Flanary Thesis 5.9.11 - draft

NEURAL AND BEHAVIORAL AGE DIFFERENCES IN EMOTIONAL BIASES
A Thesis
Submitted to the Faculty
in partial fulfillment of the requirements for the
degree of
Master of Arts
in
Experimental Psychology
by
Kristin Flanary
DARTMOUTH COLLEGE
Hanover, New Hampshire
May 2011
Examining Committee:
Catherine J. Norris, Ph.D.
(Chair)
Paul J. Whalen, Ph.D.
Jeff T. Larsen, Ph.D.
_____________________
Brian W. Pogue, Ph.D.
Dean of Graduate Studies

Abstract
Research has demonstrated a “positivity effect” in aging, such that older adults remember
and attend to more positive than negative information, compared to their younger
counterparts. The underlying mechanisms of this effect, however, remain largely
unknown. One possibility is that the positivity effect arises from changes in the
negativity bias (the tendency for negativity to outweigh positivity at high levels of
emotional input) or the positivity offset (the tendency for positivity to outweigh negativity
at low levels of emotional input) over the lifespan. The current study aimed to compare
age differences in these emotional biases in order to assess whether the positivity effect is
related to a decreased negativity bias, an increased positivity offset, or both. To do this,
we examined younger (18-25) and older (65-80) females’ behavioral and neural
responses to pictures ranging from neutral and mildly emotional to moderately and
extremely emotional in content. The age groups demonstrated a similar negativity bias in
picture ratings, but older adults showed a larger positivity offset, which was driven by
higher positive and lower negative ratings of the mildly emotional pictures. Older adults
also took more time to rate the mildly unpleasant pictures, and the longer they took to
rate these pictures, the more positive they reported feeling about them. Neural responses
to the emotional pictures appeared to be characterized by prefrontal control regions acting
to down-regulate negative and up-regulate positive emotional responses to both mildly
and very emotional pictures. Results suggest that older adults use multiple emotion
regulation strategies with varying degrees of effectiveness, but appear to successfully
regulate their responses to mildly emotional stimuli in order to more fully appreciate the
simple things in life.
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Acknowledgments
First and foremost, many thanks are due to my advisor, Catherine Norris, PhD, for
the generosity, patience, support, and instruction she has extended throughout my time at
Dartmouth. I will always be grateful for all that I have learned from you. I would also
like to thank the members of my committee, Paul Whalen, PhD, and Jeff Larsen, PhD,
whose invaluable assistance, guidance, and support I have truly appreciated.
Thanks to the members of the Norris Lab for three great years of invigorating
discussions and patient hours of data entry and reduction. Special thanks are due to the
many people who have provided technical assistance and helpful discussions regarding
data analysis and interpretation of these data over the last three years: Zachary
Ingbretsen, Lisa Sprute, Ross O’Hara, Dylan Wagner, Kristina Caudle, and especially
Katie Powers, who has been my biggest cheerleader.
Many of my fellow graduate students have made the last three years remarkable
and full of smiles: John Kingsbury, Ross O’Hara, Megan Roberts, Lisa Sprute, Kristina
Caudle, Andrea Robinson, Katie Powers, and Robert Chavez. They have all been
amazing classmates and confidantes, and I am honored to call them friends.
Thanks to my parents, Phil and Eileen Wood, and my family, Ron, Candace,
Scott, and Shane for always believing in me and supporting my every decision. Most of
all, I would like to thank my husband, William Flanary, who has been my biggest
supporter and who reminds me daily why life is so much fun. I can’t imagine a better
partner to stand by my side.
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Table of Contents
Introduction....................................................................................................................... 1
Methods.............................................................................................................................. 6
Participants............................................................................................................... 6
Materials .................................................................................................................. 7
Procedure ................................................................................................................. 8
Behavioral Task ............................................................................................ 8
fMRI Image Acquisition.......................................................................................... 9
fMRI Preprocessing ................................................................................................. 9
Results.............................................................................................................................. 10
Emotional Biases in Picture Ratings...................................................................... 10
Emotional Biases in Brain Function ...................................................................... 15
Discussion......................................................................................................................... 17
Emotion Regulation and Emotional Biases in Older Adults ................................. 20
Alternative Explanations........................................................................................ 23
Limitations............................................................................................................. 25
Conclusions and Future Research.......................................................................... 26
References........................................................................................................................ 28
Tables ............................................................................................................................... 35
Figures.............................................................................................................................. 39
iv

List of Tables
Table 1: Group activations for the mildly pleasant – mildly unpleasant contrast ............ 35
Table 2: Group activations for the mildly pleasant – mildly unpleasant contrast ............ 36
Table 3: Group activations for the older positivity offset – younger positivity offset
contrast.......................................................................................................................... 37
Table 4: Group activations for the older negativity bias – younger negativity bias contrast
....................................................................................................................................... 38
v

List of Figures
Figure 1: Emotional biases predicted by the Evaluative Space Model............................. 39
Figure 2: Younger and older adults’ ratings of neutral and mildly, moderately, and
extremely emotional pictures........................................................................................ 40
Figure 3: Standardized reaction times to mildly unpleasant and mildly pleasant pictures
by age group.................................................................................................................. 41
Figure 4: Negative and positive ratings of mildly unpleasant and mildly pleasant pictures
by age group.................................................................................................................. 42
Figure 5: Z-scored response times as predictors of positive ratings of mildly unpleasant
pictures in older and younger adults............................................................................. 43
Figure 6:
Figure 7:
Figure 8:
Figure 9:
vi

Introduction
American society often paints a dismal picture of aging, with images of
physiological systems shutting down, memories fading, and life ending. Despite
declining physical and cognitive functioning in later life, however, emotional functions
seem to remain intact, or even improve, with age. Across the life span, goals and
motivations shift, with younger adults focusing on broadening their horizons and seeking
new life experiences, and older adults focusing on strengthening close relationships and
seeking meaningful emotional interactions (Carstensen, Fung, & Charles, 2003).
Socioemotional selectivity theory posits that such motivational shifts result from
experiencing a sense of limited time (Carstensen, Isaacowitz, & Charles, 1999). Aging
inherently brings the realization of one’s remaining lifetime growing shorter, and this
sense of time running out in life may lead older adults to become increasingly motivated
to regulate their emotions in order to achieve more fulfilling daily emotional experiences
(Carstensen et al., 2003). Consistent with this theory, Gross and his colleagues (1997)
found that older adults in cultures all over the world report better emotion regulation than
their younger counterparts. Collectively, the emotion-focused motivation in later life
predicted by socioemotional selectivity theory combined with a lifetime of emotion
regulation experience may facilitate more favorable emotional responses with age.
Indeed, Carstensen and her colleagues have proposed a “positivity effect” in older
age, such that older adults respond more positively than younger adults across a variety
of domains (Mather & Carstensen, 2005). For example, older adults remember and
attend to more positive than negative information, and this bias toward positivity is larger
for older adults than for younger adults (Charles, Mather, & Carstensen, 2003;
1

