochsner, K.N., Kuhl, B., Cooper, J., Robertson, E., Gabrieli, S.W., Glover, G.H. & Gabrieli, J.D.E. (2004): Neural Systems Underlying the Suppression of Unwanted Memories, Science, 303, 232-235 Levy, B.J & Anderson, M.C. (2002): Inhibitory processes and the control of memory retrieval, Trends in Cognitive Sciences, 6 (7), 299-305 Payne, B.K. & Corrigan, E. (2006): Emotional constraints on intentional forgetting, Journal of Experimental Social Psychology, in press Method Stimuli material comprised 140 Danish nouns that were controlled for word-length (6 to 10 letters), frequency of use (all words are common), semantic relatedness (no words were related in any obvious way), abstractness (half were abstract) and emotionality (35 negative word- pairs). Participants were exposed to 35 neutral and 35 emotional word pairs. A neutral word pair consisted of two neutral words (e.g. “habit–balcony”). An emotional word pair consisted of a neutral stimulus word and an emotional response word (e.g..“collar–cruelty”). In the learning phase the subject was exposed twice to all the word pairs. In the test phase the subject was shown the stimulus word and asked to recall the response word. Test-feedback cycles continued until accuracy was at least 60%. 60 word-pairs were then selected for presentation in the think/no-think phase. Participants memorized (accuracy 90%) a subset of 20 word pairs in which the second word was to be suppressed later on. The first word in each of the 60 stimulus pairs was then presented 8 or 16 times and should either be responded to (rehearsed) or suppressed. Finally, in the recall phase each of the 70 stimulus words were shown and the subject had to try to provide the correct response to each of them. To obtain an individual index of the emotionality of the words galvanic skin responses (GSR) were obtained in the learning and the recall phase. Then, the participant was asked to come back after one week to do a retest. The subject was exposed to every single stimulus word and asked to recall as many response words as possible. Recall %