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Journal of Experimental Psychology:
Learning, Memory, and Cognition
1992,
Vol. 18, No. 2, 379-390
Copyright 1992 by the American Psychological Association, Inc.
0278-7393/92/S3.00
Remembering Pictures: Pleasure and Arousal in Memory
Margaret M. Bradley, Mark K. Greenwald, Margaret C. Petry, and Peter J. Lang
University of Florida
Incidental memory performance for pictures that varied along the affective dimensions of
pleasantness and arousal was assessed. For both an immediate and delayed (1 year later) free-
recall task, only the arousal dimension had a stable effect on memory performance: Pictures
rated as highly arousing were remembered better than low-arousal stimuli. This effect was
corroborated in a speeded recognition test, in which high-arousal materials encoded earlier in
the experiment produced faster reaction times than their low-arousal counterparts. Pleasantness
affected reaction time decisions only for pictures not encoded earlier. These results suggest that
whereas both the dimensions of pleasantness and arousal are processed at initial encoding, long-
term memory performance is mainly affected by arousal.
It has been demonstrated numerous times that emotional
stimuli vary along two primary dimensions of affective val-
ence and arousal (e.g., Russell, 1980; Tellegen, 1985; Lang,
Bradley, & Cuthbert, 1990). Using the semantic differential,
Osgood, Suci, and Tannenbaum (1957) showed that the bi-
polar factors of pleasantness and intensity accounted for most
of the variability in judgments of affective text. These dimen-
sions of emotional language map easily onto the behavioral
dimensions of direction (approach or avoidance) and vigor
(i.e.,
mobilization) advocated by a biphasic organization of
emotional responses (Hebb, 1949; Konorski, 1967; Lang et
al.,
1990). Dimensional views of emotion are parsimonious
in that, rather than assuming independent, specific emotional
states (e.g., fear, anger, and joy), two primary dimensions
define the spectrum of emotional behavior.
The questions addressed in the current article exploit this
organization of emotion to determine the contribution of the
valence dimension, the arousal dimension, and their interac-
tion to memory performance. Past research has tended to
focus on memory for a particular type of emotional event
(e.g., sad, happy, traumatic) rather than using a dimensional
analysis. In assessing recall of traumatic events, for example,
Christianson and Loftus (1987) found a memory advantage
for the occurrence of a traumatic situation, compared to a
neutral one. The purported clarity and stability in memory
for traumatic
events
has led some researchers (Brown
&
Kulik,
1977;
Bohannon,
1988)
to posit a special "flashbulb memory"
mechanism that veridically records moments of trauma. Al-
though receiving somewhat less attention, research on mem-
ory for happy events also produces evidence of increased
memorability, relative to neutral. The "Pollyanna" effect,
This research
was
supported by National Institute of Mental Health
(NIMH) Grants MH37757, MH41950, and MH43975 to Peter J.
Lang.
We would like to thank Alfons Hamm for his assistance in data
collection and interpretation in Experiment 2 and Sven-Ake Chris-
tianson and two anonymous reviewers for their helpful comments.
Correspondence concerning this article should be addressed to
Margaret
M.
Bradley, Box 100165, Health Science Center, University
of
Florida,
Gainesville, Florida 32610.
indicating better memory for pleasant materials,
is
at the heart
of
a
series of experiments that corroborate this phenomenon
with verbal stimuli (Matlin & Stang, 1978).
Running parallel to reports of improved memory for trau-
matic or happy stimuli are a number of experiments that have
explicitly focused on the arousal dimension (see Craik &
Blankstein, 1975, and Eysenck, 1976, for reviews). In these
studies, arousal has been variously operationalized
as
the rated
arousal of
the
stimulus materials, the magnitude of
a
physio-
logical index of
the
subject's arousal level (e.g., electrodermal
responses), or by the presence of a constant stimulus back-
ground (e.g., white noise). The general finding is that verbal
items associated with higher arousal at encoding result in
better memory performance on a later (especially long-term)
memory test. Thus, whereas affective memory has been stud-
ied at either extreme of the valence dimension (i.e., pleasant
or unpleasant), or along an arousal continuum, a systematic
exploration of the contribution of each dimension to memory
performance is lacking.
A necessary component of such experimentation is the
presence of emotionally evocative stimuli that are distributed
in the two-dimensional affective space defined by pleasantness
and arousal. In the current study, the emotional materials are
color photographic slides, drawn from the International Af-
fective Picture System (IAPS; Lang, Ohman, & Vaitl, 1988).
This standardized collection of pictures, gathered from a
variety of sources, samples contents across a wide range of
emotional and semantic
categories.
Contents include animals,
nature scenes, erotica, household objects, expressive human
faces,
weapons, mutilated bodies, and others. Affective val-
ence and arousal ratings for each slide have been obtained in
previous rating studies, allowing precise placement of these
stimuli in a two-dimensional affective space, which Figure 1
illustrates (see Bradley, Greenwald,
&
Hamm, in
press;
Green-
wald, Cook, & Lang, 1989; Lang, Greenwald, Bradley, &
Hamm, in press).
In addition to assessing judgments of affective experience,
a number of studies have convincingly demonstrated that
emotional responses to these materials—measured by psycho-
physiological and behavioral reactions—reliably covary with
the dimensions of valence and arousal (Bradley et al., in press;
Greenwald et al., 1989; Lang et al., in press). Facial electro-
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