Isaacowitz, Wadlinger, Goren, & Wilson, 2006; Mather & Carstensen, 2003; Mather &
Carstensen, 2005). Additionally, older adults report experiencing less negative emotion
(Carstensen, Pasupathi, Mayr, & Nesselroade, 2000; Charles, Reynolds, & Gatz, 2001;
Gross et al., 1997) and utilizing greater emotional control (Gross et al., 1997) in daily life
than do younger adults. Consistent with these findings, older adults also show this
positivity effect in neural responses to emotional stimuli. For example, older adults show
decreased amygdala activation in response to unpleasant pictures but not in response to
pleasant pictures; younger adults do not show this pattern (Mather et al., 2004; Nashiro,
Sakaki, & Mather, in press). The cognitive control model proposes that older adults
achieve such reduction in amygdala responses to unpleasant stimuli by engaging
prefrontal control mechanisms in order to regulate their emotions in keeping with their
more positive motivational goals (Nashiro, Sakaki, & Mather, in press; Williams et al.,
2006). Indeed, older adults show an inverse relationship between ventromedial prefrontal
cortex (vmPFC) and the amygdala when instructed to decrease their negative emotional
responses (Urry et al., 2006). Increased activity in the medial prefrontal cortex (mPFC)
has also been associated with better control over negative emotional responses (Williams
et al., 2006). Taken together, this evidence supports the notion that older adults engage
prefrontal control mechanisms in order to decrease negative emotion. Moreover,
previous research has revealed a large amount of overlap between the brain regions that
are activated when older adults are instructed to regulate their responses to emotional
stimuli and when they are allowed to respond freely (Nashiro, Sakaki, & Mather, in
press). This suggests that older adults may naturally regulate their emotions, even when
given no instructions to do so.
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Thus, emotion regulation may be an important mechanism underlying the
positivity effect in aging. However, there are many ways in which older adults may
regulate their emotions. The process model of emotion regulation (Gross, 1998) proposes
that people can regulate emotions through such strategies as situation selection (choosing
one’s situation so as to avoid circumstances that may produce unwanted emotional
responses), situation modification (changing one’s situation in ways that are consistent
with one’s emotional goals), attentional deployment (directing one’s attention to certain
aspects of an emotional stimulus and away from other aspects), cognitive reappraisal
(changing one’s interpretation of an emotional stimulus), or response modulation
(changing one’s response to an emotional stimulus). Any of these strategies or others
may contribute to the positivity effect in aging, though the specific regulation strategies
employed by older adults in response to pleasant and unpleasant stimuli remain unclear
(Urry & Gross, 2010).
Moreover, the extant research fails to specify whether older adults respond to
emotional stimuli with more positivity, less negativity, or both. The Evaluative Space
Model (ESM; Cacioppo & Berntson, 1994; Cacioppo, Gardner, & Berntson, 1997) can
address this issue by examining positivity and negativity separately but simultaneously.
According to the ESM, positivity and negativity are partially separable and functionally
independent, such that increasing positivity does not necessarily decrease negativity, and
vice versa. That is, positivity and negativity are not confined to a reciprocal relationship,
but can vary independently of one another. As a result, the ESM predicts differential
activation functions for positivity and negativity (Figure 1). At high levels of emotional
input, it predicts a negativity bias, such that responses to extremely negative events and
3

information (e.g., losing $100) are stronger than to equally positive (e.g., winning $100).
However, at low levels of emotional input, the ESM predicts a positivity offset, such that
responses to mildly positive events and information (e.g., finding a quarter) are stronger
than to equally negative (e.g., losing a quarter; Norris, Larsen, Crawford & Cacioppo, in
press).
These biases in emotional responding may have served evolutionarily adaptive
purposes. The negativity bias may have helped our early ancestors detect threatening
stimuli in the environment and facilitated avoidance-related behavior (e.g., running away)
in order to escape from potential harm. Given that a potentially harmful stimulus has
stronger implications for survival than an opportunity unpursued, the negativity bias may
have evolved to promote fitness. Conversely, the positivity offset may have promoted
exploration and approach-related behavior (e.g., searching for food) in more neutral
environments in order to encourage the pursuit of basic needs. Together, these emotional
biases encourage exploration while maintaining vigilance for aversive stimuli.
If these emotional biases serve adaptive purposes, then experience over time may
shape emotional responses in such a way as to enhance the adaptive aspects of the biases.
Thus, it is possible that the positivity effect seen in older adults may result from changes
in these emotional biases. One possibility is that the effect is due to a decreased
negativity bias (driven by responses to high levels of emotional input). Indeed, Wood
and her colleagues used event-related brain potentials (ERPs) to investigate the negativity
bias in younger and older adults. In an oddball paradigm, older adults exhibited smaller
amplitude late positive potentials (LPPs) than did younger adults, especially in response
to negative images (Kisley, Wood, & Burrows, 2007; Wood & Kisley, 2006). These data
4

suggest a possible elimination of the negativity bias in older age. However, a decreased
negativity bias could be maladaptive, as it could reduce vigilance for or responses to
threatening stimuli in the world. In contrast to Wood and colleagues, Mather and Knight
(2006) found that the ability to detect threatening stimuli (e.g., angry faces) more quickly
than non-threatening stimuli (e.g., neutral faces) is maintained in older adulthood. This
finding indicates that the negativity bias may remain intact with age.
An alternative possibility is that the positivity effect in aging could be due to an
increased positivity offset (driven by responses to low levels of emotional input).
Consistent with this possibility, van Reekum and her colleagues (2010) found age
differences in psychophysiological responses to neutral stimuli. Older adults showed
decreased activity over corrugator supercilli (the brow muscle, which shows increased
activity during the experience of negative affect and decreased activity during the
experience of positive affect; Larsen, Norris & Cacioppo, 2003) and attenuated startle-
potentiated eye-blink responses (marking less negative affect; e.g., Lang, Bradley &
Cuthbert, 1990) to neutral pictures compared to younger adults. In other words, older
adults exhibited psychophysiological responses that indicated more positive affect and
less negative affect toward neutral stimuli. These responses suggest that the positivity
offset may be larger in older adults.
Taken together, these patterns of responding provide mixed evidence for changes
in emotional biases over the lifespan. The current study aimed to systematically compare
age differences in these emotional biases in order to assess whether the positivity effect is
related to a decreased negativity bias, an increased positivity offset, or both. To do this,
we examined age differences in behavioral and neural responses to emotional pictures
5

