Transcript 200807 Suppression of neutral but not emotional words

DEPARTMENT OF PSYCHOLOGY
UNIVERSITY OF COPENHAGEN
Suppression of neutral but not emotional words
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.
Background
Recall %
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.
Suppress negative
Suppress neutral
Recall negative
Recall neutral
1,00
Mean
0,90
0,80
0,70
0,60
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.
0 repetitions (baseline)
8 repetitions
16 repetitions
repetitions
Error bars: +/- 1 SE
Retest
Recall
%(N=24)
Suppress negative
Suppress neutral
Recall negative
Recall neutral
0,80
Preliminary Results..................................
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 wordpairs). 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”).
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.
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.
0,70
Mean
Method
0,60
0,50
0,40
0 repetitions (baseline)
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.
8 repetitions
16 repetitions
repetitions
Error bars: +/- 1 SE
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