ranging from low levels of emotional input (i.e., neutral and mildly emotional pictures) to
high levels of emotional input (i.e., moderately and extremely emotional pictures). If
older adults exhibit a decreased negativity bias, we would expect them to respond more
favorably (i.e., more positively or less negatively) to the moderately or extremely
emotional pictures. Conversely, if older adults exhibit an increased positivity offset, we
would expect them to respond more favorably (i.e., more positively or less negatively) to
the neutral or mildly emotional pictures. Given older adults’ natural tendency to regulate
their emotions (Nashiro, Sakaki, & Mather, in press), we may also expect older adults to
show increased activation in prefrontal control regions implicated in emotion regulation,
such as the dorsomedial prefrontal cortex (dmPFC) or anterior cingulate cortex (ACC;
Goldin, McRae, Ramel & Gross, 2008; Ochnser, Bunge, Gross & Gabrieli, 2002;
Schaefer et al., 2002), or decreased activation in limbic structures, such as the amygdala
(Mather et al., 2004; Urry et al., 2006). The specific patterns of neural activation that
older adults demonstrate in response to both the milder and more extreme emotional
pictures may help shed light on the particular regulation strategies that may contribute to
the positivity effect.
Methods
Participants
Nineteen younger adults aged 18-22 (M = 19.0, SD = 1.05) and 23 older adults
aged 65-80 (M = 73.26, SD = 5.22) participated in the current study. Data from five older
adults were dropped from all analyses due to failure to follow task instructions. Data
from an additional seven younger adults and two older adults were dropped from the
imaging analyses due to excessive noise in the imaging data; an additional 11 older adults
6

who participated in the behavioral task did not participate in the imaging task. This
resulted in final samples of 19 younger (M = 19.0, SD = 1.05) and 18 older adults (M =
72.72, SD = 5.61) included in the behavioral analyses and 12 younger (M = 19.08, SD =
1.31) and five older adults (M = 71.80, SD = 3.63) included in the imaging analyses.
Younger adults were undergraduates at Dartmouth College and received either course
credit or payment; older adults were recruited from the surrounding community and
received payment. All participants were right-handed females with normal or corrected-
to-normal vision and no history of neurological disorder. All participants provided oral
and written informed consent, and the study was approved by the Dartmouth College
Committee for the Protection of Human Subjects.
Materials
One hundred sixty-eight color pictures1
were chosen from the International
Affective Picture System (IAPS; Lang, Bradley, & Cuthbert, 2005) based on female-only
normative ratings to fill seven different categories, including neutral (low in arousal and
close to the midpoint of normative valence ratings) and a 2 (valence: unpleasant,
pleasant) x 3 (extremity: mild, moderate, extreme) design. Pictures were matched on
social content, with half of each category containing at least one person, and half
containing no people. Unpleasant and pleasant pictures at each extremity level were
1
IAPS stimuli numbers: 1220, 1230, 1280, 1463, 1617, 1661, 1670, 1731, 1811, 1942, 1945, 1947, 1999,
2055.1, 2102, 2110, 2153, 2190, 2209, 2210, 2221, 2230, 2235, 2271, 2305, 2344, 2346, 2372, 2383, 2393,
2394, 2396, 2397, 2435, 2441, 2442, 2513, 2515, 2520, 2593, 2700, 2752, 2830, 2840, 2850, 2870, 2880,
3061, 3160, 3220, 4233, 4250, 4532, 4537, 4621, 4623, 4624, 4625, 4626, 4640, 5260, 5270, 5480, 5530,
5700, 5740, 5910, 5970, 5973, 6312, 6561, 6838, 6930, 7000, 7031, 7036, 7039, 7130, 7140, 7192, 7217,
7234, 7236, 7247, 7250, 7270, 7281, 7282, 7330, 7350, 7351, 7460, 7472, 7475, 7481, 7491, 7493, 7495,
7500, 7501, 7502, 7503, 7504, 7508, 7510, 7550, 7595, 7700, 7920, 7950, 8010, 8090, 8120, 8130, 8170,
8210, 8220, 8241, 8380, 8420, 8465, 8467, 8470, 8499, 8502, 8510, 8531, 8600, 9005, 9007, 9008, 9045,
9046, 9110, 9140, 9171, 9190, 9270, 9280, 9290, 9320, 9340, 9373, 9390, 9400, 9401, 9404, 9421, 9424,
9429, 9440, 9470, 9471, 9472, 9495, 9560, 9561, 9584, 9600, 9611, 9620, 9621, 9622, 9830, 9900, 9902,
9911, and 9912.
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matched on normative arousal and extremity (i.e., distance from the midpoint of the
normative valence rating scale), and all categories were matched on RGB values, hue,
saturation, luminance, and spatial complexity.
Procedure
Once situated in the scanner, participants were instructed to view each picture for
the entire time it was displayed and think about whether it was positive or negative.
Pictures appeared in one of two predetermined pseudorandom orders, counterbalanced
across participants. An angled mirror attached to the head coil allowed participants to
view the pictures projected onto a panel at the end of the scanner bore; a PC using E-
Prime version 2.0 Professional software (Psychology Software Tools, Inc., Pittsburgh,
PA) presented the pictures. Each trial consisted of a white fixation cross displayed on a
black background for 1 s, followed by a picture displayed for 4 s; jittered intertrial
intervals consisting of a black background ranged from 1 to 13 s (mean = 5 s), which
allowed for deconvolution of the hemodynamic response.
Behavioral Task. Participants viewed each picture again outside of the scanner,
this time rating how they felt about each picture using the Evaluative Space Grid (ESG;
Larsen, Norris, McGraw, Hawkley & Cacioppo, 2009). The ESG is a 5x5 grid that
allows for independent assessments of negativity and positivity. Negativity is measured
on the y-axis and positivity on the x-axis, with ratings on each axis ranging from not at all
negative/positive (coded as 0) to very negative/positive (4). Participants used the grid to
select the cell that most appropriately represented their positive and negative feelings
about each picture. A PC using E-Prime version 2.0 Professional software (Psychology
Software Tools, Inc., Pittsburgh, PA) presented the pictures and recorded negative
8

ratings, positive ratings and response times for each picture. On each trial, the ESG
appeared immediately below the picture. Pictures appeared in random order at a rate
controlled by participants, such that each picture remained visible until participants made
a rating.
fMRI Image Acquisition
Functional magnetic resonance images were acquired on a 3.0 Tesla Philips
Achieva Intera scanner (Philips Medical Systems, Bothell, WA), with an eight-channel
SENSE head coil. Functional T2*-weighted echo-planar images were acquired in six runs
with 36 contiguous 3.5mm axial interleaved slices with a 0.5mm gap (TR = 2000 ms, TE
= 35 ms, flip angle = 90°, field of view = 24 cm, 80x80 matrix size, fat suppressed).
High-resolution T1-weighted anatomical images were acquired in 160 1-mm sagittal
slices (TR = 9.8 ms, TE = 4.6 ms, flip angle = 8°, field of view = 24 cm).
fMRI Preprocessing
We used AFNI software (Cox, 1996) for processing and analysis of fMRI data.
For each participant, the data were despiked, corrected for slice timing, realigned using a
six-parameter, rigid-body transformation, and converted to percent signal change.
Individual-participant deconvolution analyses then removed variance due to motion as
well as constant and linear trends, and the voxel-wise standard deviation of the residual
signal was calculated in order to assess the signal-to-noise ratio. Output from the
deconvolution analyses underwent spatial smoothing using a 6-mm FWHM Gaussian
kernel.
A second individual-participant deconvolution analysis isolated contributions of
each condition to the fMRI signal by generating impulse response functions (IRFs) of the
9

signal for each condition of a 2 (valence: unpleasant, pleasant) x 2 (extremity: mild,
extreme) design, with a filler condition comprised of responses to the remaining
pictures2
. The analysis used a sine function, with 15 regressors per condition (i.e., one
regressor for each second of the estimated hemodynamic response) to model the
hemodynamic response to each condition. Each participant’s data were then normalized
to Talairach stereotaxic coordinate space (Talairach & Tournoux, 1988), and a measure
of the area under the curve (AUC; seconds 5-10) was calculated for use in group analysis;
each condition’s AUC was used as a measure of neural activation to that condition. All
group analyses were thresholded at p < .001, uncorrected, with a minimum cluster size of
50 voxels.
Results
Emotional Biases in Picture Ratings
The positivity offset refers to the tendency for positivity to outweigh negativity at
low levels of input to the affect system. Conversely, the negativity bias refers to the
tendency for negativity to outweigh positivity at high levels of input (Figure 1). We
examined the positivity offset and negativity bias by comparing positive ratings of
pleasant pictures with negative ratings of unpleasant pictures (i.e., “dominant ratings”).
Specifically, we sought to determine whether older and younger adults differed in the
positivity offset and negativity bias. To this end, we conducted a 2 (Age: younger, older)
x 2 (Picture Valence: unpleasant, pleasant) x 4 (Picture Extremity: neutral, mild,
2
The model was limited to these conditions in order to increase power in group analyses designed
specifically to investigate neural responses underlying the positivity offset and negativity bias. The mildly
emotional pictures were used instead of neutral pictures to investigate the positivity offset, as the positivity
offset must be calculated by comparing two conditions (i.e., pleasant – unpleasant) at relatively low levels
of emotional input. The mildly emotional pictures offered two such conditions (mildly pleasant, mildly
unpleasant), while the neutral pictures did not.
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moderate, extreme) repeated measures general linear model (GLM) analysis on dominant
ratings (i.e., negative ratings of unpleasant pictures and positive ratings of pleasant
pictures).3
This analysis allowed several manipulation checks in addition to addressing
our primary question of interest.
First, there was a main effect of Extremity, F(3, 33) = 280.50, p < .001, ηp
2
= .96;
this was a manipulation check that showed that dominant ratings increased as a function
of the extremity of the picture (i.e., distance from the midpoint of the normative valence
scale); all ps < .001. There was no main effect of Age, F(1, 35) < 1, p = .99, ηp
2
< .001,
indicating that older and younger adults did not differ in their overall ratings of the
pictures. There was also no main effect of Valence, F(1, 35) < 1, p = .41, ηp
2
= .02,
demonstrating that participants rated unpleasant and pleasant pictures equally intensely.
More importantly, we examined whether participants demonstrated a positivity
offset and a negativity bias in response to the pictures. A significant Valence x Extremity
interaction, F(3, 33) = 50.31, p < .001, ηp
2
=.82, verified that participants responded with
both a positivity offset and a negativity bias. Pairwise comparisons revealed that
participants showed higher positive (M = 1.07, SE = .09) than negative ratings (M = .57,
SE = .06) of neutral pictures, p < .001, ηp
2
= .49, as well as higher dominant ratings of
mildly pleasant (M = 1.91, SE = .08) than of mildly unpleasant (M = 1.65, SE = .08)
pictures, p =.02, ηp
2
= .16 (i.e., both findings are consistent with the functioning of a
positivity offset). They also showed higher dominant ratings of moderately unpleasant
(M = 2.72, SE = .07) than moderately pleasant (M = 2.28, SE = .09) pictures, p < .001, ηp
2
= .41, and higher dominant ratings of extremely unpleasant (M = 3.28, SE = .07) than of
3
Positive and negative ratings of neutral pictures were used as a measure of unpleasant and pleasant
valence.
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extremely pleasant (M = 2.70, SE = .09) pictures, p < .001, ηp
2
= .56 (i.e., both findings
are consistent with the functioning of a negativity bias; Figure 2).
Finally, our primary question of interest concerned whether younger and older
adults differ with respect to the positivity offset and negativity bias. A significant Age x
Valence x Extremity interaction, F(3, 33) = 9.53, p < .001, ηp
2
= .46, revealed an age
difference in these emotional biases. Compared to younger adults, older adults rated
neutral (older: M = .46, SE = .09; younger: M = .70, SE = .08) and mildly unpleasant
pictures (older: M = 1.51, SE = .11; younger: M = 1.79, SE = .11), as marginally less
negative, ps < .07, and mildly pleasant pictures as more positive (older: M = 2.10, SE =
.11; younger: M = 1.72, SE = .11), p = .02. These ratings show a larger positivity offset
among the older adults. Specifically, younger adults demonstrated a positivity offset only
in response to neutral pictures, but older adults showed a positivity offset in response to
both neutral and mildly emotional pictures. However, there were no age differences in
responses to moderately or extremely emotional pictures, ps > .21, resulting in no age
differences in the negativity bias. In sum, the age groups did not differ in the negativity
bias, but older adults showed a larger and extended positivity offset as compared to
younger adults (Figure 2).
Since this analysis revealed significant age differences involving only the mildly
emotional pictures, further analyses focused on that category. We next sought to explore
the nature of the processes underlying the extended positivity offset in older adults.
Specifically, we wondered whether this effect appeared to be the result of more automatic
or effortful processes. For example, if older adults’ extended positivity offset occurs by
relatively automatic processes, then older adults should rate the mildly emotional pictures
12

as quickly, or even more quickly, than younger adults. However, if older adults’
extended positivity offset occurs by more effortful processes, then they should rate the
mildly emotional pictures more slowly than younger adults, since longer response times
may suggest that effortful processes have been recruited.
To investigate these questions, we conducted a 2 (Age: younger, older) x 2
(Picture Valence: mildly unpleasant, mildly pleasant) repeated measures GLM on z-
scored response times (RTs), trimmed to exclude the fastest and slowest 10% of
responses (Bush, Hess, & Wolford, 1993). This analysis yielded no main effects of Age,
F(1, 35) = .62, p = .44, ηp
2
= .02, or Valence, F(1, 35) = 1.74, p = .20, ηp
2
= .05, but did
reveal a significant Age x Valence interaction, F(1, 35) = 5.95, p = .02, ηp
2
= .15.
Pairwise comparisons showed that older adults (M = .24, SE = .05) took longer than
younger adults (M = .06, SE = .05) to rate the mildly unpleasant pictures, p = .02, but RTs
to the mildly pleasant pictures did not differ by age (Molder = .02, SEolder = .06; Myounger =
.12, SEyounger = .06), p = .20. Furthermore, older adults took longer to rate mildly
unpleasant (M = .24, SE = .05) compared to mildly pleasant pictures (M = .02, SE = .06),
p = .01, while younger adults showed no differences in RTs, p = .43 (Figure 3). In sum,
older adults took longer to respond to mildly unpleasant pictures than did younger adults.
One possible explanation for this pattern of RTs is that older adults were
distracted by the unpleasant pictures, and subsequently took longer to rate them.
However, this explanation seems unlikely given previous research demonstrating greater
attention to and memory for positive (i.e., pleasant) than negative (i.e., unpleasant)
stimuli in older adults (e.g., Mather & Carstensen, 2005). A second possibility is that this
pattern reflects an effortful process on the part of older adults to feel more favorably
13

toward mildly emotional stimuli. If this is accurate, then older adults should a) assign
lower negative and/or higher positive ratings to mildly emotional pictures than younger
adults, and b) rate mildly emotional pictures as increasingly more positive and/or less
negative as picture viewing time increases.
To examine these hypotheses, we first looked at whether older adults rated mildly
emotional pictures less negatively and/or more positively. Four independent-samples t-
tests were conducted to compare older and younger adults’ positive and negative ratings
of mildly unpleasant and mildly pleasant pictures. 4
These analyses revealed that older
adults rated mildly pleasant pictures as less negative (M = .26, SE = .06) and more
positive (M = 2.10, SE = .13) than younger adults (negative: M = .47, SE = .06; positive:
M = 1.72, SE = .09), ts(35) = -2.41 and 2.41, respectively, ps = .02. There was also a
trend for older adults to rate mildly unpleasant pictures as less negative than younger
adults (older: M = 1.50, SE = .13; younger: M = 1.79, SE = .08), t(35) = -1.89, p = .07
(Figure 4). Taken together, these data support the conclusion that older adults did indeed
respond more favorably to mildly emotional pictures than younger adults.
Finally, we examined whether older adults’ more positive and less negative
responses to the mildly emotional pictures may be the result of effortful processes. As
outlined above, we expected that if older adults were engaging effortful self-control
processes, we should see that longer RTs predict better regulation (i.e., more positive,
less negative ratings) in older but not younger adults. Since older adults showed longer
RTs only to the mildly unpleasant pictures, analyses focused on those pictures. Negative
and positive ratings of the mildly unpleasant pictures were separately regressed on Age
4
This is in contrast to the omnibus GLM, which included only dominant ratings (i.e., negative ratings of
unpleasant pictures and positive ratings of pleasant pictures).
14

(younger, older), RTs to the mildly unpleasant pictures (RTs), and the interaction (Age x
RT). For negative ratings, the model was not significant, R2
= .11, F(3, 33) = 1.35, p =
.28; that is, none of the variables predicted negative ratings of the mildly unpleasant
pictures, ps > .08. For positive ratings, however, the model was significant, R2
= .28,
F(3, 33) = 4.37, p = .01. There was a trend for RTs to predict positive ratings, b = .47,
t(33) = 2.03, p = .05. However, this was qualified by a significant Age x RT interaction,
b = -.69, t(33) = -2.94, p < .01. Bivariate correlations revealed that longer RTs predicted
higher positive ratings of the mildly unpleasant pictures among older, r = .58, p = .01, but
not younger adults, r = -.20, p = .42. That is, the more time that older adults took to rate
the mildly unpleasant pictures, the more positively they rated them (Figure 5). Taken
together, these data suggest that older adults may have effortfully attempted to feel more
positive when viewing mildly unpleasant pictures.
Emotional Biases in Brain Function
We next examined whether participants exhibited a positivity offset and
negativity bias in neural activity by comparing neural responses to pleasant pictures with
neural responses to unpleasant pictures across all participants. To examine the positivity
offset, a whole-brain paired-sample t-test compared neural activation to mildly pleasant
pictures with activation to mildly unpleasant pictures (i.e., mildly pleasant – mildly
unpleasant). No regions demonstrated greater activation to the mildly pleasant than the
mildly unpleasant pictures. However, several regions of the prefrontal cortex
demonstrated greater activation to the mildly unpleasant pictures (Table 1, Figure 6).
These regions included bilateral clusters in the dorsomedial prefrontal cortex (dmPFC;
BA 9), right ventrolateral prefrontal cortex (vlPFC; BA 47), left medial prefrontal cortex
15

(mPFC; BA 9), right supplementary motor area (SMA; BA 6), and left frontal eye fields
(BA 8).
To examine the negativity bias, a second whole-brain paired-sample t-test
compared activation to very unpleasant pictures with activation to very pleasant pictures
(i.e., very unpleasant – very pleasant). No regions demonstrated greater activation to the
very unpleasant than the very pleasant pictures. However, clusters in the left medial
prefrontal cortex (mPFC; BA 10) and left parahippocampal gyrus demonstrated greater
activation to the very pleasant pictures (Table 2, Figure 7).
As our primary question of interest concerned whether younger and older adults
differ with respect to the positivity offset and negativity bias, we next directly compared
the age groups’ emotional biases in neural activity. To examine age differences in the
positivity offset, we first calculated contrasts comparing neural activation to mildly
pleasant pictures with activation to mildly unpleasant pictures (mildly pleasant – mildly
unpleasant; i.e., a positivity offset) for each individual participant. These contrasts were
then submitted to an independent-samples t-test comparing older and younger adults’
neural positivity offset. This analysis revealed three regions exhibiting significant age
differences (Table 3, Figure 8). Older adults demonstrated a greater positivity offset than
younger adults in the vlPFC (BA 47) and fusiform gyrus. That is, older adults showed
greater activation of these areas in response to the mildly pleasant pictures than the
mildly unpleasant. In contrast, younger adults demonstrated a greater positivity offset in
the subgenual anterior cingulate cortex (sgACC; BA 25). That is, younger adults showed
greater activation of the sgACC to mildly pleasant than unpleasant pictures, while older
adults showed the opposite pattern of activation (Figure 8).
16

To examine age differences in the negativity bias, we calculated contrasts
comparing neural activation to very unpleasant pictures with activation to very pleasant
pictures (very unpleasant – very pleasant; i.e., a negativity bias) for each individual
participant. These contrasts were then submitted to an independent-samples t-test
comparing older and younger adults’ neural negativity bias. Older adults showed a
greater negativity bias in two regions of prefrontal cortex (Table 4, Figure 9). The largest
cluster extended from the left frontal eye fields into the SMA (BA 8 / BA 6); a second
cluster was located in the right dorsolateral prefrontal cortex (dlPFC; BA 9). That is,
older adults showed greater activation of these prefrontal regions to the very unpleasant
pictures than the very pleasant. Younger adults did not show a greater negativity bias
than older adults in any region.
Discussion
In the current study, older adults showed a larger and extended positivity offset in
ratings of emotional pictures compared to younger adults. Both age groups demonstrated
a positivity offset to neutral pictures, as predicted by the ESM; however, older adults
continued to show a positivity offset in response to mildly emotional pictures, while
younger adults did not. This extended positivity offset in older adults was driven by
higher positive and lower negative ratings of the mildly emotional pictures. Older adults
also took more time to rate the mildly unpleasant pictures, and the longer they took to
rate these pictures, the more positive they reported feeling about them. In contrast, there
were no age differences in the negativity bias. Taken together, these findings suggest that
older adults may effortfully regulate their responses to mildly emotional stimuli in order
to feel more favorably about them. That is, older adults may regulate their emotions to
17

feel more positively (and less negatively) toward a wider range of emotional stimuli than
younger adults.
The current study also investigated the neural mechanisms underlying the
positivity offset and negativity bias across the life span. Neural response patterns were
consistent with the behavioral response patterns in that several prefrontal control regions
demonstrated greater activation to the mildly unpleasant pictures than the mildly pleasant,
including the dmPFC, vmPFC, and vlPFC. Previous work has implicated the dmPFC in
the appraisal and experience of negative emotion (Etkin, Egner, & Kalisch, 2011), as well
as in making inferences about one’s feelings (Wager et al., 2008), whereas the vmPFC
and vlPFC have been shown to be involved in the regulation of negative emotion (Etkin
et al., 2011; Wager, Davidson, Hughes, Lindquist, & Ochsner, 2008) and the selection or
inhibition of information (Aron & Poldrack, 2005). These results suggest that the
dmPFC may detect the valence of the mildly unpleasant pictures and signal the need for
the vmPFC and vlPFC to down-regulate any negative emotional responses.
In contrast to this down-regulation of negative emotional responses to the mildly
unpleasant pictures, neural responses to the more extreme pictures suggested that
participants may have been attempting to engage with the very pleasant pictures or even
up-regulate their responses to them. Specifically, the mPFC showed greater activation to
the very pleasant pictures than the very unpleasant. Previous work has demonstrated that
this region is activated when increasing positive emotion (Kim & Hamann, 2007) and is
sensitive to the self-relevance of a stimulus (Kelley et al., 2002). Additionally, the
parahippocampal gyrus, a region involved in emotion perception (Wager et al., 2008),
showed greater activation to the very pleasant pictures than the very unpleasant. Taken
18

together, these results suggest that participants may have utilized the mPFC in an attempt
to upregulate positivity by focusing on the perceptual and self-relevant aspects of the
very pleasant pictures. In sum, neural responses to the emotional pictures appeared to be
characterized by the down-regulation of responses to the mildly unpleasant pictures, and
the up-regulation of responses to the very pleasant pictures.
This approach may have been particularly effective among the older adults, as
they demonstrated these sorts of patterns to a greater extent than did younger adults. For
example, Urry, van Reekum, Johnstone, & Davidson (2009) demonstrated that the
sgACC is involved in the cognitive reappraisal of emotion. In the current study, older
adults (compared to younger adults) showed greater activation of the sgACC in response
to the mildly unpleasant than mildly pleasant pictures, suggesting that older adults may
have been down-regulating negative responses to the mildly unpleasant pictures.
Moreover, older adults showed a greater positivity offset (i.e., greater activation to the
mildly pleasant than mildly unpleasant pictures) in the vlPFC and fusiform gyrus than did
younger adults. As previously discussed, the vlPFC works to generate and regulate
emotional responses (Wager et al., 2008), and the fusiform gyrus is a relatively low-level
perceptual region that is sensitive to emotional content (Norris, Chen, Zhu, Small, &
Cacioppo, 2004). These patterns of vlPFC and fusiform gyrus activity suggest that older
adults may have utilized the vlPFC in an attempt to upregulate positivity, in part by
focusing on the positive aspects of the mildly pleasant pictures. Taken together, these
results suggest that older adults may have been down-regulating their responses to the
mildly unpleasant pictures and up-regulating their responses to the mildly pleasant
pictures to a greater extent than younger adults.
19

Finally, older adults showed a similar pattern in neural responses to the very
emotional pictures. Specifically, older adults showed a greater negativity bias (i.e.,
greater activation in response to very unpleasant than very pleasant pictures) than did
younger adults in two regions of the PFC: the dmPFC and a region including the frontal
eye fields. As the dmPFC is involved in the appraisal of negative emotion (Etkin et al.,
2011) and making inferences about one’s feelings (Wager et al., 2008), it is possible that
the dmPFC may have detected the valence of the very unpleasant pictures and signaled
the need for regulation. The older adults may then have attempted to down-regulate their
emotional responses to the pictures by looking away from the negative aspects of these
pictures (e.g., Urry, 2010; van Reekum et al., 2007), as suggested by the activation of the
frontal eye fields (Leichnetz & Goldberg, 1988). It should be noted that we did not have
a measure of eye movement, so our dataset does not allow us to be certain that older
adults looked away from the very unpleasant pictures; however, the patterns of neural
activation are consistent with this possibility.
Emotion Regulation and Emotional Biases in Older Adults
Taken together, the behavioral and neural data from the current study suggest that
older adults may be effortfully regulating their emotional responses in order to increase
positivity and decrease negativity. Socioemotional selectivity theory proposes that a
sense of limited time left in life may motivate older adults to pursue more emotionally
gratifying experiences (Carstensen, Fung, & Charles, 2003; Carstensen, Isaacowitz, &
Charles, 1999). This motivation to seek out emotionally meaningful experiences
combined with a lifetime of emotion regulation experience may result in more effective
and refined emotion regulation in older age (e.g., Gross et al., 1997; Larcom &
20

Isaacowitz, 2009). Indeed, our findings are consistent with this refined emotion
regulation. Specifically, our data demonstrate that older adults may attempt to create
more gratifying emotional experiences by regulating their emotional responses to even
mildly evocative stimuli or events. Older adults also appear to employ multiple regulation
strategies in order to achieve more effective regulation. Much emotion regulation
research focuses on the strategy of cognitive reappraisal (e.g., Goldin et al., 2008;
Ochsner, Bunge, Gross, & Gabrieli, 2002; Urry et al., 2009; Urry 2010); however,
reappraisal-related processes require cognitive resources that may deteriorate as we age,
potentially rendering cognitive reappraisal a less effective emotion regulation strategy for
older adults. To compensate for this loss of cognitive resources, older adults may employ
other types of strategies to supplement or use instead of cognitive reappraisal (Urry &
Gross, 2010).
For example, our data suggest that older adults may regulate their emotions to
very emotional stimuli by attempting to engage with pleasant content and look away or
divert their attention from unpleasant content. As it is likely easier to enhance an active
emotional response than reduce one, this may be a more feasible option when faced with
diminishing cognitive resources. However, reappraisal may remain an effective strategy
for regulating responses to milder emotional stimuli, since it likely requires fewer
cognitive resources to down-regulate the less intense emotional responses these stimuli
elicit. Consistent with this idea, our data suggest that older adults may successfully
regulate their emotions to mildly emotional stimuli by reappraising unpleasant content in
addition to attempting to engage with pleasant content. In sum, older adults may employ
strategies that require fewer cognitive resources in order regulate responses to more
21

intense emotional stimuli, while reserving more resource-demanding strategies (e.g.,
cognitive reappraisal; Urry & Gross, 2010) for regulating responses to milder emotional
stimuli.
Despite neural evidence that older adults were attempting to regulate their
responses to both mildly and very emotional pictures, the current study revealed
behavioral age differences only in response to the mildly emotional pictures. The more
positive responses to mildly emotional information exhibited by older adults suggest that
the positivity effect (e.g., Mather & Carstensen, 2005) may be driven in part by responses
to mildly emotional stimuli in particular. Interestingly, responding more positively to
mildly emotional information (i.e., an increased positivity offset) may serve as a highly
efficient way to increase overall positive daily emotional experiences, as daily life
involves many more mild emotional experiences than extreme. If the positivity effect in
older adults were due to a decreased negativity bias, then older adults would presumably
demonstrate a shift in responses to extreme stimuli (i.e., respond with less negativity or
more positivity to extremely emotional events.) However, extremely emotional events,
such as having a baby or losing a loved one, occur relatively infrequently in daily life,
thereby limiting the effectiveness of using a decreased negativity bias as a regulation
strategy. Rather, it is much more common to encounter mildly emotional events in daily
life, such as enjoying a cup of coffee in the morning or being stuck in a traffic jam.
Regulating emotional responses to these more frequent events would presumably serve as
an effective mechanism for generating the more emotionally meaningful experiences
predicted by the socioemotional selectivity theory. For example, older adults may seek
22

pleasure by savoring their morning cup of coffee or choosing to appreciate the
opportunity provided by a traffic jam to converse with fellow passengers.
Although older adults’ neural response patterns suggest that they may be
attempting to regulate their emotions to the very emotional content, the current study
revealed no age differences in the negativity bias in picture ratings. This suggests that
their attempts at regulation may not be successfully influencing their behavioral
responses. As previously discussed, it may be inherently more difficult to reduce
emotional responses to very unpleasant stimuli, especially when faced with the loss of
cognitive resources (Urry & Gross, 2010). Moreover, it may be difficult to overcome a
negativity bias in emotional responding since such a bias is evolutionarily adaptive.
Indeed, the emotional response patterns exhibited by the older adults are
consistent with the adaptive functions of the emotional biases predicted by the ESM. For
example, the maintained negativity bias demonstrated by older adults suggests that the
affect system may preserve vigilance for more extreme emotional stimuli in older age,
facilitating avoidance of potentially dangerous stimuli throughout the lifespan. However,
the enhanced positivity offset in older age promotes the strengthening of approach
behavior to more innocuous stimuli. This mechanism may further facilitate older adults’
continued pursuit of emotionally meaningful relationships and experiences. In sum, the
emotional biases demonstrated by older adults facilitate the avoidance of very negative
emotional events and the pursuit of mildly positive emotional events in later life.
Alternative Explanations
Although our findings suggest that the positivity effect in aging may be driven
primarily by responses to mildly emotional information (i.e., an increased positivity
23

offset), other evidence suggests that there may be more substantial age differences in the
negativity bias than were revealed in the current study. For example, previous research
found that older adults exhibited smaller amplitudes in the late positive potential (LPP)
component of the event-related potential (ERP) response to emotional pictures, especially
if the pictures were negative in valence (Kisley, Wood, & Burrows, 2007 ; Wood &
Kisley, 2006;). These data suggest that there may be a diminished negativity bias with
age, at least in terms of initial neural reactivity (e.g., 400 milliseconds after stimulus
onset). However, the processes reflected by this relatively early neural activity may be
quite different from the processes involved in more deliberate tasks, such as our ratings
task. Indeed, van Reekum and colleagues (2010) found EMG evidence that older adults
showed decreased recovery from unpleasant pictures (i.e., maintained corrugator
supercilii activation following the offset of unpleasant pictures) but responded more
positively (i.e., decreased startle response and corrugator superciliii activation) in
response to neutral pictures than did younger adults. These patterns suggest a maintained
negativity bias and increased positivity offset with age, consistent with the current study.
Further evidence supporting the notion of an increased positivity offset with age
indicates that older adults attempt to maintain or increase positivity in daily emotional
experiences (most of which are presumably fairly mild). Riediger, Schmiedek, Wagner,
and Lindenberger (2009) found that while performing such typical daily activities as
watching TV, having a conversation, or running errands, adolescents sought to maintain
or enhance negative affect and attenuate positive affect; whereas older adults showed the
reverse pattern, seeking to attenuate negative and maintain positive affect.
24

The brain regions activated to mildly emotional pictures in the current study also
seem to be consistent with this enhanced positivity offset in older adults. Specifically,
older adults showed greater activation of several PFC regions to mildly unpleasant than
mildly pleasant pictures. Though this pattern of neural activation is consistent with
emotion regulation, the functions of the PFC are complex, and these regions may have
been engaging in other processes. Given that the neural responses were all greater to the
mildly unpleasant pictures, it is possible that these regions were actually more involved in
the appraisal and experience of mildly unpleasant emotion than its regulation (e.g., Etkin
et al., 2011). For example, Mayberg and her colleagues (2005) have demonstrated that
the sgACC is hyperactive in patients with major depressive disorder (MDD), suggesting
that this region may be sensitive to unpleasant emotion. However, this interpretation is
unlikely in the current study, given the greater positivity and decreased negativity
underlying the enhanced positivity offset demonstrated by older adults. Moreover, even
if the sgACC and other PFC regions were demonstrating sensitivity to the negative
valence of the mildly unpleasant pictures, older adults’ ratings of these pictures suggest
that this sensitivity may have served to signal the need for regulation.
Limitations
Interpretations of older adults’ neural and behavioral responses to the mildly
emotional pictures have focused on the notion that older adults were regulating their
responses to these pictures. However, participants in this study were not instructed to
regulate their emotions; rather they were allowed to respond freely to each picture.
Therefore, any inferences about regulation processes may be limited. Still, other neural
evidence and the socioemotional selectivity theory support the possibility that older
25

adults chronically regulate their emotions, even when not instructed to do so (Carstensen
et al., 2003; Nashiro, Sakaki, & Mather, in press). Therefore, it is likely that the older
adults in this study were automatically regulating their emotional responses. In this way,
the specific neural mechanisms underlying age differences in emotional biases can also
shed light on the particular regulation strategies that may contribute to the positivity
effect in aging.
Interpretations regarding how older adults’ neural responses affected their
behavioral responses should also be made with caution, as there are several issues with
directly comparing the two types of responses. First, the imaging and behavioral tasks
were slightly different and may not be directly comparable. In the fMRI task,
participants were simply asked to view each picture and think about whether it made
them feel negative or positive. The behavioral task was slightly more complex, as
participants were instructed to simultaneously rate both how negative and how positive
each picture made them feel. Moreover, these two tasks were performed at different
times, with the fMRI task always preceding the behavioral task. Accordingly,
participants always viewed each picture for the second time during the behavioral task.
Finally, pictures were always presented for only four seconds during the imaging task,
requiring participants to respond relatively (though reasonably) quickly to each picture.
In contrast, picture duration was self-paced in the behavioral task, allowing more time for
emotional responses and regulation processes to unfold. For all these reasons, the
processes involved in the two tasks are likely not identical, so any direct inferences about
the ways in which these processes interact are limited.
Conclusions and Future Research
26

The literature examining emotional responses across the life span demonstrates
that older adults seek to increase positivity in general, but the underlying mechanisms of
this positivity effect have received relatively little attention. The current study provided
evidence that older adults show a larger and extended positivity offset compared to
younger adults, driven by increased positivity and decreased negativity to mildly
emotional stimuli. Patterns of neural activation and response times to these mildly
emotional stimuli suggest that this effect may result from more effective emotion
regulation and more varied emotion regulation strategies employed by older adults.
Future research should focus on investigating the psychological mechanisms
underlying the positivity effect in older age. Specifically, it remains uncertain under
which circumstances the positivity effect is due to decreased negativity, increased
positivity, or both. Additionally, more attention needs to be paid to the emotional
intensity (e.g., mild versus extreme) of the stimuli used in studies of emotional responses
across the life course, as we have demonstrated that age differences in emotional
responding may be limited to relatively mild stimuli. Finally, careful research is needed
to investigate the multiple regulation strategies that may contribute to the positivity
effect. For example, questions remain regarding the circumstances under which any
particular strategy is employed, which strategies older adults use most effectively, and
which they use most often.
Although the positivity effect is likely the result of a complex interplay of
processes, the current study indicates that at least one mechanism by which older adults
become more positive with age is through an increased positivity offset. This increase
may be due in part to multiple regulation strategies employed by older adults, including
27

cognitive reappraisal and attentional deployment. In this way, older adults respond more
positively to mildly emotional stimuli, perhaps allowing them to more fully appreciate
the simple things in life.
28

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35

Table 1
Group activations for the mildly pleasant – mildly unpleasant contrast
Region of activation BA Hemisphere Coordinates Volume (mm3
) t-value
x y z
Mildy pleasant > Mildly unpleasant
None
Mildly unpleasant > Mildly pleasant
Medial frontal gyrus 9 R -5 -44 29 200 -4.29
Superior frontal gyrus 8 L 3 -22 49 165 -4.03
Superior frontal gyrus 9 L 7 -50 30 111 -4.05
Superior frontal gyrus 6 R -2 -18 54 110 -4.03
Lentiform nucleus/claustrum/putamen R -27 -12 -3 93 -4.12
Inferior frontal gyrus 47 R -49 -18 2 80 -4.32
Medial frontal gyrus 9 L 3 -52 20 59 -4.15
Note. Clusters listed consist of 50 or more contiguous voxels with a t-threshold of 4.00, p
< .001 uncorrected. Coordinates are in Talairach stereotaxic space (RAI format).
36

Table 2
Group activations for the very unpleasant – very pleasant contrast
) t-value
x y z
Very unpleasant > Very pleasant
None
Very pleasant > Very unpleasant
Superior frontal gyrus 10 R -4 -61 -2 69 -4.06
Parahippocampal gyrus 28 L 19 13 -14 54 -4.21
37

Table 3
Group activations for the older positivity offset – younger positivity offset contrast
) t-value
x y z
Older > Younger
Inferior frontal gyrus 47 R -47 -28 -14 90 4.06
Fusiform gyrus 37 R -59 50 -20 78 4.58
Younger > Older
Subcallosal gyrus 25 L 0 -16 -12 188 -4.52
38

Table 4
Group activations for the older negativity bias – younger negativity bias contrast
) t-value
x y z
Older > Younger
Superior frontal gyrus 8 L 2 -38 44 1119 4.23
Precentral gyrus 9 R -42 -16 34 399 4.15
Younger > Older
None
< .001, uncorrected. Coordinates are in Talairach stereotaxic coordinate space (RAI
format).
39

Figure 1. Emotional biases predicted by the Evaluative Space Model. The positivity
offset is reflected by greater positivity than negativity at low levels of emotional input;
the negativity bias is reflected by greater negativity than positivity at high level of
emotional input. Adapted from Norris, Larsen, Crawford & Cacioppo (in press).
40

Figure 2. Younger and older adults’ ratings of neutral and mildly, moderately, and
extremely emotional pictures. Dominant ratings refer to negative ratings of unpleasant
pictures and positive ratings of pleasant pictures. Compared to younger adults, older
adults show a larger positivity offset observed in responses to both neutral and mild
pictures.
41

Figure 3. Standardized reaction times to mildly unpleasant and mildly pleasant pictures
by age group. Older adults responded more slowly than younger adults to mildly
unpleasant pictures; they also responded more slowly to mildly unpleasant than to mildly
pleasant pictures.
42

Figure 4. Negative (a) and positive (b) ratings of mildly unpleasant and mildly pleasant
pictures by age group. Compared to younger adults, older adults rated mildly pleasant
pictures as less negative and more positive, and exhibited a trend to rate mildly
unpleasant pictures as less negative.
43

Figure 5. Z-scored response times (separated into short and long RTs, representing 1 SD
below and above the mean, respectively) as predictors of positive ratings of mildly
unpleasant pictures in older and younger adults. As response times increased, older
adults rated mildly unpleasant pictures more positively, while younger adults did not.
44

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